crankshaft not turning smoothly

[Steve@Rennsport]

Originally Posted by notmytarga

So what to do?

Use the RS with CIS and deal with poor performance.

Build with the RS and change to another induction system.

Purchase new P & C's for the CIS.

Purchase JE pistons. Use 6 of the used cylinders.

What cam changes might I need?

Apparently I have some difficult and expensive decisions to make.

Those are Nikasil cylinders and therefore usable, depending on what you want the engine to be,...

If you retain those pistons (once they are all cleaned up & measured), I'd suggest either using carbs or MFI for an excellent running engine.

You can use JE's in those provided the bores in in good shape. Don't go too wild on compression if you want to run the car on CA gas in hot weather.

If you keep the CIS, I'd use CIS pistons. If you use the RS ones or JE's, you can use a variety of cams: Solex, "E", GE-40, early "S", etc. It all depends on what you will do with the car and what kind of engine "personality" you wish.

[id911T]

Steve,

I have a question about the use of non-CIS pistons with the CIS system, like we have here. I've heard time and again that CIS requires the use of the lumpy dome swirl pistons, but every other CIS application that I've seen (VW, Audi, Volvo) run flat or slighly dished pistons with CIS and seem to suffer no ill effects. So did porsche use the swirl pistons for emissions or is there real power loss associated with not using them with the CIS injection? Not trying to argue, but this has bugged me for awhile so I figured I'd ask.

[notmytarga]

My P&C inventory is:
RS 2.7 Nikasil 90 mm 6 pistons and six cylinder - one piston with surface damage
CIS 2.7 Nikasil 5 Pistons, 4 cylinders One set damaged after dropped valve, another cylinder sent to Norway.

All the cylinder bores appear OK - ovality check not in yet.

I haven't looked into changing the induction, what is involved and the cost of that?

Do these RS P & C's have much value?

[notmytarga]

Steve - What do you think about these questions?

Complexity and originality wise, sticking with CIS would be best. But if it requires a new P&C set, I'm out a lot more bucks. What are my options on the way to that cost point? Should I start a different thread?

[Steve@Rennsport]

Based on your current inventory, it seems like you have some choices:

1) Find 6 matching, good cylinders and install an aftermarket piston using carbs.

2) Same as above, using CIS and accepting some running issues and reduced mileage.

3) Buy the new Mahle P/C set thats compatible with CIS.


JMHO, but if your CIS is in good shape and runs well, I'd choose #3 unless you are looking for major performance gains.

[notmytarga]

Thanks Steve. I thought CIS gave good fuel economy compared to webers.

I have noted that you haven't recommended the 964 cam/9.5 compression piston CIS option. Is that because I use CA fuel or for other reasons?

I sourced a matching single CIS piston off eBay this morning to see if I can come up with a usable set from my 'inventory'. Any cautions against this? Ted notified me that he has started on my parts. We're moving!