Cam help

[GO67SS]

What is the proper cam I should be running? I was told at a local Dyno shop that my cam is causing me problems: backfiring on occasion under 2500 rpms I am currently running:

462 210 110 @050 i believe that is the way it reads
472 215

Here is what was done at the Machine Shop: :eek:
Line Hone block
Cam
Springs
polich crankshaft
performance valve job? (what ever that is)
resurface heads
match port intake ports
1.6 Compcams rockers
Hi volume oil pump


http://www.cardomain.com/ride/662136

[spaztikatik]

there is a lot to consider when running the right cam in your engnie. are you using an automatic or manual transmission? whats your rear end gearing if you have an auto? what size is the engine? what is the compression ratio? get back with this info and i'll be able to help out

[GO67SS]

T56 6spd, 12 bolt rearend 3:73 gears, CORVETTE LT1 350, 10:1 compression

Thanks for checking into this.

[spaztikatik]

Hey there, I just got off the phone with Comp Cams and they say it is highly unlikely that the cam would be your problem. I mean, on the grand scale of things, this cam is pretty tame, the stock ECU should be able to use it easily. What they reccomend, and I as well, is checking your rockers. If they were put on too tight, it would cause some of the valves to stay open longer than they should. next you want to check and see if the crank and cam are dialed in correctly or in sync. It isnt likely that the electronic ignition would be misfiring, i havent really heard of a case for that.

if all that fails, they say the cam they would reccomend is something around the same lift, with a 212 duration on the intake and 218 duration on the exhaust, with a 112 lobe seperation angle. Check all this stuff out, then give a shout back to see how you're doing.

Hope this helps!

-Russ

[RickWI]

Unless the cam lobe(s) went flat (in other words is ruined during break in) or the camshaft is phased completely off (which I doubt) it's not the cam. Check you lash and cut your filter open and look for debris. Otherwise I'd suspect ignition problems, as I have seen 98% of the time on the dyno (my own dyno that is).

If lash was incorrect to begin with that would also be a problem. I would never let an engine off the dyno with a miss like that. We always will resolve prior to taking it off. That's what the dyno is for.

[Scrote]

Thats a baby cam, even for a stock LT1, I am with the others here. I think you need to re-check the valve lash...

Also, have you had any programing done??? Is it backfiring out the exhaust or the intake? You might be getting a little bit of reversion in the exhaust caused by the camshaft, which is screweing with the oxigen sensor, and you could be just in need of more/some tuning.

Take 'er easy,

Erik :)

[RickWI]

You have that POS optispark ignition system as well, so that's another variable that can cause you grief.

[Scrote]

You have that POS optispark ignition system as well, so that's another variable that can cause you grief.


Yeah, I guess he would not be the first person to have an Opti go south... ;)

[GO67SS]

Thanks everyone for your input I will start the diagnosis and get back to you in a week or so after the dyno. I just changed the opti but it wouldn't surprise me if it is bad. :mad: $300 down the drain. I will use a MSD opti when I change the cam to something more agressive.

[forced induction]

I was always taught- Nothing is right until the timing is dead on. Depending on octane of fuel you should be able to run 38 to 42 degrees full advanced all in by 2500 to 3000 rpm. I have seen 10to1 motors with to weak a spark missfire when under load, the spark is so weak the plugs cant fire under high compression, its like blowing the flame out on a candle.

[Stuart Adams]

Talk with Jody, the motor/hp guy!!