79 930 twin plug tune up & waste gate

[fstarr56]

Hey Guys, I need to do a complete tune up on my 79 930 twin plug. I know the twin plug didn't come on the car originally but I need plugs, wires, cap and rotor what should I use? also the waste gate isn't working properly should I rebuild it or replace it? Thanks in advance. Fred

[T77911S]

bosch w4cs

whats wrong with the wastegate (WG).

the valve guide was leaking vacuum on mine.
parts are hard to come by for the porsche WG which makes them non-rebuildable
i put a tial on my car.

[ficke]

Pull a bottom sparkplug off first and make sure it is not a motorcycle size plug, if it is you are limited to that size and just put one back in with the same heat range like you pulled out if it has been working fine.
The cap and rotor could be very pricy depending on what cap and rotor were used, make sure you need them before automatically replacing them. Once again you will not know that until you pull yours off and look at it. Hopefully you have paper work that came with the car that said what type of distributor was used, if not with the cap off you can find out what you have.
The wires are not much of an issue, Pelican parts has them.
It is important with a twin plug set up to make sure both plugs are firing, so after you have it together unplug one CDI box and start it then do the other and make sure you do not have a miss.
Timing is also retarded compared to the single plug engine on a twin plug engine. Before you take it apart, run it and find out what the timing was set at.
Do not set to single plug timing! It will be to much advance.
By the way that is a S type or modified air cleaner to factory style S type, cool.

[fstarr56]

PP has a jb racing cap and rotor with 14 spots for wires it looks the same, are there that many different twinplug distributors? As for the waste gate as soon as i get in the boost range it starts to break up like a rev limiter

[ficke]

There are a lot of distributors made and modified to make a twin plug set up for 911/930 engines, I would find out what you have before ordering any distributor parts. Knowing who made the distributor would help in knowing the advance curve and setting timing also.
I do not know what "breaks up" when you get to the boost range, the ignition? fuel problem?
boost?

[Miguel Antonett]

The pictures show few non-stock things like hoses, chopped air filter holder, the RUF sticker... do you really know what you have there? The overall engine appears to need some attention... What about the rest of the car? Pictures will help us to help you. Do your homework before getting into getting parts. M2c

[T77911S]

ficke,
if you are talking about a plug that uses a smaller socket than the 13/16, pelican sells the w4cs in a 5/8(?) socket. i bought them by mistake.

[fstarr56]

Don't know that much about it American cars I know 930 not so much other than it's worth alot

The pictures show few non-stock things like hoses, chopped air filter holder, the RUF sticker... do you really know what you have there? The overall engine appears to need some attention... What about the rest of the car? Pictures will help us to help you. Do your homework before getting into getting parts. M2c

[ficke]

Originally Posted by T77911S

ficke,
if you are talking about a plug that uses a smaller socket than the 13/16, pelican sells the w4cs in a 5/8(?) socket. i bought them by mistake.

Yes, Good to know about the smaller socket W4cs.