carb tunning and timing with vacuum gauge link needed

[bot0611]

I remember i got the link on this site.

Setting the iddle mixture screws and timing using a vacuum gauge.

Anybody has the links.

 

[cybrfire]

I have my crew cab timed right now with a vaccum gauge reading.

All you need to do is bring the engine up to operating temp, have your vaccum advance disconnected and plug the hose. Turn you idle speed as low as possible without killing it.

Now turn the distributor until you have a maximum vaccum reading. Make the gauge go as high as it will until it starts to go back the other way, now take it back to max.

Now retard the timing until the vaccum drops about an inch to lessen ping. Might need to go more depending on some other variables.

Pretty much the same type of process for idle mix screws. You already have the gauge hooked up so do it now. Adjust them fully closed and then back them out each about 1.5 turns. From here you can work both screws in small increments or one at a time again attempting to raise the vaccum as high as possible but steady as well. Try to keep them the same so if you do one at a time, keep track of what you did and repeat it on the other side.

That's about it. You'll need to adjust your idle speed when your all done. The timing one is easy and straight forward as it gets. I have less luck with the idle mix screws.

 

[bot0611]

ok thanks.

One more thing, im adjusting the vacuum canister on the dizzy.

advance - turn clockwise
retard - turn counter clockwise

Am i right?

 

[cybrfire]

ok thanks.

One more thing, im adjusting the vacuum canister on the dizzy.

advance - turn clockwise
retard - turn counter clockwise

Am i right?

Got me there. I have never needed to adjust that so I guess I've never looked into it.

 

[COCHEV]

I have my crew cab timed right now with a vaccum gauge reading.

All you need to do is bring the engine up to operating temp, have your vaccum advance disconnected and plug the hose. Turn you idle speed as low as possible without killing it.

Now turn the distributor until you have a maximum vaccum reading. Make the gauge go as high as it will until it starts to go back the other way, now take it back to max.

Now retard the timing until the vaccum drops about an inch to lessen ping. Might need to go more depending on some other variables.

Pretty much the same type of process for idle mix screws. You already have the gauge hooked up so do it now. Adjust them fully closed and then back them out each about 1.5 turns. From here you can work both screws in small increments or one at a time again attempting to raise the vaccum as high as possible but steady as well. Try to keep them the same so if you do one at a time, keep track of what you did and repeat it on the other side.

That's about it. You'll need to adjust your idle speed when your all done. The timing one is easy and straight forward as it gets. I have less luck with the idle mix screws.

do you find you end up wit a lot of initial timing doing it this way?

i have timed my 454 this way and end up with a lot of initial advance. it runs great, but does not like to turn over easily with a stock starter and if it backfires on start up it bends the starter bolts and/or breaks the starter. i installed a newer vortec 454 starter and it turned it over real nice, til it backfired once on start up and broke the casting...$170 down the crapper. i know have it around 12* i think and back to a Napa starter and no issues. has a slight hessitation between part and full throttle i didn't have before

however, on my crate 350, i timed it this way and it runs and startes awesome...

 

[BIG*RED]

Turn you idle speed as low as possible without killing it.

Ok, I'm wondering about this part, a lot of what I've been reading says to have your idle at the "correct, or normal" idle speed.
Why do you say to turn it down low? Can you explain this to me?

 

[cybrfire]

do you find you end up wit a lot of initial timing doing it this way?

i have timed my 454 this way and end up with a lot of initial advance. it runs great, but does not like to turn over easily with a stock starter and if it backfires on start up it bends the starter bolts and/or breaks the starter. i installed a newer vortec 454 starter and it turned it over real nice, til it backfired once on start up and broke the casting...$170 down the crapper. i know have it around 12* i think and back to a Napa starter and no issues. has a slight hessitation between part and full throttle i didn't have before

however, on my crate 350, i timed it this way and it runs and startes awesome...

Yes, I do have quite a bit of initial timing but its what the engine needed so I roll with it. Different engines and different components can cause the need for more initial timing. I spoke with a few folks that know more than I do and I don't proclaim to know too much about engines. They informed me its not terribly uncommon. Mine starts harder when warm but suspect its more to do with the starter. Keep meaning to put some heat shielding around the starter to see what it does. Haven't had time.

If you are getting backfires your timing is probably off a good bit, or you have something else going on. I have to think about this everytime... You'd be too far advanced.

sheoldblaze, when you adjust your timing this way, you can use the rise in engine rpm to help you as well. Slow it way down and start adjusting and the rpm's will come up(if you needed the adjustment.) If you have it low to start its not racing too high when you start getting things adjusted. Besides that, at some point you'll start throwing some mechanical advance into the mix via engine RPM and the weights in the dizzy. If this happens you'll need to slow the engine rpms back down anyway and do it again.

Everytime I've done it this way, I've ended up pretty much where the engine rpms are the highest. Start low and bring it up.

 

[COCHEV]

yes, mine started worse when it was hot too. i was told by another hot rod guru i know that big blocks with a good bit of advance will do the backfire thing if you don't pump it plenty of times to make sure it has plenty of gas on start up...aside from that, i like this method. like is said, it ran much better set up that way as does my 350. when money allows i'll get another high torque starter and bump it up again.