Factory engine questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

FLYNAVY30 · 05-09-2013, 09:45 PM

Hey guys, my 72 should be arriving from KY on Saturday night. I was originally intending to swap in in LS motor, but as many of you have pointed out, at least from the pics, the thing looks so clean, itd almost be a shame to remove the rebuild factory motor.

My question is, what motor is it exactly. Ive read both 400 and 402? Were these factory small blocks or big blocks? Mine is a 3/4 ton C20.

Lastly, has anyone done any real hot rodding to their factory motor? I was thinking if I decided to keep it, a nice aluminum head/intake/cam and EFI upgrade with an overdrive trans might be a nice middle ground for a daily driver.

Any feedback is greatly appreciated...Ill post more pics Saturday night!

vectorit · 05-10-2013, 09:00 AM

Does your truck still have the SPID label on the glove box?
If it does, it should say what engine it came with from the factory.
If it does not, then try looking at the front pass side block deck in front of the head to see if it has your VIN.

The 400 small block is a 4.125-inch bore, and has steam holes between the cylinders and that have matching holes in the cylinder heads.

400's are good engines, just as long as the cooling system is free of sludge. Since the ones that I have seen that are suffering from clogged cooling, tend to run hot and cause head gasket failures.

There are big blocks called 400's as well, but technically they are 402 cubic inch engines. It was a weird marketing thing GM did, where they badged the cars/trucks with a 400 emblem. But the engine was just a 396 that was bored .030 over.

Bigdav160 · 05-10-2013, 11:01 AM

From the pictures in the other thread, there is a big block in the engine bay.

If it was mine, I would hesitate to do anything irreversible.

If (collectable) Chevrolet trucks follow the trend set by early Corvettes, Chevelles and Camaros; a factory born-with engine is highly desirable.

**70cst** · 05-14-2013, 10:35 PM

Quote:

Originally Posted by Bigdav160

From the pictures in the other thread, there is a big block in the engine bay.

If it was mine, I would hesitate to do anything irreversible.

If (collectable) Chevrolet trucks follow the trend set by early Corvettes, Chevelles and Camaros; a factory born-with engine is highly desirable.

05-09-2013, 09:45 PM	#1
FLYNAVY30 Registered User Join Date: Apr 2013 Location: Austin, TX Posts: 592	Factory engine questions Hey guys, my 72 should be arriving from KY on Saturday night. I was originally intending to swap in in LS motor, but as many of you have pointed out, at least from the pics, the thing looks so clean, itd almost be a shame to remove the rebuild factory motor. My question is, what motor is it exactly. Ive read both 400 and 402? Were these factory small blocks or big blocks? Mine is a 3/4 ton C20. Lastly, has anyone done any real hot rodding to their factory motor? I was thinking if I decided to keep it, a nice aluminum head/intake/cam and EFI upgrade with an overdrive trans might be a nice middle ground for a daily driver. Any feedback is greatly appreciated...Ill post more pics Saturday night!

05-10-2013, 09:00 AM	#2
vectorit What? Join Date: Jun 2007 Location: Southern California Posts: 7,617	Re: Factory engine questions Does your truck still have the SPID label on the glove box? If it does, it should say what engine it came with from the factory. If it does not, then try looking at the front pass side block deck in front of the head to see if it has your VIN. The 400 small block is a 4.125-inch bore, and has steam holes between the cylinders and that have matching holes in the cylinder heads. 400's are good engines, just as long as the cooling system is free of sludge. Since the ones that I have seen that are suffering from clogged cooling, tend to run hot and cause head gasket failures. There are big blocks called 400's as well, but technically they are 402 cubic inch engines. It was a weird marketing thing GM did, where they badged the cars/trucks with a 400 emblem. But the engine was just a 396 that was bored .030 over. __________________ Chris 1968 K20 Suburban 1972 K10 LWB PU

05-10-2013, 11:01 AM	#3
Bigdav160 Registered User Join Date: Apr 2011 Location: Klein Texas Posts: 3,852	Re: Factory engine questions From the pictures in the other thread, there is a big block in the engine bay. If it was mine, I would hesitate to do anything irreversible. If (collectable) Chevrolet trucks follow the trend set by early Corvettes, Chevelles and Camaros; a factory born-with engine is highly desirable. __________________ My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe



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