Piston Class is in !!

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SS Lancer

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Old great ones please educate me
I have the 340 Rpm heads and I saw some comments noting that the old school trw dome pistons cant be used with the 340 Rpm heads what is the difference in the Rpm head and say a J casting iron factory head that can accommodate the big Trw dome units ???
Combustion chamber different?
Thanks Chris.
 
To use the RPM heads the piston top must be at or below the deck height of the block at TDC to allow for proper quench as shown below, note the flat section of the head that has the asterisk by it.. it covers most of the piston bore, these are called closed chamber heads. With the "old school pistons" you would need to check them while installed to determine if they have a negative deck height (down in the bore) as shown in the illustration. or a positive deck height ( where the piston sticks up out of the bore).. There are a lot of variables that would apply but i was not trying to be mr technical difficult on ya..

Just an FYI

stroke.jpg
 
Old great ones please educate me
I have the 340 Rpm heads and I saw some comments noting that the old school trw dome pistons cant be used with the 340 Rpm heads what is the difference in the Rpm head and say a J casting iron factory head that can accommodate the big Trw dome units ???
Combustion chamber different?
Thanks Chris.
Use a flat top piston. A Hyper slug like the KB-107 for a stock stroke 360 is a good example to use for a Hyper slug. You can also find forged slugs that are dimensionally the same. With a .038 head gasket, your compression ratio will be close to 11-1 with the RPM head.
 
To use the RPM heads the piston top must be at or below the deck height of the block at TDC to allow for proper quench as shown below, note the flat section of the head that has the asterisk by it.. it covers most of the piston bore, these are called closed chamber heads. With the "old school pistons" you would need to check them while installed to determine if they have a negative deck height (down in the bore) as shown in the illustration. or a positive deck height ( where the piston sticks up out of the bore).. There are a lot of variables that would apply but i was not trying to be mr technical difficult on ya..

Just an FYI

View attachment 1715208508

Ten 4 - good info so ! Glad to know that if conditions are right they possibly could be used thank you .
 
Use a flat top piston. A Hyper slug like the KB-107 for a stock stroke 360 is a good example to use for a Hyper slug. You can also find forged slugs that are dimensionally the same. With a .038 head gasket, your compression ratio will be close to 11-1 with the RPM head.

Thank you - I bought um cheap with new rings so may never use them but if it was possible to run them im my 340 I might do it , I know they are old school and heavy but I still love them and they are good conversation pieces.
 
The Edelbrock Performer RPM 60179 heads are for pistons that are above the deck. I run them on my 273 with the TRW pistons. 65'
 
The Edelbrock Performer RPM 60179 heads are for pistons that are above the deck. I run them on my 273 with the TRW pistons. 65'
You are correct thats what is confusing about the topic The weird unusual concept they incorporated into the heads surely was done to accept something other than a 10.1 factory style flat top correct ??
 
Plymouth 65 here is the comments covering the modification Edelbrock made within the 340 Rpm head.

Screenshot_2018-08-02-17-24-33.png
 
Yes, the TRW pistons I run are basically the 10.5-1 reproduction Commando pistons. If you're going to run KB flat tops you would want the Edelbrock 60779 heads. That's what I'm using on a 340 build. 65'
 
Yes, the TRW pistons I run are basically the 10.5-1 reproduction Commando pistons. If you're going to run KB flat tops you would want the Edelbrock 60779 heads. That's what I'm using on a 340 build. 65'

Thank you I doing a 340 2X4 for Gasser
I need lots of compression.
 
I'm more confused than ever

OP said 340RPM heads.
With the .060 relief cut
To make room for the nominal, +.045pop-up, 340 domes.
leaving .015 clearance..... plus gasket thickness
is about .054 with an .039 FellPro, or .045 with the .028 gasket.
mathematically speaking.

Where's the problem?
 
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I'm more confused than ever

OP said 340RPM heads.
With the .060 relief cut
To make room for the nominal, +.045pop-up, 340 domes.
leaving .015 clearance..... plus gasket thickness
is about .054 with an .039 FellPro, or .045 with the .028 gasket.
mathematically speaking.

Where's the problem?


I saw several comments over the internet and even Cambell Performance list the dome piston for oem heads and said the dome want work but why would Edelbrock even incorporate the extra clearance if it wasnt for the old Heavy slugs once sold for the 340 engine ???
 
I'm more confused than ever

OP said 340RPM heads.
With the .060 relief cut
To make room for the nominal, +.045pop-up, 340 domes.
leaving .015 clearance..... plus gasket thickness
is about .054 with an .039 FellPro, or .045 with the .028 gasket.
mathematically speaking.

Where's the problem?


Im just curious if the Edelbrocks chambers were different some how and wouldn't permit the Trw dome to work if thats not relevant and the clearance is there then it CAN work .
 
i'm not sure I am following this topic correctly but those old trw forged 12.5 pistons are damn near indestructable but if you want to use them you can machine the tops down to whatever you want .I have a 340 I done that to back in 95 still running today .
 
i'm not sure I am following this topic correctly but those old trw forged 12.5 pistons are damn near indestructable but if you want to use them you can machine the tops dow*n to whatever you want .I have a 340 I done that to back in 95 still running today .

Ten 4 thank you Sir .
Hopefully I wasnt to confusing with the topic I just read a few threads over the web and a tach at Cambells Performance that said the domes were for oem heads and not for Edelbrock heads and with the special clearance incorporated into the Rpm 340 head why wouldn't the domes work unless the combustion chamber wasnt compatible thats why I was asking the forum to educate me because I found some cheap and even though they are heavy they could work for me.
 
mockup a piston in your block and measure deck,
Ten 4 thank you Sir .
Hopefully I wasnt to confusing with the topic I just read a few threads over the web and a tach at Cambells Performance that said the domes were for oem heads and not for Edelbrock heads and with the special clearance incorporated into the Rpm 340 head why wouldn't the domes work unless the combustion chamber wasnt compatible thats why I was asking the forum to educate me because I found some cheap and even though they are heavy they could work for me.
The 340rpm head is designed to use flat top OEM or L2332F/L2316F which are usually .018 above deck range. The L2322 you have has a dome. You could mock things up with an old .040 head gasket and clay the chamber to check clearance. You could also mill piston top off at .060 above deck and just use a .040 gasket to set the quench.
 
mockup a piston in your block and measure deck,

The 340rpm head is designed to use flat top OEM or L2332F/L2316F which are usually .018 above deck range. The L2322 you have has a dome. You could mock things up with an old .040 head gasket and clay the chamber to check clearance. You could also mill piston top off at .060 above deck and just use a .040 gasket to set the quench.

Ten 4 will try that soon block still at machine shop
I have some new .040 Cometics to try scenario out with.
 
Nothing wrong with them. I would not use them to do a mockup because they are to expensive for that. I use old gaskets I have laying around for mockup. A felpro 1008 is .039 compressed.
I can run by summit and pick some of those up
 
You don't need NEW FelPros either; they ain't cheap.
But I am.
I have reused my 1008s several times already and have put on over 80,000 miles
after the last install.
 
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L2322 piston does not fit edelbrock chambers,from memory i would say that the domes will hit the exhuast/sparkpluggside of the chamber,however they are solid domes so you can have the domes milled/shaped into whatever shape you want or even completely remove the dome and turn the piston into a flattop that sits above the deck just like a stock or L2316 piston but lighter weight and stronger than a stock piston but not as light as a modern pistons.
have a set of those turned into flattops and they have been run forewer in worn out bores and have clearanced themselfs to ridicules bore cleareance and are still not broken but they do kill rings nowadays due to rocking to much in the bores.
 
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