OT (somewhat) 911S 2.2l Motor maladies, Steady Throttle popping issue Options

[Cupomeat]

My Dad's 911S has an issue with intake popping while normal driving.

BACKGROUND; Engine fully rebuilt (within 1.5k miles) and valves adjusted about 2 weeks ago. Engine was an MFI engine converted to PMOs before we bought the car. (someday I dream to go back to MFI.)

SYMPTOM: Prior to the valve adjust a sporadic 'Popping" was coming from the intake as a small backfire on a regular basis.

After the valve adjust (first since rebuild), it runs better but still pops. When I go up there, I am going to check the rotor and dist cap, but anything else to check?

Sadly, the motor does not run nearly as strongly after the rebuild as it did before the rebuild (crazy, I know). The top end, just isn't there now like it was before. I don't get the needed time to spend with the car, tinkering, as I'd like to see why.

But, back to the popping, It seems to happen mostly while cruising at part throttle.

My logic says that it is ignition and that a spark plug (or carbon build up?) is firing while the intake valve is open.

Does this makes sense? David asked me if they carbs had been rebuilt, and it has been years since they have, but there are no flat spots or stumbles while driving.

Thanks

[sixnotfour]

if you went from 2.0 to 2.2 it needs rejetting

http://members.rennlist.com/webercarbs/Web...et_Settings.htm

[Cupomeat]

if you went from 2.0 to 2.2 it needs rejetting

http://members.rennlist.com/webercarbs/Web...et_Settings.htm

This is a good reference, but it shows that the 2.0s and the 2.2s have the same initial setting on all parts.

[mskala]

This is a good reference, but it shows that the 2.0s and the 2.2s have the same initial setting on all parts.
[/quote]

There will be a larger number of people on the pelican 911 tech forum who could chime in on all these issues. When I got my 'new' motor I faxed all the specs to Richard Parr of PMO and he told me the settings to use. So far they seem pretty good.

For reference, it is a 2.2 with E everything except aftermarket cams that are similar to Solex. I have 32 venturis, 55 idle, 135 mains, 180 air corrector, F1 tubes.