63 FI Timing Question/Vacuum Advance

[Dan D.]

Re: 63 FI Timing Question/Vacuum Advance

Yes, this is correct. You need a 90* fitting and a short length of hose, available from our after market suppliers. Be sure to plug the port vacuum hole on the air meter.

-Dan-

[Duke W.]

Re: 63 FI Timing Question/Vacuum Advance

I'm not sure I completely understand the 2 inch rule or why it doesn't pass or what I should do to get it to pass. I did put about 40 miles on the car this afternoon and it ran much better and had a good idle at 700-800 RPM . The only issue was getting out of first gear. it seamed like it needed too many RPMs to getup and go and wanted to hesitate at 1500-2000 RPM. It did have much more power at the low end but I think it should still be more. I'll try getting some lighter springs and see what that does but what do you suggest on how to fix the total idle advance? I'm not really looking to modify the air meter. As far as the vacuum reading I took, it was unhooked from the VAC and plugged directly into the gauge. No Tee. wouldn't this be where I want to measure it since it's going directly into the B28?

I've explained the Two-Inch Rule here a zillion times, but I can't do it any better than in my tuning seminar other than to say that to achieve best idle quality and stability FIXED total idle advance is necessary, which requires sufficient manifold vacuum to keep the VAC "locked" at full advance at idle speed.

A cardinal rule of installing engine test equipment is that the test equipment must not change the engine configuration. By disconnecting the VAC signal line from the VAC and connecting it to the vacuum gage you have violated the rule because the VAC is no longer functioning. A vacuum gage connection MUST always be done IN PARALLEL, by using a tee to tap into any convenient vacuum source. Look at the "tools of the trade" photo in the seminar to see what I mean.

The other issue is that since the ...375 system is set up for ported vacuum advance the VAC signal line does not see full manifold vacuum at idle speed, so it cannot be used to measure manifold vacuum.

Good advice on the conversion to full time vacuum advance. You should be able to find a fitting that has the proper NPT thread on one end and a 1/8" nipple on the other at a 90 degree angle. I believe such a fitting was used on the 380 system where the PCV valve is connected on the ...375.

Your idle speed is a bit low. I suggest about 900 and go through the idle speed/mixture setting procedure in the '63 Shop Manual. A slightly richer mixture may solve the off-idle issue. This procedure MUST be accomplished every time you alter the spark advance map including converting from ported to full time vacuum advance.

Duke