I was talking to my buddy and he read somewhere the reason some 305's are slower is because our pistons are domed in. I was wondering if that was true. Let me know!

 

By "domed in" do you mean dished?

I don't remember the pistons being dished when I had my heads off back a few months ago. I think that they're flat tops with 4 valve reliefs. Anyway, even if they are dished the 305s get 9.3-9.5 compression which is plenty for an iron headed, pump gas motor. The reason that the 305s are slower isn't because of the pistons (other than the fact that they're smaller than the 350's).

-Mark W.
'88 SC Camaro w/ 305 TBI

 

Dished pistons came in the LG4. All the other thirdgen F body V8s have flattops.

 

i can confirm from when i changed the heads that we have flat tops.

lata
tim

------------------
91 Camaro RS-LO3,Auto.
14.209@95.46mph
Best 60' 1.917
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Only the early LG4's, around 84 or 85 they got 9.5 to one just like we do. My friend's LG4 has flat tops, we have flat tops too. 70's chevy motors are bad for having dished pistons.

------------------
1989 Pontiac Firebird Formula LO3 Auto
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[This message has been edited by Keith5 (edited July 27, 2001).]

[This message has been edited by Keith5 (edited July 29, 2001).]

 

Many replacement/rebuit engines also come with dished pistons for some reason.

 

According to my 85 Helm manual the LG4 had a 8.6:1 CR. My other books show the LG4 (82-87) as always having a 8.6:1 CR. :shrugs:

Where did you get your info?

Perhaps your friends engine had the short block replaced?

 

https://www.thirdgen.org/newdesign/tech/techdb.shtml