["Guy]

Jim,
On the subject of my 292h cam and rocker ratio in a 406. Right now the cam is installed straight up and the compression ratio is @ 9:1. You had said to work with what I have...my idea is to bump the compression ratio to 9:7 and advance the cam 2deg.,1:52 full rocker,full 7/16 rocker studs also Rhoads lifters will be installed. My heads are 16's they are being ported on the intake side only also the crossover is being filled, valves are severe duty ferra's. The car is a 4spd 68 gto, 3:55 gear. Would I be better off with the Melling's ram air 4 cam or what I described above? I had the car running pretty good for the combo I had in Carcraft with this 292h, I'm hoping it runs way better with the changes I described.
Any advise would be helpful!
Thanks,
Guy

["Guy]

Jim,
On the subject of my 292h cam and rocker ratio in a 406. Right now the cam is installed straight up and the compression ratio is @ 9:1. You had said to work with what I have...my idea is to bump the compression ratio to 9:7 and advance the cam 2deg.,1:52 full rocker,full 7/16 rocker studs also Rhoads lifters will be installed. My heads are 16's they are being ported on the intake side only also the crossover is being filled, valves are severe duty ferra's. The car is a 4spd 68 gto, 3:55 gear. Would I be better off with the Melling's ram air 4 cam or what I described above? I had the car running pretty good for the combo I had in Carcraft with this 292h, I'm hoping it runs way better with the changes I described.
Any advise would be helpful!
Thanks,
Guy

[Jim Hand]

Guy,
If you mean by "better off" that your engine will run smoother and idle better, the 041 will do that. If you mean which would be quickest at the track, that would require a series of timed tests with each installed. In any case, try a range of shift points - the CC Magnum series of cams you are running tends to run out of power earlier in RPM then comparable duration wider lobe separation and dual pattern cams.

Concerning porting intake only, if intake porting helps, that means more air/fuel into the cylinder. That means more exhaust to get out of the engine. I would much prefer excess exhaust flow rather then not enough! And this is true especially with a single pattern cam. Why not port the exhaust?

If the cam is installed as suggested by Comp Cams, it will have the intake LC at 106 and exhaust LC at 114, for a total advance of 4 degrees. Two additional degrees of advance will move the intake to 102, which will likely shorten the existing power range. While that might crutch the bigger cam's effect with an auto trans, I doubt that that change would benefit real strip performance with your manual trans.

Jim Hand

[slowbird]

I think Jim Hand made a mistake in his math or did I miss something. 114 l/s to 106 cl is 8* advanced and 2* more would put it at 104 cl.

75bird 7.41 1/8mile at 92mph street car
73Ventura 11.88 at 113 streetcar
69GrandPrix 12.64 at 107 tow car
65GTO 10.14 at 129 tri-power dragcar

[Jim Hand]

SB,
Thanks, I did make a mistake by not specifing cam or crank degrees. Advancing the cam timing by two crank degrees from 106 Intake LC would be 104, for a total advance of six degrees. The effect on the engine would be as described.

It should be noted that a two degree cam key will move the crank timing by four crank degrees, which on the typical CC unit would set the intake CL at 102 degrees (if installed for advance). In any case, when moving the cam for better or different performance, it is important to degree the cam to find exactly where it is before and after the changes.

Most C.C. catalog cams have a 110 lobe separation (LS), with the intake at 106 lobe centerline (LC), and the exhaust at 114 Lobe CL. And that is a cam advance of four degrees. Advance or retard is measured from the "straight-up" position of the cam, which is 110/110 on a 110 lobe separation cam.

Jim Hand

["Guy]

Morning Jim,
The #16's heads are being ported on the intake first to get the best flow on the intake, then we wil go to exhaust port to look at the intake to exhaust ratio. We are shooting for a ratio of better than 75% intake to exhaust flow ratio. We are still working on porting right now.
I am steering to Melling's 041 cam, even if I get 80% on the ratio for single pattern cam. I like the idea of a broader torque band and smoother idle.
If I stay with the 292h I'll stick to installed staight up.
Last weekend I did some work on a freind's 69 Judge with a ram air IV, m21, 4:33 gear, 9800 actual miles(GM's 1st place car Carcart summer nationals 2002)a sweetie. I pulled the distrubutor for a recurve. found the vacuum advance not working and oil coming out of the coil. One good thing good I found it has a full rollar rocker set-up, he wanted to spend money to buy a rollar rocker set-up...question for you at .030 lifter travel do you set the rockers with a .020 or something clearance on a stock ram air IV? He wants me to set the lifters with a tune up.
Thanks,
Guy

[Jim Hand]

Guy,
I set the RAIV hydraulic cam valve train the same as any hydraulic. Zero clearance in the valve train is first positively located with the lifter setting on the base circle opposite the lobe. When using standard hyraulic lifters, the adjusting nuts are tightened (pre-loading the lifter) 1/4 turn from zero clearance and locked. When using Rhoads variable lifters, I set the preload 1/2 to 3/4 turn rather then 1/4. Rhoads Company suggests 3/4 turn.

For a complete procedure on accurately adjusting lifters, check out the referenced material.

http://home.comcast.net/~69bird3/jhand7.htm

Jim Hand

["Guy]

Thanks Jim,
Going with the 041 cam in my 406 build...
If my heads have air flow into the .500 to .600 lift than I should look at a 1:65 rocker or stick with 1:52?
And where the heck can I get this Melling's spc-8?
Guy

[Jim Hand]

Guy,
The Melling SPC-8 cam is still available, but carries a PN of 26308. Go the listed page to find an outletin your area. The Crower 60919 is Crower's version of the 041 cam and it is a good one.

Concerning rocker ratio, use the rockers you have on hand to get the engine running and find how it actually runs, both on the street and at the track. Then, if you wish to change to higher ratio rockers, you will have a good baseline to know if the higher ratio helped in the way you wanted after you install the higher ratio. Prepare the heads and springs for higher lift now and it will be a relatively easy test to install the higher ratio later.

Jim Hand
http://www.melling.com/distributors/default.asp

["Guy]

Jim,
I have a 1:52 magnum rollar tip rocker, but I was going to buy the bigger full rocker studs and Comp's Pro magnum 1:65 rockers to go into the build right away. Still think I should try the smaller lift? I know the bottle neck studs and rollar tipped rockers are not as acurate as the setup I want to get. Next year I was going to go to a new rotating assembly, maybe a 473ci?? Anyway thank you for taking the time to reply!
Guy

["Guy]

Jim,
One other thing, I did find the mellings cam at Wagermans here in the Twin cities. Crower or Mellings or are they the same grind?
Thanks