Collapsed lifter – what went wrong?

[RRussellTx]

Help!

I have a 427w SHP Dart block with the oem style dog bone roller lifters.
I was at the Chassis Dyno recently trying to tune in some drivability at low RPMs and this happened around 4000 RPMs.

Note, we previously had a couple of successfully full pulls with about 425HP/500ft/lb at the wheel.

We saw this when we pulled the valve covers.
https://thefactoryfiveforum.com/attachment.php?attachmentid=186588&d=1688134180

We checked all of the rockers and they were all a little loose and one other one was very loose.


Questions:
1. Any thoughts on what may have caused the lifter failure after about 4000 miles?

2. Any recommendations for replacement lifters that might hold up better?

The heads are Edelbrock 60255.
The camshaft is an Edelbrock #2281 which is 235/238@.050" .573/.582 112 LSA - installed on a 108 ICL.(4*advanced)

Thanks!
Richard


This is the offending collapsed lifter that rattles when you shake it.

https://thefactoryfiveforum.com/attachment.php?attachmentid=186585&d=1688134180

https://thefactoryfiveforum.com/attachment.php?attachmentid=186590&d=1688134308

https://thefactoryfiveforum.com/attachment.php?attachmentid=186587&d=1688134180

[Mike.Bray]

It looks like you have pushrod guide plates so I'm confused how the rocker is turned. Or is that after you removed the lifter/pushrod?

[RRussellTx]

It looks like you have pushrod guide plates so I'm confused how the rocker is turned. Or is that after you removed the lifter/pushrod?

No, it turned while it was on the dyno.
The push rod jumped out of the rocker.
It also beat up the underside of the rocker where the push rod seats pretty good before it finally jumped out.
I guess I'll need a recommendation for rockers too...

[Gordon Levy]

Those are awfully small heads for that engine. Unless you had the heads reworked your cam exceeds the max lift Edelbrock sets those heads up for. Basically you have been running at coil bind.

[RRussellTx]

Those are awfully small heads for that engine. Unless you had the heads reworked your cam exceeds the max lift Edelbrock sets those heads up for. Basically you have been running at coil bind.

THIS!!!

This is why I love this forum!
Thank you so much!

I just tried to put a feeler gauge in the spring of one of the open valves and it is closed up tight.

From the Cam and Head Specs:
Cam Intake Lift at Valve .573
Cam Exhaust Lift at Valve .582
Head Maximum Valve Lift .575

The Exhaust Lifter Failed.

Now I need a recommendation for Heads, Rockers and Lifters...

Thanks again Gordon!
You are the Man!

[Hoooper]

What are you planning to rev it out to?

[RRussellTx]

What are you planning to rev it out to?

I probably won't ever get it over 5,800 but I do like to over engineer things...

I'm leaning towards the AFR Heads at the recommendation of my tuner.
Not sure I understand benefits of the 58cc vs 72cc chamber though.

Thanks,
Richard

[Mastertech5]

I probably won't ever get it over 5,800 but I do like to over engineer things...

I'm leaning towards the AFR Heads at the recommendation of my tuner.
Not sure I understand benefits of the 58cc vs 72cc chamber though.

Thanks,
Richard

It gives you a higher compression ratio.

[bobl]

Good catch Gordon! Richard it looks like you're using the Ford 302R lifters. They are a good lifter and they weren't your problem so I'd just get a new set. If you are happy with the power you could just get your heads repaired and a new spring set up. However, a set of AFR 205 CNC heads or similar, (not the Enforcer series), will be worth around 100 HP over what you have! I like the Comp Ultra Pro rocker arms if you need valve cover clearance. Scorpion makes a good aluminum rocker at a fair price but you need tall valve covers to clear them. Of course there are numerous high end choices. If you change heads you need to measure the pushrod length and get a new set. Your current heads have 60cc chambers, so going to a 58 cc will raise your compression slightly. So it depends on what your current CR is.

Bob

[MB750]

Now I need a recommendation for Heads, Rockers and Lifters...


If you like those heads, why can't you just buy some higher lift springs?

[GoDadGo]

It gives you a higher compression ratio.

