See if the engine likes it first. What is initial timing at?
Vacuum advance?
Vacuum advance?
340 stroker 422
- Thread starter Miszny
- Start date
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No vacuum advance, 16 initial, 32 total.
Sorry, what distributor again?
could unshroud the intake a little
This set of Speedmaster heads really opened my eyes on a few things. He wanted zero chamber work done to keep compression up and with a 2.055 valve still put out some nice numbers. Some things make you go Hmmmm
IDK I think I would have worked that chamber and shaved the head to keep the compression up.
To each his own. lol
They were flowed on a 4.015 head adapter so I think his street car will be ok with a .575 lift cam.
MSD, you can see it in the movie with the truck.
For the small block I also have msd…
Dartswinger70
Well-Known Member
Ill take em you do pay pal...?
I’m sitting here grinding some pushrod tubes and thinking about this. Maybe I’m giving all the credit of a very stabile port to the valve job when part of the credit should go to the chamber not being unshrouded. Maybe it helped slow airspeed which these heads need badly. Hmmm
OK thanks. Not my favorite distributor. EZ enough to work with though.
I don’t t care about gas mileage at all. Don’t see any other advantages…
I use them because they are very easy to adjust, lock etc and all the parts are available on daily basis where I am.
No argument there. I’m running two of them right now. Daily drivers.
Rat Bastid
Dunamis Metron
There are HUGE advantages to running vacuum advance. BUT, with where you are and what you are running I seriously doubt you can make it work.
The mechanical part of the vacuum advance mechanism will not respond quick enough to keep you out of tip in detonation.
If you play with it enough and get the right curve in the distributor you MIGHT be able to make it work.
I’d connect it….. just sayin….
I had better luck with using map sensor and programmable msd box, I even use it in my Duster but I’ll leave that for the fine tuning part of this project.
What advantages are there aside of high advance when cruising?
Learn about the benefits of manifold vac adv. It is a LOT more than economy.
You may have to type in the full title. Scroll down to post #6:
www.hotrodders.com/forum/vacuum-advance-hooked-up-directly-manifold-bad-47495.html
And this from D.Vizard who has forgotten more than many will ever know.....
" At idle & low speed operation, the amount of advance reqd to most effectively utilize the air & fuel entering the engine can be as much as 50 to 55 degrees. This is handled by the vacuum advance: a function many hot rodders believe is not needed because their favourite drag racer does not use it. NOW IS THE TIME TO LISTEN UP & LISTEN UP GOOD. A FUNCTIONAL VAC ADV IS IS THE SINGLE MOST EFFECTIVE CAMSHAFT TAMER YOU CAN GET.
By taking the time to hook up the vac adv to a manifold vac source you can get a big cam to idle as it were 20* & less than it really is. Conversely, if you sre loking for a decent idle, the use of vac adv will allow you to use a cam of, at the very least, 5* more duration/overlap than would otherwise be the case."
You may have to type in the full title. Scroll down to post #6:
www.hotrodders.com/forum/vacuum-advance-hooked-up-directly-manifold-bad-47495.html
And this from D.Vizard who has forgotten more than many will ever know.....
" At idle & low speed operation, the amount of advance reqd to most effectively utilize the air & fuel entering the engine can be as much as 50 to 55 degrees. This is handled by the vacuum advance: a function many hot rodders believe is not needed because their favourite drag racer does not use it. NOW IS THE TIME TO LISTEN UP & LISTEN UP GOOD. A FUNCTIONAL VAC ADV IS IS THE SINGLE MOST EFFECTIVE CAMSHAFT TAMER YOU CAN GET.
By taking the time to hook up the vac adv to a manifold vac source you can get a big cam to idle as it were 20* & less than it really is. Conversely, if you sre loking for a decent idle, the use of vac adv will allow you to use a cam of, at the very least, 5* more duration/overlap than would otherwise be the case."
Rat Bastid
Dunamis Metron
You post this all the time. Have YOU ever done this with compression this high on pump gas and had it work?
I doubt you have because it is near impossible when the CR is that high to make the advance come off quick enough to not get a tip in rattle.
Plus, what makes you think that much compression needs that much timing at idle?
I thought we were working on a 340/422 stroker.
I don't know how relevant the timing on a 440 big block is to a 422 small stroker.
I don't know how relevant the timing on a 440 big block is to a 422 small stroker.
Cubes are cubes!
The difference is in the bore and stroke, so, would it be different for a long stroke small bore engine?
The difference is in the bore and stroke, so, would it be different for a long stroke small bore engine?
Rat Bastid
Dunamis Metron
Doesn’t really matter what it is. Once the CR is high enough you just can’t cram an assload of timing in it.
This is why so much JUNK was built in the 80’s, 90’s and even the 00’s.
High CR pump gas doesn’t tune like low compression pump gas does.
Yes and the piston design and combustion chamber needs to be taken into account. not to mention cam timing events.
I didn't say you could cram an *** load of timing into high compression. I don't agree with the Bewy.
Rat Bastid
Dunamis Metron
Right. All that matters. But, like I said you can’t just cram a bunch of timing in something if the CR is high for pump gas and not expect it to have issues.
The opposite is when guys don’t run enough compression and then over cam the turd.
Thats when you see wild assed numbers like posted above for timing.
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