hi. I am swapping my '88 TPI 305 motor over to another car b/c I recked mine, but the drivetrain is still good.. It will be going into an '81..Computer,wiring,etc..


I just wanted to know, if I eliminate all the emissions stuff, will it have an effect on the factory computer and how the motor runs?

I was planning on removing the stock manifolds with the air pipes and putting on a set of LT headers I have.. Wanted to remove the EGR,smog pump, and whatever emissions pipes/hoses goes to/comes from the smog equipment.. Also planning on no cats in the exhaust..

Will I need to still mount the O2 sensors in the exhaust??

thanks

 

From what I have seen, you may run into some performance issues as well as a check engine light or two. When I bought my car it was a 383 stroker with the factory computer and wiring still in it and the check engine light was always on just because the computer is trying to read sensors that aren't there. I eventually ran into problems with performance although I'm not positive if it was from the removal of certain sensors and smog equipment. If I could do it all over again, I would do it right or not at all. Either go carb, or upgrade the computer system. It will be cheaper in the long run. Also you may want to check your states emissions laws to see if you will be able to get it inspected with the smog equipment modified.

 

You will need the O2 sensors, if you retain the injection. They are the only way the computer has, of knowing that its fuel delivery, is right.

If you use LT headers, the sensors will be so far downstream from the engine, that they will likely never reach operating temp. You will need a heated sensor.

There is nothing to be gained by hacking all the emissions stuff. It costs little or no HP to run it, and since the computer is expectign its effects to be present, will cause difficulty getting it to run really right. I'd recommend not hacking anything off. Only hacks hack stuff off.

You can make do without a cat, if you have no emissions inspection requirements. IIRC NYC has those however. You would be well-advised to include one. They're not very expensive, and are in fact a WHOLE LOT cheaper to plan for up front, than to dink around somehow trying to avoid. Modern high-flow ones, like the other emissions devices, cost you little or no HP at all. No reason to risk the pain that comes with a car you can't license, in exchange for an unmeasurably small improvement if there's even any at all.

I don't know if you've ever had one of those cars before. I've had quite a few of them. If there is ANY ONE KIND of chassis that is hostile to headers, it's that one. Headers are GUARANTEED to be the lowest point on the car. They WILL - note that I did not say "may", I said "WILL" - scrape the ground and get flattened. I had a friend who had one of them (a 71 RS)... spent like $400 in 1980 dollars (that would be about $1200 in 2006) putting a complete exhaust system on it; took him like 6 months to save up that much money; the VERY FIRST TIME he drove into his driveway at home, with the installer's fingerprints still smoking off of the brand-new tubes, he flattened the headers on both sides and tore the pass side muffler completely OFF THE CAR. If you intend this to be a street-driven car, I'd strongly recommend re-thinking that. Use some kind of shorties. On a 305, the difference in power will be negligible; and certainly, not worth the maintenance headaches. The whole exhaust on those cars sucks. Every one I had, I added a couple of the rubber-strap muffler hangers right behind the mufflers, because otherwise there's no hanger all the way from the header collectors back to the tailpipes; and the mufflers will get shaken off the car by going over bumps. The outlet nipple will break out of the rear of the muffler.

You'll need a high-pressure electric fuel pump, probably in the engine compartment, ideally somewhere near where the block-mount pump would be for a carbed motor. Doesn't have to be real high volume or anything.

Get the WHOLE HARNESS out of the donor car. THe one in question is the one that goes from the engine to the pass side fender. Remove its bulkhead pass-through from the cowl WITHOUT CUTTING ANYTHING; there's no need to hack wires ANYWHERE. Every wire you need can be easily removed WITHOUT HACKING.

Have I used the word "hack" enough to make a point? Somebody help me out if it needs to be used some more.

Other than that, it should be a fairly straightforward swap.

 

thanks for the replies.. First, let me clarify, I no longer live in nyc.. Moved upstate, and the car the motor is going into is an '81, so it is emissions exempt up here...

The motor I plan on transplanting, is an '88 305 TPI, complete, with the 700r4 tranny.. I have the complete engine harness, complete under dash harness, computer, and digital dash from the TA I will try to install cleanly.. Also have the Alum radiator & elec fan from the TA..

The main reason I was considering removing all the emissions stuff, was not to gain power, b/c I know the gain is minimal.. But for ease of installation, and to keep the engine compartment as clean as possible..

It looks like the only emissions related stuff I am missing, are the O2 sensors, the pipe going from the stock manifolds to the cat, a Cat, and I guess the charcoal canister and associated vac hoses..

For the fuel system, I have the fuel pickup/sending unit from the TA's tank and the stock elec pump.. I plan on using this in my '81. I will just have to cut down the fuel lines connecting to the pump, to make the whole assembly shorter to fit in the '81 tank, and then add a return line.. No big deal..

Back to the O2 sensors, Summt sells a collector adapter with an O2 bung already welded on.. So if I bolted that to the collector, then the rest of the exhaust, the O2 sensors would then be right after the collector...do you think the O2s would still be too far downstream??

If they will be, then I will probably pick up a cheap set of shorties, like the Summit brand, and add the piece to the shorty collector with the bung for the sensors.. Should be OK then....??

As for adding Cats, if the budget allows, then I will, if not, then I will leave them out..
Though I dont NEED them for emissions..

I guess my biggest headache in keeping it all stock, will be figuring out the vacuum hoses.. I will probably need to get a thrid gen charcoal canister..

And being I have the motor out, i will probably do I minor overhaul.. Replace all the gaskets, water pump & timing chain, normal tune up stuff, valve stem seals, etc..


I also have a 406 shortblock that I was thinking about swapping the TPI & serp setup over too, but I'll do some searching on that and post in another thread..

thanks