alexandervdr

on a 327ci 365hp (the L76 engine), torque/power is low in the low rpm range. If I am correct the camshaft opens the valves over about 250 degrees. However I do not want to speed at 140mph, nor race in the high rpm range. My prime use would be to cruise gently at 60-80mph.
Is it realistic to put a different camshaft (more conservative timing) for more low end torque, sacrificing some top end power, anyone has done this before?

larrywalk

Sure! Try something like 225/225 degrees duration on a 112 degree lobe separation angle (110 degrees works too!). Be sure to advance the cam 4 or 5 degrees.

BTW, the L75 cam has 222/222/114 degrees and work well also (it's the 327/350 hp cam).

rustylugnuts

You have a great camshaft already, why don't you advancing the camshaft timing to 2 or 4 degrees, this will move your power band to what you’re looking for without changing your camshaft. Just a suggestion you may want to try before playing the dreaded select a cam game.

rustylugnuts

muncieman

Are you using the original piston combo and compression??? You start dorking around with the cam and shorten you will build cold crank compression, best kept under 200 psi. I like the idea of advancing the cam first.

65tripleblack

Of course, the entire discussion assumes that you have as much spark advance in your ignition system as the engine will take before detonation sets in. Ideally, if the engine will run detonation free with about 16 degrees initial, with the other 22 degrees all-in by 2500, then you can't ask for more than that. Well...actually you can, and that's 20 degrees initial with 18 centrifugal all in by 2300, but I doubt that the engine will tolerate it.

I doubt whether advancing the cam by 2 degrees will make a significant difference, enough to satisfy you realistically. Another trick would be to detune the cam by opening the lash to .030"/.030" if it's not set there already. Again, this is good for a small increase in torque at the cost of a small amount of peak power. Both are band-aids, AFAIAC.

So, the first question is whether or not you want to retain solid lifters, or not. If you want to retain solids, then the stock LT1 cam (Speed Pro CS1145R) will give you noticeably more bottom end with a sacrifice in peak power. This cam is happy with the same static compression as the 30-30 cam. If you want to use hydraulics, then another stock Chevy cam that works well with your static compression ratio is the L79 cam (Speed Pro CS179R).

mikem350

Check your timing curve, make sure the vac can is working also!!!
I like the cam advance tip also...before swapping it out

BLee

It's the same cam a 302 uses. That was the trick back in the 70s, advance the cam 4 degrees to get a little more bottom end, which the 302 really needed.

MiguelsC2

Why not go to an 097 "Duntov" camshaft?

Lots of torque and you get the revs of a solid lifter cam.

alexandervdr

thanks for you comments, I agree that changing timing is a far less risky game, but may not give enough punch increase in the bottom range.
I have never rebuild an engine, only read two books and studied one 2hr video on small block rehaul, does not make me an expert ;-). If I understand correctly, then it takes removal of intake manifold, rocker covers, rocker/rods/tappets, before the cam can be pulled out. Is there a catch somewhere ? I read that replacing the cam and NOT replacing the cam bearings is an absolute no-no. Is that true?

MiguelsC2

Regarding cam bearings, depends on how many miles the motor has on it.Among other things. But it's not a given they will need replacing.

You will also need to pull the hood,radiator,fan,pullies,water pump,timing cover etc... Cam slides right out. Make sure you get the timing marks aligned on re-install. Other will suggest advancing the cam timing. Might want to seek pro help on that one.

Be sure and do your home work before tearing it appart.

AmericanPie

No offense, but may I ask how long you've owned your Corvette? I'm just wondering if you recently purchased it, unaware that the car had a true high performance engine with a "rough edge" that you weren't prepared to live with.

IMO it's always sad to see someone lowering compression, installing milder cams, etc. in hero motors like this; it's like cutting off an alpha male's *********. Hot cams and high CR's are what make motors like this special and extra desirable to many enthusiasts.

Really, is it out of the question to sell your current Corvette and then buy a C2 with a milder motor (such as a 327/300 or 327/350) and other amenities that you might find easier to live with? If you wouldn't have to take a loss maybe this is the best solution in your case. Just a thought.

w1ctc

You might consider changing the rear gear to 4:11 or the like.
An easily reversible change.

alexandervdr

No offense at all ;-) The point is that I have not bought it yet, I am reviewing all the ins and outs of a C2 coupe I am considering to buy. I checked as much as possible ('do the homework') like VIN and body numbers, birdcage rust, and engine type. I even test-drove it but it misfired all the time because of bad ignition points. The owner now reported it's repaired, but still has a 'flat' in the bottom rpm range. He says it's the holly that needs overhaul, but may just be that this 327/365 with wide cam does not torque well anyway (as I read somewhere else on the forum). I am in europe and C2 to test-drive are very rare. So I have to learn on the fly and tap into the knowledge on this forum.

I'll know more next week when I'll do a new test ride, mainly to qualify the engine. My question on changing the cam is related to the direction I would possibly choose when more toque is as simple as swapping the cam. Now, I don't know how well this engine has survived time, so I may need to replace it anyway. We'll see, it's part of the fun too to do the homework well, read and learn, it's a great learning experience, and the cheapest part of restoring a car ;-) . I know, because I just finished building a Cobra replica

MikeM

That cam ought to be just fine for that speed. Don't let the degree numbers fool you on the cam. It has LOOOOONG opening and closing ramps.

Contrary to popular internet myths, There's nothing wrong with the low end torque of the cam in question. There's more than enough to haul that car around at low speed. Just select the proper gear in the transmission.

If the engine won't run decent at low speeds, check the carburetion and ignition.

rustylugnuts

After reviewing your replies, I strongly suggest you find a professional mechanic who specializes in American muscle cars drive and evaluate this Corvette. Guessing and assuming mixed with inexperience can be a volatile mix, not to mention very costly!

rustylugnuts

65tripleblack

Are you, me?

lovevettes

I have a '64 with the L76 engine , I do not like the take off [launch speed] in first gear also. I always blamed it on the first gear ratio in the Muncie trans. It has the original CLOSE ratio Muncie type gear box in it.
I have a '60 Corvette that has a non- original Muncie WIDE ratio gear box in it and the launch speed is much , much better.

rustylugnuts

What you're saying maybe correct, but the trans ratios are only half the problem, what are the rear end ratios. This could be why you lacking launch speed.

rustylugnuts

cv67

id change cams before dorking around with advancing/retarding, that rarely makes a sizeable difference.

lovevettes

My '60 has the automatic ratio---3:55 to 1 [wide ratio Muncie]
My '64 has the standard posi. rear ratio ---3:70 [close ratio Muncie]