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ASEMaster35yrs, Chevy Technician
Category: Chevy
Satisfied Customers: 2095
Experience:  ASE Certified since 1972,Master Auto tech,Heavy Truck Tech ,chev dealer tech
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Please, I'm trying to find out what Chevy motor I have. The

Customer Question

I'm trying to find out what Chevy motor I have. The casting # ***** it is -TM01XAA8.
What can you tell me about it please?
Submitted: 1 year ago.
Category: Chevy
Expert:  Gary replied 1 year ago.

I am very sorry for the long wait

can you tell me what the casting numbers are drivers side rear of the engine block top

like this picture here for the location of those casting numbers

Customer: replied 1 year ago.
The other number is ***** and I know that # ***** me it's a 454ci.
I want to get info on the #TM01XAA8. I was told this is an LS7 from the 70's but I can't prove that with this casting #. I would like to know which eng this is, horsepower, and year built please?
Expert:  Gary replied 1 year ago.

that is correct but the problem i am having with that stamp number is ***** never made a block with the suffix code AA8

can you double check that stamp ?

also the reason for knowing the casting number is ***** will help us to narrow down the year of this block to help us find out what year ect..

but as of now there is NO AA8 ever made

so i need that stamp rechecked and the casting number to help you out

Customer: replied 1 year ago.
TM01XAA8 is verified with an added picture.
the casting # ***** ***** my previous email to you- 14015445- I know that tells that it's a 454ci.
Expert:  Gary replied 1 year ago.

ok just using the casting numbers to narrow this down this block is from a 1978 to a 1990 2 or 4 bolts main ( which i am sure you knew )

14015445...454.......78-90...2 or 4 bolt

the problem you have is the TM which usually is a stamping used for a target master replacement over the counter engine

and with AA8 which was NOT a stock code stamp

GM did not keep any records for any replacement engines for any stamp coding for these replacement engines

the engine is a generic replacement 454 that fits 1978 - 1990 cars or trucks

with no records it will be unknown on the exact year of this engine or HP I am sorry to say

i know this is what you did not want to hear but that is what those stamp numbers and letters mean when they start with an odd 2 alphabet numbers and end with a stamp number not documented

any stock 454 engines started with stamp code AKA and went up from there

Customer: replied 1 year ago.
Hi Gary,
My original question to you was to decipher the- TM01XAA8, I already was able to get info on line anout the other casting #. Because you were unable to give me information about the TM01XAA8 I would appreciate it if you do not charge me because you did not give me any information about this number.
Thank you.
Expert:  ASEMaster35yrs replied 1 year ago.

Your engine is a 1978 LS6 454 crate engine.

Just for clarity of detail. XAA is a code for a 10.2 / 1 compression crate engine. Internally the XAA motors are exactly the same as the earlier higher compression LS6 motors.

T = Towanda

XAA = LS6 crate engine suffix code


The XAA engine ...sold with the P/N 366250 came with iron, rectangle port, open chamber heads & 2.19 1.88 valves.

454 LS7 suffix is XCH.


Customer: replied 1 year ago.
That's good information, thank you. Is it a 4 bolt main? That's the other and last thing I'd like to know about this engine?
Expert:  ASEMaster35yrs replied 1 year ago.

Yes, it is a 4 bolt main.

Customer: replied 1 year ago.
Thank you! That's the info I needed.
I would like to get the same type of info for a pair of heads. Should I start a new question through this service?
Expert:  ASEMaster35yrs replied 1 year ago.

Give me the casting number and I'll look it up for you.

Customer: replied 1 year ago.
Can you please verify the codes on the head?(###) ###-####(I think th first is an 8 it might be a 6)
Expert:  ASEMaster35yrs replied 1 year ago.

The casting number is(###) ###-#### ***** is the information:




Open chamber

425HP, 118.0cc, IP 325cc


2.19 intake, 1.88 exhaust

IP = Intake runner volume


Customer: replied 1 year ago.
Thank you. Do you know if it is an LS7 head or LS6 head?
Expert:  ASEMaster35yrs replied 1 year ago.

It is an LS7 head. The casting number is(###) ###-####for the LS7 Cast Iron open chamber heads. OTC Crate LS6 engine assemblies, got the cast iron OTC crate LS7 Open Chamber head installed to late 80,s . GM did this to lower the 11. to 1 Compression to around 9.6 to 1 because of piston damage due to diminishing poor fuel octane rating.


Expert:  ASEMaster35yrs replied 1 year ago.

Description of this head is as follows: Open Chamber LS-6 & LS-7 Service Head.


Expert:  ASEMaster35yrs replied 1 year ago.

They're basic over the counter service replacement open chamber heads.They were not specifically LS6 or LS7 heads, they were service replacements.

See forum link: