[chris.linkous]

I picked up a fairly nice 1994 Trans Am, but the LT1 has some issues.

I haven't decided to give up on it yet, but I want to know my options.

So, in a nutshell, the motor was locked up when I bought it. I tried turning it over by hand, and it wouldn't budge. I put my breaker bar up on the alternator and started turning the engine backward, and it broke loose. As it turned, it made a scraping noise from the front of the motor for about 3 turns then it went away. After that, I could turn the motor over with the starter, but it wouldn't fire. Hit her with a little brake clean, and she would pop but not run.

So having said all of that, I plan on dropping the oil pan and pulling off the valve covers tomorrow to see if anything stands out. If I find anything bad, I would like to know my replacement motor options. Is there a different motor that people have been dropping in these Gen IVs without many mods? I am not looking for anything crazy; I want a reliable car to drive around. It is a 6-speed manual.

I will let you guys know what I find tomorrow. As I said, just testing the waters!

Hopefully, I find something easy and can use this LT1, but if not, I would have zero issues dropping a 5.3 in it if that can easily be done.

Please let me know your thoughts and thanks in advance for any help

Chris

 

[roorancher]

Just my opinion, but least expensive route is to rebuild what you have, or exchange it for a rebuilt LT, so you don't incur additional expense with other modifications and changes.

 

[chris.linkous]

I do not disagree with you buddy. My plan is to see what's wrong with it tomorrow and hopefully it isn't too serious. I only ask about the engine options because LS motors are a dime a dozen around me here in Columbia SC. I have zero experience in swapping an engine though! I am a retired Air Force Crew Chief and can take apart an F-16 and put it back together with my eyes closed but I have never been in a car engine.

My goal in this situation is simple......I just want to make this car run and be dependable, paint it and have something to drive around in on the weekends. Keeping it simple is my goal!

 

[Injuneer]

The LSx family engines will not bolt up to the LT1 T56 6-speed/pull-back clutch = new trans and clutch. They will also require modifications to the K-member for the motor mounts or possibly a 1998-2002 K-member. You'll need the correct LSx PCM and engine harness, then workarounds to interface it to the body harness differences between 94 and what ever car/truck/year your new LSx engine came from. Fuel systems are different, recirculated 43.5 PSI for your LT1, dead-end 58 PSI for many LSx engines. Not sure if the instrument cluster is compatible.

I guess the point is you would need to find a wrecked 1998-2002 F-Body (Camaro or Firebird) with an intact front end, pirate all the required drivetrain and chassis components and transplant into your 94 4th Gen. Might just be easier to ditch the problematic 94, find a decent 1998-2002 and start over. Depends on the quality of the balance of the 94 chassis.

There are rebuilt and crate LT1 engines available, including high performance rebuilds if that interests you. Or if you are equipped with the skills and time to do your own rebuild, it would be the lowest cost way out.

 

[chris.linkous]

Sounds like I'm going to stick with the LT1 lol. Thank you for info, that is exactly what I was looking for! I have no desire to put that kind of work into the car. I will either fix this LT or buy a long block.

I do have one last question though. I am seeing posts everywhere about the optispark going bad and which brands are known to fail. Has that issue been worked out or is there a brand I should stay away from if it comes to replacing it?

 

[ZumpTA]

I do have one last question though. I am seeing posts everywhere about the optispark going bad and which brands are known to fail. Has that issue been worked out or is there a brand I should stay away from if it comes to replacing it?

We have 2 options now where the OptiSpark is concerned. Buy the OptiSpark Petris Enterprises builds for around $500 or so, or spend the $2k it takes to convert the LT1 over to the modern LS style ignition system. There is a 3rd option called a Bailey LTCC, but that only eliminates the cap and rotor (the spark in OptiSpark), not the optical portion of the OptiSpark itself. If you have an OEM OptiSpark now, this is a viable mid-range (cost) alternative. I think it's $400 for the electronics, then you have to buy 7 more coils, and coil brackets. Easily around $1300 "retail". If you have an aftermarket OptiSpark of any type, Bailey LTCC is a pointless upgrade as it uses the optical sensor to do it's thing and it's the optical side of the OptiSpark that fails on aftermarket OptiSparks. You're literally still in the same boat, only you spent $1300 to get on board instead of $100.

