2 liter throttle body mod., vac advance hole

Anyone know the diameter hole needed to add a vac. advance to a 2 liter thottle body?
The later thottle bodies only have retard. I understand adding advance improves performance.
Also, whats an acceptable compression test reading for a 2 liter motor?
thanks

[Dave at Pelican Parts]

When new, the compression is supposed to be up to about 150 PSI. The wear limit is listed as just under 95 PSI in the factory manual.

I think I recall Haynes quoting 150 PSI new and 110 PSI as the limit.

When I bought it, my 2.0 had dead-even 100 PSI in all four cylinders. My mechanic thought that was low, but not awful since the readings were so even across the board.

It turned out that the heads were not in very good shape, and the even-ness was just a coincidence. About 10K miles after that, I had to have the engine rebuilt due to crank endplay, and found that the valves had not been sealing very well at all.

The motor is a LOT stronger now.


I have a friend who has added vacc advance ports to a couple of throttle bodies in the past couple of years. I have sent him your e-mail address--hopefully he will contact you. (I didn't think it was fair to just publicly post his address without asking him.)

--DD