ihengineer76

Well fellas, (and ladies too) I'm building a 350 and trying to decide what cam to go with. Any insight on my possibilities will help.

Here is the motor: Its a 350 bored to 362 (sonic tested good) running forged rods, flat top forged pistons with 2.5cc valve reliefs. #5 heads ported, bumps smoothed, bowl work, 2.00 intake, 1.625 exhaust both stainless, hardened seats, chambers smoothed, cc'd at 62. Has adjustable roller tip rockers. Should be 10.85 static cr set up for 45 thou quench distance. Will be running headers. Intake is an eldelbrock OL4B with a Holley 750 vacuum secondaries. I will be running 3.36 or 3.42 gears with a 4 speed. The car will be street driven and race on weekends. (I live 15 minutes from the strip) I was thinking on going with and Engle 22-25 (.512 int .523 ex, 230 int 236 ex duration, and 110 degree LSA) If possible, I would like to go with the 20-22 which has .498 int .512 ex, 224 int 230 ex duration, and 110 LSA but am afraid that with the really high cr, I might have a pinging problem. I plan on running an aluminum radiator and 160 degree thermostat to keep the heads a little cooler also. I am just not sure if the smaller cam will bleed the cylinder pressures down enough to keep my dynamic cr low enough to run pump gas.

Thanks for any advice!!

Tom

Rickman48

Do you have power brakes to contend with?
Must retain 16 lbs of vacuum for them to work right.
Cutlass EFI will know just what you need.

ihengineer76

Yeah, I'm running power brakes, so the vacuum was another issue I was thinking about. Forgot to mention it, thanks!

cutlassefi

Thanks Rickman.

You would have a bit of a dilemma but the 4 speed helps. You have high compression and the need to bleed off pressure but need to retain vacuum.
Headers? Exhaust size?
I'd probably do something along the lines of an Erson High Flow 1 or similar, 296/296 adv., 228/228 @.050 on a 110 with .504 lift on both. You'll need at least that much off the seat time to bleed off some pressure. You could also add some exhaust duration depending on how high you're going to spin it.
As far as vacuum levels, you'll have to expect to raise the idle speed to give you what you'll need.

Hope this helps.

captjim

Tis is just my personal opinuion, but I don't think it is realistic to try and run pump gas on an 11 to 1 iron-headed engine with a big, slow chamber.

ihengineer76

Thanks cutlassefi, I am running headers w/ 1 3/4 primaries and 2.5 inch x pipe exhaust with pypes race pro mufflers. I bought the motor with most the parts and machine work already done by a guy who never assembled the motor. He sold the car about ten years ago and I bought the engine and parts very reasonably considering the work put in and quality of parts. The guy had a Mondello JM40 cam which is only good for a 455 Jet boat or all out race motor so Im not sure what he planned on doing with it. Its now just takin up space on my bench so it anyone wants it, I would sell it VERY reasonable.
I plan on winding to about 6000 rpm before I shift, so do you think the 22-25 would be too much cam, cutlassefi? I can deal with the brake issue if I have to.
Realistic or not, it's what I have and I'm going to make her run.

captjim

I have do doubt that it will run good, the question is; "will it beat the bearings to death"? The tune better be dead-nuts or it will detonate, whether you hear it or not.

ihengineer76

captjim, you're right about having to have the tune right on, and I will have to read my plugs a lot when I get it running. I think that if I get the timing and fuel ratio right and run a cam with a little longer duration, I can keep the dynamic cr down to about 8.4. I may run a 38 or 40 thousandths head gasket to lower the cr a little more as well. I am running .010 in the hole.

joesw31, what are you running for gears? And I will probably stick to the hydraulic flat tappet cam just because I already have the lifters.

cutlassefi

Thank you and yes I do offer something very close in a roller.
Jim is right, it will be marginal at best but you may get by with a little octane boost, a good cooling system and something that wil bleed off enough pressure. I'm not sure the JM22-25 will do that.

ihengineer76

cutlassefi, how much would a cam like you described in your first reply run? maybe with a little more exhaust duration and hydraulic flat tappet?