I took my 15th Anniversary to the track saturday and somethine is really wrong. The car has a new GM crate 305 H.O. motor, new high flow cat, t-5, and 3.73 posi. The car is a factory HO. My best run was a 16.0@87mph, with a 2.40 60' time. I dont understand it. It does run funny though. Its ok when its cold, but when it warms up, it is totally gutless. As it warms up, it has a pretty good miss and hesitation. Also, the idle varies. Ill pull up to one stop light and it will idel at 1500, while the next time I stop it will idle at 900. I think one of the temperature sensors is bad because my electric fan dosent come on unless the AC is on. There are no codes or anything. My knock sensor is totally destroyed though. the part in the center where the plug goes in is completely gone. Could this be causing all that to happen? The fuel economy couldnt be better. A friend of mine also has an 84 HO 15th anniversary TA, but with an automatic and 3.42's, and out of the box stock with 90,000 miles on it, he runs 14.90's all day long. My old LG4 with 3.73's and a catback was running 15 flat@91mph. I dont get it though. The motor only has about 5,000 miles on it. Everyone tells me these cars will run high 14's easily. Please point me in the right direction. Im getting to the point to where Ill pay someone to advise me as to what is wrong with this car. Thanks in advance.

 

The "HO" 305 service part may or may not be capable of what a real HO motor is. I have no clue what's inside of it, so I could be wrong, but just because GM chose to stick those 2 letters in its name, doesn't guarantee that it has the same compression, cam, or anything else, as the original HO motor did.

Definitely fix whatever you know for a fact is wrong with it before you try troubleshooting any further. It's alot easier to find one defect than it is to slog through the "maybe it's this, maybe it's that, I can't tell because so many other things aren't right" syndrome.

Sounds to me like the primaries are lean. May ened a carb rebuild. If you do that, DON'T just go to the store and buy a "rebuilt" carb; get the one you have rebuilt. The L69 motors came with a different carb, that has different metering internally; it's highly unlikely that you'll get the same thing at the store. Kind of like the motor itself.

It would help if you could find out the motor specs, in particular the CR, the head castings, and the cam. That would help toward making an educated guess as to what it's really capable of.

 

Ok. Is there anyone I can talk to about finding out what they put in the replacement H.O. motors? Anyone at GM? Ill look into it and see whats going on. It has a new carb....I dont think its ever been set up though. Ill put it on the Tech1 and check it out. I will say this though.....its definately getting slower. It used to be pretty quick when I got the car. So something is getting worse. Anyway, let me know who I can talk to about finding some stuff out about this motor. Thanks