Ok, this one is not for me but it's for my buddy. He has an S10 with a 327 in it. The motor has 461X casting camel hump heads w/ 2.02/1.60 valves, Comp Cams 282S solid flat tappet cam, Victor Jr. Intake and a Holley 700 double pumper. The compression ratio is around 10.5:1.

The truck ran 15.6 at the strip :( . I told him that motor shouldn't have any problem breaking into the 13s. He has 3.42 gears out back and the stock S10 5 speed that was behind the original 6 banger. The RPMs drop a good bit whenever he shifts from 2-3rd gear (I suspect it's from the trucks unevenly spaced gear ratios). He was running through the traps at 5000RPMs in 3rd gear. Also he has shorty style headers with 2"exhaust pipe! I told him that the exhaust system was his main problem...he has all that gas going in and combusting but nowhere to go. I'm currently trying to convince him to pull the entire exhaust system back about 2 inches or so to see what it runs like with open headers.

Well I told him to bring his truck over and I would check the timing for him. He was only getting 9 degrees initial advance and 14 degrees total advance with the vacuum advance removed . I knew it wasn't advanced far enough whenever he pulled the vacuum advance off of the carburetor and the truck stalled. So I had him tach it up to 3000RPMs and I set the total to 36 degrees. I had him tach it up to 3500RPMs to insure that no more advance occurred (which it didn't).

I had him take it out for a spin with the vacuum advance unhooked and the timing advanced. He said "I can't really notice much of a difference, but it's hard to tell."

Here's my question, is it safe to hook the vacuum advance back up? I don't run a vacuum advance on my car and I get around 28 degrees initial and 38-39 total so I couldn't really tell him for sure. Can anyone help me out here. Does it sound like I did everything correctly?

 

The worst that could happen is he might get some pinging under light load and have to change the vacuum canister. I'm amazed that he couldn't tell the difference in SOTP between 14º and 36º!

I am curious about why his curve is only 5º though (9º initial, 14º total before you reset it). I'm assuming that you had to set it at 31º initial to get to 36º? I'd have expected some starter kickback problems with that much initial but it doesn't sound either your car or his is having any problem with that.

 

vetterodder:
I was amazed he couldn't feel a difference too! Changing my timing from 29 degrees total to 38 degrees total picked me up 1.8MPH and 3 tenths in the 1/4 mile.

Whenever I set the timing to 36 degrees total he was getting 24-25 degrees initial. My starter kicks a little bit whenever the motor is hot even though it is a high torque starter.

 

I am amazed the truck is so slow!

Bence, hook a chain to him and tow him through the 1/4 with your Vette so he can say he has been in the 13's :lol:

 

Curtis:
You're too much sometimes :lol:

 

Hi

I run 51 Degrees total advance at 3000 RPM, this including vacuum on my 427 CI big block. No pinging so far.
Yes, you should be able to hook the vacuum back up again.

Gunther