Cam Selection

[canuck coupe]

Hello everyone,
Only my second post here. I've been lurking around the "other" FF forum for almost 15 years.

Hate open a can of worms, but I'd like some recommendations for a camshaft.

Engine is a pushrod 5.0. Stock bottom end. "Stock" heads with 1.94/1.60 valves, porting in progress (should flow similar to GT-40 when I'm done. Hell of a lot of time and effort, but I'm doing it for the experience and the bragging rights. It's the journey that matters to me, not the destination), Edelbrock Performer RPM intake. Holley Sniper EFI. Expecting ~300 at the crank (depending of course on my success at porting and the final cam choice).

Street only. Maybe some lapping days. I'm not really concerned about peak power. I'm more concerned with a reasonably flat torque curve and mild street manners.

What I'm mostly interested in hearing about is behaviour at idle. I don't want a sewing machine-smooth idle (these are race cars after all, so they should sound mean). And I don't want it so lumpy that the car shakes and you feel like you have to blip the throttle to prevent it from stalling. On that scale, I want a cam closer to the smooth end. Let's say 3/10 for roughness.

To keep the "can of worms" small, I'm not looking for lessons about duration or lift or LSA or ICL or IVC. I've done a ton of research already, and I can get those specs on the web. What I can't get from the specs is real-world experience about idle quality.

If you're running an engine that's like mine and you've got a slightly lumpy noticeable idle, I love to hear what cam you have.
Thanks!
Philip

[NAZ]

Instead of asking this question on a forum -- contact a cam grinder such as Comp Cams and ask them (800-999-0853). They are the experts and give solid technical advice on cam selection to gear-heads every day.

I spec my own cams by using modeling software from Comp Cams but it's much cheaper to give them a call and they have hundreds of off the shelf performance cams to meet most any need.

[Big Blocker]

All that being asked, I'll give you my specs:

Stock block 5.0 (302), stock heads with stock valves, upgraded valve springs for the cam, which is one of FORD's "letter cams", an "E" cam. Nice idle that lopes a bit but not in the nitro burning fuelie class by any means, but also not a "Singer" sewing machine - I actually get a lot of compliments about the sound of my engine. I'm running the tubular GT-40 manifold with a bit of port matching done for flow, factory stock EFI without all its emission related stuff - canister purge, TAB, TAD and EGR disconnected and by-passed with appropriate valued resistors to fool the EEC into thinking it's all there and working. 23 mpg at a sustained 80 mph out on the open road, 18 around town - 3.73 rear gears. Car is an absolute dream to take on long road trips and can still blow off a few doors now-n-then . . .

She's 18 years old this last Christmas.

Doc

[Sdonnel]

Comp cams 35-518-8. Had it in my last cobra. 306 with AFR165 heads. Stainless headers and pipes It sounded awesome. Nice lope and very good manners. Also ran a 3.73 in the rear end. It would cruise all day and scream when you wanted it to too. Power ran out at about 6,000 rpm. Comp has audio files on their cams and YouTube has an audio clip of just about whatever you want.

Scott

[FF33rod]

Comp cams 35-518-8.....

Very similar to my Trickflow Stage 2 cam https://www.trickflow.com/parts/tfs-51403002
Love the way it idles!!!

[canuck coupe]

Thanks, Doc. Considering how close to stock I am, an E cam makes sense. Your engine sounds perfect to me. 18 years with your car! Congratulations!

Thanks Scott and 33FFrod. Those cams have more lift than my heads can make use of. I built a DIY flowbench so I could track the progress of my porting efforts, and I got some pretty surprising results. Stock heads don't flow much better at 400 and 500 than they do at 300. Unfortunately, my ported heads aren't doing any better so far. Might end up with AFR 165s! Now that's a head than can make good use of higher lift.

[narly1]

Check out this video on cam selection: https://www.youtube.com/watch?v=JPAeepqrY-0

My build plan includes AFR165 heads and EFI (likely Pro Flo 4).

AOD trans and 3.55 rear end.

