okay so when i figured out my dcr i used the right # 68, all the same dude do you think my symptoms are consistent with a timing chain error?

 

T/A Racer - Just wondering if you degreed the cam in to make sure that it's real world spec matched the quoted spec, and to make sure it's stabbed in there correctly? I'll tell ya man, if I was even suspecting that I had installed a tooth off, I would be pulling that cover and making sure. BTW, that's a pretty small cam for a 383. You might wanna think about going to something a bit more appropriate for a stroked lt1.

Dave C.

 

http://www.compcams.com/Technical/Se...=305&Submit=Go

There's your link.

BTW a flat tappet has an all together different profile. The IVC may be the same but how it got there and the duration numbers are way different.

 

I checked years ago how much a tooth off was and it was a bunch(maybe 20*?) don't remember.
Before I ripped it apart I would make doubly sure the tune was right along with everything else.

 

Thanks for the link and I now understand the shorthand.

IVC is the only variable that matters for cranking compression however. Profile and duration are irrelevant.

Crank gear 18 teeth Cam gear 36 teeth. Every cam tooth would be 10 cam degrees or 20 crank degrees.

 

I am well aware of that.

 

Then stop busting my ***** over the flat tappet bit. : )

 

alright well we have checked basically everything else, besides the timing chain, we even put in a stock pcm. it didnt ping nearly as much hardly at all actually, but i just figured the spark advance was less than my madz tune. but the idle surge was still there, and the low rpm bucking was just about as bad. is there anyway to figure out if my timing chain is close. i dont understand why they never took the 5 seconds to put a timing mark on these freakin balancers.
okay so can someone tell me what the symptoms would be if i were advanced 10* like off one tooth.
if they match this
-hard low rpm bucking, that cleans up with higher rpm
-bad idle surges until it cant hold it anymore than dies
-low power
-pings like crazy under hard load
-but starts easy???????

 

CCCCCYA- i realize my cam is small BUT-
heres my reasons
#1 nobody likes it but money, i had the cc305 and i have none, studying mech engineering and its putting quite the stress on my budget. if you give me one id be more than willing to put it in.
#2 im on stock heads, (as the 383 crowd cringes) i home ported them and although they look great i gurandamntee they wont flow up to the rpm needed for some of those huge cams.
#3 due to the very limited budget i CANNOT afford another rebuild right now and dont wont to be spinning my engine past 6200rpm where those big cams shine and my heads wont flow
#4 i drive it on the street and want the torque so its fun to drive
#5 i cant even get the damn thing running right, another cam is the last thing on my mind

 

Hole in intake tube between mass air meter and throttle body?

Mass air backwards?

 

haha no the mass air is on right, and we injected propane into the intake to see if there was a vaccum leak and it was running lean, no go the propane didnt do a thing as far as speeding the revs up or anything

 

Low on funds. Nuff said (and no, I'm not donating a cam. heck man, I've had my hand out waiting for donations on my OWN builds so I can hardly support someone ELSE's HP/Crack habit!)

I wont bust your chops for the cam selection anymore You WILL have a good running motor if you can get it tuned in. If you've dropped in a totally stock computer and it's running better with less retard, then I think you may just need a good solid dyno tune. It should idle almost like stock (the 305 really IS a very mild cam for a 383). Of course make sure the mechanicals are correct, but you might be pleasantly suprised at just how much of a difference a good tune can make in terms of idle and power - not to mention part-throttle driveability.

Dave C.

 

Change injectors, or maybe accidentally get a tune for larger injectors than you have? Tough to verify I know. You really should try to get hold of a scan tool...AutoTap or something similar. School maybe have something?

 

As I said in one of my posts in the other thread, I have installed a timing belt(2.5 in a Sebring) a tooth off and experienced the exact same symptoms. It started just fine and idled decently, but under load it bucked and pinged like you wouldn't believe. I'm not trying to bust your *****, but I'd hate to see something happen to a brand new engine. I know it takes quite a bit of time to get to the chain, but I strongly feel it's worth a look at this point.

 

madz said hes had nearly this exact tune on 383's with my cam specs and its run great. im not lookin for every drop of hp, all i know is it shakes at idle! not crazy but definately some. plus my other symptoms it definately does not idle like stock. so heres the only things left
-tune, had a guy look at it who tuned his computer and he said it didnt seem computer related, talked to ion, went through my code on his computer and said it looked great.
-injectors, at like 5,00rpm at WOT they were 75%duty cycle yeah so theyd be over the 80% recommended at 6200 but im having so many problems down low i dont think thats where my main problem is
-timing chain, i really just want to know if having a tooth advanced theoretically raises compression, b/c i still think 225psi seems high to me, and it is pinging. i think this would explain my shaky idle, but usually they start hard when this happens and mine definately starts easy