LT1 or Olds 350-rebuilt? Congrats, its an olds!

[olds307 and 403]

Re: LT1 or Olds 350-rebuilt? Why?

You can reuse all accessories, I did a 403 swap in place of a 307 in place of a 307. -
I did a 350 Olds swap into 2 chevy trucks that had a sbc 350. You may need the 307 water pump to properly align the 307 pulleys on the 350. All brackets will bolt on to the 350 Olds like factory. The starter will work for now. A large body Olds starter or after market mini will eventually be needed. Your exhaust manifolds are probably tiny steel 307 manifolds, no good. The exhaust manifolds he has are probably early manifolds which have a different exit angle due to no catalytic converter. I would just get a new pipe put in to hook up and replace the converter with a straight pipe, if no emission testing.The conerter is probably plugged .

 

[Bar50]

Re: LT1 or Olds 350-rebuilt? Why?

If you do the swap, they 350 Olds is a direct replacement for the 307 that is in the car now.

Olds motors have to quirks as do any motor. They use a non-adjustable valve train, so that have tappet/rocker noise with mileage. There are kits to swap on SBC roller rockers with an 'adapter' rocker arm stud. They put Olds 350's in all sorts of cars from 1970 until 1987-ish, where as the LT1 motor is 1992-1996, only 4 years of production, only found in F-Bodies(Camaro & Firebird) B-bodies (Caprice, Impala, and Roadmaster Buicks) and in some Cadillac Fleetwoods (D-body). The other deal is exhaust manifolds, yours will work. Oil filter adapter, yours will work. Motor mounts, yours will work. Brackets and pulleys, yours will work. The Olds oil pan will fit and clear. Look around, might find a 403 out of a 6.6 Litre Trans AM...they are the same too!

Yes, the LT1's are durable motors. The Opti-spark can be a pain. The hurdle will be the fuel lines (can be sources from a TBI Monte or El Camino) as can the fuel pump/sending unit...you will have to buy a new pump as the TBI one runs at a different pressure. You will then have to modify the LT1 wiring harness and have the ECM flashed. Wiring for gauges to work. New exhaust system to attach to the SBC style motor. Your transmission may be multi-pattern so it may fit...use the Camaro 4L60 will require a new cross-member. The different trans and cross-member will require the drive-shaft be cut down. You will require a throttle cable to reach the throttle body(probably rob that from the donor car).

Economy, for fuel that is, will be the same or close enough. There is no power advantage to fuel injection. The advantage is drivability, or it will start and run without an issue on a freaking cold day.

The flip side, not a whole lot of hunting pressure for an Olds motor, so, if 'the guy' has had it for sale for some time, he may work on the price. Sometimes they (off breed) are usually the sum of the neat stuff on them like the cam, intake and whatever. Might let it slip you have been looking at a 403 out of a Smokey & the Bandit T/A...

 

[olds307 and 403]

Re: LT1 or Olds 350-rebuilt? Why?

Yes, the swirl port tubular manifolds will bolt on. They will be horribly restrictive, all SBO suck performance wise, those late 307 manifolds are beyond awful. BBO manifolds are the same bolt patterns but supposedly hit and won't work. The 403 is a good big bore, big torque motor but the early Olds 350 has a better bottom and much thicker cylinder walls.

 

[mheath717]

Re: LT1 or Olds 350-rebuilt? Why?

With the motor sitting for 7 years I would definately tear the motor apart to inspect it, and get a FULL gasket set. I bought my motor from a guy who only pulled it to go bigger. It "supposedly" ran fine. I decided to take it apart, and I am GLAD I did! There was a bolt sticking through the intake valve on cylinder #3. The piston had a couple nicks on the top of it. There was sludge all over the engine. So I dropped it off at the machine shop. I am very happy with my motor now.

 

[QS442]

Re: LT1 or Olds 350-rebuilt? Why?

The block numbers are 395558 2, I looked it up and those are the numbers for a 70. I have decided to go with the olds motor. Seller will take $500 instead of $600 and he was a true olds guy. Even inspected my 442 and stated the same things about the swap you guys said. Even gave my a old school way to get out dent. I am taking his word on motor but I will take to machine shop for inspection. I not a motor inpector yet. This is my 1st olds and real project.

Ok, I am hearing that i can use my exhaust manifolds from the 307 and also hearing that I can't. Which one is it and what other issues do I need to prepare for the swap?

 

[olds307 and 403]

Sorry brain fart. Your car is a 442, should have cast iron manifolds. If they are the cast iron, not stainless steel you can reuse them. Sorry, for some reason I forgot that. You can use the stock exhaust but the catalytic converter especially is restrictive.

 

[mheath717]

Re: LT1 or Olds 350-rebuilt? Why?

Ok, I am hearing that i can use my exhaust manifolds from the 307 and also hearing that I can't. Which one is it and what other issues do I need to prepare for the swap?

You can use them no problem. People are just saying that they are restrictive.

 

[QS442]

Thanks for clarification.