Need Some Help with Cam Specs for a Weber Carb’d 289 Max Effort Type Deal…

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Need Some Help with Cam Specs for a Weber Carb’d 289 Max Effort Type Deal…

Post by crazy_caseys_customs »

Hello,

Once again I have found more good “general” information on Speed Talk than on any of the other forums that are more tailored to a Small Block Ford running a nostalgia reproduction of the original Shelby Cobra Weber induction package. I’m still a bit of a novice; this is only going to be my fourth engine build, but I kind of want to challenge myself this time.

Now that Crane is basically gone, I’m not sure where to turn for my camshaft selection. I reached out to Howard’s, and the tech that responded said he didn’t know anything about Weber’s. I was leaning towards Howard’s because they at least sell decent lifters with their camshafts (Morel and Gaterman). After my last experience with Comp, I’m never going back.

Anyway, I know that Weber’s aren’t as sensitive to overlap as the people who sell them suggest (Jim Inglese spec’d a cam for me that was 220°@ 0.050” w/ 0.550” lift on a 115° LSA). And I have read several posts here that would suggest that running a crazy wide LSA isn’t a magic bullet, but a sort of band-aid approach to ease tuning. BUT, a lot of those posts also mentioned tuning the runner length to deal with excessive overlap, and I am confined to the Shelby intake’s VERY short runner length (about 1-1/2”), so overlap (reversion and stand-off) might actually be an issue for this particular combo.

Here’s where I’m at:

I’m building a 289 that will run a 4.030” bore with the stock 2.87” stroke, and a short skirt domed piston at 11.5:1 on a 5.400” rod. That combo should like to spin. The heads are the little AFR 165’s, but flow plenty of air for such a small displacement. I’ll build the headers to suit the ultimate cam selection, and was toying with the idea of playing with a 180° design just for the wow factor. The Weber’s are 48 IDA’s w/ 40mm Chokes. I want to make the meat of my power between 3-7k, to hopefully live happily with Comp Magnum steel roller rockers and a stud girdle on 7/16” studs (I will upgrade to a shaft rocker setup if I have to). I’m also hoping that the 11.5:1 static with enough camshaft will live on 91 pump gas, as that’s the best we get here in California.

I was looking at an off the shelf hydraulic roller cam from Howard’s with a 4° split, which typically kills power with a head as good as the AFR, BUT would also minimize overlap (which I’m not sure that I need to do); it spec’d out a 247°/251° @ 0.050” and 0.576” lift. It’s advertised power band of 2,800-6,700 is in line with my goal of having the meat of the power between 3-7k. I’ve read that these days a really good hydraulic roller lifter can handle sustained high rpms and a 7,500 redline, but I wouldn’t take issue stepping into a solid roller if that’s the right call. It’s just that everything off the shelf seemed way bigger than I need on such a small displacement engine.

Usage for this package will be track days, auto cross, and limited street. I built a much milder version of this engine a few years ago, and I’ve only put about 500 street miles on it in that time, so who am I kidding!? I should have just gone for it the first time.

Thanks for the help!
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Re: Need Some Help with Cam Specs for a Weber Carb’d 289 Max Effort Type Deal…

Post by PackardV8 »

Brings back memories. The cam experts will be along soon with recommendations for 21st century cams. My 289" cam info is fifty years old and I'd have to run it through DynoSim to get the airflow for your AFRs and I'm too lazy to do that today.

But just asking, is there a reason you're stuck on the 289"? I wasted some of the best years of my young life building those and today, any kid with a checkbook can build a 347" which will blow the doors off the best 289" I ever built.

Another OT, but somewhat relevant, I was at a vintage sports car race recently and there were the usual group of Cobra/GT350/TransAm clones running externally correct SBFs. When they went out on the track, one guy with a '69 Boss 302" PJ TransAm clone was way faster and from the sound was obviously running a NASCAR takeout. I remembered he was the one who never opened his hood when anyone was around. I'd bet he didn't pay any more for that than some of the SBFs with all the good internals, machine work and Webers.
Last edited by PackardV8 on Tue Jul 06, 2021 3:24 pm, edited 1 time in total.
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Re: Need Some Help with Cam Specs for a Weber Carb’d 289 Max Effort Type Deal…

Post by frnkeore »

You might be interested in the specs of the Ford LeMans cam.

It was 251/252 @ .050 on a 107 LSA, ICL @ 102. It had 85 deg of overlap. The Howards shelve cam, sounds similar, depending on LSA.

You can reduce the seat to seat, overlap with a little less duration and quicker ramps. There AR series. A little harder on the valve train tho.

You could also use the .875, Howards, FT lift rates and come close to a roller.

Ben Herheim is gone from Howards but, could have helped you, I'm sure. A great guy!

I'm sure Mike (camking) could also help, if he see's your post.
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Re: Need Some Help with Cam Specs for a Weber Carb’d 289 Max Effort Type Deal…

Post by crazy_caseys_customs »

PackardV8 wrote: Tue Jul 06, 2021 3:14 pm Brings back memories. The cam experts will be along soon with recommendations for 21st century cams. My 289" cam info is fifty years old and I'd have to run it through DynoSim to get the airflow for your AFRs and I'm too lazy to do that today.

