305 compression ratios?
Thread Starter
Joined: Dec 2007
Posts: 1,924
Likes: 12
From: Minnesota
Car: 84 camaro, 88 trans am, 98 camaro
Engine: Modded , stock, LSX modded
Transmission: 700r4, 700r4, t-56
Axle/Gears: 327, 308, 373
305 compression ratios?
In some of the early 305ci 3rdgens they supposeable had a 9.5:1 CR
how was this achieved over the later 9.3:1 CR 305ci engines?
did they have better pistons? heads with smaller CC's? etc . . .
how was this achieved over the later 9.3:1 CR 305ci engines?
did they have better pistons? heads with smaller CC's? etc . . .
Joined: Jul 1999
Posts: 10,950
Likes: 26
From: Orange, SoCal
Car: 1990 Pontiac Trans Am
Engine: 355 TPI siamesed runners
Transmission: Tremec T56
Axle/Gears: 12-Bolt 3.73
Re: 305 compression ratios?
The 305 heads were all 58cc's, so the pistons were different.
Senior Member
Joined: Oct 2004
Posts: 965
Likes: 2
From: SE, Ohio
Car: '86 Z28, '91 RS
Engine: 305ci, 305ci
Transmission: TH200c (no kidding), TH700r4
Axle/Gears: 2.73, 2.73
Re: 305 compression ratios?
My 82' 305 out of a z28 has dished pistons.
My 86' 305 out of a z28 has flat-top.
Both have the same exact casting heads too.
My 86' 305 out of a z28 has flat-top.
Both have the same exact casting heads too.
Joined: Jan 2005
Posts: 10,404
Likes: 492
From: Hurst, Texas
Car: 1983 G20 Chevy
Engine: 305 TPI
Transmission: 4L60
Axle/Gears: 14 bolt with 3.07 gears
Re: 305 compression ratios?
Some of the 305s had 53cc heads on them. I have seen factory Crossfire cars runninng 14022601 casting heads on them.
That being said the difference is mainly in the pistons. Flat-tops vs. dish with relief vs. deep dish. Three different pistons were used during the Thirdgen era alone.
That being said the difference is mainly in the pistons. Flat-tops vs. dish with relief vs. deep dish. Three different pistons were used during the Thirdgen era alone.
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