Pinging At High RPM

[Roupp]

Hey Guys,

Today is supposed to be a beautiful day so of course I drove the roadster in to work. This is really the first “long� trip I have had in it since I replumbed the fuel system so it was a good shake down. Once up to temperature everything felt great the only problem was when cursing steady state in 4th gear and around 3-4k rpm I would get very slight pining.

So far my analysis is thus: Under acceleration it seems fine which makes me think it’s not a fuel delivery issue; The car has all the smog equipment removed by a PO; The timing before I set it last week was 0 deg and I moved it out to 14 deg.

This makes me think that Im getting too much advance. I have heard mention that the curve on the pre smog dizzys are different then the post smog dizzys. Is this true and what is the difference?

Thanks
-chris

[S Allen]

You definitely need to fix it sooner than later otherwise you might just burn a hole in the top of a piston. Pinging indicates a lean running condition. The later smog dizzy's were setup to run close to 0 degrees. The early dizzy's run around 16 degrees. You cannot just adjust the timing on a later dizzy to correct the problem. You can recurve the late distributor, buy a rebuilt early dizzy, or replace it completely with an Electronic Ignition unit. I am biased but I prefer the EI over recurving. Gary Boone does a heck of a job on the EI's. If money is an issue-recurving is cheapest. If it is a 30 year old dizzy the bushings could be worn and I would not waste any time on the old dizzy. The last rebuilt I bought cost me $125.00 but that was several years ago. My two cents on the matter.

Steve

[Roupp]

Thanks for the reply Steve.

After I got the car home tonight I pulled the plugs and they look suspiciously clean. I found an article over at Rallye about how to tell if the dizzy has a re curve kit or not so that seems to be the next order of business.

-chris