DOes any company offer a 9 key way crank sprocket with their timing set for a LT1. I am even having a hard time finding one with a 3 key way sprocket.

Which sets are you guys running. Also were you able to advance the timing 4 degrees with that set.

Thanks in advance for any help.

ken

 

I am running Cloyes True double roller chain. It has 3 keyways and I believe you can advance or retard timing by 4 degrees. It's a nice chain and only runs about $70, but you will need to clearance your timing cover to make it fit. You will also need to run an electric water pump.

 

Like he said, there are no "LT1" timing chains out there really besides stock and maybe lunati, but not sure if its a true LT1. Any aftermarket timing chain requires a vented opti and electric waterpump.

Rollmaster makes a very good 9 keyway true double roller timing chain, you can get it at competition products

Make sure its the 86up set

 

i have never had to clearance an LT1 timing cover to run a Cloyes Double Roller chain, and i have used them on at least 10 engines. i have heard of people having to clearance to use the Comp Cams double roller chain though.

IMO a quality double roller is the way to go. a stock LT1 chain is far too weak to trust with any combo using a larger than stock cam, and for the price of a LT4 extreme chain you can buy both a stronger cloyes double roller chain and an electric waterpump

i would advise against using anything other than the straight up keyways on an LT1 that is still using an opti unless you are prepared to adjust the timing accordingly in the PCM. after adjusting the spark timing the injector timing would still be off, but i dont really see that mattering

 

Chevy:

What do you mean exactly by changing the timing inthe PCM. Are you saying that if you advance the cam you can run less timing in the motor. Or vise versa. This is a little above my head.

Thanks

 

the PCM uses the optispark to decide when to fire the coil and injectors. the opti is basically a camshaft position sensor, however engine timing is based on piston position (crank degrees). if you advance or retard the camshaft, the opti will be advanced or retarded the same amount in relation to the crankshaft which will cause the PCM to not be seeing the correct timing

if you wanted to you could compensate for that with tuning though. for example, if you advance the camshaft 4* (crankshaft degrees), then you could take 4* of timing out of the PCM at all load and rpm conditions to compensate for the false reading the PCM is getting from the opti. that wont cure the fact that the injectors would still be 4* off, but injector timing at WOT doesnt really matter, and i doubt being 4* off would even make any noticable change at idle and part throttle. the ignition timing being off would be a big deal though

 

I'm following you now. I run a DFI gen 6 system. It would be affected just like the stock PCM right. THis is also a Race only car so part and idle conditions are not that important.

Thanks again

Ken

 

if the Gen 6 is still using the optispark to get its timing signal, then yes it would be affected just the same. if you were using a crank trigger with it, then it wouldnt matter

also being that the Gen 6 is bank-bank or batch fire(dont recall which) rather than Sequential, the injector timing wont matter at all

 

Damn your fast.

Thanks for all the help. I believe the gen 6 is batch. Well I am not running a crank trigger, well not yet anyways. I will just have to play around with it on the dyno after the motor is together. One last thing. Do you have a part number for the cloyes chain set.

Thanks

Ken

 

I just bought a Lunati chain for an early (non-vented opti) LT1. Interestingly enough, the top gear in the Lunati set has GM stamped into it...With a GM part number! While searching for a chain, I found the Cloyes for $343, and the COMP for $500. The Lunati is still a link belt design...NOT a double roller.

Frank

 

the cloyes chain you would want is 9-3145 if my memory is correct

 

Cam timing off would be a bigger deal

 

if i am sent a cam that specs out farther off than i am comfortable with (especially retarded), i send it back rather than screwing with it. only had to do that once so far at least