[tom s]

The dizzy with no VA is not a issue on the street,issue will be gas mileage.My 63 421 SD engine with factory dizzy has been in the car and driven all over hell and back without the VA.Tom

[steve25]

It is a issue Tom, you just stupidity don’t want to see that and take every chance you can get to prove your stupidity!

Stop suggesting to owners to not activate or ditch there vacuum advance!


If it was not needed then why has ever major auto manufacturer that has produced millions upon millions of street vehicles gone thru the expense of having it as part of there cars ignition system?

You have a specialized race motor , and you want to keep it stock , and that’s fine, but it too would run better with what your always telling everyone they don’t need.

[grivera]

Good news- the dizzy has a vacuum canister- I missed it under the ignition wires.

Does anyone recognize these headers? There is no metal tag on them.

Also, if I were to eventually remove the headers and install log manifolds or RA manifolds, will the head-pipes line up with the current exhaust?

[tom s]

Steve!I did not say NOT to not run one.IF you have a dizzy without one its not a panic to run out and buy one that day!Obviously you did not or dont know 421 SD dizzys did NOT have VA!I have 3 421ish pontiacs in my garage and drive them pretty much every week,2 have VA and the SD does not and I cant tell any driving dif in the 3 cars!Tom

[tom s]

Anytime you come out to the left coast you are welcome to drive any of my cars and if you want you can jump in and tune them!Tom

[Stan Weiss]

Originally Posted by tom s

Steve!I did not say NOT to not run one.IF you have a dizzy without one its not a panic to run out and buy one that day!Obviously you did not or dont know 421 SD dizzys did NOT have VA!I have 3 421ish pontiacs in my garage and drive them pretty much every week,2 have VA and the SD does not and I cant tell any driving dif in the 3 cars!Tom

Tom,
It is not just Pontiac. In the '60s and '70 in my SBC I ran a Corvette cast iron body dual point distributor (I believe it was from a '57). It also had no vacuum advance.

Stan

[77 TRASHCAN]

Might be Hedman headers...
I'd remove the DP carb, put some gas in the bowls, so the bowl gaskets can expand, if needed, making sure the carb is not somewhere that gasoline fumes could be dangerous. You never know how good or bad a carb is by just looking at it. If the accelerator pumps both work and don't leak after adding, that's a huge deal and indicator of carb condition.
Cylinder pumping pressure will tell you tons about the innards of this engine.

[grivera]

Thanks Trashcan.- for the cranking compression test does it matter if engine is cold?

[77 TRASHCAN]

It's best to do a compression test with engine warmed up. Remove all plugs, allow the throttle to be open. Beware the fuel pump may need to be disconnected.

In your case you are just trying to get an estimate of the engines capabilities. Test it as it sits now...

I'd test it as is, you've got some things to do JUST TO get the engine running.
Finding the pumping compression of each cylinder in its current condition will be good to know, those numbers will likely be higher when engine is warmed up AND AFTER the engine has been run a while

Of course try to turn the crank first with a break over or ratchet to make sure it is not stuck. Squirting some kind of lubricant in each cylinder is a great preventive measure on a long sitting engine.

[grivera]

Thanks for the tips - the engine turns over easily with a breaker bar.

[steve25]

Tom, all I am saying is that there is no reason not to when you get right down to the bone.
I even ran it on my 462 with a roller and a 671 blower.
I had to put a 180 degree stat in it just to bring the temp up and have it average 190 driving down the highway at 2800 rpm, and this was with a3500 stall converter no less.

Gez, even the 1970 Chevy 450 hp 454 HAD vacuum advance, so while your 421 is a specialty engine and street wise it performs well enough to your liking you can't do a Apples to apples comparison between your 421 and a 9 to 1 motor with 2.73 to maybe 3.23 rear gears, and especially if your trying to stuff more Cam into that may put you on the edge with having less then 10 to 1 in the cylinders.

PS.
And thank you for the drive time offer by the way.

[Cliff R]

As far as vacuum advance goes it is a "load sensing device" and there are no negative anyplace from using it, ony positives. It allows the use of a much leaner mixture at light engine load, which has many positives starting with improved fuel economy. You will also put out less emissions, less carbon fouling, less carbon build-up, and improved throttle response and engine power in the "normal" driving range. IF you don't use it just "fatten" up the carb or use something that guzzles gas right to start with and you'll never have any need for a VA in the first place.

What really AMAZES me with the VA topic is that a LOT of very well educated folks ditch the VA on all their builds whether it's for a customer or their own vehicles. They also beleive that installing light springs in the distributor to get the mechanical advance curve to start sooner and "all-in" sooner somehow works better or makes up the difference, which is does not. If you think that way read this: You are still missing a LOT of timing at light engine load, it's not there, even if your distributors mechanical curve is "all-in" early in the RPM range.

I lost count decades ago of how many vehicles were brought here to custom tune their carburetors that I fixed by going into the distributor, throwing out all that advance curve kit crap, installing stock parts (with minor enhancements), then putting the VA back into the equation. Yes, at least 80 if not 90 percent of the issues folks are having with these engines are distributor related.

Then all you have to do is come in and give the carb a little help. Once I nail down the carb tune I send the customer on a test drive and they come back smiling from ear to ear right up until the moment I empty their wallet!

Seriously , without exception they tell me the engine has "never ran that good" or the car felt that fast in all the years they've owned it........FWIW.......

[grivera]

This thread has gotten off track - the dizzy happens to be a VA unit so it’s a non-issue. Back to topic. Thanks

[PunchT37]

Keep the intake and the holley and run that b!tch like it is. Might run decent as is.

[grivera]

Originally Posted by PunchT37

Keep the intake and the holley and run that b!tch like it is. Might run decent as is.

Yep - that’s the plan at this point- just needed a little push! Hahaha

[PunchT37]

Originally Posted by grivera

Yep - that’s the plan at this point- just needed a little push! Hahaha

Alright, den. Get r done.

That 650 holley runs better and starts better than a holley 700 or 750 on my buddies 340 mopar with a single plane intake with a 230/236 cam.

[MarkS57]

Originally Posted by grivera

Yep - that’s the plan at this point- just needed a little push! Hahaha

Maybe pull the dizzy with good positional makings so you can re-pressurize the oil feed prior to re-starting?

[grivera]

I will do that too. I dropped the fuel tank as it has old fuel in it and I want to clean it/examine the pick-up assembly. Will also replace any rubber lines in the fuel system before start up and rent a scope to see if it has the 8 valve relief pistons.

[PunchT37]

I believe the 8 relief stuff is for the 389/400 crowd.

[steve25]

Sorry for going off the vein of your post with the vac advance stuff!