I am now rebuilding a 350 for my 1969 corvette. It will be a numbers matching car, driver. The original motor was a 350 hp motor. 64 cc double Hump heads. I want to put a roller hd cam in the motor and have between 350 - 370 HP. Can you make some suggestions on which cam might work.

Thank you
Cal

 

Which transmission and what rear end ratio?

 

4 speed original Muncie, M20, and 3.56 gears.

thanks

 

If it is going to be a driver I would use the original L-46 cam. The original cast iron intake manifold doesn't make power above 5600rpm. Any cam that sees gains above those rpm's is wasted.

See my post on the NCRS forum.

http://www.superchevy.com/technical/..._dyno_testing/

 

Here are some Competition Cams choices

http://www.compcams.com/Company/CC/c...?csid=158&sb=2

http://www.compcams.com/Company/CC/c...?csid=150&sb=2

 

The manifolds will be stock. Is there a roller cam that will produce numbers close or better than the L-46.

thanks
What is the title of your post.

cal

 

That's interesting I am using the 270 roller in a mild 383 build now. Not sure how it would work with a stock bore 350.

cal

 

Your compression is high, iron heads, good gearing and manual trans.
http://www.summitracing.com/parts/hr...make/chevrolet.
Good operating range for your engine & combo. Check valve to piston clearance.

Edit: Might want to go with the next size bigger on a 110 LSA. You likely have an actual 10.5 to 1 compression ratio.
http://www.summitracing.com/parts/hr...make/chevrolet

 

These seem big for a 350. have you used these lifts. Is vacuum
ok and low end. I am using the stock intake and exhaust manifolds.
thanks

cal

 

The intake duration @ .050 is less than the L46 cam on the smaller one. This is where street manners are determined. That said your compression plus iron heads will not allow the use of a smaller cam due to the intake closing point. The L46 cam had slow ramps and 114 LSA that made the intake closing point much later reducing DCR avoiding detonation. The roller has fast ramps that close the intake valves faster trapping more compression increasing cylinder pressure and DCR. Makes more power but increases probability of detonation. Your rear gear combined with the wide ratio trans will take care of bottom end. Operating range of 2000-5400 or 2200-5800 is not radical for your combination. The factory heads, intake and exhaust manifolds need more lift and duration than good heads, intake, headers and free flowing exhaust would need and call for a split duration cam. Will see if I can find something better suited but your combo calls for big, I would lean toward the 2nd one. Vacuum will be fine. I have run over .600 lift with domes but you ALWAYS have to check clearance. Put the piston @ TDC and pull the springs on one cylinder. Lower them to the piston top till they touch. Then measure the difference and subtract the lift. This gives you clearance. You will need to do the rope trick or make an adapter to pressurize the cylinder with the valves closed to reinstall the retainer and locks. Put the car in gear if you pressurize the cylinder to keep the engine from turning over. I ran a Camaro that I shifted @ 7200, when we tore it down you could see the exhaust valve marks on the piston tops where the carbon didn't accumulate. That is too tight but it ran like a scalded dog and didn't have any damage. If your @ .100 clearance your fine since the piston is never @ TDC when the valve is all the way open. Will come back after I run some calcs and search a little more. Is the bottom end and pistons 100% stock? Are the heads decked? Gasket thickness and bore?

 

To 63 mako

What about these two Comp Cams

http://www.summitracing.com/parts/cc...22-8/overview/

http://www.summitracing.com/parts/cc...23-8/overview/

thanks

cal

 

If it is all stock with a .049 gasket with 4.125 gasket bore you need an intake closing point of 67. This gets you a hair over 8 to 1 DCR. That is cutting it as close as you can and run pump fuel with a performance timing curve. This cam has that closing point and is comparable to the 2nd cam I listed as far as operating range and advertised duration. http://www.compcams.com/Company/CC/c...?csid=160&sb=2
I think the Crane Cams do not have the 4 degrees advance ground in. This allows a little smaller cam. Could widen the LSA. That can gain you a little in both peak cylinder pressure reduction and vacuum. Still looking.

 

This is the one. Right split, right closing point, right lift, wider lsa, no advance ground in, same Intake Duration @ .050 as the stock cam. Should have similar manners and work real well. Don't let the advertised duration numbers fool you. The factory cam likely had a duration of about 300.
http://www.summitracing.com/parts/cr...make/chevrolet

Edit: I was wrong. 288/292. Here is your factory blueprint cam specs. http://www.summitracing.com/parts/HRS-117091-14/

 

Scary. I have done so much reading I am actually understanding this.

cal

 

I think with your compression and Iron heads you will not be able to run pump gas or you will have to dial your timing back and run it rich to avoid detonation. You might get away with the second one but I doubt it. The first one won't work.

 

Check the specs on these two cams. Stock L46 vs Crane roller.

If you ever looked at your piston tops they have a huge trough relief for the valves. I think you could lift to close to .600 with them. Flow peak @ about .500 with your heads so duration at the higher lifts is what you want, area under the curve without to big of .050 duration to increase your operating RPM. Crane cam is a great fit, it ain't a tow truck! The comp 276 you linked had Duration @ .050 of 224/230. The Crane 284 has duration of 222/230 Stock cam has duration of 222/222. Very similar manners on all, Crane get your intake closing point almost exactly where the stock cam is due to the 4 degree advance not ground in. Comp cam XR276HR closing point is 64, trouble.

 

Ok let throw a curve because I may be in trouble on a different build. I have recently retired and have saved 5 corvettes to work on. I used to do a lot of racing and built my own motors however things have changed and I am learning all over. Especially camming.

So I am building a 383 10.1 com. with Sportsman 2 heads. I have been guided to the following cam. for a 4 speed, 3.36 geared 72. Is this going to work?

http://www.summitracing.com/parts/cc...22-8/overview/

Thanks
again
cal

 

You can figure the operating range will drop about 400 rpm from what your seeing due to the increased CI. The XR276HR would be a lot better choice both in RPM range and DCR/compression with iron heads. My 383 with AFR heads & 10.4 to 1 is running a Comp XR288HR ground on a 113 LSA for nitrous. I got a 4.11 and close ratio T56 so my gearing is more optimal for the bigger cam but my DCR is around 7.85 to 1.

If your exactly 10 to 1 compression your DCR with the XR270HR will be be 8.24 to 1. With an operating range of 1200 to 5000 RPM. I would not do that with iron heads and with a 4 speed and torquey 383 I would up the operating range.

The XE276HR would be 8.05 to 1 DCR with an operating range of 1500-5200. That would be the cam size I would look at with that combo. It will need premium.

If you want to flatten the torque curve, smoother idle and still have very similar manners go with the marine version. It is almost identical except it is a 112 lsa and must have 2 degrees less advance ground in. It would have a DCR of 7.8 to 1 and operating range of 1500 to 5500.
http://www.compcams.com/Company/CC/c...?csid=170&sb=2

 

Thanks I got some work to do.

cal