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Finally digging into my 71 LT with NOM and trying to align facts from verbal history and current reality. I bought the car from the second owner who purchased it in late summer 73 with current engine.
This was related to me from 2nd owner as reason for replacement engine; The original owner told me that he tried to change the camshaft when the car was new and did it wrong, pumping a rod through the block. He ordered a new 11 to 1 compression LT-1 engine assembly from Chevrolet, same as issued for 1970 LT-1s (the original 1971 engine had 9 to 1 compression), ergo, the CE stamp on the block. He told me he had an engineering shop install the new engine, changing the camshaft to a General Kinetics solid lifter, milling the heads, and performing a competition valve job on it.
The fellow I bought it from put minimal miles on it and never was inside the engine so I think everything I'm seeing is from the early on replacement. I'm trying to figure out what might have been replaced (block only?) vs swapped from the original engine. (if anything) Happy to have best guesses and or experience form having done this back in the day. Pics below of what I have, head stampings, underside of piston, 4 bolt main stamped CEB 1373 8 7, including crank weight stamp of Jul 24 1971 (which seems to predate the car?)
Guesses on current compression ratio?
thx
Mike
I'm trying to figure out what might have been replaced (block only?) vs swapped from the original engine. (if anything)
...
crank weight stamp of Jul 24 1971 (which seems to predate the car?)
Not sure how one would send a rod through the block by way of swapping the camshaft...
What is the body date of the car (upper left alpha-numeric on trim tag) and the last 5 of the VIN?
Head casting date of A111 seems to be Jan. 11, '71. Is the other head's date about this same time period - within a week or two? If these were original to the car, the body and VIN should place it around mid to late January.
I've not seen cranks dated like that... but, if the crank's 7/24/71 date "predates" the car, then there's something amiss, given the head date.
What is the block casting number and date? (Located on the top of the block's transmission mounting flange - cast # on driver's side, date, I believe passenger side.)
I thought LT-1s came with aluminum intake manifolds... could be mistaken on that. What's the casting date of the intake?
I realize this is a lot of questions, but when you're trying to answer another you've got to look at all the clues.
Can you get a picture of the top of the piston? You can tell visually if it’s a dish/flat/dome.
From there you can guesstimate the CR easier.
492 heads are 64cc I think.
so dished pistons would be 9ish:1
flat top 10ish:1
dome, well depends on how aggressive but 11-12ish:1
You could also just do a compression test and get a good idea of what your CR is, it’s not a direct relationship, because the cam can bleed off some pressure from the static compression ratio(this is why there’s dynamic compression ratio)
but 150-160psi is about 10ish:1
492 head w/ guideplates, underside of a forged piston
OP make it clear this ain't motor his car was born with.
I can see the guideplates in first pic as well as 492 casting as well as piston underside indicates forged.
What I see is consistent with Configuration of an OE 70 LT1 and not a ZQ3 aka L48.
But you'll never KNOW exactly what's there without complete disassembly.
Compared to today's standards (lighter w/ thin metric ringpak), those OE 70's forged pistons are Very heavy. If/when it's rebuilt; better choices available.
*add* head casting number 3991492 (aka 492) offered as either straight plug or angled plug versions. Only straight plug on production motors.
Both straight & angle offered OTC all with same 3991492 Casting Number. *** again, it's clear this is a CE replacement motor; Not OE
Last edited by Rebelyell; Jun 17, 2025 at 04:15 PM.
I'm guessing it was originally a 270 HP 350 since it has a Q-jet on it.
Looks like they bought an early LT-1 long block with heads and stuck the cast iron intake/carb, ex manifolds on it from the original engine. Pretty common thing to do. Now if they swapped the LT-1 cam for something else...it's anyone's guess if they helped you or not...depends on what it is. Same with head porting if they did any. You might be able to look closely and see if they used steel shim head gaskets like the factory did?
Not sure how one would send a rod through the block by way of swapping the camshaft...
What is the body date of the car (upper left alpha-numeric on trim tag) and the last 5 of the VIN?
Upper right? I06 April of 71 14160
Head casting date of A111 seems to be Jan. 11, '71. Is the other head's date about this same time period - within a week or two? If these were original to the car, the body and VIN should place it around mid to late January.
Yes, I read it as 11 71
I've not seen cranks dated like that... but, if the crank's 7/24/71 date "predates" the car, then there's something amiss, given the head date.
My mistake I was thinking 70 instead of 71. July of 71 would be for MY 72?
What is the block casting number and date? (Located on the top of the block's transmission mounting flange - cast # on driver's side, date, I believe passenger side.)