Here is a tool, by Summit Racing, to help you configure your engine combination:

https://www.summitracing.com/newsandevents/calcsandtools/compression-calculator

As an example, here is my combination for my 383 SBC:

Bore: 4.030"

Stroke: 3.75"

Cylinder Head Volume: 72 CC

Effective Dome Volume: 5 CC (Dish)

Deck Clearance: .005"

Compressed Gasket Thickness: .035"

Number of Cylinders: 8

Compression Ratio:............ 10.18 - 1
Total Displacement CID :..... 382.67
Total Displacement CC :...... 6,273.28

[RRussellTx]

Good catch Gordon! Richard it looks like you're using the Ford 302R lifters. They are a good lifter and they weren't your problem so I'd just get a new set. If you are happy with the power you could just get your heads repaired and a new spring set up. However, a set of AFR 205 CNC heads or similar, (not the Enforcer series), will be worth around 100 HP over what you have! I like the Comp Ultra Pro rocker arms if you need valve cover clearance. Scorpion makes a good aluminum rocker at a fair price but you need tall valve covers to clear them. Of course there are numerous high end choices. If you change heads you need to measure the pushrod length and get a new set. Your current heads have 60cc chambers, so going to a 58 cc will raise your compression slightly. So it depends on what your current CR is.

Bob

Thanks Bob!
Very helpful info!

Hey, I finally found a Holley tuner I was talking to you about in San Marcos.

He is an Army Veteran that is into Aviation and Aerodynamics. He identifies with Carrol Shelby in many ways and his office is full of Shelby stuff and Army medals.
The Army helped to get him started on his post injury career and he is doing great.

Dude has a sweet setup in the middle of nowhere. Very peaceful until he fires up the Dyno.

Below was his post from our first session back in May. I upgraded my MSD Ignition after that session and was back in for round 2 when the lifter gave out.

https://www.facebook.com/100063585009773/posts/pfbid0Axf7u7q5WjzowGqVCmmFTYs9KjS1Lu9GmrHfLtnxf1A3 JLkJguNydeF4yWv5C1PRl/?mibextid=SDPelY

[GoDadGo]

We all have set backs, some big and some small.
Just keep your cool and keep moving forward.
You'll get through this quicker than you think.
Good Luck!

[RRussellTx]

We all have set backs, some big and some small.
Just keep your cool and keep moving forward.
You'll get through this quicker than you think.
Good Luck!

Thanks,
I'm actually very happy about everything.

I have never been very comfortable with the engine.
The valve train always just sounded a little bit off but not enough to really stand out, the MSD ignition coils kept failing, the idle and low end cruising out of the neighborhood was never quite right, the water pump leaked from a casting flaw, the oil pan leaked from bolts that the engine builder used that were too long... The list goes on.

We made great progress working with the tuner and I'm pretty confident that I'll get to a place where I'm actually happy with it soon.

There was little hope until Gordon chimed in though.

Thanks for the positive vibes though - always helpful!

[Railroad]

Through the guidance of someone more familiar than me, I changed my Edel head springs to some conical LS=1's.
The stock springs were not rated for hyd roller. With that said, the heads are still on the bench, but am confident I am good.

[Mike.Bray]

I'm running a Comp Cams hyd roller and they have recommended roller lifters, springs, retainers, keepers, and roller rockers. No reinventing the wheel for me so I'm running everything they recommend. I'm sure Edelbrock can do the same for your cam. Install the springs and shim them to the specified height using one of these (https://www.summitracing.com/parts/pro-66902) and obviously check for coil bind.

FWIW I would never run aluminum roller rockers on the street due to concerns about fatigue. Stick to chromoly steel or heat treated stainless like 17-4.

[Ford & Jeep Fan]

I'm running a Comp Cams hyd roller and they have recommended roller lifters, springs, retainers, keepers, and roller rockers. No reinventing the wheel for me so I'm running everything they recommend. I'm sure Edelbrock can do the same for your cam. Install the springs and shim hem to the specified height using one of these (https://www.summitracing.com/parts/pro-66902) and obviously check for coil bind.

