383 stroker

[RobertO58]

I have a 383 stroker in a 68 camaro that when accelerate from 1000-2500 rpms with or without a load on it will back fire throught the carb does not make any difference what kind of carb does the same with a holley or edlebrock 26 total timing

[TheYellaBrick]

Is this street-street/strip - or strip only car ?

At what point of acceleration does this happen ?

If it's just as you stab it, it could be not enough accel pump volume, even on 2 different carbs, it could be weak or not enough. Also could be your advance is not working or is gummed up within the distributor.

[zipper06]

26* is not enough timming even for a stock engine, should be 32*/36* total timing.

JMO

Zip.

[cepx111]

26* is not enough timming even for a stock engine, should be 32*/36* total timing.

JMO

Zip.

X2
I'm pretty sure my lawn mower has more timing than that!

Double check your firing order too.

[cncmotorsports]

Needs more timing

[et7333]

26* is not enough timming even for a stock engine, should be 32*/36* total timing.

JMO

Zip.

x4

[RobertO58]

when I put more 32-36 in it it diesels when i try shut it off and i still get a back fire through carb, also when i remove vacum advance hose the motor dies,

[bowhay]

check for vacume leaks

[Scooterz]

Are you sure that you have the correct vacuum source connected to the vac/adv? It may be that you have too much constant/high vacuum to the vac/adv & it is advancing too soon... while not enough timing on motor which maybe is why it dies when you disconnect the vac/adv hose... not sure, just a guess.

[kwkracing]

Sounds like your timing marks are not accurate

[RobertO58]

Sounds like your timing marks are not accurateHow can I check to make sure they are right

[ccperf721p]

What distributor are you working with? Has it been curved?

Timing should be set with the vacuum advance disconnected. 34 - 36 degrees total.

Vacuum advance to ported vacuum.

[kwkracing]

With the engine assembled you can not do it 100 percent accurate....

pull all 8 spark plugs so the engine is easy to turn with a breaker bar. Rotate number one cylinder to tdc the best you can, take a small 1/8 rod and probe in the spark plug hole. The fun part is you are trying to rotate the crank till the piston is at its farthest upward point. Now make sure your timing mark on your balancer and your timing marker line up perfectly.

Hope this is understandable

P.S. dont just stick the rod in the hole and rotate the crank..... you dont want to smash it between the head and piston, you have to get the piston almost at the top before you go sticking it in there, carefully.

[curtisreed]

That is not how I would check the timing mark. Pull the plugs yes, get a screw in stop that goes through the spark plug hole. Try to set it as close to TDC as easily possible by the mark you have now or close it really doesn't have to be perfect.

When you have the piston up against the stop make a mark on the balancer where the pointer is. Rotate the motor backwards to the stop and make another mark where the pointer is on the balancer. The middle point between these two marks is exact TDC.

This is just my 2 cents.

Curtis

[zipper06]

The 2 previous posts will tell you if you have sheared the the crank key or the balancer has rotated the outer ring on the hub, but it won't tell you anything about where your cam timing is. The only way to check that is too pull the timing cover and check cam location. If the balancer has not moved on the crank ofcourse the timing mark will be in place at TDC on the balancer because it's keyed too be on TDC.

Zip.

[curtisreed]

Sounds like your timing marks are not accurateHow can I check to make sure they are right

Was pretty sure this is what I was answering about, not cam timing. :?: :?: Am I missing something?????

[zipper06]

No not missing anything, but you know how these timing chains/sprockets have several different key slots and timing marks, it's pretty easy for someone too screw up. I know a guy down here put a b/blk together and the valves were hitting the pistons. He then pulled the pistons out and had the valve reliefs cut .100 deeper without even pulling the front cover, they still hit, he then pulled the timing cover and set it right, he now has over .200 valve clearance, so after $200.00 it wasn't funny too him.

Zip.

[cepx111]

it diesels when i try shut it off and i still get a back fire through carb, also when i remove vacum advance hose the motor dies,


I'm gonna go out on a limb here and say that you have the vacuum advance hooked up to the incorrect vacuum port.

It has to be hooked to a ported vacuum source, NOT manifold vacuum.
There should be NO vacuum present at an idle.

Find a vacuum port that only has vacuum when you rev motor up.

Further more, you always set the intial timing with the vacuum advance un-hooked.

Also if the motor is idled UP too high it will desiel when u cut it off.

IMO> This is part of your problem(s)

Cp