I have a chance to pickup a 350 engine, 4 bolt main from a 1994 chevy truck. The engine has 31,000 miles on it and originally was a TBI engine.

Question: What model engine would this be and will this engine swap into my 84, using the Cross Fire from my original engine, without too many problems?

Thanks.

BTW. I can get this engine, complete from manifold to pan for $200.

 

wonder what the compression ratio is ?

 

you will have to use the heads from your 84

 

Darn!

I'm working on a really limited budget. This is my first vette and I think I may have bit off more than I can chew. It was in a flood and the original motor is stuck. I'm pretty certain it spun a bearing when I turned it over the first time.

I know it's going to take me a while to get it going again, and I have to do it one step at a time. I was hoping the engine would bolt in without problems. But I guess not.

I wonder how well it would run if I just put a single throttle body back on for now?

Do you know if the engine from the 94 truck is an LT1 or not?

 

I haven't seen the engine yet, so I don't know what the numbers on it are.

 

Fit wise, that swap should be a no brainer. I see two areas of concern. The bigger of the two, is the head to manifold bolt pattern. The center bolt holes in the later heads are vertical. Your intake manifold is made for bolts that are at a 90 angle to the manifold gasket surface. You may be able to machine up some sort of wedge to put under the heads of those 4 bolts so that they hold evenly and don't cause a vacuum leak. The second item is much easier. Because of the bolt pattern and the balance, you will need to use a flywheel or flexplate for the later, one piece rear main seal engine. Your '84 won't work on the late engine. Whether automatic or manual, it will have to be a 153 tooth version, for the least hassles. Other than that it should be a piece of cake, unless someone thinks of another snag.

RACE ON!!!

 

the engine should bolt in however the pass side head may need to have work done to put the temp sensor in for the fan if there isnt a hole there already. this is not verry expensive or hard to do. ya should also check your exhaust on the heads to make sure you have proper clearances for your spark plugs. if there is an issue ya may want to get a set of headers that will work with the style head you have. the headers probably be pretty expensive unless ya get shortys and there aint much gain from those as basically they are what comes stock. a stock set from a 92 to 96 vette might work and be the cheapest route. youll havta do some homework when it comes to the exhaust. depending on your cam and such ya may havta get a chip burned for the ecm. if you can get the ecm from the truck you get the motor from and its a 7747 ecm get that as well as that can be modified to go in your car you can get more info on this here http://www.crossfire.homeip.net/cftest/default.asp this forum is also a good source of help on crossfire motors. i hope this helps.

 

Thanks for the info.

The engine comes complete, including the flywheel from the truck.

I'd really like to get it running for now, just to be able to move it around easier, so I wonder If I could just bolt a single TBI on the manifold that comes with the new engine.

Once the old engine is out I can pull the heads and work on replacing valve seals and guides and then swap the heads later.

 

Would the exhaust headers from the truck work? They come with the engine.

I know I'm 'nickel and diming' this, but for now it's all I can do, unless I can sell my 85 Trans Am. Even then, it probably wouldn't be enough money for everything I'm going to need for this project.

As far as the ECM chip is concerned. I can burn a new one myself. I have a programmer that should work fine.

Thanks for the link.

 

probably depends on what headers they are and if they clear the wheel wells inside of vehicle and such if they do ya might havta cut the exhaust pipes and have it hooked up. but i dont see where installing the engine will be hard to do. worst case scenario is keeping the throttle body setup thats on the motor already and programing the ecm for it. im not sure weather its a vortec motor or not im not familiar with newer trucks. if thats the way ya havta go just keep the crossfire setup until funds alow you to get a motor better suited for it. either way that motor can go in just gotta do the research on what ya have and bolt patterns and such.

 

I guess I could just swap the motor in for now and work on the other things as time and money come available.

I just hate to let a 350 go that has only 31,000 miles on it for $200.

Or..I could just buy the engine and see if I can get someone to swap with me!

 

you could go with a cheap edelbrock air gap manifold, and put a 4 barrel carb on it, HEI dist, you will have waaaaay more power if you go carb and get rid of the cease fire sys, plus you can sell your x-fire sys, for $400 or so, (i did on ebay) go back to the 60's style power with no smog, didnt read your profile so im not sure what state you are in, i just did the same on my 84, i can help you get through this,

 

Putting a carb on it was one option I had thought about. I've actually found a couple of Eldelbrock manifolds on Craigs List fairly cheap.

I live in New York, so smog wouldn't be a problem because of the age of the car. Gas mileage is a concern too. I plan on using the vette as a daily driver, mostly in the summer, so until the price of gas comes down, I'll probably be keeping a 'light foot' on the throttle.

How's the mileage on your 84?

 

not sure, high i think, all my gages dont work, so i am making an instrument bezel outta aluminum and installing analog gages, gonna make the alum swirlly!! so it looks cool. LOL intake and carb are best, and easiest to work on!!! not a lot of sensors to go wrong and stuff, just oil temp, volts, oil press, water temp, etc... easy!! you can get headers for like $89 but coated are better but xpensive, that car will fit long tube full headers!!! you will have to use a TCI vacuum switch to lock up the tranny converter in 4th gear, its like $ 70 or so,(if you have and automatic tranny) HEI dist. and a holly fuel bypass regulator $28 or so,
bypass the fuel pump relay, a few other minor things, but, PM me and i will break it all down for you including the best prices i found and where to get em, we can get rid of that 205hp x-fire and put in 350hp easy, cheap!! lol.

 

As cfi-efi said, no big worries. Easy swap

 

yep with guys like Pete K helping you out, you'll have NO WORRIES!!

 

Thanks Pete.

I had thought about swapping the CFI for a carb, but I might try the 'wedge' thing, under the manifold bolts, CFI-EFI mentioned first.

Would save me time AND money!

 

Another issue that hasn't been mentioned is that the 84 has flattop pistons. If you use your heads to retain the CFI the compression ratio with dished pistons will be quite low. You need to determine which pistons the truck block has but I believe they are dished. If you decide to retain the CFI,port the intake while you have it apart. I've read of at least a couple of folks who have modified the bolt holes on the stock intake to work with Vortec style heads.

 

The flex plate issue 'got me to thinking'. Can you elaborate on the tooth count issue difference between the two engines?

I've never been under mine to count the number of teeth on my 96 LT1 flex-plate, I just assumed it has 168 teeth. I need to order one for the engine I'm building and just want to be sure I order the correct one.

Take me to school.

Thanks,

Jake

 

I can comment on this because I did the exact same swap in my '83 CFI Trans Am; I went from the original 305 (dimensionally identical to your stock motor) to an '88 Truck 350 (dimensionally identical to your replacement motor). Two points;

*I addressed the center intake manifold bolt-to-head holes by simply using a die grinder to oblong the holes, and mill a flat "pad" on the boss where the original bolt hole was. It worked fine for years, and I later installed a SBC 400 (same head/manifold bolt pattern as your STOCK motor again), and w/o any further modification the CFI manifold bolted onto the 400 and worked fine, for years.

*The Truck motor uses the infamous "swirl port" heads, which are garbage, from a performance stand point. They flow terribly, and you'll LOOSE hp by switching to that long block, because of the heads. It also features the wimpyest cam GM ever used: less than 200* duration on both sides and about .400" lift on both sides. Pitiful. In the truck, w/a dual plane TBI intake, TBI, and the truck exhaust manifolds, it made 190 hp.

*The truck engine uses a 168 tooth flywheel, my Trans Am used a 153. I'm betting that the Corvette uses a 153 too.

The motor will function fine, give you decent gas milage (I got 25 hwy in my Trans Am) but it won't win many races.