# Need help choosing a cam



## 1972LeMans (May 4, 2014)

I'm building a 461 stroker since I just blew up mine. I'm wanting a comp cam and I want the performance with the traditional muscle car sound. I'm looking for a solid loping cam. 

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## 05GTO (Oct 6, 2004)

You will get the rough idle lope by going with a lower LSA, but if you have an auto transmission you will need a torque converter and power brakes will be starved for vacuum at idle.


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## mbspeed (Sep 25, 2012)

check out the 041 grind muscle car cam from comp cams


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## eodprice (Jan 7, 2014)

Best thing to do is email/ call or fill out the Cam selection guides on some of the major grinders. They will almost all come up with almost the same thing. If you call first, get on crower and look at there recommendation sheet so you know the question they will ask. 


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## Cory (Mar 2, 2014)

Look a choosing a cam like painting picture. It's hard to know what colors to use without knowing what your trying to paint. Need more info (specs) before giving advice.

I'm running a comp roller cam, that's docile enough my wife can idle it around in traffic, but also runs low 12's in street trim.


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## Chris-Austria (Dec 23, 2010)

I remember when I had to choose a cam.. I calculated and tested for weeks.. Bear gave me some great information and I'm very happy now.

I think something with an intake duration between 230° and 240° @.05" will work well for you, but more information is necessary like what transmission, read end ratio and information about the rest of the engine.


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## 1972LeMans (May 4, 2014)

I have a turbo 400 and 4.10 in the rear but I'm going to go to something around 3.24.

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## PontiacJim (Dec 29, 2012)

1972LeMans said:


> I'm building a 461 stroker since I just blew up mine. I'm wanting a comp cam and I want the performance with the traditional muscle car sound. I'm looking for a solid loping cam.
> 
> Sent from AutoGuide.com App



This has been discussed many times. It is just not that easy. A number of specs have to be hammered out first before you actually choose the cam. The cam should be one of the last things you select. You can get that rumpty-rump muscle car cam idle and have a dog for an engine. The rumpty-rump usually means a lot of valve overlap which in turn means a fairly high RPM running engine at the sacrifice of low speed operation which is what you will be mostly cruising in.

What RPM do you plan to spin? What horsepower/torque range do you want - lower,middle,upper? Do you have the compatible parts to spin at your desired RPM? What is your actual compression ration? Do you want any gas mileage out of it? What type of heads -aluminum/cast iron? What kind of CFM flow numbers do you have? What type intake/carb? Headers, factory manifolds, duals -what size? Transmission type? Converter stall? Flash stall? Rear end ratio? Tire size? 

Not as simple as it sounds in picking a cam -parts have to match one another. And, you can have great numbers on a dyno, but have a slug once you install it and the "real world" takes over. Always build for good torque numbers with a Pontiac. Pontiac has its own unique sound and it really doesn't have that rumpty-rump sound a chevy can have because they can RPM way higher -this is why you always know its a Pontiac just from its sound. 

As suggested, a good cam producer or Pontiac engine builder can help with this one. Other members, as well as other blogs, can give you advice or recommendations that have worked for them. I think cams with 112-114 LSA in the 270-290 degree duration and up around .500 gross inch lift for a solid is about right in choice. But a smaller cam might actually work best all around -and the big cubes will offset the need for a radical cam and still smoke tires. Hydraulics will be a little different choice as well as a roller cam. 

I am building a .060 455CI and kinda am leaning towards the Crower #60310 solid using 1.65 rockers. The lift is a little higher with the 1.65 rockers than I would like, but the .022 and .024 lash knocks this down. I could use the 1.5 rockers which the Crower cam spec provides and drop it down to some good numbers as well. SO, when I have figured out my true compression ratio, I will then call Crower or email them, give them all the details and see what they say as to if I can use this or not for my application. Should be a real stump puller by my estimates in the build I am doing. May not work at all on someone else's ride -heck, might not be what I need either.


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## 1972LeMans (May 4, 2014)

Well I guess I didn't know how much went into picking a cam. Thanks for all the info! 

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## 666bbl (Apr 13, 2014)

You already rec'd some good info here, but there's always the OEM selections too. Most were able to offer plenty of grunt with the stock convertors and gears. They spent millions developing an overall high performance car in most any combination. With a Turbo 400 you'd need a loose convertor for most of the hipo cams in the aftermarket. With the gear you plan to drop to you may end up with a lame combination even with a loose convertor, and to add insult to injury it would probably have an insatiable appetite for premium fuel and lead additives. I'm building a 61 Belair bubble top, and if I had a $100 bill for everyone that yells "...you gotta put a 409 in it.", I still couldn't afford the fuel!!


