Ok im thinking about throughin a 400 under the hood of my 85 z28. now from what i hear its a pretty strait forward swap. but i'm wondering about any engine swap laws?? I live in New Hampshire and can't find anything on it so some help would be greatly appreciated. Thx

Legally I don't think you can put a bigger motor in then what the car came with, has to be from the same year vehicle or newer, and if it's fuel injected it has to remain fuel injection. It would be very easy to get away with the first two, but if you switch to carb you won't pass state inspection.

by law it is illegal to modify your car in any way unless using oem parts. but the chance of you ever getting caught is bout 1 in a billion. there are ways around it buy getting carb certified parts and making sure that you will pass emissions if you have them. you also need to know that you have to tell your insurance because if you get in a wreck and they see that the engine vin doesnt match up with they original vin they can refuse you clam and you are out in the cold. i know that because it happened to my friend.

ace, welcome aboard thirdgen.org.

Technically, by Federal rules (doesn't matter what state you live in), you can't put in an engine that is older than your chassis. You can put a bigger engine in as long as it is the same year or newer passenger car engine than your chassis, and you have all of the emissions equipment that was used to certify the engine in the vehicle it was removed from. That makes your choices pretty limited.

Since a 400 was not offered in a certified passenger car by 1985, it isn't technically legal. You can make it sniff as clean as the original 305, but an alert inspector may be able to tell it isn't an allowable engine.

A 400 swap isn't completely straight forward, as externally balanced flexplate or flywheel can cause expensive issues, especially if you use headers.

ok but what if i were to put in say a 350 out of an 85 or up camaro would that be legal?

Yes, if you had all of the factory emissions equipment that the factory used on the 350.

How will the externally balanced flexplate and harmonic balancer cause issues with headers?

The typical 168-tooth externally balanced flex plate requires the starter to be moved farther out from the center of the engine, where headers often need to be routed (not much room there in 3rd gens).

I didn't say the externally balanced harmonic damper would cause problems.

That would be the case if you were going 168 tooth, close fit. I added the external harmonic balancer just in case someone might think you could use one without the other.But if you use the 153 tooth flexplate clearance is normal. If you cant find one balanced take the weight off the 168 put it on 153.

Use a starter off a 99 chevy truck. It's a mini starter and has the right bolt pattern for the block and clears the larger flywheel. It's one good thing GM did for us.