My main concern is making more power at low RPM due to the AOD's 1st gear ratio.

Thus I'm going with the Comp Cams XE264HR-14/35-349-8.

[canuck coupe]

NAZ and narly1, Thanks for the comments, but as stated in my initial post, it's not advice or lessons in cam selection I'm looking for. It's real-world opinions from owners of these cars who have mild to moderate street engines.

[narly1]

One thing you might try is searching videos on line showing cars/engines that are running the cam you're interested in.

For example here's one for the cam I'm going with: https://www.youtube.com/watch?v=NmEHiZmEVEE

[canuck coupe]

Thanks for the link, narly1. I like the slightly rough idle of that one.

[narly1]

Thanks for the link, narly1. I like the slightly rough idle of that one.

Me too! Sounds very driveable but you know there's something more there.

But the reality is that there's way more to picking a cam than just how it sounds at idle.

The way I see it is you have a couple of choices:

1. Go to a custom grinder like Ed Curtis and give him all the necessary info (see http://www.flowtechinduction.com/cam-tech-form/) and let him do the thinking and apply his vast experience to get exactly what you want.

or

2. Define your needs for yourself and then do you own learning/research into the various design considerations required to achieve same, and then pick an "off-the-shelf cam (or cams). From there you can further add in the experiences/recommendations of others to confirm/narrow down your choice.

Hope this helps....whatever you decide have fun and enjoy the ride.

[GoDadGo]

Instead of asking this question on a forum -- contact a cam grinder such as Comp Cams and ask them (800-999-0853). They are the experts and give solid technical advice on cam selection to gear-heads every day.

I spec my own cams by using modeling software from Comp Cams but it's much cheaper to give them a call and they have hundreds of off the shelf performance cams to meet most any need.

I'm a big fan of Comp Cams and have been so since 1982.
Here's an off the shelf grind that may be of interest to you:
https://www.compcams.com/magnum-230-230-hydraulic-roller-cam-k-kit-for-ford-221-302.html

As The Naz suggested, give them a call because they are super helpful.
I currently am running a dual pattern cam which I really like and is shown below:
https://www.compcams.com/xtreme-energy-236-242-hydraulic-roller-cam-for-oe-roller-sbc.html

[jwhit]

ford b-303 is great cam with good lopy idle i have used e 303 and b303 and i think the b303 sounds better

[Mike N]

Good info here. http://www.mustangandfords.com/how-to/engine/138-0402-347-comp-cam-hydraulic-roller-cams

The cam that Scott listed, Comp cams 35-518-8 is the XE274HR. As noted it is similar to the Trick Flow Stage 2. Both are excellent cams.

[FF33rod]

The cam that Scott listed, Comp cams 35-518-8 is the XE274HR. As noted it is similar to the Trick Flow Stage 2. Both are excellent cams.

I enjoyed the youtube link posted on how to choose a cam. I learned a lot (I didn't pick a cam separate, bought a packaged top end kit that had everything matching). After looking at the video, I personally understand now that these 2 cams are likely NOT a good match for the heads Philip is referring to despite the appeal of the idle. Philip knows all that stuff so I only mention it here for others who might read the thread at some point....

[canuck coupe]

Since starting this thread, I have spent several more hours crunching numbers on a lot of cams. It's quite a process. So far they either have too much lift or too much dynamic compression. Except for.......the E303. Not a whole lotta love out there for the letter cams, probably because they aren't oriented towards peak power. But the E303 checks all my boxes. I'm not done looking, and I might end up with a custom grind, but the E is a tempting solution.
Thanks, Doc for putting the letter cams back on my radar, and thank you everyone else for your comments.
(And BTW, the video narly1 suggested a few posts up is excellent. I've watched it twice. The guy tends to ramble on a bit. He could have done it in half the time. But don't give up on him! He imparts a lot of great info. Here's another one from Pete's Garage: https://www.youtube.com/watch?v=HrtQVhcTPFc&list=PLnNvjsdE7fTO3kLd5ZTTn4y5CPeExeLga&index=5)
Cheers, Philip

[narly1]

The guy tends to ramble on a bit. He could have done it in half the time. But don't give up on him! He imparts a lot of great info.

