427's & TKO-600 OD gearing

[JayTee]

Hi All,

I've got a question for the guys with 427/351W stroker motors. Mine is on it's way, and I need to make a decision on the TKO final drive gearing (.64/.82) so I can order it. I've read the countless threads on the TKO-600 OD gear selection, and while there's been lots of great feedback on lots of different engine/final drive ratio's, I haven't seen anyone chime in specifically with a 427 and whether it lugs or not on the lower (say, 2300) rpm's of the .64 gearing, while cruising down the highway at 70-80mph. I've plugged in all the numbers in several calc's, so here's what I'm looking at (3.55 rear, w/ FFR 17"'s)

.64:
2000 15 22 33 42 65
2500 18 28 41 52 82
3000 22 33 49 63 98


.82:
2500 18 28 41 52 64
3000 22 33 49 63 77
3500 26 39 57 73 89


Thanks,
-jaytee

[GoDadGo]

I'd go with the .64 overdrive with the 3.55's if you expect to do a lot of Highway/Interstate Cruising; however, what is the operation range of your engine, specifically lower RPM range of your camshaft and intake manifold?

To give you an example, my camshaft operation range is 2,300-6,500 RPM with my intake manifold a tad higher. The good news is my 5th gear will get me to 70 MPH @ 2,600 RPM and I can't grab 6th because it drops the RPM down to about 1,750 which will lug the engine.

That's The Big Deal To Answer Your Question!

[Mark Dougherty]

.64 is what I would run.
.
.
I would only use the .82 if I was going to race it ( road race ) or use it for short hops.
if you plan on going long distances then the .64 is IMO the best choice.

[Garry Bopp]

Ditto on the .64. Unless you have a very high hp full race motor, it's not going to be lugging at 2,300 rpm.

Garry

[Jim1855]

427w, 3.27 gears, 315/35-17, TKO-600 w/ .64 all by choice and a fully evaluated decision. My decision, maybe not yours. Starting a new build with the same engine/trans combo except will have 3.31 gears because 3.27 are not available. This is after about 65,000 miles, 2 cars and 12+ years.

80mph in 5th is about 2,200rpm, my cruising speed and I've run for 12 hours in a day. I could run down to about 2,000 in 5th.

My 427 had about 535 hp and 525 tqe at the crank. Good power started at 2,500 and got better all the way to 6,500. Would pull 4th to +/- 7,000 for 157mph on GPS.

The cam & manifold will make a big difference in what you can do. Your combination and how you drive or want to drive will be the real determining factor.

This topic is getting beat to death. It's right up there with Mustang / Camaro, Chevy / Ford, 9mm / 45acp.

Good luck on your search. I'd recommend you spend time on gearing calculators, look at max and potential realistic minimum speed in gears, the splits (change between gears), expected tire sizes, expected torque curves (bigger motors generally minimize the concerns). Then how fast or slow you want to drive on the various roads. What RPM range you want to run at, how much noise you want to make, how much noise you can tolerate over short or extended time periods.

Just a personal comment. I drive the TKO-600 .64 as a 4 speed with a cruising gear. I don't use 5th on the track or when I'm trying to go fast. I find 140 a reasonable max speed on the track, easy in 4th. I'm not racing, just having fun. If I needed five gears to get speed because of engine restrictions for a class and had to run 3.73+ gears to get acceleration then I'd have the .82 5th.

There are no right or wrong answers, just a lot of gray.

Jim

[Bad Moose]

Roush 427r-235 pushing 531hp with 524ft/lbs backed by a TKO 600 with .68 5th with 3.55 irs rear end.

In fifth 70 to 80mph you'll be good, 60 to 65mph completely sucks (you lug the motor and it does not like it at all, fuel mileage sucks), and anything below 60 is completely useless.

Your rpm calculations are about spot on to maybe a touch high.

Like Jim said your power comes on at about 2500 rpm. My car loves 2200rpm for fuel mileage.

[rich grsc]

With that many cu. in. I would change the reared to 3:27. The 3:55 gears are perfect for a small block, but not if you have all that HP and torque.

[Bad Moose]

Leave the gears at 3.55 the power is really good and drivability is good. Launches well with them also.

7500rpm 2nd to 3rd is at 105 mph
6000 rpm 2nd to 3rd is at 95 mph

You would absolutely fly with 3.27

[smithbks]

I have nearly the same setup as Jim1855 and have to 100% agree with him. My experience is the same. Only thing I will add is that the 3.27 gears are still plenty to fire off the line because there aren't enough tires out there to hold these little beast.

I chose my combination because I plan to own this car for a long time and I want the cruising aspect to be as comfortable as it can be.

