[Zio]

Hey guys I am currently running a 85551 dist. locked out at 38* in my 10:1 468 with a 248/252 hyd roller cam. I want to run a vacuum advance dist. to help clean up the idle and at cruising speeds. I plan on locking out the timing again beause I have great throttle respose at full throttle, but would like to improve the part throttle response with the vacuum advance. My question is how much timing does a stock vacuum advance on a msd 8361 added? Am I going to need to get an adjustable unit so I do not causing pinging? Just wanted to know so I can order both at the same time.

thanks
Tom

 

[MrBill66Malibu]

Tom,

I would suggest a adjustable vac advance so you can tune it properly.

 

[BB_Mike]

I"ll 2nd that. I ran my HEI with no vacuum for a long time because it pulled too much advance, and the worse part was that it was slow to "blead off" when I went WOT. So I'd detonate at part throttle. I did some home-brew limiting of the advance and I really like the improvement. I was able to use my idle circuit again! There was a post about it I made, but it was HEI specific.

 

[JimM]

my msd added 18 degrees.

 

[Zio]

thanks guys for the help. 18 degrees sound like alot when my engine likes 38*. I will probably lock out the timing again,but I think 12* is all I would like but we will see.

Is there a certain adjustable vacuum advance that you guys would recommend I should buy?

thanks
Tom

 

[Zio]

anyone?

 

[69-CHVL]

Put it on "ported" so yo dont add anymore to your idle, just cruise. Crane has a limiter plate you can buy for like $5 so as long as the vac advance unit you have starts at the appropriate inches of vacuum, you can use the plate to give you the # of degrees that you need. My unit gives 20* of advance, and I trimmed it down to like 14-16*, cant remember which one. When I had the MSD distrib the vac advance did add 20*.