Hi Guys,

I've got a 350 crate engine from eagle, that has been running in my '73 vette for the last couple of years. I've never been happy with the performance (lag on acceleration, excessive heat buildup), and it's finally quit on me.

I was having some issues (Which I thought were distributor related - trouble starting, rough running, massive lag/stall when putting the foot down), and had that re-curved and serviced, and after putting it back in, the car still ran really roughly, and eventually didn't start at all. The engine turns fine, but doesn't crank at all. I've checked all plugs and leads, and get a spark through all of them. Fuel seems fine through the holley 750CFM carb, so I'm at a bit of a loss as to what could be the problem.

I've tried moving the dizzy around to change the timing, but haven't had any luck. Checked for TDC to make sure I wasn't 180 degrees out, and all seems fine there. I don't have enough cash to take it to someone at the moment, but would really appreciate any thoughts on what the issue might be / how to fix it.

My old man had a crack at fixing it for me prior to it not starting at all, and managed to mix up the 5 and 7 leads, which ended up blowing out one of the rear mufflers - not sure what other damage this might have done, but it did start a couple of times after that happened, so I'm hopeful it isn't anything too terminal.

Thanks in advance,

Lee

 

Start with a compression / leakdown test.

 

Thanks, should have mentioned that - have done a compression test, everything seemed ok (don't recall the exact numbers, but they were all consistent, and seemed reasonable)

 

Start over and keep it simple and go steady. Unplug all your wires from the distributor. Remove the #1 spark plug which is first on the driver's side. Bump the starter or manually turn it with a finger over the #1 plug port. When you feel air being forced out past your finger, look down, and get the 0 degree mark on the pointer. You now know the engine is at TDC on the compression stroke. Now, mark where the #1 plug tower is and remove the cap and see how close it is. If it's way off, simply reorient the distributor until the rotor is at #1 with the engine at TDC on compression. Put the cap back on, one by one install all your wires being very careful to double check the firing order going clockwise. Then double check. Finally, try starting it, and re-timing it from there. By the way the backfire couldn't have damaged the muffler unless it was already in need or repair.

 

-holley 750 prob a bit big for a mild 350.
-old gas ?
-doubt you have a cat converter but if you do check its not blocked.
-check float heights on holley.
-powervalve in carb may be blown if its been backfiring.
-any vacum leaks?...eg carb to manifold , inlet manifold gaskets etc.
-plug wire boots arcing out on headers maybe?
-fuel filter blocked
-check and double check your timing and firing order.

 

Hey mate, old gas could be a good point - it was sitting around for a while. Agree that the 750 is a bit big, got some bad advice when I was buying the engine. Float heights were ok, but will check them again to be sure. Will do some research on how to check the powervalve - haven't got that deep into a carby yet!

Vacuum leak could be an interesting path - I had a new intake manifold installed, as the old one was apparently the wrong type (again, bad info when buying the engine) - how can I test for that? Or is it a matter of taking the inlet manifold off first?

Fuel filter is new, and looks clean (see through plastic filter).

Plug wire boots could be an issue - they were meant to be new leads, but I have a sneaking suspicion that they are not - they look a bit rough for the amount of time they have been in the car.

Will double check the timing again on the weekend.

Thanks for the advice,

Lee

 

hope something helps

 

Thanks for that - I've had a bit of a look around, and I think I'm going to try pressurising the manifold by taking off the carby, and putting on a blanking plate - I presume I'll lose some pressure somewhere, but if there is air coming out around the manifold I'll have my answer.

 

maybe some bungs in your exhaust while your at it