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Do i really need to hook up the vacuum advance on a small block chevy . The timing is 16* initial and 35* all in by 3500rpm .

For street use, it would be a good idea. For running down the track, vacuum advance is useless because you're running wide open.
You might find some more power by experimenting with the weights and springs of the mechanical advance.Read this link for some good info that might help you with your particular application.

http://home.comcast.net/~chadwick.rober ... lained.pdf

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Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.

Blue Meanie has got it right, all the vac. adv. is for is fuel milage ont the highway.I took my adv can off my dist. bolted the adv plate down then worked on my adv curve.Hint buy a curve kit through the weights away and use the springs to get your curve dialed in.

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1978 pro street step/side 455Buick, 4sp,4.11s, 31/18.5s

Or you can have someone - shop with a distribitor machine. I have had Ray Martel do a few. Martel Brothers in Houston -Katy. It used to be out of Ray's house and then a shop. They have a web site, Ray was a guy a lot of us trusted, but I have not need his services in a while. I bought some parts from a few race cars before. Last time I saw them at the track a year or so ago, they were running a mustang convertable with a chevy engine in it.

Richard

There should be someone closer to you, just ask around some drag racers.

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75 Luv, 350 V8, TH350, Camaro rearend. New 1975 Luv Step side. Stock for now.
Grandmaster of the "Shade Tree" way.. I can't see the yard for all the cars. Come on down and we will sit on the porch and watch the grass grow.

If you're running a stock, H.E.I. distributor, it would do you good to get your distributor reworked by professionals. H.E.I vacuum advance distributors are of late 70's design at best. Even for street use they are more than capable to do the job. But for serious track runs, the stock limitations are hindering the motors full potential.
There's a reason why MSD and Mallory are making a fortune on ignition systems.
The upgrade from a Delco points distributor to the Delcotron H.E.I. unit was the smoothest ignition gain in the industry. Fords "Black Box" system and Chryslers "Solid State Pointless" system had major flaws that damaged engines as well.

At minimun, ensure that the stock H.E.I. unit is functioning at its best (fresh springs and weight bushings). Or go the extra step and get it modified by a pro to get better than stock performance. Or go all out with an aftermarket ignition system that you can tailor to your specific application, track condition and weather. You'll need to do your homework with the serious aftermarket system to get the most out of it.

Go to MSD and download their catalog. They have tons of charts and graphs that show what their stuff is capable of doing.

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Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.

O.K. a little more info . I have a factory hei with a msd module I have moroso recurve kit and an accel super coil. It will rev freely and I ahve not had any ignition stumble so far . The motor is fresh and tight and has about 150 miles and 5 passes . I have not spun the mptor past 6000 yet . I like to do a little break in.

Higher revs is were the stock H.E.I. unit starts having problems. It was originally designed for street use so it's made to work from idle on up. Average V-8 motors never see that kind of r.p.m's.
It looks as though once you get to some serious passes, The H.E.I. system will hold things back. Stock mechanical advance will max out at 3500-3600 r.p.m. so at 6000 r.p.m., the ignition is falling short of the motor. That's why going to a professional to get the distributor modified is important. Trying to modify the mechanical advance curve by routing out material can leave you with a ruined ignition.
Find out what it cost to mod the stock unit and compare that to the cost of an aftermarket system.

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Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.

I've had lots of good luck with HEI's up to 8000+ in the past. I honestly don't do much more than a gold spring from the kit (go for gold is what I always say). low resistance center bushing. a good coil (I've used a DUI, Hypertech but external MSD kit or similar works the best). plus an MSD box and a good cap and rotor (Accel seems to work ok). sometimes I used a hypertech module but burned one out and ended up swapping the stocker back in. At the track I lock it out and use an MSD timing control dial which allowed me to leave it locked out and still fire the car on a hot day with no problem cranking it. the timing dial would work great for taking timing out for nitrous pass vs motor pass. run it set at X degrees on motor and when i want to make a jug pass, just open up the bottle, hit the switch and turn the dial to 0. no more distributor wrench and timing light between rounds.

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1978 LUV Truck 2WD
450 "Small Block" Chevy
3.70 Ford 9
28x10 Goodyears

that should be fine. I'd add a multiple spark discharge box and spend $10 and get a low resistance center bushing too. dont forget a bronze distrbutor gear if you are running a billet bump stick. I like the accel coils and they are pretty cheap too.

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1978 LUV Truck 2WD
450 "Small Block" Chevy
3.70 Ford 9
28x10 Goodyears