But just asking, is there a reason you're stuck on the 289"? I wasted some of the best years of my young life building those and today, any kid with a checkbook can build a 347" which will blow the doors off the best 289" I ever built.

Another OT, but somewhat relevant, I was at a vintage sports car race recently and there were the usual group of Cobra/GT350/TransAm clones running externally correct SBFs. When they went out on the track, one guy with a '69 Boss 302" PJ TransAm clone was way faster and from the sound was obviously running a NASCAR takeout. I remembered he was the one who never opened his hood when anyone was around. I'd bet he didn't pay any more for that than some of the SBFs with all the good internals, machine work and Webers.
I’ve been getting the “why not build a stroker” thing a lot. In short, I’m pretty happy with the power level of the little 289 I’m running now; I just want it to be a little snappier, and rev out a little quicker/higher, and I finally want to install these Weber’s that have been sitting on my desk for a year. Basically, I think I can get there just rebuilding the short block. Adding cubes will start to make those AFR 165’s feel a little small, and thus starts the “snowball” effect. Right now the goal is just to have a little fun and have something a little different from the rest, but I’ll have the added benefit of being able to swap the heads and intake and be SVRA or VARA legal if I keep the cubes at or below the 289 + 0.040” B-prod class limit.

FWIW, I had looked into the NASCAR take-out thing. It seemed like all the Ford stuff was in the high $20k’s. I won’t have half of that in this thing…
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Re: Need Some Help with Cam Specs for a Weber Carb’d 289 Max Effort Type Deal…

Post by PackardV8 »

crazy_caseys_customs wrote: Tue Jul 06, 2021 3:44 pmI’ll have the added benefit of being able to swap the heads and intake and be SVRA or VARA legal if I keep the cubes at or below the 289 + 0.040” B-prod class limit.
Vintage racing technical inspection seems to vary from strict to "whatever". At the recent race I attended, there were many period correct cars, but there were also several Factory Five, et al, Cobra and Daytona replicas, the aforementioned cheater Parnelli Jones Mustang and a C3 Vette with a 496" BBC and aluminum heads.

When I asked about scrutineering, the answer I was given;

"Boomers are aging out and vintage racing participation is dropping. To keep the grids full, as long as it externally fits the loosest definition of Vintage, let 'em run. It pisses off the purists, but ya gotta do what ya gotta do."
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Re: Need Some Help with Cam Specs for a Weber Carb’d 289 Max Effort Type Deal…

Post by crazy_caseys_customs »

PackardV8 wrote: Tue Jul 06, 2021 4:24 pm
crazy_caseys_customs wrote: Tue Jul 06, 2021 3:44 pmI’ll have the added benefit of being able to swap the heads and intake and be SVRA or VARA legal if I keep the cubes at or below the 289 + 0.040” B-prod class limit.
Vintage racing technical inspection seems to vary from strict to "whatever". At the recent race I attended, there were many period correct cars, but there were also several Factory Five, et al, Cobra and Daytona replicas, the aforementioned cheater Parnelli Jones Mustang and a C3 Vette with a 496" BBC and aluminum heads.

When I asked about scrutineering, the answer I was given;

"Boomers are aging out and vintage racing participation is dropping. To keep the grids full, as long as it externally fits the loosest definition of Vintage, let 'em run. It pisses off the purists, but ya gotta do what ya gotta do."
Interesting. I mean, it makes total sense; it’s just a very different sense than I got from discussing my aspirations on the Vintage Mustang boards. But perhaps every region is different. And I’m sure more tech officials would let an unseen displacement increase slide than would pass a car with aftermarket aluminum heads.
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Re: Need Some Help with Cam Specs for a Weber Carb’d 289 Max Effort Type Deal…

Post by Geoff2 »

I am a bit confused by your comment that Ws are not sensitive to overlap but Inglese specced a cam with 115 LSA, which would reduce overlap.

Anyhow, good luck with the Ws. You will LOVE them. I have four 48 IDFs on a 455 Pontiac, been on 15+ years, street driven.

Some words of warning. Keep fuel pressure between 3-4 psi & use a bypass reg. A dead head reg causes pressure spikes & strange behaviour.

Make sure the throttle linkage have minimal play at idle/off idle & are synchronised. Any play or variation here will cause rough running. I did not like the commercially available linkages, so I made my own.
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Re: Need Some Help with Cam Specs for a Weber Carb’d 289 Max Effort Type Deal…

Post by Rick! »

I had two flat tappet cams made for a 9.5:1 289 with 4 IDA's back in 1989. I believe I had called a Jones up at the time and can't remember if it was Mike or not. The first cam wasn't making the power we wanted so a second grind was made and it hit 400HP and made the owner happy. IIRC, max effort back then was around 425ish and the owner did not want to run race gas all the time which is the reason for the low compression. I think you are going to want bigger chokes as I started at around 40 and put in the biggest ones I had to make the power number. Driveability was fine but it was a really light car with limited traction on cold tires. YMMV

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Re: Need Some Help with Cam Specs for a Weber Carb’d 289 Max Effort Type Deal…

Post by Walter R. Malik »

Some 4 cylinder engines running true Individual runner Webers usually like the slightly larger lobe on the intake side.
The V8 may act the same way.
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Re: Need Some Help with Cam Specs for a Weber Carb’d 289 Max Effort Type Deal…

Post by crazy_caseys_customs »

Geoff2 wrote: Wed Jul 07, 2021 4:16 am I am a bit confused by your comment that Ws are not sensitive to overlap but Inglese specced a cam with 115 LSA, which would reduce overlap.

