Serious LT1 problems. Motor builders please read
Melting Slicks
Joined: Jun 1999
Posts: 2,872
Likes: 3
From: Wilmington NC
Re: Serious LT1 problems. Motor builders please read (MrJay)
what kind of cam is it? and did you degree it or install it straight up? always degree a cam, some recent advise i got from a forum member who has told me that he has seen cams as much as 8 degrees off from the manufacturer. Jay also has a good point, a bent Ex valve would certainly dump fuel and air into the exhaust on a compression stroke, i hope it not that because if flames are coming out both sides, that only means theres more then one bent valve. when you put the opti on did it sit tight against the block or did you have to push it to get it flush? if you had to push it, its on wrong! i would check the cam tioming at TDC and the take a look at the rockers to see where they are in relation. this may shed some light on the matter if your cam timing is off, the dots again are not always accurate. just somehting to check. have your friend revolve the motor as you watch the valve timing events. after TDC, does the exhaust valve open note the degree of revolution of the crank to rocker movement, this will also help decipher if everything is copasetic! best of luck and i hope you find somehting simple!
chris :smash:
chris :smash:
Safety Car
Joined: Mar 2000
Posts: 3,620
Likes: 2
From: Hillsboro OR
Re: Serious LT1 problems. Motor builders please read (lcvette)
BBA - If he has shorted the injector system out, the injectors would not open and no fuel would go into the cylinders and therefore no fire in the exhuast.
Mr Jay - I think your thinking of the non-vented opti. The drive shaft for those is keyed so they are only supposed to go on one way. The truth is that they can be incorrectly installed also. This motor is going into a 95 LT1 engine that uses the vented opti. The opti has two slots that the cam pin can fit into. One is for #1 TDC and the other is for driving the us nuts. The correct one has a notch or triangle mark on it.
Here is what we know based on the posts so far.
The cam is installed correctly.
What we don't know.
Was the distributor put on correctly ?
Were the plug wires put on correctly ?
Were the valves adjusted correctly ?
At this point its just a matter of getting the those three unknowns eliminateed by making sure they are done correctly. The motor should run after that. I seriously doubt the cam is off enough to cause the problems these guys are having.
Then start the motor. I also suggest putting some oil in each cylinder to get some oil back on the walls.
Mr Jay - I think your thinking of the non-vented opti. The drive shaft for those is keyed so they are only supposed to go on one way. The truth is that they can be incorrectly installed also. This motor is going into a 95 LT1 engine that uses the vented opti. The opti has two slots that the cam pin can fit into. One is for #1 TDC and the other is for driving the us nuts. The correct one has a notch or triangle mark on it.
Here is what we know based on the posts so far.
The cam is installed correctly.
What we don't know.
Was the distributor put on correctly ?
Were the plug wires put on correctly ?
Were the valves adjusted correctly ?
At this point its just a matter of getting the those three unknowns eliminateed by making sure they are done correctly. The motor should run after that. I seriously doubt the cam is off enough to cause the problems these guys are having.
Then start the motor. I also suggest putting some oil in each cylinder to get some oil back on the walls.
Safety Car
Joined: Dec 2000
Posts: 3,767
Likes: 5
From: Jacksonville Fl
Re: Serious LT1 problems. Motor builders please read (AquaMetallic94LT1)
BBA - If he has shorted the injector system out, the injectors would not open and no fuel would go into the cylinders and therefore no fire in the exhuast.
Now...I say again, check for pinched wires!
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Re: Serious LT1 problems. Motor builders please read
I like the idea of making sure the cam is degreed correctly.
Also, the opti can only be installed a little bit off, and in combo with a poorly degreed cam, the vision is icky.
Also, the opti can only be installed a little bit off, and in combo with a poorly degreed cam, the vision is icky.
Burning Brakes
Joined: Dec 2000
Posts: 1,023
Likes: 0
From: Marietta, South Carolina, USA
Re: Serious LT1 problems. Motor builders please read (Nathan Plemons)
Aqua like I say I dont know much about the opti but the one I put on had three holes and you could only put the pin on the cam in to one of the holes on the opti because the others had a thing that blocked it from going in so that is why I was saying that you could not put it in but one way.
He has told us that he has tried another opti and that it is hard to put the plug wires on wrong because they are marked so it is hard to think it could be that and the cam is right too.
You have a good point about the lash on the valves maybe they are just to tight maybe that is why he is getting fire in the exhaust maybe they never close?
I work more with carb engines but willing to learn about the EFI that is why I come here.
Jay
He has told us that he has tried another opti and that it is hard to put the plug wires on wrong because they are marked so it is hard to think it could be that and the cam is right too.
You have a good point about the lash on the valves maybe they are just to tight maybe that is why he is getting fire in the exhaust maybe they never close?
I work more with carb engines but willing to learn about the EFI that is why I come here.
Jay
