Seeking engine gurus advice/opinions as I'm not in the know. I have a 1979 L82 close ratio 4speed. I was in the process of installing Hooker Competition 1 5/8" long tube headers and true duals with no cats. I had plans to add aftermarket heads sometime in the future. Unfortunately, an exhaust manifold bolt broke off on one of the heads. After a chain of really poorly conceived ideas I find myself with the need to replace the heads now.

The car has 46,000 original miles and I want it to be a weekend ride. Plans are for said driving to be quite spirited when opportunity allows. So, what I'm thinking about at this point is Promaxx 185cc runner, 64cc chamber Freedom Series heads. I spoke to my local machine shop guru and he has used these heads with success and considers the quality good enough to use on one of his own personal builds. What I'm needing help with is cam. I'm tempted to change the cam while it is apart, but I am on a budget (especially because I hadn't planned on heads at this time). I also don't like to do things twice. Please throw out opinions and support of either changing cam or staying with the stock L82 fare. For opinions leaning to change, what should I change to? Any supporting facts regarding said opinions will most certainly be appreciated and help me to arrive at an ultimate decision. Thanks in advance for your time and expertise!

 

I would keep the stock cam if you are on a budget. When the funds permit, go ahead and upgrade to a hydraulic roller cam.

 

What are the real benefits of going roller based on this cars usage? What specs would you recommend based on the same?

 

Flat tappet cams and the current oils available today don't really work well together.I would just save up and do it right the first time. IIRC, a 79 L82 has 9.0 compression with a 76cc head. Your 64cc chambers should raise that, so I would look at a cam with a duration of around 225 degrees at .050.

I'm running a 350 with AFR 195 heads with a Comp HR 224-230 duration and 502-510 lift with a 4 speed and 3.73 gears.

 

Isn't that duration the same as the L82 cam?

 

Couldn't I get that same lift with different rockers? Any ideas on the HP and tourque you are generating with your combo?

 

I agree with using the stock cam for the time being. I would add 1.6 rockers to help it out a little, the increased breathing and compression will amaze you. I'd strongly recomended a double roller timing chain as the factory unit was junk. Good luck, you will be happy.

 

I had to look up the L82 cam specs. 224 duration and 450-460 lift on a 114 LSA. Adding 1.6 rockers will raise the lift to 480-490.

I'm not sure of my HP but I'm planning on some dyno time after my front suspension project is completed.

 

If you research the benefit of changing to a hydraulic roller I think you will see it's nothing but good. Cam for cam you may see an increase of 25-50 hp or there about by converting, and that's ABOVE a new flat tappet. They will both annihilate the stock cam. But it's not cheap. About $1000 vs a couple hundred for a flat tappet replacement.

Sooooo... The common train of thought is build the motor and then do the cam based on what you built. But if you don't add the cam to the equation, you've just bolted a bunch of parts on without tying them together. Leaving a lot on the table. Like, a LOT with the stocker I would guess.

I would ask you builder friend what he recommends and probably do it. The cost of a cam compared to what you are already spending is almost negligible. And the difference would be dramatic, even if you stay flat tappet.

But honestly, Google the upgrade and edumicate yourself. Don't restrict yourself to Corvette island for that kind of knowledge.

 

Thanks all for the input. I did talk to my machine shop guy, in fact he had a engine on the stand that was built as an E85 engine. It had the same heads I'm contemplating, but with I think, 12:1 compression and a roller cam. I asked and he said that a roller would probably run about $700.00 with the pushrods and lifters. That said, he is of the opinion that unless you are going to get into higher lift scenarios a roller isn't necessary. Additionally, he is of the opinion that after break in, the concern of flat tappet cam wear is not an issue. I'm curious what folks think about that?

 

I have never had an issue with flat tappet cams. The cam in the L-82 IS THE LAST THING I'D WORRY ABOUT. Use a high zinc oil and you will be just fine.the L-82 cam is the number 1 chevy small block street cam of all time for a reason. If you want to spend close to a thousand bucks for a roller cam you better be thinking of just building the entire engine.I don't care too much for hydraulic roller cams they weigh a good bit and I'm not a fan of valve train weight.solid rollers are better but they don't like low speed operation. Not slamming hydraulic rollers but iv seen them have issues too.

 

I appreciate the input. I'm leaning to sticking with the stock cam at this point...unless someone makes a very compelling argument to the contrary. Knowledgeable input is what I was seeking as I want to make sure I don't go a direction I may regret.

