Just joined this group and have a few questions about my project

[dodgedart340.]

I would like to know what year of pistons my 340 has. And if they are the high or low compression.

 

[missing linc]

from
What year is the car and the engine block?

 

[dodgedart340.]

The car is 1970 but engine is not original and I'm not sure of the year.

 

[AJ/FormS]

Well I've never seen a date code on a piston lol. and I cannot imagine wanting to know.
Now, had you asked are they hi or low compression, that's another matter.

 

[Car Nut]

 

[junkyardhero]

early 340's had two valve reliefs, later 72~73 had four valve reliefs, but they were nowhere near that deep.

i'd bet a slice of ham they're TRW or badger replacements (or mayyybe silvolite's)

scrub the top and see if there's a part number or a designation that they're oversize.

 

[dodgedart340.]

Ok thank you I will do that tonight

 

[dodgedart340.]

They are .30 over pistons. I had no idea that engine was rebuilt. Thank you guys fit the help. If anyone knows the compression ratio that would be nice to know. Pistons are trw .30 over and it will have j heads as those are currently being rebuilt

 

[junkyardhero]

without knowing all the info: how far the pistons are in the hole, head gasket thickness and the CC's on the heads any guess is at best *SSWAGITD

J heads are usually in the lower 70's range but are listed as having anywhere from 65~74cc chambers. so, let's go with the middle at say 71cc, with a .039 compressed gasket and the piston isn't a million miles downtown and you *should* be darn near 9.5:1

however, if those are positive deck then you're probably closer to 10.5 but if they're down in the hole a ways 8.5

*somewhat scientific wild *** guess in the dark

 

[CUDACOX]

By the way... Welcome to this site!

 

[dodgedart340.]

without knowing all the info: how far the pistons are in the hole, head gasket thickness and the CC's on the heads any guess is at best *SSWAGITD

J heads are usually in the lower 70's range but are listed as having anywhere from 65~74cc chambers. so, let's go with the middle at say 71cc, with a .039 compressed gasket and the piston isn't a million miles downtown and you *should* be darn near 9.5:1

however, if those are positive deck then you're probably closer to 10.5 but if they're down in the hole a ways 8.5

*somewhat scientific wild *** guess in the dark

Alright thanks