1994 Chevrolet Caprice, LT1

So, last week 3 different LT1-powered cars came across my Craigslist radar. A wrecked '94 Wagon with 20" wheels, a ran-when-the-starter-conked-out '94 Camaro, and this '94 Sedan (which ultimately followed me home):

I was really looking for a drivetrain donor for my G-body Malibu. And this car may be that...but I think I'll try to drive it a bit first. It just might be worth using as a commuter (I hear they get fuel mileage on par with my '97 Subaru).

It wouldn't start for the previous owner (dead battery), but it ultimately fired up for me and I drove it onto the trailer. It's got a bad miss and a leaky radiator. The digital dash doesn't work (might be an easy fix according to the Impala SS forums). The mufflers are blown out too.

So...It's too new for historic tags (which are my typical M.O.). However, these engines are supposed to be pretty fun in these cars. We'll see.

I'll see if I can get the engine to run right and go from there...

Thanks for looking,
Clem

I know the LT1 in my brothers Z28 had some good scoot in it right up until the FPR failed. Did good burnouts.

Sweet find! put a T56,some steeper gears, and a posi in that thing.

First, though...it needs an Oil Cap. While the one the original owner equipped it with had sufficient bling...

It does not have the exacting 710 qualities that some of us generally require.

However...I went to my 710 cap supplier who had two choices..."cam" type or "Screw-on". Neither of these seem to work on the standoff that this valve cover is equipped with. I bet someone here can have a look and see what's going on.

I've never worked on a Chevy with center bolt valve covers before. I think something is broken...

What's up?

Do I need a new valve cover? Or one of those expanding rubber plugs from the tractor store?

Thanks!
Clem

I'm also going to plan to change the spark plug wires on this thing (along with plugs)...but that doesn't look like fun. Wheee!

Pointers accepted.

I've worked on many LT1 Corvettes. The FSM will tell you to take the water pump off to replace the Opti (the Optispark Distributor). Lies! Haha. Just unbolt the crank pulley from the hub for better access to the Opti. The pulley only bolts to the hub one way, there is no way to put it back on wrong, so don't be scared.

I can't recall if the Opti style changed from unvented to vented in 94 or 95. It's important you get the right one. Once you know which one to order, you can spend a few bucks on various brands of OEM-style or upgraded Optis. I had perfectly good luck with a generic got $130 or so off Ebay. Hint: some listings are for just replacement caps - avoid them and get a complete replacement Opti.

There is plenty of room in the Caprice engine bay to make dist. and wires not a bad job. Remove the big civilian fan shroud to make the job easier if you need the space. And pick up a couple of generic wire looms because the old ones may be brittle and break when you take the old wires off.

Finally, if you get into the Opti job and find any evidence the water pump is leaking, go ahead and do it at the same time you do the Opti. They leak out the front weep hole as the impeller bearing starts to let go. If everything is dry and happy and the water pump can stay in place, use the method above to change the Opti, it saves draining, refilling and burping the cooling system.

Unscrew the filler neck and just put a screw on cap directly into the valve cover.

This thread definitely aligns with my interests, I know my way aorund the LT1 engine so Im more than happy to help with any technical questions.

Please put the Impala SS wheels on it.

In reply to conesare2seconds:

Is the optispark unit something I need to replace, you think? It has a consistent miss (like one cylinder) so I expected I could just do plugs and wires (and maybe the optispark equivalent to "Cap and Rotor") and see how it runs. I have no experience with this system though...so maybe my symptoms are indicative of problems that point to "just replace it while you're in there."

Opti wrote: Unscrew the filler neck and just put a screw on cap directly into the valve cover. This thread definitely aligns with my interests, I know my way aorund the LT1 engine so Im more than happy to help with any technical questions. Please put the Impala SS wheels on it.

I'd like to be absolutely sure that filler tube screws out before I tear something up (more). Are you pretty certain it does? Something's missing from the top of the filler tube...there are no threads or quarter-turn style feature for a cap to lock onto.

About wheels...I'd love to sport some Impala SS wheels...but I don't think I'll come across an affordable set anytime soon. I'd kinda like to put steel "truck rallies" on it because I think they look alright. in all reality, though...the wheels it has will probably work fine for me (even though they're UGLY).

ClemSparks wrote: I've never worked on a Chevy with center bolt valve covers before. I think something is broken... What's up? Do I need a new valve cover? Or one of those expanding rubber plugs from the tractor store? Thanks! Clem

I poked around on the Impala SS Forum and saw an image of what the oil fill tube is supposed to look like. It appears mine is just missing a part of the tube that the cap screws to. No big deal. I'll remove the tube and get a new cap this weekend.

You may just look at the plug wires while it is dark and look for spark jumping. The "cap and rotor" on an opti are uber spensiv last i remember. If you could get by with wires it may be the way to go.

In reply to TRoglodyte:

Yeah...I actually planned to do that last night but it wouldn't start (battery cable connection was poor..."Click click click click").

