73 911E p/c question?
 

I am putting back together a 73E motor and I am having second thoughts of using the P/C's My piston cylinder clearance is pushing .004 to .005.
Question: I have a set of NOS porsche 2.4T first oversize pistons. Could I use these if I bore my cylinders. I realize the compression will be .5 point lower, but maybe that will be better than having that large P/C gap? Any thoughts?
thanks,
Mike

Not sure about your engine but thats a comfortable clearance for a liquid cooled turbo motor with forged pistons . Just a guess but if your jugs are true(round) it should work out fine.


Kurt Williams

bump

2.4 TE or TK pistons?

The T pistons are kobelscmitt(sp?) 1rst oversize.

Now what I am about to recommend, BA duly castigated me but hey it worked on my 2.4 T motor the first time around when $ were tight and I had a great Porschephile friend, Bob Spindel suggest it to me.

Find a very reputable machine shop in your area. Have them cut each of your six pistons' top ring land gaps consistently such that a metal spacer can be inserted to bring your top ring gap back to spec(and use stock rings). I did this with my T motor back in '96 when I was in Seattle, where there was such a competent machine shop. This would be a far better approach in my perspective to using T pistons, the E cams might (and I do not know this) be moving your valves enough to hit the T piston crowns. YMMV and HTH

Mike,

911T pistons do not have valve pockets that are large enough to run 911E cams ... that is why the factory had progressively larger pockets in the 911T, 911E, and 911S pistons!

My suggestion is to bore out your cylinders to 85.0 mm and get forged JE 9.5:1 pistons with the large reliefs for 'big' cams. Then you can run any cams you want in the future ... including 'S' or GE-60 cams!

Oh yeah! Duh, I wasn't even thinking about the valve pockets. This motor is going in a car that I am selling so I don't really want to spend another $1K on pistons. What do you guys think about runnig a .004 to .005 piston to cylinder clearance/gap???
Mike

Having the ring land cut and spacers added should not be more than $200, plus the price of your new rings. Assembling your engine with the ring land out of spec, the new rings will likely break early and lead to an oil burner. and several cylinders having low compression, and a quite unsatisfactory engine. HTH.

It's not the ring land gap I'm talking about, which is fine, it's the piston to cylinder claerance.
Mike

Mikey I think everyone here missed the boat with your question. I guess you should ask again if .004-.005 is to much piston to cylinder wall clearance(for your E pistons) ? Maybe then you will find an answer.

Kurt Williams

Mike

Pistons with 0.004" - 0.005" clearance in the cylinders are WORN OUT ... and I wouldn't even waste the time putting such a set back in an engine! You would be selling a ticking time bomb ... but if your reputation isn't worth spending an extra $900 to put a quality engine in the car ... then that's your prerogative!

really bad huh? Guess I won't use them. What's the best place to buy some JE or Arias pistons??? What comp ratio should I go for? 9.5:1

Yep I concur with Warren. I somehow thought the clearance was ring land rather than the piston/cylinder gap. Your pistons are junk. 9,5:1 is about as good as you can go with pump gas. Check out EBS for the best pricing on JE. That is to say after you seen what Pelican pricing is...
Good luck and I am sorry I wasted the bandwidth.