FWIW I would never run aluminum roller rockers on the street due to concerns about fatigue. Stick to chromoly steel or heat treated stainless like 17-4.

I don't quite buy that. I worked for a cam company many years ago that made cast aluminum roller rockers for Ford that were OEM on the 1993 5.0L SVT Mustangs and extruded aluminum Roller rockers for the 1994 350 GS Corvette. These rockers were tested quite extensively, by both Ford and GM. I had a set of the Cast rockers on my 5.0L (with a hydraulic inverted roller grind) for right at 100K. When used with the correct springs and clearances like retainer to guide, They can easily last the life of the engine build.

[Mike.Bray]

I don't quite buy that. I worked for a cam company many years ago that made cast aluminum roller rockers for Ford that were OEM on the 1993 5.0L SVT Mustangs and extruded aluminum Roller rockers for the 1994 350 GS Corvette. These rockers were tested quite extensively, by both Ford and GM. I had a set of the Cast rockers on my 5.0L (with a hydraulic inverted roller grind) for right at 100K. When used with the correct springs and clearances like retainer to guide, They can easily last the life of the engine build.

I'll stand by what I said. Metallurgically the difference in fatigue resistance between aluminum and steel is huge. Take am aluminum and a steel paperclip and bend them to failure. It won't take very long for the aluminum one to fail.

Airplanes are made from aluminum for obvious reasons but they have a cycle life due to fatigue. This is what happens when an airplane exceeds its cycle life and has a major fatigue failure.

https://www.imagecoast.com/images/MichaelBray1/aloha243color.jpg

On the other end of the scale is titanium which is as close to fatigue-proof as it gets. The SR 71 Blackbird could have flown for centuries as far as the titanium airframe is concerned. Because of the heat cycles the titanium skin actually got stronger over time.

I have no doubt some OEM's have used aluminum roller rockers in special instances. An OEM will also do literally thousands of hours of design/FEA analysis/prototype/destructive testing/redesign/further testing before coming to a finished design. And not just on the rockers but the entire valvetrain to insure everything works together perfectly. Outside of OEM's no one is putting in that kind of engineering effort.

I've run plenty of aluminum roller rockers and they look very cool with their bright colors; until you put the valve covers on. I've also had a couple of failures of aluminum rockers. So for me the very marginal gains you might get aren't worth the risk for a street engine. For my peace of mind I'll stick with chromoly or a precipitating grade of stainless steel for my rockers.

[Mastertech5]

Just to add what OEMs figure into there calculations on parts usage is for a part to last long enough to clear the warranty period. I agree with Mike Bray.

[MB750]

I'll stand by what I said. Metallurgically the difference in fatigue resistance between aluminum and steel is huge. Take am aluminum and a steel paperclip and bend them to failure. It won't take very long for the aluminum one to fail.

Airplanes are made from aluminum for obvious reasons but they have a cycle life due to fatigue. This is what happens when an airplane exceeds its cycle life and has a major fatigue failure.

https://www.imagecoast.com/images/MichaelBray1/aloha243color.jpg

On the other end of the scale is titanium which is as close to fatigue-proof as it gets. The SR 71 Blackbird could have flown for centuries as far as the titanium airframe is concerned. Because of the heat cycles the titanium skin actually got stronger over time.

I have no doubt some OEM's have used aluminum roller rockers in special instances. An OEM will also do literally thousands of hours of design/FEA analysis/prototype/destructive testing/redesign/further testing before coming to a finished design. And not just on the rockers but the entire valvetrain to insure everything works together perfectly. Outside of OEM's no one is putting in that kind of engineering effort.

I've run plenty of aluminum roller rockers and they look very cool with their bright colors; until you put the valve covers on. I've also had a couple of failures of aluminum rockers. So for me the very marginal gains you might get aren't worth the risk for a street engine. For my peace of mind I'll stick with chromoly or a precipitating grade of stainless steel for my rockers.


