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400 engine with small valves

W

weisel

1/2 ton status
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Feb 22, 2001
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Laveen, AZ
My engine spun a few berrings and I am rebuilding it. I just measured the intake valve and it is about 1.75 inches? Is this right? I would have thought that it would have come with large valves. What is the exact measurment of the valves? Is there a place on the net that I could look up the casting nmbers to find the combustion chamber volume?
 
All small block 400 engines were 2 barrel engines and 2 barrel engines come with 1.72" intake valves in them. The casting number you have i'll bet is "882" being the last three numbers which is a 76 cc head.
 
My 400 has a 4 barrel on it. Do you think someone changed it over? It looks like it came that way. I'll check what casting numbers I have when I get home.
 
I have a 1979 KZ with a 400SB and it has an original 4 barrel on it also. We bought the blazer new in 1979 so I know mine has not been changed. I took it over to a friend last night to help me with a rough idle problem and he too was amazed to see a four barrel and not the old chevy 4-2 setup
 
I also would bet the farm (if it is the original engine) that they are 882's which are a decent casting for smog heads.

The 400's don't spin really high from the factory, and the smaller valves are conducive to good, low torque.
 
Chevrolet NEVER put a 4 bbl on a 400 small block nor did they ever put a 2 bbl on a big block. This is also how you tell a 400 small block from a 400 big block in the parts store. If you have a 400 small block with a 4 bbl then someone has changed it somewhere along the line.
 
I have a 400 small block, all factory original with a factory equiped 4bbl. It is true that most 400's came out of the factory with 2bbl's, but the 4bbl was a option in the mid-late 70's. Remember the mid-late 70's there was a gas shortage, so not meny new truck buyers ordered the 4bbl's. I bought my blazer from the original owner, and got the option sheet as part of the paper work. It's clearly marked as a option from GM.
 
I don't believe that you have a factory 4 bbl 400 small block. I have checked with GM back in detroit and they said they were never made not even as an option. I also know several people who worked at the GM plant here in Fremont when they were building trucks at that plant and they have even said that GM never installed a 4 bbl on a 400 small block. Now if someone were to show me guaranteed documented proof that GM is wrong I would like to see it.
 
I was looking thru some of my dad's old repair manuals from the '70's and in there they do show a few 400's with factory 4 barrell carb's.
 
I live in Detroit. I work in the auto industry. I also have a '79 blazer with a 400 and a 4 bbl. Bought it from the original owner. This thing has never been touched. I would like to see some documentation that says GM never put a 4 barrel on a 400 from this vintage. Anything is possible with the auto industry. By the way, my blazer has a factory air cleaner housing from a 4 bbl.. If someone retro-fitted the 4 barrel do you really think they would buy a factory air cleaner too? I also have a '79 suburban that had a 400 with a 4 bbl. Come to think of it, every 400 I have seen that hasn't been touched had a 4bbl. Never is a pretty strong statement.
 
<a target="_blank" href=http://12.232.225.208/cars/brochures/1977blazer/page8.jpg>sales brousure for 1977</a>
As you can see in the engine specs a 400 had a 4 barrel carb.
The 305's came with a 2 barrel carb.
 
i must agree, i had a factory 400 with a 4brl carb. and by factory i mean it was sold new from the dealer, brand new truck with a 400 small block and a 4brl carb.
 
Man, don't EVER say Never when you're talking about GM. They did some strange stuff from time to time and the 4-bbl on the small block 400 thing is DEFINITELY true. I have seen the original 400 in a Firebird with the original 4-bbl. I never knew they come with a 2-bbl, because every one I've ever seen had a 4-bbl. Another example: The parts stores and some people say there was never a 305 with a 4-bbl, but that's true, too because I've seen several of them.

Will
 
Ok guys, I sure did stick my foot in my mouth this time. With an overwelming response to my NEVER I must be mistaken or rather mislead sometime in the past. SORRY, I should have listened to my boss a little better when he told me to NEVER say NEVER, he says I should say I never SEEN one before. LOL. Oh well, sometimes we just have to insert foot in mouth and chew a little. LMAO.
 
No 305 4bbl? Who said something like that? 1/2 ton pickups weren't even available with anything besides that or a Diesel from 81-85 before. I know it sounds strange, but in 1984, when my truck was new, it was a 4 bbl 305 or a Diesel, one or the other, no 350s.
 
Just spoke with the original owner, and yes, this 400 small block did indead come with a 4bbl strait from the factory.
 
Yup, never say never.

I think there were lots of passenger 400ci's in the early 70's especially that came with 4bbl carb...

The 305 in my 2wd has a Quadrajet on it

I also have a 350 from 79 that had 1.72" intakes on it, and also a Quadrajet, rather an unlikely combination, but they did it. The casting# on those heads is 462624 and this head should be avoided at all costs. If you thought the 333882 was a low perf. head, well the 624's are a thinner casting yet /forums/images/icons/frown.gif
 
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