 

If you got it stripped down that far do the roller cam take advantage of what they offer. It will be right in front of you

 

Try the existing cam and see how you like it. If you decide to change it later you will have a reference point to start with. I've seen more people tha I can count wish they'd have stayed with that very cam.

 

Those Promaxx heads are cheap azz heads with quality issues. Hobbiest's like them because of price and they have a machine shop go through them to ensure they will seal before installing.

Options for the sbc are unlimited and only you can know what you want. You already have a performance cam in the motor and if you have never installed a flat tappet cam before I give it less than a 50% chance of success. In that case I would recommend a mechanic that will guarantee his work. What you need are better heads with higher compression and better flowing exhaust. L82 had/has forged pistons and forged crankshaft with a GM performance camshaft - a great block to build on. Yours has low miles to - they have a long long time left to last. IMHO heads are easier to swap than the camshaft. Go with the head swap first and later if you find a cam swap is where you want to go do it then when you are ready to tune the motor also.

So what I'm saying is if you buy cheap heads have them checked for spring height, valve sealing, and flat surface. If you want a new cam have someone that will install it and guarantee it. BTW a roller cam will cost you $1000 when done. Long tube headers and larger exh pipe only helps this combo and I read you are already going there.

Something new owners overlook is tuning their car. Late model C3's had terrible smog tuning. Carb and ignition tuning costs little but takes a lot of patience. Recurve your distributor and upgrade your carb jetting for performance is must whether you install go fast parts or not. Now a wideband air/fuel monitor is not cheap but you can buy them under $200 and they don't lie.

Hope this can help and if you have any specific questions comm'on back.

 

I would change the cam and make sure the heads and cam will work well together.

I have the Voodoo 268 cam (http://www.lunatipower.com/Product.aspx?id=2325) in my 79 with a close ratio 4 speed and 3.73 rear. Take-off can be a little tricky if the RPMs get below 1,500 (I'm probably going to be putting the original 2.64 1st gear transmission or going with a 5 speed at some point), but it pulls hard from 1700-6200rpms. I haven't had it higher than 6200rpms since I've still got the original L48 crank (though the hypereutectic pistons do save on weight). If you want something a bit milder, there are slightly smaller Voodoo cams available for different power ranges.

 

The L82 cam is a great street cam. I swapped it into a couple of builds many years ago with great results. I would only consider a cam swap if you are willing to go to a hydraulic roller.

 

The L82 was a great cam about 40 years ago; times change.

CAMs and Heads should be a matched pair.

Right now it seems like your choices are being framed as "keep existing cam" or "Spend $1,000 on a hydraulic roller cam". If budget/ value is a concern, then I'd look at going with an appropriately matched, modern, dual profile hydraulic flat tappet cam.

Those heads are going to support higher levels of lift and will probably need it to get to max airflow. Modern cam lobe profiles are going to have much more aggressive ramps. Take the #'s from your head's airflow chart and plug them into CompCam's CAM QUEST software (free download) and then select your goals from the drop down (performance level desired and balance between fuel economy and perf). -And you'll get an idea of roughly what a good cam can do for you vs. the stock one and what it should ROUGHLY look like (duration and lift).


You can support more high-end HP if you want by going with a bigger cam as you've got a manual transmission and don't have to worry about stock TC stall speed, but get all of the details about your combo together including airflow #'s from the heads, any exhaust info and give a couple of the big cam companies a call to get their recommendations for your build- you'll also need rear end gearing and tire size info.

The duration that's recommended for your heads and goals might be SIMILAR to the L82 cam, but there's still other gains to be had from modern lobe profiles and a dual profile to help out the flow on the exhaust side. Getting some more lift will also likely help with those heads.


Get a HARDENED flat tappet cam and new lifters; be careful with non-hardened Extreme Energy CompCams' cams and be sure that the springs that come with those heads are appropriate for your selected cam- many modern heads will come with high pressure springs setup for hydraulic roller cams -these plus the soft metal base chepo flat tappet, high ramp cam lobes will result in wiped lobes in no time.

OR: If you decide you're not up for a new cam right now figure out if 1.65 ratio rockers will work with your heads and springs. The faster open/ close rates with higher ratio rockers and the old L82 lobes might mimick a more modern cam lobe's faster open/close rates and could get you a little bit more lift.

Adam

 

No question there have been substantial improvements in cam technology in the last 40 years, but in my opinion, you aren't going to see enough of an improvement in performance going from one flat tappet grind of 220 degrees duration to another albeit 40 year newer design flat tappet grind of similar duration to justify the expense. Stick with the L82 cam until you can afford a roller cam. You WILL notice the difference when you go to a roller.