Dark Man C

I have a 1989 T/A GTA with 350TPI 5.7 L98 engine with a knock.I have been told that it is a knocking or loose wrist pin.I need some planning help hints on what to do with my engine.

1) What type of rebuild so I do? 350,355,383 or so?
2) What type of rebuild kit to use?
3) What to look for in a engine rebuilder person?

I would appreciate you guys input a whole lot.Thanks...

RB83L69

It's a 350. If you rebuild it without boring it, it will still be a 350.

If you rebuild it and it needs to be bored because of cylinder wear, it will end up 355 CID. It's still a 350. A 355 isn't some kind of separate engine, with some exotic bore/stroke combo or something; it's merely the first incremental increase in size after routine maintenance is performed on the block.

A 383 is a different engine size. It's basically a modified 400 crank in a 350 block; except that since youors is a L98, the crank will have to be for 1-piece rear main seal, which means you'll need a purpose-built aftermarket 383 crank. With that you'd also need a set of rods (350 rods are usually used, but not necessarily), and 383 pistons.

First thing to do is find out what's really wrong with it. Without knowing that, you don't even know whats left over from what you already have, that might be salvageable.

What's the oil pressure when it's hot? Is it about the same as it's always been, or is it alot lower? If it's lower, it's probably a spun rod bearing, and there's a good chance the rod is damaged. The crank of course would be toast and would need a regrind at the very least.

If you have a wasted rod and crank and the block needs to be bored anyway, the additional cost to go from a 350 (that you'd have to buy all the parts and/or machine work for just to fix it) to a 383 is not that great.

Are you sure it's really something in the short block?

Dark Man C

I've been told by 2 different mechanics that it's a loose wrist pin.
The vehicle starts and drive okay but after it gets warm it starts to make a pinging noise.All of the cars vital signs like oil,volts and so on remain under normal operating conditions.I bought this car for $1,000 bucks with this knock with the intention of fixing it over the winter and having it ready for the spring.I am gathering my information so that I can determine where to start spending my money.I would love to make my GTA a 383.

doc

Please read another thread on this tech board "what would you do with a 350 block". There is some good info in it for you.

But, I would try to find out what the noise really is. A bad wrist pin would make noise all of the time, not just after the engine has warmed up (at least that is my inexperience assumption).

Could it actually a collasping lifter? I have this problem with my LS1 car, same hydraulic roller lifters are in the L98 and LS1 engines.

Anyway, if you want to biuld a 383, go for it!!!! In rebiulding the engine into a 383, you should be able to find out what the problem is when you dismantle the engine.

Dark Man C

I will check that Tech Board...Thanks Doc.

Insomniac92z28

I don't know WTF that noise is either, but I have the same noise and so does a friend of mine with an L98 TPI car. I spin mine to 6000-6500 regularly and I am pretty sure it is not a wrist pin or it would have made a new access hole in the side of my block by now. My car has done this since I bought it, and I have drove it over 20K miles since then without any problems. Please let me know if you find out what it is.

Later,
Charlie

91 GTA Ramair2

well for one I wouldn't rev a stock 350 up that high.......

But i my self have reved my L-98 350TPI out 7250Rpm's a Few times...........In anger.......

But it sound's to me like you have a rod bearing about ready to spin.....350's love to spin #7 and #6 Rod bearing's.......

I've Notuced l-98's have a knack for spin them both and what a mess it make's......

if your enigne idle's hot Under 25-30pis Oil pressure with
20W-50 oil it's time for a Main's,Rod's Oil pump.......

If it was me i'd fill it with some SAE60 or SAE50 oil Drive it till throw's a rod and build nice 406TPI or TBI or even 406CARBed.

either on of the 3 engine would fly in a third gen with a nice set of 3.73 gear's.

My 406TBI Dynoed 540HP&620TQ@Fly wheel can't wait to get it in the 91 GTA and Run it...



:hail: :hail: :hail:

Insomniac92z28

Mine idles hot at 30 psi with 5w30.

91 GTA Ramair2

Then your engine is fine,As fare as the lower end goe's.....
Not sure what the Knocking noise would be.....