jamienoel

Okay.. I may be getting a 1978 350 engine very cheap, but don't know if it will work with my existing RS computer and injection stuff. Are they that much different other than the heads/intake?

My engine is making a terrible knocking noise after it is warmed up decelerate, along with low oil pressure, so I figured it would be best if I just get another engine and put new rings and bearings in before the swap.

The engine I have in now is from a 1989-1990 truck and is a 350, but I know the 1978 doesn't have a 1 piece rear seal, but could I use my 89 heads, intake and all the other hardware? Including my lifters and cam, which are not very old at all?

I've been negotiating with the guy because he now simply wants the engine off his property, so I may get it for as little as $25.00.

jamienoel

I was just on Northern Auto's site and noted that the cam and lifters will work.

I'm going to assume most other stuff will work as well, but I'm still not 100% on the heads. BTW, the heads are from an 89 305, so that's kind of a sensitive area anyway.

Hard to imagine those things haven't changed in all those years.

Apeiron

Cam and lifters will work only if you have a flat tappet cam right now, but if you do I wouldn't bother reusing it.

Everything else will fit except the oil pan, flywheel, and maybe the starter.

jamienoel

The ones I have really don't have many miles on them.

Atilla the Fun

If the lifters aren't roller, then you can't reuse them, unless they stay in the block they were first installed in, in the exact hole they were first installed in, with the exact cam they were first run with.
You can put any '89 305 heads on any '78 350 block, but the '78 350 better have dished pistons. If they're original, they should be dished, unless they came from an L82 'vette.
You can reuse the '89 cam, assuming it hasn't wiped a lobe, but it'll need new lifters.

jamienoel

They will each be placed in the exact same hole location and the cam will be reused as well. The parts really don't have that many miles on them. Maybe 10-20k, if that. Timing components will also be reused. All the replacement parts are 8 years old, but the car hasn't been driven much until lately, which is when everything started going bad. The engine has been knocking for that entire 8 years since the rebuild, but I am not currently able to buy a new or reconditioned crank, rods, pistons and everything else that's needed, so I would rather just do a swap and use some of my current parts such as the heads, but I'm not really sure about the heads since they are the original 305 heads. I could just drill the intake bolt holes I've heard about.

The guy told me the 1978 engine has been under a cover for some time and he wants it off his property, but he wants more than $25. I'm going to raise the offer another $25 and see what he does.

I don't know if the original 305 exhaust manifolds will bolt up to the older 350 block should I not use my heads.

And since the engine came out of a 78 truck, the manifolds that are on it (if they are on it) must be different than the ones I have.

On a brighter note, the 1978 had a slightly higher HP rated engine.

Atilla the Fun

Use your 305 exhaust manifolds. They'll bolt right up, flow is similar enough, and they fit the car properly.

Apeiron

Are they going into the same block?

Atilla the Fun

If it's not the exact block that the lifters were first installed in, then you still have to buy a new set of lifters.

drunkenwhippet

i'm just curious, why is this? as long as all parts are machined to the same specs, i cant think of a reason why this would be. but i might be missing something tho.

Apeiron

Tolerances during machining vary. During break-in, the cam and lifters wear to match each other. Putting them in a different block where the exact positioning in relation to each other varies even slightly will make them eat each other. Once in a whiel it works, but for as cheap as a new set of lifters is, or even a cam and lifters, it's not worth taking a chance.

drunkenwhippet

I didnt really think about positional tolerance on the holes, just diametrical. I can see how being a couple thousandths to one side or another could really affect the wear matchup.

I'd love to see a set of gm blueprints, to see what kinda tolerances they have to adhere to during production. I'm used to holding positions within about .0015, even tho most of the jobs we ran had tolerances of .005 to .0015 depending on the job.

Atilla the Fun

GM blueprints don't show just how far the actual production lines were allowed to vary. It's when they began having issues with the pre-installation test-running that they'd stop the line and replace whatever was too worn.