Noenav

Ok so I just recently rebuilt my lt1 engine. I did a full rebuild I changed every bearing also polished the crank and new piston rings. I installed an advanced induction cam and spring kit. Put new valves, seals and did some minor porting to the heads. I got the intake ported and 58 mm tb. The cam was installed correctly in timing and the pushrods were measured to the correct lentgh and adjusted. The problem with the car is it won't fire up unless I have the throttle all the way down and once it fires up it won't stay idling unless I have the throttle down. There's spark since I bought a new optispark so I don't think that's the problem. It is untuned. Do any of you guys have any suggestions as to what's wrong

raroz28

what does it sound like when it's running when u can keep it running with the throttle?

Noenav

To me it sounds good. No popping and runs smooth as long as I'm on the throttle. Could it be the throttle body is to much or the iac?

Injuneer

Did you change the injectors (larger)? How big is the cam?

Noenav

No I left the injectors stock and the cam is a 241/237 I was told it would work with stock heads just needed a stall and gears which I have.

Injuneer

Strange to find a 4-deg split favoring the intake.... most LT1 cams have a 6-deg split favoring the exhaust.

In any case, a cam that big - assuming those are the durations at 0.050" - is probably in serious need of a tune. What is the LSA?

Noenav

Oops sorry it's a 237/241 at .050 duration I wrote it wrong sorry about that but I was thinking it needed a tune as well the lsa is at 110

raroz28

should still run, IMO. I ran stock computer and injectors with a custom cam not much smaller than that and it ran fine.

Noenav

Ok so i just seen that fuel is coming out of the exhaust seems to be flooded. Could it be bad spark plugs or injectors? I disconnected the injectors and it seems to want to fire with me pushing the throttle down

Noenav

Without*

raroz28

what plugs and gap? Do you have a cat?

If you are confident that you have spark (which you said you did), then I would maybe run a compression test on all cylinders to ensure that a valve isn't bent or you aren't losing compression elsewhere.

Noenav

They are ngk not sure which ones tho but they were the old ones that were on before the build. They're gabbed at .50.
Well it's a new Optis from chandlermotorsports so it should have spark but I'll run compression test as soon as I can.
The car only fires up for a second and shuts off now doesn't even stay on when I'm the throttle ugh this frustrating

raroz28

if everything checks out in the fuel/ignition system, you may have bent valves. It has happened to me in the past.

Assuming your pushrods are correct and your valve lash is set properly.

Noenav

I will recheck the valves

Noenav

What is the common valve lash