I recently purchased my first Corvette. It is a 1981 model with 95,000 miles. It was alleged to be bone stock by the seller.

one thing I noticed as I began poking around is that the engine has center bolt valve covers. This made me begin to question just how bone stock the car was because I did not believe these came along until 1985/7.

I didn’t think too much of it because it still had the smog pump on it and I could not imagine anyone leaving that on if they did a motor swap.

Notice center bolt valve covers




it also has a three speed automatic transmission. For some reason I thought that a 4 speed automatic trans was the only thing available that year.


I would appreciate the expertise of the group of you could help me solve the mystery.

 

It is my understanding the 700r4 was in the Vette first 1982. valve covers I am not sure, but my 82ce has perimeter bolts. You can verify if engine is original by looking at the engine stamp pad. Located on pass side front at head/block joining behind the a/c compressor. last digits of VIN are same on engine stamp pad if original hence matching #.

 

Yeah.....center bolt covers means it has Vortec heads at a mininum. NOT STOCK, NOT ORIGINAL. Its not a bad thing really, The rest of the block could still be original and someone just installed Vortec heads.

 

Welcome to the group first up, lots of knowledge here, you will learn a bunch! My 81 was a survivor with 19,500 miles , this picture shows it before I did new radiator and remove smog pump. They came with magnesium black painted valve covers , so looks like heads have been changed. Curious to see the carb under the air cleaner too. It had a computer controlled QJet, one year only. Good luck and keep posting pictures and questions!

 

Thank you all for your feedback. As I dig a little deeper under the hood, there is no telling what I might find.

so far I have been focused on suspension a getting bushings changed.

not too much to do with the interior.

I will need also to change that front bumper.

 

Looks nice! White on red is the best color combination for 80 and 81.

When you want to go digging, this site has the engine, trim, paint, etc codes.
http://corvettec3.ca/

Look for the engine stamp pad, just in front of the passenger-side head, underneath the AC compressor. Your block will have blue paint on it if it's original, and you may have to clean some grime to read the numbers. The three letter code will tell you what engine you have, and the last few digits of your VIN will be there, too, if the block is original. I've never seen a head swap that kept the smog pump, but anything is possible.

 

DJ...the engine is incorrect and has been replaced. In fact it may not even be a 350.(5.7) The 5.3 litre had the same valve covers. I have found numerous C-3's with this set-up. WHY because the 5.3's are CHEAP.

Look at the front right stamping pad number on the engine...we will decode it for you.

The tranny is 'sposed to be a 3 speed. the 4 speed 700-r4 was incepted in 82.

Bar bet! The 700R4 had a shift quadrant (indicator) with no #1!!!!!!!! it read 2,3,4,P,R!!!!!

unkahal

 

Hard to read, but this is the stamp on the passengers side front below the head. It says M0526 and then below that is 2VH

I think it is a post 85 5.7L. Possibly a crate engine.

it still has the 3spd automatic trans

I have made a few more changes since my last post. The radiator core support was shot so I have replaced that and installed a three core aluminum radiator with dual electric fans and a 160 thermostat. Car seems to be running a little warmer than I remember before the change.

I also upgraded the alternator to a 140 amp to help with the added load from the fans.

 

Well, I guess you owe me a beer then. The indicator for the 700R4 reads 2,3,D,R,P. There is no 4 either. Put a can of your local craft brew in the mail to me.

 

No "N"?

 

Typed too fast in my excitement to get my beer. Yes there is one; 2,3,D,N,R,P

 

Are you confirming your engine temps with an infrared thermometer?

Thanks for the update on the engine stamp! M0526 2VH must be marks from the rebuilder. The block was decked, and whatever information was there is lost. Odd that they would leave the smog pump after swapping the engine.

But whatever. You have a running, driving C3, and a great looking one at that! Go drive it and enjoy it!

 

This is why I tell every buyer to check the numbers themselves rather than believe anything a seller says (if this mattered to you).

 

so I found some casting numbers on the drivers side back behind the valve cover.

it say heche en mexico and the casting number is 10066086.

any thoughts?

 

Yes. I have been confirming them with the laser thermometer. When I did the radiator, I replaced the water pump. And it was getting to 240+. I decided to clean up the old one and put the old water pump back on it. Seems to be an improvement.