[edwardb]

I've had both .64 and .82. Prefer the .64. More discussions in this recent thread: http://thefactoryfiveforum.com/showthread.php?24958-TKO-600-final-drive-gear

[Crawleyscobra]

.82:
2500 18 28 41 52 64
3000 22 33 49 63 77
3500 26 39 57 73 89

Like Bad Moose said, these numbers are really close. I have the Ford Racing Boss 427 crate engine with the TKO-600 (.82) and in 5th it starts to lug around 1800 RPM. I do not do much highway driving, I spend 90% of my time on the local side streets so the .82 works out for me.

[Bobby Doug]

You might think about what the speed limits are on your local roads. It you live back east where most if the speed limits are 65 or below then the .82 might be the way to go. If you live in the Midwest or west then go with the .64. Here in Ks our two lane roads have 70 mph speed limits. I choose the .64 for just this reason.

[chopthebass]

I have 351W/427, 3.55, 0.64 Fifth, and it is great!

[JRL16]

351W/427 TKO600 with .64.

[JayTee]

I just wanted to thank everyone for all the great feedback! Especially to the guys chiming in with the 351W/427's. (my Z2427 ships next week!)

This has been one of those decisions where I thought I read every thread I could find over the years, used all the calculators, and had decided on the .64. Then when it came time to actually place the order, I was second guessing my decision, so you all helped me with my indecision, and I ordered the .64.

A some point down the road when I finish, I'll have to loop back to this thread, or jump in on the next guy's thread, asking the same question, and let you know what I thought about the combo!

Many thanks again all, -jt

[Bad Moose]

I think you'll like your decision. You are going in with both eyes open and understand the ups and downs of it. I enjoy driving mine with the gearing it has, which is basically the same as what you're getting.

[ThickCobra]

I'd go with the .64 overdrive with the 3.55's if you expect to do a lot of Highway/Interstate Cruising; however, what is the operation range of your engine, specifically lower RPM range of your camshaft and intake manifold?

To give you an example, my camshaft operation range is 2,300-6,500 RPM with my intake manifold a tad higher. The good news is my 5th gear will get me to 70 MPH @ 2,600 RPM and I can't grab 6th because it drops the RPM down to about 1,750 which will lug the engine.

That's The Big Deal To Answer Your Question!

Go Dad Go

I am doing some research on diff and trans ratios compatibility. What caught my eye was your comment of your cam range of 2300 to 6500 and your inability to grab 6th gear as the rpm will drop to around 1750. At that rpm you begin to experience engine lug. Are you suggesting that in any gear, you can experience engine lug below 1750 rpm with your engine/trans set up.

Background: my set up is a tko600 .64 overdrive, 351w/427 stroker, 2015 IRS mustang 3.31. After extensive professional tuning, I continue to experience engine lug when cruising in any gear between 1,000 and 1800 rpm. And I'm wondering whether my semi aggressive e comp cam is the culprit?

Thoughts?

[Jim1855]

Wow, nice save on an old thread. I'll chime on ThickCobra's cam question.

Yup, it's a cam issue but you have to consider the carb and header size, intake manifold, ignition timing and tolerance to less than ideal operation.

My 427W started with a 670 Street Avenger with vac secondaries, Performer RPM manifold and small tube headers. It would run nicely at 1,300-1,500 rpm, don't remember exactly as it was 15 years ago.

Then I added AFR 225 heads, Vic Jr. manifold, 780 double pumper and larger, 1-7/8, tube headers. Made about 80 more HP but doesn't like to run under about 2,000 in 5th. Cam stayed the same. Bigger headers yet, 2", and a 940cfm carb again made more power after 5,000 but low RPM drivability suffered.

I think the only way you'll manage any drivability at under 1,200 is to use EFI or a really small carb.

Jim

[GoDadGo]

Go Dad Go

I am doing some research on diff and trans ratios compatibility. What caught my eye was your comment of your cam range of 2300 to 6500 and your inability to grab 6th gear as the rpm will drop to around 1750. At that rpm you begin to experience engine lug. Are you suggesting that in any gear, you can experience engine lug below 1750 rpm with your engine/trans set up.

Background: my set up is a tko600 .64 overdrive, 351w/427 stroker, 2015 IRS mustang 3.31. After extensive professional tuning, I continue to experience engine lug when cruising in any gear between 1,000 and 1800 rpm. And I'm wondering whether my semi aggressive e comp cam is the culprit?

Thoughts?

Yes, in any gear my engine lugs at that RPM, but it gets worse as I progress through the gears for obvious reasons.

What is your camshaft specs, intake runner size of your head and intake manifold type?