Mike, you raise a compelling point. I've never really thought about the failure rate of aluminum rockers compared to steel (or stainless), but there has to be one. When I did a search on "roller rocker failure" and sifted through the BS there's some threads around the internet about OEM failures at premature timeframes, but nothing pointing directly to aluminum rockers that I could find without conducting an exhaustive search. That doesn't mean it's inconclusive, but it doesn't answer any questions either.

For the time being, I went with AL roller rockers for a few reasons, the first being I didn't think about the alternatives. I wanted full roller, and aluminum came up first in my search at Summit. The added weight savings of AL means there will be less stress on the valvetrain during high revs, but I'm not racing my engine so that's really a moot point. Also, now that I search deeper there's SS full roller rockers available for similar money.

Well, I'm not changing them out so time will tell if they last.

[Mike.Bray]

Mike, you raise a compelling point. I've never really thought about the failure rate of aluminum rockers compared to steel (or stainless), but there has to be one. When I did a search on "roller rocker failure" and sifted through the BS there's some threads around the internet about OEM failures at premature timeframes, but nothing pointing directly to aluminum rockers that I could find without conducting an exhaustive search. That doesn't mean it's inconclusive, but it doesn't answer any questions either.

For the time being, I went with AL roller rockers for a few reasons, the first being I didn't think about the alternatives. I wanted full roller, and aluminum came up first in my search at Summit. The added weight savings of AL means there will be less stress on the valvetrain during high revs, but I'm not racing my engine so that's really a moot point. Also, now that I search deeper there's SS full roller rockers available for similar money.

Well, I'm not changing them out so time will tell if they last.

Aluminum roller rockers were developed for racing engines to extract that last bit of power. But racing engines are serviced a lot more than a street engine and parts are replaced on a schedule. As you discovered there is a nice selection of chromoly and stainless steel full roller rockers available today that weren't in the past. These (https://www.summitracing.com/parts/CCA-1631-1) are what I'm running, pretty much bullet proof.

Odds are you'll be fine and never have an issue. Just like the odds are in your favor every time you get on an airplane.

[RRussellTx]

Ok,

Still hunting for answers/solutions...

To recap, I stated that I had the following:

The heads are Edelbrock 60255.
The camshaft is an Edelbrock #2281 which is 235/238@.050" .573/.582 112 LSA - installed on a 108 ICL.(4*advanced)

Then, Gordon said the heads looked small for the cam and that it might be running at coil bind.

I pulled the specs and indeed it looked like that was the case:
From the Cam and Head Specs:
Cam Intake Lift at Valve .573
Cam Exhaust Lift at Valve .582
Head Maximum Valve Lift .575
My problem is the Exhaust Lifter collapsed and failed on #7 and #3 exhaust was starting to go.

New info, I researched the heads and cam following the advice of keeping them and making sure they all match up and found this:

From edelbrock.com, the camshaft documentation said it was tested with the 60255 Head:
https://www.edelbrock.com/rollin-thunder-camshaft-for-small-block-ford-351w-v8-2281.html
Where is says:
"This cam produced 449HP and 413 Ft Lbs of Torque when paired with RPM Air-Gap Dual Quad intake manifold #75354 and Performer RPM cylinder heads #60255"

Here are the Head stats:
https://www.edelbrock.com/rpm-small-block-ford-2-02-cylinder-head-hydraulic-roller-camshaft-60255.html



My question, are the Cam and Head actually compatible per the documentation or did Edlebrock make a mistake on the Dyno test combination?
I plan on calling them tomorrow but I want to make sure I'm not missing something first. (and share interesting information)


Thanks,
Richard

[MB750]

My personal opinion - those are great heads for a hot street engine, just put springs in that can take a higher lift cam and you'll be golden. 190cc intake runner is good for street use, and that RPM range for those heads compliments that.

Define "bigger" heads... The size of them? The valve sizes? The intake runners? Based on the specs of these heads they'll work just fine on your 427.

You could move the cam around a bit too, adjust the timing of it. I see 4 degrees advanced, that'll move your torque curve lower. Retard the cam timing will move your torque curve UP the RPM range and make your engine more "peaky".

[narly1]

To me making sure you have the right spring pressure is a big part of cam/head compatibility.

