: LT1 Differences between '94-95 and 1996



turbojimmy
10-10-10, 09:06 AM
Hi all,

I've asked this before but I want to capture it all in one thread. I have a lead on a good 45k-mile '95 LT1 from a hearse and am looking for the differences between the '94-95 engine and my '96. So far I've got:

- Crankshaft position sensor: doesn't exist on the '95. Need to swap over the timing chain cover and the reluctor wheel behind the cover
- Knock sensors: There are two on the '96, I think there's only one on the '95. Is there a plug or something on the '95 block that I'd just remove and use my '96 sensor?
- 02 Sensors: 4 on the '96, 2 on the '95. From what I understand, the "extra" 2 on the '96 are post-cat so I should be good there.

What else?

Thanks,
Jim

Cadillacboy
10-10-10, 02:24 PM
Holy cow, I didn't know we have 4 O2 sensors in a '96 lol

jayoldschool
10-10-10, 03:53 PM
Yes, it is part of the OBD2 requirements. The rear O2s don't actually do anything for the tuning of the car, they simply tell the system that the cats work. For this reason, you never need to replace all four O2s, you just move the two old ones to the back (as long as they still work) and put the new ones in front of the cats (because those ones DO affect the tuning of the car).

sven914
10-10-10, 09:29 PM
The first two, pre-cat O2's should be on the exhaust pipe after the manifold. They don't plug into the engine, so if you aren't swapping the exhaust with the motor, there shouldn't be a problem.

jayoldschool
10-10-10, 09:32 PM
That is correct.

Also, the AIR pump fittings on the manifolds are different on 94s and early 95s than the late 95s and the 96s. I know you have disabled your AIR pump, but not sure if you have plugged the manifolds.

turbojimmy
10-10-10, 10:19 PM
That is correct.

Also, the AIR pump fittings on the manifolds are different on 94s and early 95s than the late 95s and the 96s. I know you have disabled your AIR pump, but not sure if you have plugged the manifolds.

I haven't plugged them off. I was thinking of going with headers with the engine swap. It would clean things up quite a bit under the hood. Right now, I just have the AIR system plugged at the air cleaner per the TSB.

I drove the car 150 miles today with 8 people in it. It's a shame because it runs so strong, but it is blowing a lot of oil out the crankcase.

I haven't been able to get rid of the P0300, which may not necessarily be related to the compression problem I think I have. In open loop, it runs great. When it warms up and goes to closed loop it idles rough and has a flat spot just off idle. Maybe the exhaust leak? All the plugs showed lean when I changed them.

But I digress.....thanks for the tips everyone. I will probably wind up with a '94-96 LT1 from a D/B-body so it's good info.

csbuckn
10-10-10, 10:50 PM
I remember hearseman having this same problem because of that exhaust leak. Studder off idle and no power during driving. The exhaust leak was making the O2 sensor read lean and flood the engine when it hit closed loop.

turbojimmy
10-10-10, 11:23 PM
I remember hearseman having this same problem because of that exhaust leak. Studder off idle and no power during driving. The exhaust leak was making the O2 sensor read lean and flood the engine when it hit closed loop.

That's what I was afraid of, but it makes sense. Both rear bolts are broken off of the RH manifold and it's leaking pretty good. I can't seal it unless I yank that head and get the busted bolts out.

I'm going to yank the whole thing out anyway.

All the headers I've looked at have provisions for the secondary AIR injection system. I'd go with long tubes and a "tune" to eliminate the cats, but then I have to hack into the stock exhaust system for flanges. The stock system is holding up very nicely so I don't think I want to do that.

Stingroo
10-10-10, 11:28 PM
Cats? Who uses cats?

:D

drmenard
10-11-10, 01:07 AM
Here what I have done when the last two bolts were broke off the exhaust manifold...There is a bolt hole in the head that is not being used . It's close to the port.. I drill the hole in the exhaust manifold to use that hole.. some gaskets have the hole , some don't... might have to make the hole in the gasket.. Now the hole is close so the head of the bolt won't clear... so I take a piece of 3/8" pipe maybe a inch or little longer and grind a flat on the side so it clears the exhaust port when put on the side of it... now just get a longer bolt , I Always use grade 8.... now you have a bolt on the end and it will keep it quiet ...

drmenard
10-11-10, 01:20 AM
Here is a picture... I did have to trim a little piece of the shield off to make it fit..

turbojimmy
10-11-10, 09:05 AM
Here is a picture... I did have to trim a little piece of the shield off to make it fit..

Thanks for the info. I need to take the engine out of it anyway, so I think I'll correct it at that time.

turbojimmy
10-13-10, 06:33 PM
So apparently people think that 150k-mile LT1s are gold plated. I refuse to pay $500-600 for an engine that needs rebuilt. In a fit of frustration/insanity I called the guy who built my Grand National engines. The conversation went something like this:

Me: "Dan, I bought a limo."

Long pause.

Dan: "A what? WHY?!"

Me: "That's not important right now. I need an LT1."

Dan: "You want it to go fast, right?"

Me: "Need you ask?"

So he's getting me a core from one of his connections and building me a nice, new LT1. Stroked to 383 CID to get the big limo moving. Hardened internals for N20 or forced induction later on.

It's going to be a lean Xmas for the kids this year - daddy needs an engine :-p

Stingroo
10-14-10, 01:01 AM
Their Christmas is the limo. They get to ride in it, and don't have to pay for gas.

Tell them be grateful of walk. (LOL I'll make such a wonderful parent!)

N0DIH
10-15-10, 08:56 AM
The 96 LT1 got a crank sensor (1x or 4x, very simple, not needed on a 94/95 engine) and diff knock sensors, easily swapped back to 94/95. 94 has a bit diff exhaust manifold AIR fittings than 95/96. AIR system was EPA allowed to be disabled on 95/96, note GM TSB on it and factory reflash to disable it.

turbojimmy
10-15-10, 01:19 PM
I had my PCM "tuned" to eliminate AIR and EVAP as well as misfire detection. Needed to get it through inspection.

I chickened out on the go-fast build. Sorry to disappoint. I called the guy today. With the holidays coming up I don't want to blow $2k+ on a new engine. Got a nice 71k mile engine for 1/3 the cost instead.

I'll keep the old one around for hot rodding at a later date.