Last year when I had to change my block I went down a good bit with the camshaft duration and added a bit of lift which helped tremendously even though the rest of my set up remained unchanged. Also, please know that I am stuck running a single plane intake because I've got the a tall port head so a dual plane intake isn't an option. Since the camshaft change the car lugs around 1,500 RPM, but is pretty darn happy at 1,700, even though the RPM range of the new cam is roughly 2,000 - 6,200 RPM. This has allowed me to get the car into 6th at 70 MPH which equates to 1,700 RPM in spite of the big heads and single plane intake manifold.

The fact that my engine is a lot smaller than yours 383 vs 427 is a big factor too.

Shown below is my entire setup:

1. 383 Small Block Chevy (Dart-SHP Block) 10-1 Compression Ratio.
2. Eagle Internally Balanced Rotating Assembly With 6" H-Beam Rods With Floating Forged Flat Tops.
3. Dart Iron Eagle 215 CC Tall Port Heads with 2.05 Intake & 1.60 Exhaust Valves.
4. Harland Sharp Roller Rockers & Other Go Fast Goodies.
5. Comp Cam Extreme Energy 288 Hydraulic Roller Tappet Cam.
6. Edelbrock AVS 800 Feeding A Weiand 7530 Team-G Single Plane Manifold.
7. Schoenfeld IMCA Modified Headers & They Really, Really Fit, But Stuff Had To Move A Bit!
8. New Old Stock Corvette ZF 6-Speed Transmission With Hydraulic Clutch. (.75 5th & .50 6th Gear Over Drives)
9. Standard Front End Set Up With Mustang Brakes & Forte’s .75” Sway Bar.
10. Standard 3 Link Moser TSD 500 Rear With 3.73 Gears & Explorer Brakes.
11. The wheelbase has been shortened by .875" to better center the rear wheels within the wheel arches and improve pinion angle adjustment.

The video below is what the Dark Side MK-4 looks like today:

https://youtu.be/CaRlqMmKIzk

[ThickCobra]

Jim and GoDadGo,

I was afraid it may be the cam, which I don't plan to change. Now that I know what the driveability trade off is, I think, for now I'll live with it.

I believe my cam specs are the following:

E303 Ford Performance Cam
2500 -5500 basic operation rpm range (I did not know what this meant, I guess I do now.)
Exh and int lift .498
Exh and int duration 220 deg


Also, 450 hp
MSD Blaster2 coil
Steel 30 lb fly wheel
Compression 10.25 :1
Idle about 900 rpms
Distributor MSD 83541 Ready to Run steel gear
Quickfuel Hot Rod 780 cfm vs
Petronix ignition
Edelbrock airgap intake manifold

Thanks again, Jay

[Jeff Kleiner]

Jay,
You and I have had this discussion previously. That E cam is mild in a little 302 inch Windsor and is especially so in a 427. My finger still points at the big runners in that Air Gap intake which don't promote good fuel atomization at low velocity (i.e., low RPM)--Edelbrock says it's operating range is 1,500-6,500. You mention that you "continue to experience engine lug when cruising in any gear between 1,000 and 1800 rpm". That intake is just barely beginning to work at 1,800.

Jeff

[RRussellTx]

Jay,
You and I have had this discussion previously. That E cam is mild in a little 302 inch Windsor and is especially so in a 427. My finger still points at the big runners in that Air Gap intake which don't promote good fuel atomization at low velocity (i.e., low RPM)--Edelbrock says it's operating range is 1,500-6,500. You mention that you "continue to experience engine lug when cruising in any gear between 1,000 and 1800 rpm". That intake is just barely beginning to work at 1,800.

Jeff

I can confirm Jeff's recommendation. I swapped out the taller Intake in my 427w and it made a big difference at low speeds (and improved the hood clearance). Still not smooth, but much more manageable.

[NAZ]

ThickCobra, you may want to reevaluate your performance expectations. Running those low RPMs is more useful in a diesel application where gobs of torque are available than a performance car.

Typically the equipment that provides the greatest overall power for track performance also suffers at low speed city street driving. As mentioned by others above, your manifold & carb selection will certainly not provide snappy off idle or low speed performance. In addition, the relatively longer rods in the your engine will also tend to produce less low RPM vacuum, exacerbating the problem. If you put a wide band AFR meter on your exhaust during that low RPM cruise you'd probably see some very lean AFR readings. That's would likely be from incomplete combustion due to low booster signal & the fuel dropping out of of the intake charge from low vacuum / low velocity in the intake tract and more free oxygen exiting the exhaust.

BTW, your lift and duration specs are no where near "aggressive", I'd actually refer to this as "mild" but you don't mention LSA, if it's less than ~108-deg that could be providing some additional poor low speed performance.

