All right guys: How smart are you?
limestang05
08-29-2005, 07:56 PM
I've been trying to ID this 396 block I have. It is date coded Dec. of 1970 (making it a 1971 model). Its casting number is 854. Its block suffix code is "CLB". Pretty simple huh? Now heres the kicker.....Its a four bolt block with the big oil passage above the oil filter. It is built like a 375hp 396 but in '71 did they offer this combo? I've never heard of an LS3-402 of having four-bolt mains(not aftermarket)........you tell me!
jesse1970ss
08-30-2005, 12:48 PM
I've been trying to ID this 396 block I have. It is date coded Dec. of 1970 (making it a 1971 model). Its casting number is 854. Its block suffix code is "CLB". Pretty simple huh? Now heres the kicker.....Its a four bolt block with the big oil passage above the oil filter. It is built like a 375hp 396 but in '71 did they offer this combo? I've never heard of an LS3-402 of having four-bolt mains(not aftermarket)........you tell me!
by 1970 the 396 was 402 but chevy did not actually call it that they stuck with 396 with fear that the public would not embrace it as well as they did the 396 so a 71 "396" is actually a 402.
by 1970 the 396 was 402 but chevy did not actually call it that they stuck with 396 with fear that the public would not embrace it as well as they did the 396 so a 71 "396" is actually a 402.
limestang05
08-30-2005, 06:24 PM
Actually, It started in Late '69 Chevelles. But, that still doesn't explain the 4-bolt block in a '71 Chevelle. Anyone need one?
ctesla
08-30-2005, 09:40 PM
Actually, It started in Late '69 Chevelles. But, that still doesn't explain the 4-bolt block in a '71 Chevelle. Anyone need one?
you're both right.
by aug'69 more so in trucks than passenger cars, but nonetheless,
Chevy and GMC played with 396/402, 454, and the odd-ball 400 big blocks (400 BBC in trucks only, usually camper specials, Cheyennes, etc.)
the Mark IVs in passenger cars, most commonly, the 396" was a great engine, and the public did love it; however, GM PR could not call it anything else, even though it was... at the turn of the decade, they already knew an impending doom: SMOG devices, and so by changing some int/exh components to a 402" mystery motor" (also the nickname of the 400), a little more squeeze, and huff, and emissions pass alot easier.
also, GMC had phased out its industrial blocks the 305"V6, and the 348, for the big parcel trucks and buses, so they needed a "commercial/industrial" block, which the 396 wasn't (supposedly, as it was for consumer cars), so the need for a different "heavy duty" badging such as a 402, meant not as torque driven as the 454, and 'smaller' on the front axles.
the 454 (7.4L by the late '80s) stood alone, but the other three:
396, 402, and 400engines are ALL the same except for external decals, with an actual displacement of 401.9cubic inches.
...the head combinations and manifolds is where the main variance lies.
hope this helps.
oh yeah, I hope the fuel prices come down so you can REALLY enjoy your big block.
chris
nrt racing
you're both right.
by aug'69 more so in trucks than passenger cars, but nonetheless,
Chevy and GMC played with 396/402, 454, and the odd-ball 400 big blocks (400 BBC in trucks only, usually camper specials, Cheyennes, etc.)
the Mark IVs in passenger cars, most commonly, the 396" was a great engine, and the public did love it; however, GM PR could not call it anything else, even though it was... at the turn of the decade, they already knew an impending doom: SMOG devices, and so by changing some int/exh components to a 402" mystery motor" (also the nickname of the 400), a little more squeeze, and huff, and emissions pass alot easier.
also, GMC had phased out its industrial blocks the 305"V6, and the 348, for the big parcel trucks and buses, so they needed a "commercial/industrial" block, which the 396 wasn't (supposedly, as it was for consumer cars), so the need for a different "heavy duty" badging such as a 402, meant not as torque driven as the 454, and 'smaller' on the front axles.
the 454 (7.4L by the late '80s) stood alone, but the other three:
396, 402, and 400engines are ALL the same except for external decals, with an actual displacement of 401.9cubic inches.