I thought LT-1s came with aluminum intake manifolds... could be mistaken on that. What's the casting date of the intake?
Rear block numbers covered in grime. Original alu intake and Carb removed from car in favor of iron and Quadra jet back in the day! I have both original pieces. No casting date on the intake.
I realize this is a lot of questions, but when you're trying to answer another you've got to look at all the clues.
I would check date codes and casting numbers on all engine parts. Make a list post it here. Use carb cleaner and a brush to cut thru the grime if needed. 70 LT1s had 186 heads, but AFAIR the 492 was a later casting number for those, perhaps on warranty crate or counter engines. 71 heads were a larger 76cc. 71 s had flat top pistons, 70 pop ups. So it is possible you have a complete 1970 LT-1 long block, with it's 11:1 CR. I would stick a borescope in the spark plug hole and take a pic of the piston top and any dome, and post here.
The stamping on the block is Not "CE' it's"CEB".
Googling Chevrolet code CEB produces lots of sources that claim CEB is a bare block not a short or long block.
The stamping on the block is Not "CE' it's"CEB".
Googling Chevrolet code CEB produces lots of sources that claim CEB is a bare block not a short or long block.
No CEB in LimeBook either.
so, if CEB means bare block
does CEB mean Replacement Block rather than Replacement Motor?
six or half-dozen?
No CEB in LimeBook either.
so, if CEB means bare block
does CEB mean Replacement Block rather than Replacement Motor?
six or half-dozen?
That appears to be the case, replacement block.
Not necessarily 6 or half dozen. No way of knowing what is stuffed into the block, cast or forged crank and rods and which pistons, etc.
What is the body date of the car (upper left alpha-numeric on trim tag) and the last 5 of the VIN? Upper right? I06 April of 71 14160
Sorry, upper right - was thinking C2 trim tags. Yep, April 6, 71 coincides with your VIN.
I've not seen cranks dated like that... but, if the crank's 7/24/71 date "predates" the car, then there's something amiss, given the head date. My mistake I was thinking 70 instead of 71. July of 71 would be for MY 72? More than likely for a '72 since it's so late in the '71 production, but again, that sort of crank date is not typical Chevrolet and may be the rebuilder's date from the block swap.
I thought LT-1s came with aluminum intake manifolds... could be mistaken on that. What's the casting date of the intake? Rear block numbers covered in grime. Original intake and Carb removed from car in favor of iron and Quadra jet back in the day! Have both. No casting date on the intake. The casting date on Winters aluminum intakes is on the underside (maybe under the heat shield?).
Show part no and date code from the front choke horn on the original holley.
Originals have a 3 digit date code. Replacements have 4.
It is much more easily accessible than the intake date.
The stamping on the block is Not "CE' it's"CEB".
Googling Chevrolet code CEB produces lots of sources that claim CEB is a bare block not a short or long block.
Originally Posted by Rebelyell
so, if CEB means bare block
does CEB mean Replacement Block rather than Replacement Motor?
According to John Hinckley's article on CE engines, the character following the CE should be a single digit for year and then a 5-digit sequence number. Flint had the sequence range from 20000 to 49999. The B code would have been used after the sequence rolled over; C after that, etc. For example CE2B12345 would be 1972, round 2 #12345 – meaning this was actually the 42345th CE engine for '72. The CE engines came as a short block, and all internals but no heads, intake or exhaust manifolds.
This block does not fit the CE coding protocol John explained as it's missing the year and doesn't have the 5 sequence digits.
found it ! It's a RHSC motor; red headed step-child
regardless, doesn't seem to have any particular significance or value.
For my own personal use, I'd rather run this bastaard sooner: a good 638 roller block w/ a decent steel crank & no-crack Vortec heads.
*and may our Lord always Bless & Keep John Hinckley+
Last edited by Rebelyell; Jun 18, 2025 at 12:01 AM.
That appears to be the case, replacement block.
Not necessarily 6 or half dozen. No way of knowing what is stuffed into the block, cast or forged crank and rods and which pistons, etc.
Well, we can see the crank and rods and at least the undersides of some internals. (Until I replaced the pan ASAP) I think I may have a small enough scope to try and view pistons tops. No idea what might necessitate a block swap while reusing most internals. If the original owner did successfully backdate the car a year, I'm guessing it is all in the pistons as the only change was CR and by extension HP?
LT1 short and long blocks were cheap back then and were often installed. There were also some "fitted" blocks where pistons/rings were inserted into the block...but no rods or crank.
In the late 70's/early 80's I installed 11.0 forged pistons in quite a few smogger 350's along with the original heads to kick the compression up a good bit.
Any engine archeologists out there?
