I timed my truck to achieve the best vacuum (20 inch's or so)and when I check it with the light its off the scale...25+, I assume that my distributor is off a tooth or something but not sure what the best way to fix it would be anyone care to take a shot? I have a mild 350 with rv cam....

thanks, Matt

No that sounds about right, I race oval track and there is a vaccum rule stating that 16" is min at 900 RPM, to beat this some people hide an MSD timing controller in the car and advance the timing in the 50 degree range to bring the vaccum up.

You need to borrow a timing light that is adjustable, the way these work is you adjust the knob until the timing mark is back at TDC and read the knob. Your timing is a bit high IMO but my ECM keeps mine in the 20 degree range at idle, I would be more concerned with yout total timing, you will need the adjustable light and need to check it at about 4000 rpm after all the mechanical advance has kicked in, you don't need to go over 34-35 on pump gas, you may get a ping if you do...

Hope this helps :p

Most chevy performance books call for about 38 total advance and at idle with no vacuum and very stiff springs I'm almost straight up with the light but I will go get a variable light and see if this helps me dial it in. My vehicle has been over heating badly and when I just timed it the old fashion way with vacuum it pointed this out....many thanks...looks like I will solve two problems at once...overheating and exhaust temps...that and I need a new timing light.....

thanks..Matt

I feel that 38 is a bit high for most street use, I ran 34 degrees of timing on my old gas race engine and turned it 7000+ without a catch on 110 octane, I run a 358 on methanol now and am locked out at 38 degrees. If you don't get a ping with your total advance at 38 go for it.... but when you do set it at 38 make damn sure you are getting ALL the advance out the distributor cause 40+ you are going to do damage..

Let me know when you're gonna work on it, I'd love to stop by and help out... Why do you care about vacuum, for brakes??

Vacuum is the best sign of a good performing engine and will work on it tomorrow around 4:30 or 5 after work...seems like a no brainer to fix, just some trial and error to get it dialed back down a bit...two to three teeth back..call 602-524-5478 if you want to and I'll give you directions tomorrow...did you weight that pig yet, Elf?

I weighed in at 4480...

I'll give ya a call tomorrow!

That's it? damn I was way off....I still don't see how but I guess you did loose weight with no top and what not....guess you got the money...

actually the bet didn't happen. I'll explain tomorrow...

You are checking the timing with the advance off right?

Yep...think I need to rotate the distrbutor counterclockwise about 3 teeth...my exhaust got cooler and no over heating so I'm getting closer....

damn, if you had it that far adv and the manifolds were glowin, I hope it did not blast a hole in a piston.

Retarded timing makes the exhaust manifolds glow. Too much advance causes detonation which leads to disintigrated pistons.

Originally posted by Keith
damn, if you had it that far adv and the manifolds were glowin, I hope it did not blast a hole in a piston.

No sir you are wrong, if you retard the timing the combustion event it still taking place when the exhaust valve opens this allows the burning air fuel mixture to escape out the valve causing the headers to glow...

Now advancing the timing will not cause the headers to glow but will cause a ping if it gets out of control which will burn a hole in a piston.

Now if you are running to lean you will get glowing headers also, if you are running to rich your whole exhaust will be extremly hot due to the excess gas burning in the pipes and mufflers...

Awhhhhhhhhhhh...were arguing definitions again....the fact is that 38 should be the limit for me and being at 25 without the advance module connected means I'm off a couple of teeth...

Originally posted by coyote
Awhhhhhhhhhhh...were arguing definitions again.......

Who me? :rolleyes: :D

TPI and Black Dog, you read words into what I had stated. I was not relating the glowing manifolds with the adv timing. There could be a number of reasons for the red exhaust. I was stating that if the manifolds were that hot, and his timing was at 25 without the adv connected, then with the adv connected it must have been timed way out there. With that kind of heat and that much adv, it could have easily burnt a piston.

Now if his timing was so far retarded that it was causing red manifolds, it would have to be pretty far retarded. I pretty sure he would have been able to tell it was fawked by the lack of power it would have, like probably half of normal.