I bought a 1990 blazer that I just got running. It does not have much power. The shop I bought it from told me it is a 350 but after getting it running I am not sure. Its has a 700r with a 241 c and it is 4x4.

Is there anyway to tell if it has a 350 or a 305 with out using the vin #.

Thanks

The VIN will tell you what the truck originally came with BUT, there is no way to tell if its ever been changed out.
The only way to tell is run the casting numbers off of the block.

Arent those on the back of the motor?

What is the easiest way to find those numbers. What numbers in the casting number will tell me if it is a 305 or a 350.

Go here for an idea of where the casting numbers are located.

http://www.mortec.com/location.htm

Also, on the same site you can find pretty much all the casting numbers and what size your motor is.

The casting numbers are near the parting line of the engine and trans in a groove , sloping down. usually 6 to 8 numbers long .Write'em down and just google "chevrolet casting numbers 72xxxxx and it will appear like magic !

thanks

If it wasn't swapped out it's a 350. '86 was the last year they came with a 305 from the factory.

Should be a TBI.
If so then check the numbers on the top of the injectors.
5279's are 305
5206's are 350's

Also being a 90' model, it should have a 5.7 or 5.0 back behind the driverside head on the block. All the newer 1 piece rear main motors have it cast in back there.

Looks like my 350 is a GM5.0 based on the casting on drivers side of the block.

No wonder it wont go.

Take the truck back. If they told you it was a 350, and it's a 305, they misrepresented a fact material to your decision to buy.

Take the truck back. If they told you it was a 350, and it's a 305, they misrepresented a fact material to your decision to buy.

Good luck with that.

Looks like my 350 is a GM5.0 based on the casting on drivers side of the block.

No wonder it wont go.

Its easy to swap in a $300 5.7

The previous owner might not have known either.

i learned a few years ago to look and check before i buy.

I have a folder with sbc suffix codes in it. on the front, passengers side of the block behind the alternator, theres a pad. on that pad is stamped a few numbers and a few letters. the last 2 or 3 letters are the suffix codes. using the suffix codes, you can see if it was a 125 hp 262 or a 375 hp 350.

to find your own version of the suffix codes, go to www.73-87.com and look up parts identification, and you will find Suffix Codes listed.

the casting number on the back of the block is a VERY general guide to what BLOCK you have, but not the specific application for the engine.