The story: 1988 GTA with LB9 & 5 speed, 70k miles, just developed a rod knock.

I am considering GM crate engine, but I'm having a hard time figuring out which one would be equivalent.

Since I'm no spring chicken anymore, I am satisfied with the performance of this completely stock LB9 engine. This will not be a performance upgrade, I am looking for a replacement. I am keeping the TPI, A/C, all emissions equipment, and the exhaust manifolds.

On this site I read that stock TPI engines have different heads than TBI engines. Also, although the stock LB9 is no screamer, I like the stock cam that's in it (207/213, .425/.430, 117 LSA).

My question is: Is there a 305 crate engine that has the same heads and roller cam specs as the stock one? If anyone knows, please post link.

I am somewhat opposed to upgrading to a 350. I'm o.k. with buying a new spark module, knock sensor and injectors. The issue I have is that a 350 5 speed PROM is not an off-the shelf item, and I don't have time to learn how to burn chips myself.

This is the 8th new thread I've started out of 391 posts on TGO. I try to contribute as much as I can, and now I need some help.

Advice that fits my criterea would be much appreciated.

Thanks in advance.

 

Considering what you want, your best option is to forget the crate engine, and get your engine rebuilt.

 

X2

 

Holy rocking chair, Batman, I was your age when if first got my Camaro in 1999!

As I see your options:
1) Get your engine rebuilt.
2) Pull your engine apart, make sure what is wrong with it. If it is a rod knock, then the crank can probably be turned. You may also need a rod (or rods) resized. New bearings, new rings, new oil pump, new timing set, have the heads freshened up (valves & seats ground, new valve stem seals installed). Put it back together, go drivin'.
3) Instead of having the crank ground and rod(s) resized, get a rebuilt crank & rod kit from your local chain parts store.
4) Buy a rebuilt 305 shortblock. You can probably pick one up from the same source as #3. Have your heads freshened up, slap 'em on the shortblock & go drivin'.
5) Get a rebuilt 350. Honestly, the '88 TPI is MAF, and it doesn't go nuts with a displacement change like the '90-'92 speed density system does. If you aren't going for all-out power, even the 305 injectors will be fine. Put a 350 under your 305 TPI system, do nothing else, and it'll drive fine (and have more power than your 305 did).

A GM 305 is probably the most expensive option possible (short of over-building a 305).

 

Thanks for responses, especially five7. You make the 350 option sound tempting.

I don't suspect finding a 350 roller type core will be too difficult, but not to sure about the heads. I assume they would have to be L98, not truck style. I'll have to do some research to find the appropriate casting numbers if I decide on that route.

 

Roller type cores are fairly easy to come by, as most '88-'99 trucks had them.

If you get a truck shortblock, assuming the cylinders aren't toast (which is a good probability), the truck 350 dished pistons and LB9 heads play very nicely together. All of your 305 roller lifter parts should fit into a roller-ready 350 block (with the possible exception of the cam retainer plate - they made two different bolt hole spacings).

 

five7 you make a great case. But I don't have time to locate a block. Summer is very short in Canada, and I have to get this thing going ASAP so I'm getting the old 305 rebuilt.

Just got the motor out tonight. What an ordeal. I've changed a few engines in my day, but this thing must hold the world record for the most pipes and wires installed in an automotive appplication. Holy ****.

 

Going to rebuild the old 305, but thinking about changing cam during rebuild.

Stock: 207/213, .425/.430, 117 LSA

The cam I am thinking about is Comp 08-302-8: 210/220, .480/.480, 112 LSA

The longer duration on the exhaust side should be o.k. since I am keeping the stock exhaust manifolds.

The car is manual transmission, so a slightly rougher idle would be acceptable. Will this cam work with stock tuning since the car is MAF?

 

That would be a pretty decent cam upgrade. You will need to replace the valve springs, though. While the heads are off, have the machine shop cut the top of the valve guides for positive-type seals. This will give you better seals, and more valve lift capability.

 

Update: Ended up going with a stockish rebuild.

Bored .020 over.
206/210, .450/.480 112 LSA cam with matching lifters and springs.
All new valvetrain including double roller chain.
Mild home porting job on plenum and intake just to smooth those nasty edges off.
Magnaflow Y pipe into 3" cat and 3" catback.

No screamer, but usable midrange torque is fabulous. Very nice to drive with 5 speed and 3.45 axle.

Thanks five7kid for advice.

 

I always like reading the follow-ups. Thank you for posting one. And congrats on the good results!

 

Were those standard off the shelf pistons ? 305 plus .20 sounds like an odd ball.

 

Continuation of this story:

Unexpected on a 1.5 year-old rebuild, but valve cover gaskets on both banks, as well as the timing cover-to-oil pan seals all have slight oil leaks and I'm going to repair them.

This is my son's car, and we are thinking about changing the cam while we are in there fixing the oil leaks:

Current: Comp Cams 08-300-8, 206/210, .450/.480 112 LSA
Change to: Comp Cams 08-302-8, 210/220, .480/.480 112 LSA

It's a minor change which usually induces comments of "it's not worth it" in terms of time and cost. Neither are a factor in this case.

General consensus seems to be that .470 is maximum valve lift with stock 14101081 casting heads. The current cam is .480 on the exhaust side, but I'm not sure if the clearance was acheived through machining or through some other means such as special retainers. Since the exhaust is o.k., my concern is the intake side, so I removed the spring and took these pics:












Have these guides been cut?

The real question is, can the guide and the retainer in the pics accept .480 lift?

 

Sorry, third pic: