[Cable]

Hey guys, the TRW book says the L2465 are open chamber heads only. But they also list a compression table listing 100cc heads (11.3:1 CR). They also list 106.9 which is a chamber size listing for BBC factory closed-chamber head.

So does that mean these pistons will or won't work with a set of '69 '290' closed-chamber castings? They CC's at 105-106 cc's. I know V/P clearence will be an issue too, but I can get a cam to match.

If anyone has used these pistons with closed chamber heads or has any info, any help is thanked in advanced.

[ToyzRMe]

I have a set of the Probe version of the 2465 piston on order from Flatlander right now.

It's an 18 cc dome piston like the TRW/Speedpro 2465 but per Probe tech the valve notches have been deepened, the skirt updated, and the oil returns revised.
The price is right in line with the Speed Pro/TRW but I believe it may take less rework to use so it should be cheaper overall. Might be something worth looking into.

I'll post my observations when they get here if you're interested.

Randy

[SILVERSS454]

Why not use the #2349's? I believe they ar edesigned for closed chambers and will get you close to the same compression.

[Troy70SS]

The TRW version of those pistons are 25.7 cc. I think they would take an enormous amount of work to get them to work with the closed chambers. I have not tried it though. I'm with Silver - use the 2349's.

Troy.

[JRS70LS5]

These are the speedpro pistons I used with my 820 open chamber heads,H581 I don't remember the dome volume.Dome heigth was .340

[Cable]

The trouble is the pistons (L2465) are already sitting in a balanced short block.

I might have a nice set of '290' closed chambers pretty soon and he wondered if they'd work on his 454 with L2465's.

I believe you guys when you say they won't work, I just don't understand why TRW/SpeedPro has a 100cc listing.

[SILVERSS454]

JRS, I noticed you are running power brakes. How well do they work with that cam? I was under the assumption that there wouldn't be enough vacuum to operate the brakes properly.

[Cable]

Originally posted by JRS70LS5:
These are the speedpro pistons I used with my 820 open chamber heads,H581 I don't remember the dome volume.Dome heigth was .340

Unless my eyes are fooling me, those pistons don't have an exhaust valve relief, right?

Your cam is EXACTLY what I would like to run, but was told valve to piston clearence would be an issue. Did you have any problems?

Thanks.

[JRS70LS5]

I run a vacume canister to assist in the low vacume about 8" at 900rpm.These pistons have both intake and exhaust reliefs and I had plenty of room,just remember to check everything,these are closed chamber pistons with open chamber heads.

[Troy70SS]

I would suggest finding some open chambered heads then. Too much work to make everything go together using closed chambered heads. You can forget the balance too. It will have to be redone if you cut the pistons anyway.

Troy.

[Cable]

Originally posted by Troy70SS:
I would suggest finding some open chambered heads then. Too much work to make everything go together using closed chambered heads. You can forget the balance too. It will have to be redone if you cut the pistons anyway.

Troy.

Yup, I've come to the same answer.

[Troy70SS]

10-4 Good luck with it. I must say my 781's work pretty well. I'm thinking of having them professionally ported and flow tested. I think they are good for 11's easy if I have someone with some real knowledge work on them and not just my educated guessing.

Troy.

[michael n mississippi]

the 2465 and a set of semi closed heads is a perfect combo. a friend of mine has that combo in a 71 468 he adds one small bottle of 104 to a tank and drives the car to the track and consistant low 11 s car. doest overheat. great combo. he built the engine as a joke. said he would have less than 1500. dollars total in the build. he runs truck thumb rods and the 2465 forged trw they are cheap,heavy and his cheap build runs like a dream. good luck

[Cable]

Originally posted by michael n mississippi:
the 2465 and a set of semi closed heads is a perfect combo. a friend of mine has that combo in a 71 468 he adds one small bottle of 104 to a tank and drives the car to the track and consistant low 11 s car. doest overheat. great combo. he built the engine as a joke. said he would have less than 1500. dollars total in the build. he runs truck thumb rods and the 2465 forged trw they are cheap,heavy and his cheap build runs like a dream. good luck

Just so I am not misunderstanding you...

So you are saying that your buddy is using L2465's with closed-chamber heads and he doesn't have any problems? Did he have to modify the pistons or heads to make that work?

Oh, here is a pic of the heads:

[Cable]

Here's a shot of my L2365's.



Here is a shot of some L2349's which is suppose to be a closed-chamber piston. Is it me or does it looks the same as my L2465's?



I can't help but look at the dome and compare it to the chamber on the heads and wonder why it wouldn't work.

Where on the dome and/or chamber is the interference that is suppose to make these parts clash?

Speed-Pro/TRW Catalog:

http://www.21cgt.com/FMWebCatalog/default.htm

Here's TRW's drawing of L2465 pistons:



If you'll notice the pop-up drawing of the dome looks nothing like my pistons.

Now take a look at TRW's drawing of a L2399 piston:



That's what my L2465's look like, as well as L2349 and L2399 pistons.

I don't get it. Could TRW made a mistake and that's why they are listed as a open-chamber only piston?


If I had the heads in my hands, it would be easy to check, but I don't.


Thanks guys.