Since then, It’s been cool these last few days and I have hit 205 a couple of times when in traffic.

just a thought... I think the long water pump part number is the same for all SBC 350’s...except for corvettes. Larger shaft or something... not sure.

So I wonder what other parts and components I need to be aware of with this engine since it is not original and I don’t really know anything about it.

... if I buy a water pump for a 1981 corvette... and this engine is not out of a 1981 corvette... hmm

 

The pad stamp indicates the engine is either a "Target Master 350" or "GM Goodwrench 350" crate engine. If my memory's correct, "M" indicates the engine was built in Mexico, "05" is May, "26" is the 26th day, "2" I think is 1982 and "VH" is a crate engine, likely a Target Master 350. The Target Master was a GM crate engine made in Mexico, and introduced in the late 70's. It was originally intended to be a cheap 4 bolt main 350, replacement truck engine, but quickly became popular as a replacement engine for anything with a small block Chevy in it. A few years later, GM changed the name to "GM Goodwrench 350", likely to better reflect it's popularity as a 350 for uses beyond trucks. I think the Target Master originally listed for about $1300, but could often be bought for as little as $900. The only thing that doesn't line up are the heads, since the center bolt heads came out in 1987.

Are you sure the casting number isn't 10066036, the cast "3" often fills in making it look like an "8". "Hecho en Mexico" and casting 10066036, are common to the Target Master & Goodwrench 350 engines.

Like modern cars, the 81 Corvette was designed to operate at around 210. The higher operating temperatures were intended to help reduce emissions. The sensor for the stock auxiliary electric cooling fan, wasn't set to turn the fan on until about 235-240 degrees.

 

"Like modern cars, the 81 Corvette was designed to operate at around 210. The higher operating temperatures were intended to help reduce emissions. The sensor for the stock auxiliary electric cooling fan, wasn't set to turn the fan on until about 235-240 degrees"

This is encouraging to hear.

I double and triple checked the casting number. I am pretty certain that it is 10066086.

is it possible that the 2 in the 2VH is 92?

 

@gbvette62, I'm not questioning the validity of this statement, but I would like to know how this is done. Is it simply the retarded timing imposed by the 1-year-only computer controlled carb and distributor? I have 180 degree thermostats in my 79 and 80, and that's what they run at, around town and on the highway (I won't bore you with the plots). They also have Lars-style ignition tunes with more advanced timing than what GM ever put in a smog motor. This helps keep them cool, while planting them firmly in the smiles-per-gallon side of the fuel economy spectrum. Is a hot running engine an 81 thing that is perfectly fine?

 

The following is taken directly from the 1981 Corvette owners manual. "During normal operation, gage will indicate between 190 F and 260 F (88 C and 127 C) (start of the red zone). If the gage indicates 260 F (127 C) the engine is overheated." This is found on page 2-18 of the owners manual, under the heading "Engine Temperature Gage" and yes, that is how GM spells gauge in the owners manual.

As to how it's done, 81's came with a 195 degree thermostat, a GM specified coolant that had a 262 degree boiling point, and a 15 psi cap. As I said in my previous post, the factory installed auxiliary cooling fan is designed to kick on somewhere around 235 -240 F (I can't check the exact temperature right now, because a friend borrowed my 81 Shop Manual).

I'm the original owner of a 1981 Corvette built in October 81 at Bowling Green. The car is all original and unrestored, has about 44K miles on it, and has received an NCRS Top Flight award. I'm very familiar with 81's, probably knowing more about them then I really need to. I was on the team that created the NCRS 80-82 Judging Manual, back in the 90's.

 

I agree with the previous poster. If you don't use a 195, you will have drivability issues. The caveat is you don't know what was done to the engine because 195 was for a stock engine. Depending on what you paid, if you paid a lot because it was sold as original and stock, and this is what you wanted, then it's a problem. If it's not an issue, then live with it, but get yourself a scan tool to read the data to make sure it's running OK. The computer makes decisions based on the assumption that everything is in place, This is one of the early systems which had very little feedback to the ECM other than oxygen sensor, TPS, coolant and map sensors. Is there the stock carb and dist?