TRW Piston Info???

[zimmy]

I just completed pulling my FE 427 apart to get it rebuilt and when I checked the pistons, I found that they are TRW L2205 pistons. Does any one have the specs for these pistons. Especially interested in the cc's of the small half moon eyebrows in the flat tops. Any other help would be appreciated.

Thanks. Trying to determine just how bad the compression ratio was before the rebuild.

[SCOBRAC]

Zimmy,

Everything I can find refers to these as a standard replacement for the 427 which was 11.5 but something tells me that isn't right. They could be 10:1 or 10.5:1 but the real measure is what heads they were with, gaskets etc.. All the literature I see refers to them as "flat top" units.

What was the compression readings you got before you tore it down? It isn't rocket science but you can correlate the pressure with the C/R

[Bubb Rubb]

Originally posted by SCOBRAC


What was the compression readings you got before you tore it down? It isn't rocket science but you can correlate the pressure with the C/R

To some extent, yes, but in other ways you can't correlate it at all. Short cam duration will cause cranking cylinder pressure to go up. Long duration will cause cranking cylinder pressure to be way down. That's why a high compression engine with a big cam might produce less CRANKING (key word) compression than a low CR engine with a short cam.

You are best off measuring everything and doing the math.

[SCOBRAC]

Yes, but we know zimmy's cam duration was 232.. Given the symptoms presented and the pre-webber build / post build results, it is as good an indication as we are likely to get given the parts show no sign of failure. The only other answer may be in the cam timing, which as Bubb indicated, in the case of duration, will cause pressure to increase or decrease, just as it would in a long or short duration situation despite not being a particularly long duration cam.

Either way it's a moot point as the engine is in pieces again.. :-(

Bubb I have a 390 performer intake. I paid $150 for it on e-bay you can have it for that if you are interested.. It isn't a particularly large port (GT) head manifold but isn't cracked or damaged and can easily be match ported.

[zimmy]

Hey, Folks:

Thanks for the help. Here's what I know. Engine had 390 truck crank with standard 427 stroke of 3.78". Standard length Ford rods. The TRW pistons had a short compression height. Apparently, the original builder cheated me by using 390 heads with the casting numbers ground off instead of the 427 Med Rise heads that I had thought I paid for and got. Block was also 0.030" over instead of stock as promised. We didn't actually cc the heads, but they were estimated by an experienced builder to be about 76 cc. With all of the measurements that could be made or estimated, I calculated the compression ratio to be about 8.5:1. The Webers like it to be about 10.5 or 11 to 1. No wonder I had so much trouble getting them to run right. No where near enough air getting pulled in. The smaller valves of the 390 heads didn't help either.

New engine will have 10.5:1 with nicely worked Edelbrock aluminum heads and a stroker kit. Expecting about 500 hp. Keeping my fingers crossed.

[SCOBRAC]

8.5:1 you might want to have put a paxton on and called it a day..

Bummer in any case.. Let us know when you want to start flogging your old mechanic..

[zimmy]

If I could find him I certainly would!!!!!!!!!!!!