If running your engine at low RPM is important then you need to make a manifold and carb change to increase low speed intake velocity (that be smaller runners) and low speed vacuum (that be smaller CFM carb, smaller plenum, and shorter runners). You'll be rewarded with snappy throttle response and better mixture control which will equate to improved torque output. However, I still would't expect great things at 1000 RPM, some engines idle at that RPM.

[Jeff Kleiner]

...BTW, your lift and duration specs are no where near "aggressive", I'd actually refer to this as "mild" but you don't mention LSA, if it's less than ~108-deg that could be providing some additional poor low speed performance...



The E cam lobe separation angle is 110 degrees.

Jeff

[ThickCobra]

I'm calling uncle. I will change out the intake manifold for a lower profile...lets start there. RRussellTx, is the one you installed, #2181 Edelbrock? Jeff, I believe you gave me this # and I want to confirm before I purchase it.

Thanks, Jay

NAZ, the LS is 110 degrees.

[NAZ]

The 110-deg LSA with your stated duration is a good choice for a street car and will support EFI if you think you might want to go that route in the future. The only thing I'd add is that a dual plane manifold is usually a good choice for a street driven CARBURETOR equipped car but if you think down the road you want to run EFI consider using a smaller single plane manifold as EFI typically plays better with the single plane.

Good luck.

[mike223]

I'll put in a limited endorsement on Weiand Stealth.

It will still buck on you (but almost certainly not at 1800 rpm).

Many variables - and I have a pretty big solid roller cam - 35-770-8.

I've got to get down to 1200 - 1500 rpm before I buck (depending on how much throttle you're lugging it with).

[GoDadGo]

I'd play with the carburetor & timing a bit more before I started changed parts.

1. Unfortunately not a lot of today's mechanics know how to set up a Holley or any carburetor, but they can be tuned.
2. I honestly suck at it so I installed an Edelbrock AVS, but have had to do some tuning to make that carb run right.
3. Don't throw the baby out with the bath water just yet because I think you can make it run a lot better than you think.
4. My entire set up is way more radical than yours so I really think this issue can greatly improve.

Here is a little video from Jegs that may help:
https://youtu.be/xscWLSpB5Go

Another option would be do what I do when I'm mechanically frustrated and sleep at a Holiday Inn Express.

Good Luck!

[GFX2043mtu]

A E303 can with a moderate single plane manifold and if you are running decent headers,heads and a 780 carb is a mismatched combo at best. The cam is defiantly a possible choke point. If you don’t mind spinning the motor a bit get the .64 5th gear and get a cam that will work with your heads and intake and and have good performance with a 2500 rpm cruse. Otherwise go with the .82 and build a mild motor that wants to run at 1800 rpm. Big single plane intakes take a lot of air movement to to work correctly and the smaller the displacement the more revs you need to make it efficient. Direct port FI can help this but you still have low air velocity at 1800 rpms. I’m running 461ci Windsor in mine and it’s fine at 2k rpm at 70-75 on the high way with 3.31 gears and .82 OD. But I have displacement to keep the air velocity up. You need to pick if you want a cruiser or performance and focus on that. I don’t know the rest of your engine but my recommendation is ditch the cam and get one that matches to the intake carb and heads or ditch the carb and intake for one better suited to the cam.

[RRussellTx]

I'm calling uncle. I will change out the intake manifold for a lower profile...lets start there. RRussellTx, is the one you installed, #2181 Edelbrock? Jeff, I believe you gave me this # and I want to confirm before I purchase it.

Thanks, Jay

NAZ, the LS is 110 degrees.

Yes, 2181.
FYI, I also needed a spacer between the intake and EFI to get the air cleaner to clear the top of the distributor.

[ThickCobra]

Yes, 2181.
FYI, I also needed a spacer between the intake and EFI to get the air cleaner to clear the top of the distributor.

Good to know. Thanks.

[mike223]

I'll put in a limited endorsement on Weiand Stealth.

It will still buck on you (but almost certainly not at 1800 rpm).

Many variables - and I have a pretty big solid roller cam - 35-770-8.

I've got to get down to 1200 - 1500 rpm before I buck (depending on how much throttle you're lugging it with).


Update:

Went out tonight with closer attention to bucking.

1- 393w
2- ~10.2:1 compression
3- TFS 170 heads
4- Aggressive solid roller cam (noted in detail above).
5- Weiand Stealth intake.
6- Holley 750 mechanical secondary double pumper.
7- 4 into 4 headers / sidepipes.



Definitely down in the 1000 - 1200 range on "bucking" (all gears) - depending on load + throttle input.