I know in the case of Comp Cams you can go on their website to see which model of their springs that they recommend for use with a specific cam (of theirs). From there you can then compare those specs to those for the springs in the heads you have.

That's what I did. It turned out that the specs for the springs used by AFR in the heads I got from them (brand/model not specified) were almost identical to the Comp ones suggested by Comp.

Earl

[Hoooper]

Mike, you raise a compelling point. I've never really thought about the failure rate of aluminum rockers compared to steel (or stainless), but there has to be one. When I did a search on "roller rocker failure" and sifted through the BS there's some threads around the internet about OEM failures at premature timeframes, but nothing pointing directly to aluminum rockers that I could find without conducting an exhaustive search. That doesn't mean it's inconclusive, but it doesn't answer any questions either.

For the time being, I went with AL roller rockers for a few reasons, the first being I didn't think about the alternatives. I wanted full roller, and aluminum came up first in my search at Summit. The added weight savings of AL means there will be less stress on the valvetrain during high revs, but I'm not racing my engine so that's really a moot point. Also, now that I search deeper there's SS full roller rockers available for similar money.

Well, I'm not changing them out so time will tell if they last.

Aluminum roller rockers that last the life of an OEM street engine (100k+ miles, not a 40k mile warranty) likely weigh more than a well designed low MOI steel rocker built to last the same timeframe, or are subjected to very low lift loads. Aluminum has no fatigue limit, so aluminum subjected to cyclical loading eventually fails no matter how overbuilt or well designed it is, the metallurgy of aluminum is such that there is no such thing as infinite cyclical lifetime. Steel on the other hand does have a fatigue limit, so if designed to cycle below that fatigue limit it will theoretically last infinite cycles.

In my opinion, aluminum is good for short use race engines or hot street engines with low RPM limits and low loading. Steel rockers are preferred for endurance racing or high lift/pressure applications.

[cc2Arider]

All,

Good discussion...some theoretical, plus some practical anecdotes...

What puzzles me is how most Al pistons can be made to last a full lifetime of an engine but other parts not so much?

Craig C

[bobl]

Ran across this Ford bulletin the other day. Not your issue, but relevant for sure.

Bob

[J R Jones]

Unless you are racing competitively and getting beat, I do not see the wisdom of trading durability for incremental performance. Lighter rockers, potentially have less valve float at high RPM. It is about inertia.
Not all aluminum has the same physical properties. Cast is not as dense or as strong as extruded or forged. Regardless, if the performance is not challenged, why risk the durability?
jim

[RRussellTx]

Update:

I talked to Edelbrock Support today.
They confirmed that the heads and cam should work together.
I pointed out the specs above and they acknowledged them and said it was very close but that they should work fine.

I asked if they had a spring recommendation to get a little more wiggle room and they punted to PAC Racing Springs as they are the Valve Spring supplier for Edelbrock.

Called the PAC support and they also felt like the existing springs should be fine but acknowledged that it was tight.
They also did not have a recommendation for a higher lift spring for that combination.

So now I'm left with doubts about what really caused the lifter failure and having to choose between just installing new lifters and hoping for the best or just biting the bullet and replacing the heads and/or cam. I never checked/changed the lash since I trusted the engine builder more than myself. Maybe that was where it went wrong...

Anyway, thanks for all the help!
Much appreciated!

[rich grsc]

I find that answer to be a bs answer. Any good supplier or engine builder would be able to find the proper spring so as to not have coil bind.

[Mike.Bray]

So now I'm left with doubts about what really caused the lifter failure and having to choose between just installing new lifters and hoping for the best or just biting the bullet and replacing the heads and/or cam. I never checked/changed the lash since I trusted the engine builder more than myself. Maybe that was where it went wrong...

If it was me I would probably call Comp and talk about springs.

Whatever you do all springs have a recommended install height, make sure all of them are shimmed to that height using one of these (https://www.summitracing.com/parts/pro-66902). I bet no two of mine have the same number of shims. I'm kidding of course but I did use a variety of shims.

