2 or 4 bolt engine?
Thread Starter
Advanced
Joined: Jan 2004
Posts: 51
Likes: 0
From: Edwards CA
2 or 4 bolt engine?
I was wondering what is the easiest way to tell if you have a 4 bolt or 2 bolt engine, the reason is I would like to get a 383 crate engine but it is hard to find them for 2 bolts which is what I think I have. It's a '79 with the stock 350 auto with California emissions (or at least it is suppose to) Thanks for the help.
Drifting
Joined: Jun 2003
Posts: 1,455
Likes: 5
From: Upstate South Carolina
Most 70s Corvette 350s had a 3970010 block. The block came with both a 2-bolt and 4-bolt main depending on year and engine. Most high performance (LT-1, L-82) were 4-bolt with the base engine being 2. Yours is probably 2-bolt.
Safety Car
Joined: Jul 2001
Posts: 3,921
Likes: 2
From: York PA
Originally Posted by l979 Corvette
I was wondering what is the easiest way to tell if you have a 4 bolt or 2 bolt engine, the reason is I would like to get a 383 crate engine but it is hard to find them for 2 bolts which is what I think I have. It's a '79 with the stock 350 auto with California emissions (or at least it is suppose to) Thanks for the help.
2 bolt or 4 bolt refers to the number of bolts on the main caps. Any parts that fit a 2 bolt will fit a 4 bolt and vice versa. (with the excption of the main caps) The only way to be sure what you have is to pull the oil pan and look. However you probably have a 2 bolt, if you have a L-82 you might have a 4 bolt but I'm not positive about that. The 4 bolt is stonger than the 2 bolt, but unless you are going to build an engine an plan to spin it above 6000 rpms regularly, a 2 bolt will be fine on the street. 
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
Le Mans Master
Joined: Mar 2004
Posts: 7,450
Likes: 1,479
From: Little Rock AR
Not sure but here is something to check....Look at the boss on the rear of the block at the top center. See if it is just a hole or if it is tapped with threads. If threaded, you probably have a 4 bolt block.
-Mark.
-Mark.
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by Kalway
I believe all 350s in Corvettes up to 1981 were 4 bolt. At the top of my head the only 2 bolt was the L-81.
my l48 in the 77 was a 2 bolt
Race Director
Joined: Apr 1999
Posts: 15,133
Likes: 477
From: NM
Originally Posted by Kalway
I believe all 350s in Corvettes up to 1981 were 4 bolt. At the top of my head the only 2 bolt was the L-81.
tom...
Pro
Joined: Sep 2002
Posts: 653
Likes: 0
From: Dickinson (Houston) Texas