It looks like changing the plug wires on this thing with the engine in the car is a real chore. I think I'll do plugs first and see if that helps. If not, I'll do plug wires...and I'll disassemble half the engine compartment to get to them

I wouldnt change the opti as a preventative thing, they are way more reliable than the internet would have you believe. My OEM was changed as a while you're in there thing when doing the cam at 108K, I broke two shortly after due to my stupidity (left the vent tube laying in the framerail which then filled the opti with water during the first rain, the second one I cracked the rotor, installed anyways and it exploded on a 7K rpm pull.) Since then a crappy parts house reman has been running to 7K atleast once a day for 70K miles, just ask the internet thats impossible.

Id do the plugs, they are probably due anyways, they are quite the whore in the fbody, you can get a short spark plug socket from craftsman/slp that makes a lot easier.

The wires are a damn nightmare, If you do them, don't use the crappy parts house wires, they coating is too thin on many of them and causes arcing everywhere. I think 7.5mm is the biggest that will fit in the OEM wire holders. I got some nice 7.5mm Taylors from summit for like 50 or 60 bucks. I really dreaded doing it but you'll need them eventually so might as well do it once and do it right.

The cap and rotor isnt that expensive, but given how much of a pain it is too change, not many do it for maintenance like you do on every other distributor equipped car. If you decide to do an opti or cap and rotor Id probably buy one from chandler motorsports, there like 80 bucks.

About the water pump, Ive never worked on a vette lt1, but FWIW the vette and bbody pumps are a different part number, and on an fbody I dont think it would be possible, too much of the opti is behind the water pump. It may be possible, but hell its only 6 bolts and a few hoses I wouldnt spend half an hour fighting with it when I could just pop the water pump off and do it the way every one else does. Also if you do a waterpump, I would strongly recommend an electric water pump, I put one on right after I bought the car and mine leaked. It was about 200, now they are about 260 but it makes changing them SOOOOOO much faster, just pull like 6 bolts off the face of the waterpump and you can swap them out, plus it frees up some HP, and takes some stress off the front cam bearing since the OE pump is cam driven. You only buy the EWP, you can reuse the case of and old failed waterpump.

Also verify you have the LT1 and not the L99 (a 4.3 baby LT1) They look identical on the outside, and Ive seen a bunch of people get burned buying "LT1s" and finding out they are L99. 8th digit of VIN should be a P if its an LT1.

Typical symptom of a failing Opti is ignition breaking down at high rpms. So by all means, try plugs first, it may solve the problem.

Well...we had Ice a few days ago and then a hefty snow after that...so progress is pathetic (even more so than my usual).

I got the Driver side plugs changed...still have that miss. I'll get the other side when the weather improves (March).

It also dawned on me that this could be an injector that's not firing. So...I'll check that out too, if it's not the plugs.

I figured out that the filler neck does, in fact, unscrew (I figured as much)

Opti wrote: Also verify you have the LT1 and not the L99 (a 4.3 baby LT1) They look identical on the outside, and Ive seen a bunch of people get burned buying "LT1s" and finding out they are L99. 8th digit of VIN should be a P if its an LT1.

THIS. I don't follow these too much anymore, but as far as I know, the LT1 wasn't available in civilian sedans, just the 4.3. The LT1 cars are QUICK, and you'll know it; the 4.3 cars are DOGS.

I still need to verify on the block itself (but the PO said it's been in the family since new...no engine swap...yeah, yeah, yeah), but this will at least show you that this car has a sticker that says it's an LT1:

They very much did come with 5.7 LT1s.

Probably wouldn't be a bad idea to do a compression check, just to be safe.

Opti wrote: 8th digit of VIN should be a P if its an LT1.

Check. Now I've done everything except buy a periscope to try to get a look at the casting number on the block...lol. When the weather is nicer and I'm feeling more acrobatic.

Do you have a CEL? I dont work on OBD 1 cars so I dont know what kind of codes they trigger, but if you have a code for a specific cylinder misfire and you're worried about injectors, just flash the code, move that injector around and reset codes, If misfire comes back on same cylinder its not an injector.

Also injectors arent common failure items on LT1s.

Good call, thanks. I'm waiting for the weather to warm/dry out so I can do anything. I'll do some research on how to pull the codes via the blinky light on this one.

In reply to ClemSparks:

Good to know! I always thought it was only the 9C1's and wagons/other stuff that got the LT1's.

So a series of events has kept me from doing anything to this car (except ventilate the interior every now and then) since the last post.

Yesterday, I just started digging into the removal of the front accessory setup. I had deduced that changing sparkplug wires would realistically require this type of work.

Oh...I had changed the spark plugs (finally) and the only thing I got out of that was a citation from the city for having a car up on ramps too long for their taste.

So, anyway...I started with a mess of polyethelyne and iron

and just started slowly (very slowly) dismantling stuff. The end result, I hope, will be actually seeing both ends of the spark plug wires without acrobatics.

More to follow...

I really don't think it's a coincidence that Tetris became popular on the Gameboy in ~'89 and this engine was introduced shortly thereafter.

The accessory package is CRAZY. There's so much stuff bolted to this engine. several hours of skinned and dirtied knuckles netted this:

I have plenty of knuckle skin left to donate, it seems. I still can't see much of the passenger-side spark plug wires (or the bolts holding the accessories on).

You might have to pull power steering pump the wires run through an opening in the bracket. And work from underneath.