Anyhow, good luck with the Ws. You will LOVE them. I have four 48 IDFs on a 455 Pontiac, been on 15+ years, street driven.

Some words of warning. Keep fuel pressure between 3-4 psi & use a bypass reg. A dead head reg causes pressure spikes & strange behaviour.

Make sure the throttle linkages have minimal play at idle/off idle & are synchronised. Any play or variation here will cause rough running. I did not like the commercially available linkages, so I made my own.
I’m sorry, let me clarify. There seems to be a general consensus on the Internet that wide LSA’s and low overlap are essential to a happy Weber induction, and this idea seems to be propagated by the folks selling these induction systems. Yet there are several fast cars running some pretty tight LSA’s and big durations with Weber’s, and there are more than a few posts here on Speed-Talk suggesting that the wide LSA and low overlap thing is just a pervasive and persistent rumor. Still, getting people to share “their own” cam specs, is always like asking for the secret family gravy recipe or something.

Also, thanks for the tips on linkage and fuel pressure.
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Re: Need Some Help with Cam Specs for a Weber Carb’d 289 Max Effort Type Deal…

Post by CamKing »

For 7,000rpm with a 289 ,you don't need anywhere near the duration you're looking at.
Here's what I recommend for a mechanical roller.
228/232 @.050"
.360"/.360" Lobe Lift
.576"/.576" Gross Valve Lift
110 LSA
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Re: Need Some Help with Cam Specs for a Weber Carb’d 289 Max Effort Type Deal…

Post by BILL-C »

PackardV8 wrote: Tue Jul 06, 2021 4:24 pm
crazy_caseys_customs wrote: Tue Jul 06, 2021 3:44 pmI’ll have the added benefit of being able to swap the heads and intake and be SVRA or VARA legal if I keep the cubes at or below the 289 + 0.040” B-prod class limit.
Vintage racing technical inspection seems to vary from strict to "whatever". At the recent race I attended, there were many period correct cars, but there were also several Factory Five, et al, Cobra and Daytona replicas, the aforementioned cheater Parnelli Jones Mustang and a C3 Vette with a 496" BBC and aluminum heads.

When I asked about scrutineering, the answer I was given;

"Boomers are aging out and vintage racing participation is dropping. To keep the grids full, as long as it externally fits the loosest definition of Vintage, let 'em run. It pisses off the purists, but ya gotta do what ya gotta do."
SVRA will usually let these cheater cars run, but not score them. That way they don't screw up the legal guys for points or trophies and can still add to the show.
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Re: Need Some Help with Cam Specs for a Weber Carb’d 289 Max Effort Type Deal…

Post by BILL-C »

crazy_caseys_customs wrote: Wed Jul 07, 2021 10:43 am
Geoff2 wrote: Wed Jul 07, 2021 4:16 am I am a bit confused by your comment that Ws are not sensitive to overlap but Inglese specced a cam with 115 LSA, which would reduce overlap.

Anyhow, good luck with the Ws. You will LOVE them. I have four 48 IDFs on a 455 Pontiac, been on 15+ years, street driven.

Some words of warning. Keep fuel pressure between 3-4 psi & use a bypass reg. A dead head reg causes pressure spikes & strange behaviour.

Make sure the throttle linkages have minimal play at idle/off idle & are synchronised. Any play or variation here will cause rough running. I did not like the commercially available linkages, so I made my own.
I’m sorry, let me clarify. There seems to be a general consensus on the Internet that wide LSA’s and low overlap are essential to a happy Weber induction, and this idea seems to be propagated by the folks selling these induction systems. Yet there are several fast cars running some pretty tight LSA’s and big durations with Weber’s, and there are more than a few posts here on Speed-Talk suggesting that the wide LSA and low overlap thing is just a pervasive and persistent rumor. Still, getting people to share “their own” cam specs, is always like asking for the secret family gravy recipe or something.

Also, thanks for the tips on linkage and fuel pressure.
We have run as tight as 105 lobe separation on race winning engines. The worst aspect of running weber carbs is the fact that you can't run a progressive linkage. All 8 throttle plates open at once, so it is very difficult to ease into throttle coming off of technical corners. Average drivers are quicker with a single holley carb with the same power. It is absolutely essential to sync carbs perfect and not have any slop in linkage. Also the bigger you make the venturis the worse the driveability and fuel curve gets. You won't be able to fit an air cleaner under a stock cobra hood and those screens that fit over stacks really kill the power.
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