VIN # Questions About Engine Swaps

[Drikprix]

Hey all,
I have a '78 grand prix sj with a 4.9l 301 4bbl in it and i know i should just get rid of that limp noodle of a motor; problem is im not sure what i can put in it. The 5th vin id letter on my car is "W" i have researched that a "W" means a 1979-1981 301 non-turbo or a 1974-1976 455, if i decide to drop the 455 in my car will an emissions test be able to find my shinanigan? also i live in colorado if that helps for my emissions question.

 

[Ribbedroof]

VIN digit would be specific to the year, so an earlier engine (even though it had the same VIN indicator) would not be smog-legal...whether the inspector would know the difference between a 301 and 455 is anybody's guess.

About a million years ago when I lived and worked in TX, the inspection stations had a book that indicated what equipment was to be present on each year/model/engine/chassis. May be the case there as well. Really, all that should matter is if it meets the regs for that year/model/engine/chassis, but I doubt that will be the case....that'd make too much sense.

 

[LS1GN]

My guess would be that you could get away with a swap as long as everything looks somewhat stock under the hood, you have a cat and you pass the sniffer.

Could you get the 455 to look something like what is there now?

 

[85GPLef41]

If I remember correctly the 301 and 455 look almost identical.. I Would be willing to bet you can get away with it as long as all your emissions components are there.. it being a 78 would make it be tested once a year but you can take it to a local garage and get it tested"hint hint" 8) Where in Colorado you at? BTW Welcome!

 

[Drikprix]

thanks for the info all. thtas kinda what i was thinkin with the engines looking almost identical b/c the 301 is a barely classified as a "short deck" engine and the 455 is a standard pontiac v8,also getting 6X heads so the exhaust manafolds bolt in similar locations. Im in the city so i cant get away with that rural-area-no-emissions nonscence🙁

 

[85GPLef41]

I'm in the same boat as you in regards to emissions :x Oh well, we can work around it and keep our GP's on the streets..

 

[Bonnewagon]

That car is 34 years old! What kind of emissions do you need to pass? Tailpipe sniffer? Yes, a 455 is visually identical to a 301, just a bit larger and a younger guy probably would never even know the difference. In '78 all the car had was a CAT, EGR, EFE, charcoal canister, heated air cleaner, no computer or AIR junk. Any Pontiac 455 from '73 to '76 has all that stuff and would smog check the same as the 301. So I would use a bone stock 455 and play dumb. A stock 455 would be PLENTY of motor.

 

[grandamman]

I would think the tech would type the VIN into a computer system. The cars VIN would show a 78 301 4 barrell.
The emissions requirement would be for this engine, wouldn't it?

 

[85GPLef41]

That car is 34 years old! What kind of emissions do you need to pass? Tailpipe sniffer? Yes, a 455 is visually identical to a 301, just a bit larger and a younger guy probably would never even know the difference. In '78 all the car had was a CAT, EGR, EFE, charcoal canister, heated air cleaner, no computer or AIR junk. Any Pontiac 455 from '73 to '76 has all that stuff and would smog check the same as the 301. So I would use a bone stock 455 and play dumb. A stock 455 would be PLENTY of motor.

You're right, For the most part it has to pass the sniffer test and visual. He shouldn't have any issues though 8) If he takes it the air care station which is contracted by the state,then that's where the nitpick everything... After 81 then it required to to go them... If it was 73 and older then it would get tested initially once and as long as it remained registered to one owner it would be exempt..... :| we had the rule of 25 yrs and older that would exempt it but that got repealed,, 😢

 

[Bonnewagon]

Rats, that sucks. In NY we are exempt after 25 years. They only do a Safety looking at tires, brakes, glass, lights, etc.