Fire breathing Corvette!

[dave]

here's a video link to my present problem! lol

http://www.xmembers.co.uk/photopost/showphoto.php?photo=667


dave

[Andy Dean]

Hmmmm... Interesting!

Where's Hemi Haggis when you need him!

[ross@rmrrestorations]

The fact that it sounds sweet on idle makes me think it's not an ignition issue.(you know, timing in the wrong place), so that leaves it to the carb.
When blipping the throttle from idle, a carb backfire is usually a sign of a lean mixture.
I would check that the accelerator pump jets are clear and unblocked and thet they are of the right size.

[dave]

The fact that it sounds sweet on idle makes me think it's not an ignition issue.(you know, timing in the wrong place), so that leaves it to the carb.
When blipping the throttle from idle, a carb backfire is usually a sign of a lean mixture.
I would check that the accelerator pump jets are clear and unblocked and thet they are of the right size.

Ive tryed the timing at lots of different settings, but it makes no difference

the car has done this since I got it, It came with a quad jet carb, I changed it to the holley 750cfm, but no change, still does it.

it does run very low vac levels, sits at 12/13hg, it was lower, but I have inproved it, by setting up the carb better.

there are some oil spots on the driveway coming from the zorst, I think the engine is old, and worn, leading to low compression, etc

Im thinking of either a new crate engine from the USA or a good 2nd hand engine over here, im abit of a power freak! lol, so looking for something with a big punch!

cheers

dave

[ross@rmrrestorations]

http://www.nsra.org.uk/newforum/showthread.php?t=3951

Check that out.....
I would do a leakdown test on it to see what may be wrong with the mechanics of the motor first.

[dave]

http://www.nsra.org.uk/newforum/showthread.php?t=3951

Check that out.....
I would do a leakdown test on it to see what may be wrong with the mechanics of the motor first.

cheers for that info mate

dave

[V8Dieselpower]

I know this is an old post but here goes. Check the mechanical and vacuum advance on the distributer. Ive seen many an engine tick over sweetly then misfire and blow back as soon as the throttle is touched then run smooth again as the revs climb. Usually the mechanical advance weights in the dizzy have siezed or the mechanism has worn out due to lack of lube. Sometimes the vac advance return spring fails or weakens resulting in too much advance.

Another cause is a badly seated inlet valve. If the engine has high miles then it would benefit from a good old decoke and valve regrind.

Simon.

[quattrothedog]

" Holy thread resurrections Batman !!"

http://www.impoverishedpoet.com/USERIMAGES/039_45125~Batman-Robin-Posters.jpg

[corvettedave]

I know this is an old post but here goes. Check the mechanical and vacuum advance on the distributer. Ive seen many an engine tick over sweetly then misfire and blow back as soon as the throttle is touched then run smooth again as the revs climb. Usually the mechanical advance weights in the dizzy have siezed or the mechanism has worn out due to lack of lube. Sometimes the vac advance return spring fails or weakens resulting in too much advance.

Another cause is a badly seated inlet valve. If the engine has high miles then it would benefit from a good old decoke and valve regrind.

Simon.

thanks for info mate, but ive got a brand new 383 from the USA now, problem solved!

cheers

dave

[corvettedave]

" Holy thread resurrections Batman !!"

http://www.impoverishedpoet.com/USERIMAGES/039_45125~Batman-Robin-Posters.jpg

lol

dave

[dlamerton]

thats one way of fixing it!

[corvettedave]

lol, yep, I took the easy route!