OEM OptiSparks are damn near bulletproof. The cap and rotor is a wear item like any distributor, and the optical portion is no more than a laser pointer shining through a shutter-wheel to a light sensor. OEM used the Mitsubishi Optical Sensing unit that has existed since the '80s. Petris uses the same reliable Mitsubishi sensor.

EVERYONE ELSE regardless of Brand or cost now uses the lowest grade of Chineseium they could get their hands on. I wouldn't be surprised if the $500 MSD OptiSpark comes from the same Chinese Factory (and assembly line) as the $50 no-name OptiSparks on Amazon.

If you're serious about the car, the LS Ignition System conversion is really the way to go, but a Petris Enterprises OptiSpark can certainly be trusted at a fraction of the cost.

With the Pertis OptiSpark, you still need to be vigilant about not going through car washes that do the under-carriage wash, not entering puddles deeper than the rocker panels, and servicing your radiator hoses before they rupture and protecting the Opti from coolant spill when changing those hoses. It's not a big deal to avoid these things, but they are things you wouldn't need to consider with the old fashioned distributors or the 100% distributor-less systems like the LS family has. The OptiSpark is kind-of the Bastard Son of HEI and Distributor-less Ignition Systems. It shares the strengths and weaknesses of both systems.

So much on this topic depends on what kind of OptiSpark you have now. My best recommendation is since you're going down there; pull the OptiSpark, open it up, and see what sensor it has. If the Mitsubishi "Diamond Logo" is crisp and clearly visible, it's OEM. Keep that sucker and service the cap and rotor as necessary (75,000 miles give or take). If the diamond logo is fuzzy/blurry/not crisp and clean; it's a counterfeit, replace it. If there is no logo to be seen, or anything other than Mitsubishi's logo, it's aftermarket and 100% Chineseium; burn it with fire.

OptiSparks are only unreliable nightmares when they don't have that rock-solid, tried and true, bulletproof Mitsubishi Sensor.

Now seems like a good time to point you to the Factory Service Manuals member GaryDoug has scanned and uploaded to MediaFire link I'm including below. The '94 manual is there and you will need Adobe Reader to search through it effectively. ...it's a few thousand pages. Familiarize yourself with it, remember you have it, and use it; more importantly, trust it. The engineers thought of everything and documented every scenario very well in the form of easy to follow diagnostic flow-charts. The Factory Manual, a multi-meter and a few basic hand tools solves damn near everything. Special tools (where not able to substitute) can be rented "free" (requires 100% refundable deposit) from AutoZone, Advance, and O'Reilly.

Welcome Aboard by the way!

MediaFire

MediaFire is a simple to use free service that lets you put all your photos, documents, music, and video in a single place so you can access them anywhere and share them everywhere.

www.mediafire.com

 

[roorancher]

Sounds like I'm going to stick with the LT1 lol. Thank you for info, that is exactly what I was looking for! I have no desire to put that kind of work into the car. I will either fix this LT or buy a long block.

I do have one last question though. I am seeing posts everywhere about the optispark going bad and which brands are known to fail. Has that issue been worked out or is there a brand I should stay away from if it comes to replacing it?

From what I've read, (and I've only had my 94 Trans Am convertible since August) (I'm 69, and I'll R&R a motor, but won't dig into it,) if it's an OEM vented unit, it's good, but you don't want your water pump to leak on it. MSD and parts store brands are crap, I'm told. There's a company in Alabama called Petris that makes good ones and is highly recommended. If you join LS1LT1.com, there's all kinds of posts on it.

 

[Injuneer]

If you've been reading the posts on this site, you should have seen the name “Petris Enterprises” mentioned for the Optispark. In the 25+ years I've been helping LT1 owners on sites like this Petris is the only reliable supplier that exists today. On the other hand, if you have an OEM part that works, keep it. I've seen people report in excess of 150,000 miles.

There is I hierarchy of OEM parts. 93-94 LT1 used an “unvented” unit that suffered from corrosion due to ozone generated by the internal high voltage discharge, and water/coolant intrusion through the harness connector tower. 95-97 units had a vent system added to remove the ozone and a revised harness tower design. But with a 94 you can correct the ozone issues with a replacement vented cap, always a good idea, and rotor. Add a bit if sealer to the harness tower, because that is part of the unit base that houses the optical cam position sensor module.