...the head combinations and manifolds is where the main variance lies.
hope this helps.
oh yeah, I hope the fuel prices come down so you can REALLY enjoy your big block.
chris
nrt racing
limestang05
08-31-2005, 12:58 PM
Ctesla.....very correct....but, can you tell me about a 4-bolt 402 in 1971?
ctesla
09-01-2005, 12:11 AM
Ctesla.....very correct....but, can you tell me about a 4-bolt 402 in 1971?
I've never heard it; but I wasn't on the plant floor.
do your numbers match from VIN and block stampings?
is so, get it appraised before modding.
I do not have all my archaic literature here in houston,
but am returning to colorado over labor day weekend, and will bring back my books...
in the mean time:
1-800-950-9503
Year One
these guys can crunch your VIN, your cowl tag, the block and heads...
even tell you what color carpet and if there was a chip in the dash (ha).
pretty sure you got a good one there:
4-bolt AND "CL" was it B?
usually a CLB/CLT/CLK was reserved for trucks, vettes, SSs, and the high end builds.
does it look like the engine been gone through?
if these 4-bolt caps ALL go straight up, its stock, from something.
splayed 4-bolts didn't show up in those years.
do you have any other components from break down;
piston? main or rod bearing? that may have either GM OEM # or aftermarket number and bore or mike size?
YOU ARE THE ONE!!!!
you REALLY DID GET the mystery motor!
seriously, at the plants (knowing from personal exp; GM-Inland, Dayton, Ohio), even though you have a 12/70 (70-1/2 or 71), at the end of the year, production slows, and they might have uncovered a crate of five or ten motors in the corner, and said, "let's hit or quota," or, "let's get those outta here," and suddenly, the one-off is born.
:2cents: had a '77 Chevy20 Van roll out with a 74-5 inline 292" which the build sheet said 250" (which is still a six cylinder, but inventory showed it as a 350"), so needless to say my father got a great work van for about one thousand off sticker, and somebody ELSE got a SBC engine falling off (or out of) the truck somewhere...
there is a company out of nebraska, okla, or somewhere corn is grown, called Four Star. if they have a website, or an 800 #, I'll do some digging, as these guys could find out anything GM engine related.
I'll check in after the weekend.
chris
I've never heard it; but I wasn't on the plant floor.
do your numbers match from VIN and block stampings?
is so, get it appraised before modding.
I do not have all my archaic literature here in houston,
but am returning to colorado over labor day weekend, and will bring back my books...
in the mean time:
1-800-950-9503
Year One
these guys can crunch your VIN, your cowl tag, the block and heads...
even tell you what color carpet and if there was a chip in the dash (ha).
pretty sure you got a good one there:
4-bolt AND "CL" was it B?
usually a CLB/CLT/CLK was reserved for trucks, vettes, SSs, and the high end builds.
does it look like the engine been gone through?
if these 4-bolt caps ALL go straight up, its stock, from something.
splayed 4-bolts didn't show up in those years.
do you have any other components from break down;
piston? main or rod bearing? that may have either GM OEM # or aftermarket number and bore or mike size?
YOU ARE THE ONE!!!!
you REALLY DID GET the mystery motor!
seriously, at the plants (knowing from personal exp; GM-Inland, Dayton, Ohio), even though you have a 12/70 (70-1/2 or 71), at the end of the year, production slows, and they might have uncovered a crate of five or ten motors in the corner, and said, "let's hit or quota," or, "let's get those outta here," and suddenly, the one-off is born.
:2cents: had a '77 Chevy20 Van roll out with a 74-5 inline 292" which the build sheet said 250" (which is still a six cylinder, but inventory showed it as a 350"), so needless to say my father got a great work van for about one thousand off sticker, and somebody ELSE got a SBC engine falling off (or out of) the truck somewhere...
there is a company out of nebraska, okla, or somewhere corn is grown, called Four Star. if they have a website, or an 800 #, I'll do some digging, as these guys could find out anything GM engine related.
I'll check in after the weekend.
chris
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