[MB750]

I really don't see why this is so complicated. Summit sells TONS of springs capable of .600" and more:

https://www.summitracing.com/search/part-type/valve-springs?N=maximum-valve-lift-in%3A0-600-in_0-625-in_0-640-in_0-650-in_0-660-in&PageSize=100&SortBy=DisplayPrice&SortOrder=Ascending

All you need to know is the current dimensions on your springs, and the installed spring height, all measurable. Then buy a new set and install them. It's not rocket surgery.

Of course Edelbrock suggested their own supplier... Keeping money in house, makes business sense, but there's nothing special about valve springs.

[bobl]

Did you get a PAC part number for those springs? Edelbrocks specs on those heads seem a bit sketchy. They list the 60259 and 60255 as both having an installed height of 1.800 and .575 as max lift. However the 60259 is for flat tappet cams and the 60255 for hydraulic roller cams, which use 2 totally different springs. I only found 2 spring sets on PACs website that would fit those heads and both had much higher coil bind clearance. Maybe they make a special spring for Edelbrock. But no matter what, you need to get an accurate measurement You can measure them on the car but it’s not straight forward. You have to take into account the lifter has about .150” travel, so it will collapse when the valve is open giving the impression of more clearance. It’s best to remove the spring and measure it correctly. Give me a call if you would like to cuss and discuss. There is too much to type it all out. Be glad to help you out. I’ll message you my number.

Bob

[RRussellTx]

Did you get a PAC part number for those springs? Edelbrocks specs on those heads seem a bit sketchy. They list the 60259 and 60255 as both having an installed height of 1.800 and .575 as max lift. However the 60259 is for flat tappet cams and the 60255 for hydraulic roller cams, which use 2 totally different springs. I only found 2 spring sets on PACs website that would fit those heads and both had much higher coil bind clearance. Maybe they make a special spring for Edelbrock. But no matter what, you need to get an accurate measurement You can measure them on the car but it’s not straight forward. You have to take into account the lifter has about .150” travel, so it will collapse when the valve is open giving the impression of more clearance. It’s best to remove the spring and measure it correctly. Give me a call if you would like to cuss and discuss. There is too much to type it all out. Be glad to help you out. I’ll message you my number.

Bob

No, I did not get the corresponding PAC part number for my springs.

The PAC guy pulled up the information from the Edelbrock heads and used that spring part number (#5845) to analyze the specs.
https://www.edelbrock.com/sure-seat-valve-springs-5845.html

That's when he said they should be fine for my cam.
I pushed for an alternative spring that would allow more lift. He searched for a few minutes and said that he did not have one that he would recommend.

I have only pulled the passenger head at this point. As you know, the drivers side header is a beating...

I'm painting a couple of parts for that old mustang I'm working on. When that dust settles I'm going to do some measurements on the bench with the head that I have pulled. If it has plenty of lift then I may just replace the lifters and the damaged rockers and put it all back together the way it was.

Still not crazy about the smallish heads flattening the HP curve starting at 4000 RPM, but it already has tons of power and it's a lot easier/cheaper than new heads and a cam. First world problems...

Anyway, just doing some measuring and thinking for now...
I'll probably take you up on your offer when I get farther down the road.

My latest assumption for what caused the lifter to fail is the lash was not set correctly from the engine builder. When we originally checked all of them them, one was obviously loose as it jumped the valve stem, one was almost a full turn loose (another exhaust valve), and the rest were at basically at zero lash and the cam instructions call for 3/4 past zero.

Let me know if that's a bad assumption!

Thanks again for the lifeline offer!
Richard

[bobl]

I recently pulled a new BluePrint 347 apart that had a lifter failure. This had a rocker locknut not properly tightened and it backed off until the pushrod popped out, then the (Ford) lifter blew apart and broke the retaining plate allowing the lifter to rotate. We sent it back to BP and they totally rebuilt it and even paid my labor.

Bob

[bobl]

Just looked at your spring spec. That spring doesn't reach coil bind until .650 actual lift. That puts you over .060 clearance, not counting the various deflections in the valve train which adds even more clearance. So assuming everything is made as advertised I think those springs should be fine.