It's the optical module that suffers from corrosion and liquid intrusion. Only the original Mitsubish module seemed to be reliable. The Chinese rip-offs used in most replacements are trash. The Petris module is described as “MITSUBISHI-QUALITY”, so it isn’t the OEM. Appears he has someone manufacturing them to his specifications.

Another “fix” - the Bailey Engineering “LTCC” system. A black box that requires only the optical cam position data from the Opti, and drives 8 independent LT1 coils, totally eliminating the high voltage/ozone problems by taking the “distributor” function out of the Opti. I ran a similar setup (MoTeC engine management system w/ 8-channel ignition driver) for 20 years with no problems, relying on an OEM 95-97 Opti with just the optical module. The only reason to run the 95-97 unit on my 94 was because it was required to utilize the LT4 Extreme Duty roller chain timing set.

 

[Injuneer]

Seems like our timing overlapped….. my two-finger typing technique is too slow

And to clarify, you need 8 LSx style “coil near plug” setups. Here's how I did it (not so “near”):

1133 Picture

View Camaro picture 23150628 uploaded by 1133 on

www.camaroz28.com

1133 Picture

View Camaro picture 23150629 uploaded by 1133 on

www.camaroz28.com

https://cimg5.ibsrv.net/gimg/www.camaroz28.com-vbulletin/600x450/80-coils_all_e1aade04de8b87aa8d2cfb27de46f6bc2e8891fd.jpg

 

[chris.linkous]

Thank you all for the great information. Its nice to be a part of a group that is active.

Just updating you as to what I found today. I removed the valve covers and found one of the valves flopping around. The pushrod was just sitting there. I loosened up the valve and put the pushrod back in the roller seat, tightened it back down and turned the engine over. Everything turned over fine and without noise. The ol girl still didn't start so I checked for fuel pressure at the manifold and had zero.

Tomorrow I am going to troubleshoot the no fuel pressure issue and will give an update.

Thanks
Chris

 

[roorancher]

Thank you all for the great information. Its nice to be a part of a group that is active.

Just updating you as to what I found today. I removed the valve covers and found one of the valves flopping around. The pushrod was just sitting there. I loosened up the valve and put the pushrod back in the roller seat, tightened it back down and turned the engine over. Everything turned over fine and without noise. The ol girl still didn't start so I checked for fuel pressure at the manifold and had zero.

Tomorrow I am going to troubleshoot the no fuel pressure issue and will give an update.

Thanks
Chris

You can remove the line from one side of the fuel filter and that will tell you real quick if it's the pump. Right in front and inboard of the left rear tire.

 

[chris.linkous]

Update - fuel pump wasn’t working! I replaced the fuel pump and now have great pressure up to the engine. Started the car and heard knocking so I shut it off. Checked the valves again and others were very loose. I tightened them down until they were touching and still hear knocking! I’m not sure what’s going on but it doesn’t sound good lol.
Tomorrow I am putting her on the lift and dropping the oil pan so I can get a better look inside.
On a good note, I fixed the fuel issue and verified the OptiSpark was working I guess. I will let you guys know what I find under the oil pan.

 

[roorancher]

Sure changed that fuel pump quick!
Trap door??

 

[ZumpTA]

Make sure all cylinders are firing. I had what sounded like a real bad rod-knock one time, couldn't place it exactly, but it seemed louder at the bottom of the engine. I decided to pull the Oil Pan and look at the bottom end to see if there was anything obvious or "sloppy". As I was looking around the underside taking inventory of the task ahead, I noticed a sparkplug boot dangling. Plugged it in, noise gone.

It is an extreme PITA to do plugs and wires on these cars. While I had owned the car for 13 years at that point, I had never touched the plugs or wires. Previous Owner or Mechanic must have installed them "just good enough", but not exactly to spec. Maybe it was driving on 4 blown shocks down my bumpy road that threw the boot off? Regardless, shouldn't have happened, and I would have never suspected that; but I can understand how it could happen. Such limited space to work in, nobody has an easy job of it with these cars. I certainly don't have the patience, dexterity, or mobility to do it if I'm being honest.