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## PontiacJim (Dec 29, 2012)

666bbl said:


> You already rec'd some good info here, but there's always the OEM selections too. Most were able to offer plenty of grunt with the stock convertors and gears. They spent millions developing an overall high performance car in most any combination. With a Turbo 400 you'd need a loose convertor for most of the hipo cams in the aftermarket. With the gear you plan to drop to you may end up with a lame combination even with a loose convertor, and to add insult to injury it would probably have an insatiable appetite for premium fuel and lead additives. I'm building a 61 Belair bubble top, and if I had a $100 bill for everyone that yells "...you gotta put a 409 in it.", I still couldn't afford the fuel!!


You gotta put a 409 in it! Ok, where do I send the $100 bill? HaHaHa. It is funny how certain makes/body styles conjure up a specific engine/combo. Say 1970 Chevelle SS and it has to have an LS6 454 4speed. '69 Plymouth RoadRunner and you think Hemi/4 speed. AMX and its 390CI/4 speed. Yet all these makes and others offered base line engines with far less horsepower, automatics, and stiff highway cruising gears. Nice to see you look forward to driving and enjoying the car more than having to save up a nest egg of cash in order to take it out once in a blue moon. The 409CI I had got 8-10 MPG. I myself in today's world, making more money than when younger, would be hard pressed to drive it regularly with gas prices as they are. I think I would have to trailer it to the shows and then drive it around - like a lot of owners do with low gas mileage/high HP cars.

Ditto on the factory cams. Some good proven choices that are no slouches either. Most cam providers have these available as well. Cam selection has to be tailored to so many variables. Not saying you can't "pick" a cam and not be happy with it, but do you want to spend your hard earned money and be disappointed - that's what it really boils down to.


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## 666bbl (Apr 13, 2014)

Pontiac Jim, you'd be the 1st and only "C" note I get for it! To make matters worse, I live in a rural area of S.E. MI and everything that's fun with these cars is a minimum of 30+ miles away except for 1 local "cruise night" event, and that's 16 miles away! It's going to like it's 350 tri-power just fine. My 65 GTO will be thirsty enough!


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## BearGFR (Aug 25, 2008)

Lots of good advice so far (Hi everyone! just got back to town after a 2 week vacation- will be spending the next week MOVING out to the country...).

Changing to 3.24's from 4.10's is a VERY WISE MOVE!! You won't regret that.

Cam choice... What causes an engine to have that "hot rod lope" is the amount of overlap - period of time when both intake and exhaust valves are open. It sounds cool because we all associated that sound with a hot engine, but in actuality when then engine is loping like that it's stumbling all over itself just trying to keep itself running. Power and torque are both WAY down from what they would be if it were running smoothly/efficiently. It's a trade-off we "pay" at lower rpm in order to get better cylinder filling and increased volumetric efficiency (translation: more torque and power) at higher rpm.

So, picking a cam becomes a matter of compromises beginning with an honest assessment of the rpm range where your engine is going to be running _most of the time._ Once you know that, then you choose "everything else" to "allow" it to spend lots of time at that rpm. For example, if you pick a cam that produces best torque say between 3500 and 5500 rpm, then you want to be running a converter/rear gear combination that will allow the motor to quickly "flash" to 3200-3500 rpm in order to get into the "meat" of the torque curve as quickly as possible. Everything in the whole system has to be optimized to work together - not just the cam.

So, back to overlap. That rumpity-rump sound comes from overlap. Overlap is influenced by several things: LSA (lobe separation angle), the shape of the lobes themselves (how quickly the open/close the valves), and indirectly influenced by lobe duration. The real "reason" for running a "hot" cam is to get the longer duration - amount of time the valves are open - in order to allow the cylinders to fill better at higher rpm. Everything else, including the lope, is just a "side effect" of the longer duration that we have to "live with" in order to get the longer valve-open times.

If you have vacuum-assisted power brakes, overlap is your enemy because of the negative impact this "lope" has on idle vacuum. Once you get much below 15" of idle vacuum, you've got to either give up your power brakes or convert them to work off something other than engine-generated vacuum in order to stay safe (my opinion). The two most popular options seem to be an electric vacuum pump (can be noisy) or a hydroboost system (uses a different type of brake booster that's powered by hydraulic pressure from the power steering pump). I went with hydroboost on my car.

A roller cam can (and usually will) have much steeper opening and closing ramps than a corresponding flat tappet cam. This fact allows you to get more duration (rpm power) out of a roller than you can from a flat _without having a negative impact on overlap_. However roller systems are more expensive and you have to pay closer attention to quality. Having an 'inexpensive' roller lifter fail and come apart on you can destroy the whole engine.

