Lock out my centrifugal advance or not?

[The Warlock2]

Hey all,

A bit of background as for my question. I bought a ‘76 Camaro drag car and the owner (he inherited it) didn’t know much about it. I got some info from one of the builders (luckily). It has a 468 BBC with a TH400 in it. The stall is about 4000-4500.

Anyway, it had a modified HEI ignition/distributor in it. I’m replacing that with an entire MSD system (distributor, 6AL2, 8.5mm wires, blasters SS coil). They told me the total timing was 36*, which was correct. They also said an MSD module was installed on the HEI dist and the advance was removed/locked out. Again, correct.

I just installed my new MSD dist with the lightest silver springs it came with and the smallest (red) advance stop. However, then I was wondering if I should lockout the advance like the HEI unit was.

Thoughts? I only race the car, so it doesn’t have to be streetable, per se.

I don’t know if I should lock the advance out and then set the total timing at 36* at about 3k RPM or just leave the light advance in there and still set the total timing at 36* around the same RPM.

Not sure of the full reasoning of locking out the advance. I’m guessing full advance instantly? The redline is 6k if that matters.

Thanks,
Mat

 

[CorkyE]

I would, I did, and drove it on the street. Not the best manners but can be done.

 

[FS87LT]

I suspect that some tuners desire "less factors" in getting the engien tuned to their desires. Locking out the mechanical advance just removes one variable for them.

Try it like you now have it and see if it works as you desire. Including how it starts when hot.

Just some thoughts,
FS87LT

 

[The Warlock2]

Much appreciated by you both. I’ll see how it goes now and go from there.

I did some research and found out why it is preferred for racing. So now it makes more sense to me.

 

[Twisted_Metal]

The behavior when starting (especially hot) will tell you if it’s going to work.

If the engine kicks back during startup… you can break the starter.

 

[2ndGenCrazy]

If the car starts OK, AND YOU ONLY RACE IT, no problem. Lots of racers do that.

If the car cranks hard, you can add a seperate power switch for the coil, and turn it on once the the engine is cranking.

I assume you are drag racing this car.

 

[The Warlock2]

The behavior when starting (especially hot) will tell you if it’s going to work.

If the engine kicks back during startup… you can break the starter.

Well that could be a problem. LOL! I just installed a new starter for it (different reason), so I hope that won't be the case. I didn't have any starting issues with the HEI that was locked out with the MSD module, so I hope that will be the same with the MSD distributor if I lock that one out too.

 

[The Warlock2]

If the car starts OK, AND YOU ONLY RACE IT, no problem. Lots of racers do that.

If the car cranks hard, you can add a seperate power switch for the coil, and turn it on once the the engine is cranking.

I assume you are drag racing this car.

Crazy,

You are correct. It is only a drag car. It does not see the street at all. Hopefully the MSD setup will be enough to start it without any issues. Other people I have contacted at the drag strip all have their distributors locked out. The only reason I thought of it is because I remembered the HEI was locked out. It does/did have the MSD module put into it originally from the builder (not me), so that's what made me think of it (plus seeing it on the instruction sheet).

That's why I figured I'd ask about it. I can understand the point of locking it out now, so it is making me think. I might lock it out and then see how starting goes and go from there. If I have an issue, I'll unlock it and put it back to how I have it now (lightest springs and smallest advance bushing).

 

[67johnny]

A lot of guys use a start retard option (MSD) to help out with the timing issues caused by full time advance lockout distributors or crank triggers.

https://static.summitracing.com/global/images/instructions/msd-8982_frm28662.pdf

 

[The Warlock2]

A lot of guys use a start retard option (MSD) to help out with the timing issues caused by full time advance lockout distributors or crank triggers.

https://static.summitracing.com/global/images/instructions/msd-8982_frm28662.pdf

Ok, that makes sense. Of course that's about another $300 to spend. Ughhhh. I'll wait to see what goes the first time or two when I have to start it hot and if it acts slow, then I'll just order that box and figure out where the heck I'm going to mount it. LOL! I already had to be creative on where to mount my Blaster SS coil and the MSD 6AL-2 box. So, to add another box is going to be fun. LOL! But I appreciate the info johnny!