2 or 4 bolt mains

[84K30]

Does anyone know if any 454 powered (factory) C/K 30 trucks came off the assembly line with 4 mains? My 84's fender "tag" says it came with a 454; that is what I'm told is in the engine bay now. Obviously, I have no idea whether the engine is the original without checking the casting numbers. I would but I'm away for work right now. Also, I understand that the only for sure way to tell is to pull the pan. Thanks!

 

[Nonstop]

I pulled a 454 out of a square suburban with a 4 bolt main (original block). I do not know how to tell without dropping the pan. I am running a 2 bolt 454. I studded the mains and I have had no problems with it. I tow with it, and use it for typical truck stuff. I would not dwell much on the 2 vs 4 bolt thing unless you are doing some crazy high hp build or abusing it.

 

[75Monza]

Casting number isn't going to tell you if it's stock, the only way for that would be the info on the vin pad at the front of the block. Here is one breakdown of 81-89 vin numbers (vin tag on the dash) http://www.usa1industries.com/1981-1989-gmc-chevy-truck-vin-decoder-chart.html and some basic info on the block pad http://nastyz28.com/chevy-engine-code-stampings.php . I noticed MadMike pointed out that if you're going by casting numbers, 350's could be assumed to be 2 bolt if in a 1/2 ton truck whereas 3/4 ton or 1 ton could be assumed to be 4 bolt. Don't know how that would apply to a big block though. My big block casting book doesn't really get down to listing as 2 or 4 bolt for 80's gen IV's, just went through this trying to figure out exact year of the 454 I got for my 80 K30, casting number gave me generic info as in "it's a 454", vin pad got me specific year and build plant, but dropping the pan gave me only clue on the mains.

 

[nvrenuf]

In short, some did but most didn't. I don't know what dictated 2 vs 4 bolts whether it was related to an option or random assembly line luck. That said the few that I've seen were mid-late 80's, never seen one older in a pick up.

I lucked up and got a 4 bolt motor from an '89 Suburban. The block casting number on mine is 14015445 but that number doesn't guarantee anything as it was available 2 or 4 bolt. The only way to be sure is to physically check; pull the oil pan, scope through the drain plug hole (?) or pull the timing cover (you can see the front main).

 

[Camar068]

You could get one of the endoscopy camera's below for about $25. I bought one to find out if the 350 I had was 2 or 4 bolt. Pull the drain plug and insert there. Make sure you get one that works with your phone (android or iphone....or you can use a laptop).

https://www.amazon.com/DEPSTECH-Ult...words=endoscopy+camera&qid=1570569638&sr=8-17

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[shiftpro]

In short, some did but most didn't. I don't know what dictated 2 vs 4 bolts whether it was related to an option or random assembly line luck. That said the few that I've seen were mid-late 80's, never seen one older in a pick up.

I lucked up and got a 4 bolt motor from an '89 Suburban. The block casting number on mine is 14015445 but that number doesn't guarantee anything as it was available 2 or 4 bolt. The only way to be sure is to physically check; pull the oil pan, scope through the drain plug hole (?) or pull the timing cover (you can see the front main).

My '81 2x C30 crew cab (avatar) is a 2 bolt 454. My '89 K30 4x4 crew cab is a 4 bolt.

 

[Rick Dobbins]

2 bolt mains are the norm on big blocks. The older hi perf 427s, etc., came with 4 bolt mains. My 454 out of a donor '74 C20 is 2 bolt. Some 'Vette 454s had 4. Hard to find one around me. What breaks on the 454s is the crank. Steel forged cranks are best. Most have them, but I've heard of cast cranks in the 1980s.

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[Wumbo]

Cast crank 2 bolt main in my original 454.

You really can't tell without looking at the mains. The same casting numbers were used on both 2 and 4 bolt blocks.