I'm running a 'custom' grind Comp Cams solid roller in my 69 GTO, powered by a 461 stroker. It has Scorpion 1.65:1 aluminum roller rockers, ported Edelbrock heads with larger valves, and headers. The cam profile is 236/242 degrees intake/exhaust durations at 0.050" lift, 110 degree LSA, and just a taste over .600" lift at the valves (with the 1.65's). At idle it makes about 13" of vacuum - hence the hydroboost brakes. It makes around 560-570 lb ft. of torque at around 4200 rpm, and is over 500 lb ft by 3000 rpm. It has a Ford 9" rear with 3.50 gears, modified TH400, a 10" converter that lets the motor flash to around 3200 rpm when I hit it. It has runs a best e.t. so far of 11.86 @ 113. (That's allowing the transmission to do its own shifting - the upshifts occurred at about 4800 rpm). If I had a flat tappet cam with similar duration and LSA, it would have more overlap (and sound "nastier" because of that) and it would also make even less idle vacuum, all because the ramps on a flat tappet cam can't be as steep as on a roller.

The 3.50's are great for cruising and racing, but a little short for long distances. 70mph is about 3200 rpm. I took it on the whole Power Tour last summer but I still haven't found the courage to add up all my gas receipts. :leaving:

You can get an idea of how it sounds from these videos.
https://www.youtube.com/watch?v=3lNMRM8LsvQ

(Hear it run at about 1:37 into this one)
https://www.youtube.com/watch?v=EIzXIQDUxmc

So, it's up to you. If you're main goal is to just "sound" good then go for a profile that provides as much overlap as you can stand, keeping the braking concerns in mind. If you want it to actually RUN good, then you've got to balance a lot more variables and put more thought into it. :thumbsup:

Bear


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## Cory (Mar 2, 2014)

I don't know your budget, and this may not be a concern. But I almost had to sell a kidney by the time I added up all the receipts converting over to a good roller cam.

Cam, lifters, pushrods, distributor gear, special valley pan, beehive valve springs. Street manners don't come cheap.


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## 1972LeMans (May 4, 2014)

I want to thank y'all for the information it's all been teaching me a lot. I'm still up in the air about the correct route for me to take. On one hand I would love to put a Pontiac engine back into it and rebuild the 461. On the other hand I could easily put an LS engine into it. 

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## BearGFR (Aug 25, 2008)

1972LeMans said:


> On the other hand I could easily put an LS engine into it.


....and there arose a horrible wailing and sounds of gnashing teeth... :jawDrop:

Bear


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## 1972LeMans (May 4, 2014)

I figured that would air up done problems. I truly do want to put a Pontiac engine back into it so I think that's what I'm going to do.

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## BearGFR (Aug 25, 2008)

(Actually the guy spending the money [you] gets to make the decisions.) Do what makes you happy and don't look back.

Bear


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## 666bbl (Apr 13, 2014)

The only thing that makes an LS easy it's that it's figured out already. The sum of it's parts would probably be over what a fresh Pontiac going back in would be. I did some looking into the LS swap for my 61 bubble top. No thanks, not when it's already set up to take ANY old school Chevy engine already. The difference was considerable and I'd be a "me too" at the end of it all. Just sayin. Remember what the Beastie Boys said: "YOU GOTTA FIGHT...FOR YOUR RIGHT...to PAAAARRTAAYYY!!! Good luck with the car.


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## 1972LeMans (May 4, 2014)

How much different are the engine mounts from a Pontiac engine to a Chevy big block? 

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## Instg8ter (Sep 28, 2010)

It's not just the mounts, you will have to 
Re-route gas line down passengers side
New downpipes for the exhaust to meet the headers
New trans or bell housing adapter to your BOP
Possibly shorten driveshaft

It's true a SBC can be a lot cheaper to build than a Pontiac, but when your Talking BBC they are on par cost wise. Then you have to do all the above work and more where the Pontiac will bolt back in in an afternoon. These cars did not become legends losing to 396's on the street. 

Wipe out a lobe on a brand new motor and have to take it out, go through it again, re-install and the roller set-up doesn't seem so expensive.


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## leeklm (Mar 11, 2012)

Instg8ter said:


> Wipe out a lobe on a brand new motor and have to take it out, go through it again, re-install and the roller set-up doesn't seem so expensive.


Yep... I lost 1 hyd and 1 solid flat tappet cam last summer, with everything being done "right" from what I can diagnose. I tore the engine down over the winter to inspect any damage. Did not find any, but still upgraded to KRE heads and a roller cam from SD Performance. I spent way more money than I planned, but it would have been MUCH cheaper if I would have done this in the first place!!

It seems that most people are doing fine with flat tappet cams in a reasonably mild build, but the failure rate increases when you start pushing the limits with higher lifts, etc.


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## BearGFR (Aug 25, 2008)

1972LeMans said:


> How much different are the engine mounts from a Pontiac engine to a Chevy big block?


AlkyGTO is your man on that one. He's running a _nasty_ blown BBC in his 69.

