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In my case 38* from the time the car is started. It helps low end and takes out the variable of the advance mechanism messing up,timing fluttering, no longer have to worry about a timing curve.
 

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Discussion Starter · #3 ·
Bob would you only recommend this on a strip only car? What about something that is raced at the track and then driven to the cruise in?

Also what did you have to do to lock out your timing? Did you just eliminate the vacuum advance or something?

And doesn't 38 degrees at start up make the engine a bear to start? Or do you just run one of those MSD automatic timing retards for starters?
 

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I'd probably keep the vacuum advance for street driving if interested in fuel mileage. I have a mallory unilite distributor w/no vac adv., the plate in the bottom is adjustable for the desired advance, just set it at zero, removed the weights and springs. I do drive mine on the street, just not that much anymore, mainly cuz I'm working on it when I actually might have a chance to drive it to town. I have a gear reduction starter on it now, which helps. I do not have a start retard on it or a switch to turn the ignition on/off.
 

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i have a m.s.d digital 6 ignition box and a m.s.d distributor that is locked out and i run 36 degree's of total timing but my ignition box has a start retard, but i also have a toggle switch that kills the power to the ignition box, what i do is get the motor cranking and then flip the power to it and i have never had any issues with starters or flywheels that is the poor mans start retard....lol but it works....jmo....Mike
 

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i have a m.s.d digital 6 ignition box and a m.s.d distributor that is locked out and i run 36 degree's of total timing but my ignition box has a start retard, but i also have a toggle switch that kills the power to the ignition box, what i do is get the motor cranking and then flip the power to it and i have never had any issues with starters or flywheels that is the poor mans start retard....lol but it works....jmo....Mike
 

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Discussion Starter · #9 ·
I'd probably keep the vacuum advance for street driving if interested in fuel mileage. I have a mallory unilite distributor w/no vac adv., the plate in the bottom is adjustable for the desired advance, just set it at zero, removed the weights and springs. I do drive mine on the street, just not that much anymore, mainly cuz I'm working on it when I actually might have a chance to drive it to town. I have a gear reduction starter on it now, which helps. I do not have a start retard on it or a switch to turn the ignition on/off.
Bob,

Performance is first and foremost. You can't really expect good gas mileage from any big block.;)

Plus my car is a weekend car.

Right now I have a Mallory HEI but I also have an MSD 8361 sitting around waiting to someday go in.

If I wanted to run locked timing would I need to purchase a distributor without a vacuum advance?

It sounds like you're saying you also remove the weights and springs for the mechanical advance unit?
 

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You should be able to remove the vacuum cannister, I dont have the weights and springs any longer either. When you grab the rotor and the dist gear, it should be like a solid shaft, no movement. So when you set the timing at the adv of your choice, thats where it is/stays. Mine used to flutter a bit when I brought the rpms up to check total advance, now its rock solid with it locked.
 

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Discussion Starter · #11 ·
Thanx Bob. If I may ask did you have to somehow secure the center shaft so that it doesn't move at all?

I know normally you're able to grab the rotor like you said and it will move (advance) some and when you let go it snaps back via the springs. That center shaft that the rotor sits on....has got me wondering if and when you remove the springs/weights if you have to secure the shaft somehow so it's not flopping all over the place as the distributor main shaft is turning?

Also with locked out timing, is total timing the only way of timing the engine?
 

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Yes, locked out, total is the only way of timing it. The Mallory was easy to lock out, not quite sure how you would do the same with an HEI for example. I believe the MSD is also easy to lock out, but never used one.
 

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i welded mine (hei), i have before ran a small bolt and double nut to secure the plates from moving.

i would recommend to all to run a vacuum canister on your unit. if your a big block man you know they can be a bear to keep cool and having your vacuum canister hooked to full vacuum port you will be able to run more timming while idle and at cruise to keep the engine cool not so much for gas mileage but to keep the engine cool.

and if anyone says otherwise ( not to run it) then they dont understand the vacuum canister and its benifits.
 

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I am running a DUI distributer, just a fancy GM HEI style dizzy, has vac advance. Swapped the little advance springs, full timing at 2500 RPM. No fancy ignition boxes / coils. Plain Jane wires. Autolite plugs at 1.75 each. 38 degrees all in. Locked timing, about the only benifit MAY BE a little more consistant performance at the track, but only if the advance weights and springs system are in poor shape. Here's me saying my ignition is way more consistant / repeatable than the driver will ever be! I just put the 400 trans in "D" and mash the gas. If it's a race car, lock it down and gut the interior. If it's a street car worry about something else! :)
 

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Discussion Starter · #15 ·
Hey....I just went out to the garage and dug out of storage my MSD 8361 I plan to run on the Chevelle in the future.

When I removed the cap and rotor it looked like on the advance center plate there was a lock nut on the underside....perhaps this is to keep the plate from moving?

Bob how does your unilite lock out?

I'm guessing on a locked out distributor you set it for 36-38 at 3k rpm?

Never have heard of the vacuum advance being for better cooling...I have heard it's supposed to help with fuel mileage....

But then again my engine makes very little vacuum at idle. While I had the MSD out of storage I decided to test out my new vacuum pump on the MSD's can.....it starts actuating at 9 hg and it's all done by 15 hg.

My engine only pulls 11 hg in park and 6 hg in drive. :eek:
 

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the lock nut on the underside of the MSD is for the mechanical advance bushing. look on the MSD website and they tell you how to easily lock out the MSD distributor
 
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