Mechanical Advance Distributor

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Feb 28, 2007 | 12:55 PM

jeffboyd

Thread Starter

Heel & Toe

Joined: Mar 2006

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Mechanical Advance Distributor

I have a '72 with the 330HO (330 hp, 350 cu. in) GM crate engine. It has a Mallory Unilite distributor with mechanical advance only - no vacuum advance. It is set to add 24 degrees by 3,000 to 3,200 rpm, which seems reasonable, but I wonder why no vacuum?

Does anyone have any experience with mechanical-only advances? Why this over the ususal vacuum advance?

Jeff

Feb 28, 2007 | 02:14 PM

tfi racing

Drifting

Joined: Jan 2006

Posts: 1,832

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From: Cedar,BC

That distributor was probably cheaper and easier to find than one with an advance. That missing vacuum can is only costing you a lot of gas mileage!

Feb 28, 2007 | 02:41 PM

Ironcross

Race Director

Joined: Nov 2002

Posts: 12,142

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From: Taylor Michigan

Quote:

Originally Posted by jeffboyd

Jeff

Most of your performance engines dont use a VC can. As soon as you step on the gas your at full advance anyway. Conflicting statements about gas mileage as being poor with out the VC can is really not correct. Early FI engined Vettes never had them nor did the L88`s. My personal experience besides the racing engines that never used VC cans was with my FI Vettes and low ratios as per a 4.11 and at freeway speeds and above, 20 MPG was the average. Non vacuuum advance distributors were always dual point and considered a must for performance engines. Mallory was one of the first companies to mass produce them for every engine. We sold many of them for all makes.

Feb 28, 2007 | 04:25 PM

comp

Team Owner

Joined: Sep 2003

Posts: 88,393

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From: eville in

i got better mileage at part throttle with Vac. Adv. on everything i have had

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