Bear


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## 1972LeMans (May 4, 2014)

Thanks for all the info but I decided to buy the same cam that was in it. It's a comp cam extreme energy. 

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## PontiacJim (Dec 29, 2012)

1972LeMans said:


> Thanks for all the info but I decided to buy the same cam that was in it. It's a comp cam extreme energy.
> 
> Sent from AutoGuide.com App


If you liked what you had, then no need to take a chance on something else. Thanks for giving the update. Get rid of those 4.10's as its way too much for the street and a Pontiac has plenty of torque. I think you will like the 3.42's better.

Don't know what you have for a converter, but check out Edge Racing Converters. I did a little research when I was looking for one for my brother's 360 Six-Pack I assembled for him. The converter was reasonable in price and they are built "tight" with little slip so it doesn't run hot, responded well, probably helps a little with gas mileage under normal driving conditions. The difference between off the gas coasting and then applying normal gas was only a 200 RPM difference, yet it was a 2,500 RPM stall converter which acted like stock until you nailed it from a stop and it climbed right up. I also added a Trans-Go shift kit to his trans that allowed automatic shifting in Drive, or manual shifting once you pulled it down into Low or Second.


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## 1972LeMans (May 4, 2014)

I have a 3000 billet stall in it.

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## PontiacJim (Dec 29, 2012)

1972LeMans said:


> I have a 3000 billet stall in it.
> 
> Sent from AutoGuide.com App


You must have a pretty stout race prepped engine and be spinning about 6,500 -6,800 RPM with it. Many modified street/strip Pontiacs shoot to begin their torque band around 2,500 and run to about to 5,200 -5,500 RPM's depending on cam profile and cubic inches. You can RPM higher several hundred RPM's above that, but the torque drops off quickly -so you choose a cam with a torque window based on the engines RPM range, cubes, and head flow numbers while taking advantage of the maximum RPM's your engine can spin.

If you go to the 3.42 gear, it will take more gas pedal to move your car forward and you will be on the converter a lot as it will slip at the lower speeds. Your gas mileage will be extremely poor if you cruise around at all. If your goal is to race it, then not really a problem. Have a 1977 Pontiac Lemans I used to drive as a daily driver with 350 CI, TH-350, and 2.73 gears. Around town, maybe 13-14 MPG's because the car is about 5.600 pounds and stop and go killed mileage. On the highway at a steady 70 MPH I could get 19-20 MPG with the Quadrajet.


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## 1972LeMans (May 4, 2014)

I'm not too worried about gas mileage, more about drivability. I want to have the power and be able to go on the interstate and cruise at 55 without being at high rpms. I'm thinking that I'll go 3.23 in the rear. 

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## Cory (Mar 2, 2014)

At 55mph I spin 2400rpm with 26.5" tire and 3.23 using a "tight" converter. Enough torque and gearing isn't an issue .


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## 1972LeMans (May 4, 2014)

What do you mean a tight converter? 

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## Cory (Mar 2, 2014)

Stock


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## 1972LeMans (May 4, 2014)

Bear, what heads are you running? 

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## BearGFR (Aug 25, 2008)

72 cc Edelbrock RPM round ports. Ported by Dave Wilcox at CVMS. They're gorgeous. 

Bear


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## 1972LeMans (May 4, 2014)

I want to go that route with my heads, im looking for more power and lower my compression ratio. 

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## BearGFR (Aug 25, 2008)

One of the nice things about aluminum heads is that you don't have to worry as much about compression. The greater heat conductivity of aluminum means that they tend to run cooler and thus are not as prone to detonation, so you can get away with more compression ---- the down side is that conductivity also has a negative impact on combustion efficiency so the heads also tend to "like" more timing.

Where as with factory iron heads on a street engine, 9.5:1 or less is, in general terms "the limit"; that same engine running aluminum heads can get away with as much as 10.2:1 or even a little more. (Again, I said "general terms" - I'm not looking to re-ignite the dreaded compression ratio debate...)

Bear


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## 1972LeMans (May 4, 2014)

I called cvms and decided to go that route, I'm returning my cam and buying kre heads. I hoping for around your numbers. My car is going to be completely different following this deployment. I'm having a shop store it and work on it while I'm gone. 

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## BearGFR (Aug 25, 2008)

You won't be disappointed. Tell Jim I'm going to be mad at him if yours makes more power than mine... 

(Just kidding - I know he'll build you a good 'un.)

Bear


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## 1972LeMans (May 4, 2014)

That's what I'm going for haha! I do have a bigger displacement though. I told him that you recommended me to him. 

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## 1972LeMans (May 4, 2014)

So I just got off the phone with CVSM and they said that they will definitely be building mine with more power just so you have to go up there and see him. I'm going around with KRE aluminum D-port heads.


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