Ignition setup advice for a rebuilt hotrodded 3.0

[AndrewCologne]

Originally Posted by PeteKz

One other thing: Did you use base gaskets? If not, you can add one or two to decrease the CR slightly. Those copper base gaskets are about .004"/.1mm, if I recall correctly.

IIRC 0.25 mm and 0.5 mm. The 0.5 copper ones on the bottom of the cylinder will be used if the heads have been re surfaced by common 0.25 mm.

But if you simply add those gaskets so the full height of the cylinder head exceeds the factory length then you have to add gaskets to the key chain housing as well IIRC so the hole for the cam shaft in that housing is still properly aligned.

[gsxrken]

Originally Posted by AndyLuft

Hey guys,

Thanks for all the feedback.
Im sticking with my builders recommendation with single plug, and adjust (if necessary) after it had some time on the dyno. The deck height and all other procedures was done and measured to spec, but I don't have those numbers on me.

You might be a good candidate for one of these:
J&S Electronics • Tech Articles

[mikedsilva]

Originally Posted by PeteKz

First, I don't think anyone else mentioned it: The Dilivar head studs are a bad idea. I've had a half dozen broken ones myself, and the pro engine builders here have seen hundreds. Since you already built the engine, you will have to decide whether to halfway disassemble it to replace with steel studs. You could just run it for awhile, and pull the engine and halfway disassemble to fix them when one breaks. Eventually, they will.

Second: Advertised CR's are usually optimistic. You can measure the Cr by setting one of the pistons at TDC with the valves closed, then use a graduated cylinder to pour a light oil into the spark plug hole until it is full to the bottom of the spark plug thread. You will have to tilt the engine so that the spark plug hole is at the highest point in the head, so you don't leave air pockets. Then you will have the combustion chamber volume as assembled. Calculate CR from that. It might be less than 10:1.

If you end up at 10:1 or less, stick to single plug, and stick to the original Bosch CDI system. Going to dual plug is expen$$ive. Not worth the price for a street car IMO. If you were a serious racer, you would need it to be competitive. The Bosch CDI works very well. After you get the engine running, then consider the A123 or other ignition systems. They have advantages, but they are easy to swap after you have the engine in the car. Get it running and driving first.

One other thing: Did you use base gaskets? If not, you can add one or two to decrease the CR slightly. Those copper base gaskets are about .004"/.1mm, if I recall correctly.

Looks like he has used the fully threaded dilavar as per 993 turbo.. so should be fine.
Std base copper gaskets are 0.25mm.