Ya you need to have your favourite beverage in hand and a comfy seat under your butt before clicking on the "play" button for that one, LOL.

[Garry Bopp]

I agree with Mike N. I chose the Comp Cams XE 274 HR when my 331 was rebuilt 2 years ago. Nice lope at idle and the driveability is great. I can chug around at 1,500 rpm in 5th gear, mid-range is great and a strong top end. I had the car on a chassis dyno last year and the torque curve was nearly flat. HP was still climbing when I stopped the run at 5,850 rpm. Trick Flow heads and FiTech EFI. 331 rwhp and 332 lb.ft.

Garry

[Tolypeutine]

Comp cams is also the best that I can recommend.

[GoDadGo]

I agree with Mike N. I chose the Comp Cams XE 274 HR when my 331 was rebuilt 2 years ago. Nice lope at idle and the driveability is great. I can chug around at 1,500 rpm in 5th gear, mid-range is great and a strong top end. I had the car on a chassis dyno last year and the torque curve was nearly flat. HP was still climbing when I stopped the run at 5,850 rpm. Trick Flow heads and FiTech EFI. 331 rwhp and 332 lb.ft.

Garry

One Pony Per Cubic Inch At The Rear Wheels Plus The Ability To Chug Along @ 1,500 RPM Is A Fantastic Feat!

For the record I have heard the car and seen it too which can be viewed at last year's Parade of Speed at the H.S.R. Walter Mitty Race:

https://youtu.be/RkRVLuM6Xjo

[canuck coupe]

After having so much fun rebuilding a 302 during covid lockdown, I decided I needed to build a car around it. So, three weeks after I started this thread, I bought a Type 65! It only took 14 years!

Update on my cam selection: I ended up with a Comp Cams XE270HR-14.
In my search, I spec'd out 24 cams. I was looking for one that would give me no more than 8.7 dynamic compression, because that's the max recommended by the manufacturer of my pistons (cast aluminum. Long story that started with a mistake I made over a decade ago!).

I put all the specs in a spreadsheet and arranged them by Intake Valve Closing (major determinant of DCR). I found something very interesting. All the cams with early IVC had low operating ranges (like 1500 to 5500). Later IVC had higher operating ranges (like 2500 to 6500).
In my research, I learned that Lobe Separation Angle is an important determinant of operating range (narrow LSA: higher operating range. Wide LSA: lower operating range). Not on my spreadsheet! There didn't appear to be any correlation between LSA and operating range. The lowest LSA on my list (107 degrees) had a range of 1900 to 5600, and the highest range on my list (3500 to 5600) had the highest LSA of 114 degrees. My chosen cam has LSA 114 and range 1800 to 5500.

Anyway...the XE 270 had the right operating range, the right DCR and, by happy coincidence, the perfect amount of lift for the flow my heads can deliver.
Cam chosen, cam purchased, cam installed, and cam degreed!

I pick up my heads from the machinist tomorrow. By the end of the weekend, I should have my 302 ready for final assembly. I still need to measure and order pushrods. Then off to the engine dyno to see what I've accomplished!

Cheers!

[narly1]

Philip, you're fast! I'm still waiting on my block and rotating assembly back from the m/c shop.

Just curious, What pistons are you using?

[canuck coupe]

I'm using Silv-O-Lite pistons from UEM.

I don't think I'm fast. I started this engine rebuild back in March. I'm taking my time to make sure I get it right.

I guess if I add it all up, I've accomplished a fair bit in four months: rebuilt an engine and a transmission (knowing very little about either at the onset), built a rudimentary flow bench, ported two sets of heads (one success, one failure), installed a compressed air system in my garage, and bought a coupe kit.

[narly1]

I'm using Silv-O-lites too. 3101HC-020's. My static/dynamic compression ratio numbers calculate out to 9.7:1 and 8.5:1 give or take a bit depending on what I end up using for head gaskets.