[MB750]

Still not crazy about the smallish heads flattening the HP curve starting at 4000 RPM, but it already has tons of power and it's a lot easier/cheaper than new heads and a cam. First world problems...


You could try retarding the cam 4 degrees (8 degrees from where you are now). That'll give your engine more peak power.



My latest assumption for what caused the lifter to fail is the lash was not set correctly from the engine builder. When we originally checked all of them them, one was obviously loose as it jumped the valve stem, one was almost a full turn loose (another exhaust valve), and the rest were at basically at zero lash and the cam instructions call for 3/4 past zero.

Let me know if that's a bad assumption!


Now I'm really confused. I thought you had hydraulic lifters? Those get preload, not lash. Lash is the small space between the roller tip of the rocker and the valve stem when using solid lifters. Hydraulic lifters don't get lash. Did you mean preload?

[RRussellTx]

Now I'm really confused. I thought you had hydraulic lifters? Those get preload, not lash. Lash is the small space between the roller tip of the rocker and the valve stem when using solid lifters. Hydraulic lifters don't get lash. Did you mean preload?

Did not mean to confuse, here are a few points to clarify what I have:

Picture of the lifter is in post #1.
It is a PERFORMER RPM HYDRAULIC ROLLER CAMSHAFT.
Cam Documentation here:
https://edelbrock-instructions-v1.s3.amazonaws.com/edelbrock/2281.pdf

The 'Zero Lash' term and specs is from the Valve Adjustment section at the bottom of page 3 in the above link.

I understand your point, I was just trying to communicate the information from the document about where the valves should have been.
That section also states "The above procedure assures correct hydraulic lifter preload."

Also, I seem to confuse people on the power side of things. I don't necessarily want more power, I would just rather have a more linear power curve. Right now, I have a 75 HP increase from 3500RPM to the 4000RPM followed by the 40HP increase from 4000RPM to 4500RPM and the HP/500RPM's gets worse from there peaking at 5500RPM.

I assume my problem is airflow at higher RPMs with the 427 but I'm definitely not an engine guy. Your suggestion would probably help that too but if I do anything that get's the engine open enough to change the timing on the cam then it will probably just get a new cam.

Again, I appreciate the info.
Good information to know!

Thanks again your you help!

[rich grsc]

Also, I seem to confuse people on the power side of things. I don't necessarily want more power, I would just rather have a more linear power curve. Right now, I have a 75 HP increase from 3500RPM to the 4000RPM followed by the 40HP increase from 4000RPM to 4500RPM and the HP/500RPM's gets worse from there peaking at 5500RPM.

I would say thats a cam issue, not a head issue. Look at the RPM range of the cam. You could put a huge set of heads on it and gain a little at the top, but drivability may be worse in the RPM range where you drive at on the street. WHAT RPM do you drive at the most, 1500-2500, or 4500-6000?

[RRussellTx]

I would say thats a cam issue, not a head issue. Look at the RPM range of the cam. You could put a huge set of heads on it and gain a little at the top, but drivability may be worse in the RPM range where you drive at on the street. WHAT RPM do you drive at the most, 1500-2500, or 4500-6000?

Oh, I hear you.
Your logic is why I'll probably just stick with what I have and be perfectly happy with it.

My pattern is that I overthink everything and then do what I think is best/cool and fun. I don't go over 5,000 rpms often, but when I do I want it to be cool and fun. If I replace the cam I will also replace it with matching heads that are focused on my driving style. The overthinking also helps me learn and understand much more than I would otherwise.

I don't worry about the money so much since I don't spend money on new cars.
I still drive the base 2005 Silverado that I bought new for $26k while my wife has had 5-6 new cars since then.
Parts are like fun car payments for me...

Thanks again for all the help and guidance!

[Mastertech5]

One more thing you should be aware of is that the roller tip of the rocker should be at the center of the valve stem, on average from closed to full lift. This can be adjusted by changing pushrod lengths. It can give you too much side pressure on the valve stem and possible bind.

[MB750]

I assume my problem is airflow at higher RPMs with the 427 but I'm definitely not an engine guy. Your suggestion would probably help that too but if I do anything that get's the engine open enough to change the timing on the cam then it will probably just get a new cam.



Actually, my suggestion would make your engine even more "peaky", and it sounds like you want it to mellow out a bit. If your current setup was 4 degrees advanced and it's too much than more drastic changes sound like the path to take.

Yes, I new cam is what I would suggest too. You've got a stonkin' engine. If you wanna mellow it out, get a cam with something south of .550" lift and less than 240 degrees of duration at .050" on both intake an exhaust. You can narrow down searches for cams based on RPM range as well, they mean the same thing. And you'll never have to worry about lifters and springs again because most springs can handle .550" lift. That'll tame that 427 down but it'll still rip when you spin it.

As a VERY general rule of thumb; displacement gives torque, RPM gives HP. You've got the shortblock to pull a house off the foundation, just reel in the horses a bit and it'll be more streetable.

[Hoooper]

Also, I seem to confuse people on the power side of things. I don't necessarily want more power, I would just rather have a more linear power curve. Right now, I have a 75 HP increase from 3500RPM to the 4000RPM followed by the 40HP increase from 4000RPM to 4500RPM and the HP/500RPM's gets worse from there peaking at 5500RPM.

I assume my problem is airflow at higher RPMs with the 427 but I'm definitely not an engine guy. Your suggestion would probably help that too but if I do anything that get's the engine open enough to change the timing on the cam then it will probably just get a new cam.

I would interpret this to mean you want more high RPM HP at the cost of low RPM TQ, is that right? It would make sense with your numbers being 425hp and 500tq


I would say thats a cam issue, not a head issue. Look at the RPM range of the cam. You could put a huge set of heads on it and gain a little at the top, but drivability may be worse in the RPM range where you drive at on the street. WHAT RPM do you drive at the most, 1500-2500, or 4500-6000?

I never understood this sentiment for a sports car. Tow truck, sure. In a roadster how often are you at full throttle at 1500-2500 RPM compared to 4500-6000 (or hopefully more)? I would only be there in 1st gear and even on an 8000 RPM build theres enough tq at 1500 RPM to light the tire in 1st gear. If youre having drivability issues with a "high" RPM 427 in a 2500 lb car thats a tune issue not a lack of low RPM tq. My lowly 376 only makes 275 lb ft at 1500 RPM but it drives down the freeway in 6th gear at 1500 RPM and 70 MPH no problem

[RRussellTx]

I would interpret this to mean you want more high RPM HP at the cost of low RPM TQ, is that right? It would make sense with your numbers being 425hp and 500tq


Not really, my goals have always been to have a stump puller of a big cube engine that would that not even notice being asked to accelerate from 1/4 throttle to 1/2 throttle at 70mph to pass in a passing lane going up a hill out on a country road with my .64 overdrive and my 3.31 rear end. I picked the tall gears because I like cruising the country roads with my wife at 1800ish rpms. It is geared perfectly for that.

My current setup lugs pretty good when I ask it to do that but it has gotten much better with the help of my tuner. Basically, I can live with it now but I really expected more. I just need to drive it like a 4 speed most of the time around town and downshift more often when I need to pass on the highway.

That said, I do like to have a little fun when the wife gets out of the car. That's when I notice the top end power band curve. Basically, I want a Terron Armstead - the 306lb NFL Tackle with a 4.71 40 yard dash.
Also, years ago I had an RX-7 with the Wankel engine that had a linear power curve and that car was fun to drive! Not a lot of power but it just kept getting better - more of that would be nice.

Again, nothing wrong with what I have right now. These are all 'if I had to replace them anyway" considerations. Early in this thread, the thought was that the head was too small for the cam which led to lifter failure. After talking to Edelbrock and PAC - they should be fine. Taking advice from this thread and my tuner, I'm still considering both options.

My tuner is working up a new head and cam combination to meet these goals if I decide to swap out what I have.
He has a pretty cool simulator tool that he uses.
He will also be able to show me the existing head/cam overlay so I can see the difference.
I also think he is going to factor in wheel torque based on my gearing.

Thanks again for all the help and advice.
Richard