A couple months later, I developed a miss and exhaust leak. Reaching down into the engine to feel where the chuffing noise was coming from, I got a nasty shock. Apparently, the plug behind the one that dropped the boot completely backed itself out and jumped ship. The boot just happened to land in a way that the opening was in line with where I placed my fingers. Right hand ring-finger slipped right into it. $8 for a new plug, done.

Hopefully, it's this simple for you. I know it's a long shot, and hopeful thinking, but I still have to mention it. Lord knows I was greatly relieved to have solved what could have been a disaster with $0 and 0 effort, and then something that could have been serious for only $8.

Pretty sure the timing cover has to come off to properly remove the Oil Pan which you stated you intended to do. That is why I said earlier: "My best recommendation is since you're going down there; pull the OptiSpark, open it up, and see what sensor it has. If the Mitsubishi "Diamond Logo" is crisp and clearly visible, it's OEM. Keep that sucker and service the cap and rotor as necessary (75,000 miles give or take). If the diamond logo is fuzzy/blurry/not crisp and clean; it's a counterfeit, replace it. If there is no logo to be seen, or anything other than Mitsubishi's logo, it's aftermarket and 100% Chineseium; burn it with fire. "

Given the labor and expense of anti-freeze, when you pull the OptiSpark to remove the timing cover, that is the best time to see what you have. If it's OEM, get a cap and rotor kit or consider the Bailey LTCC kit. If it's not, now is the time to get that Petris Unit installed. Otherwise, you may end up stranded, need to be towed, then have to disassemble the thing to the timing cover, refill with anti-freeze, etc.

Good Luck!

 

[Injuneer]

Define “great pressure up to the engine”. Does the pump prime for 2-seconds, and shut down, showing at least 40 PSI. Does the pressure drop after the pump shuts down? How fast does the pressure drop?

 

[chris.linkous]

Sure changed that fuel pump quick!
Trap door??

Yeah, I cut it out and have a nice piece of diamond plate aluminum to put in its place.

 

[chris.linkous]

Make sure all cylinders are firing. I had what sounded like a real bad rod-knock one time, couldn't place it exactly, but it seemed louder at the bottom of the engine. I decided to pull the Oil Pan and look at the bottom end to see if there was anything obvious or "sloppy". As I was looking around the underside taking inventory of the task ahead, I noticed a sparkplug boot dangling. Plugged it in, noise gone.

It is an extreme PITA to do plugs and wires on these cars. While I had owned the car for 13 years at that point, I had never touched the plugs or wires. Previous Owner or Mechanic must have installed them "just good enough", but not exactly to spec. Maybe it was driving on 4 blown shocks down my bumpy road that threw the boot off? Regardless, shouldn't have happened, and I would have never suspected that; but I can understand how it could happen. Such limited space to work in, nobody has an easy job of it with these cars. I certainly don't have the patience, dexterity, or mobility to do it if I'm being honest.

A couple months later, I developed a miss and exhaust leak. Reaching down into the engine to feel where the chuffing noise was coming from, I got a nasty shock. Apparently, the plug behind the one that dropped the boot completely backed itself out and jumped ship. The boot just happened to land in a way that the opening was in line with where I placed my fingers. Right hand ring-finger slipped right into it. $8 for a new plug, done.

Hopefully, it's this simple for you. I know it's a long shot, and hopeful thinking, but I still have to mention it. Lord knows I was greatly relieved to have solved what could have been a disaster with $0 and 0 effort, and then something that could have been serious for only $8.

Pretty sure the timing cover has to come off to properly remove the Oil Pan which you stated you intended to do. That is why I said earlier: "My best recommendation is since you're going down there; pull the OptiSpark, open it up, and see what sensor it has. If the Mitsubishi "Diamond Logo" is crisp and clearly visible, it's OEM. Keep that sucker and service the cap and rotor as necessary (75,000 miles give or take). If the diamond logo is fuzzy/blurry/not crisp and clean; it's a counterfeit, replace it. If there is no logo to be seen, or anything other than Mitsubishi's logo, it's aftermarket and 100% Chineseium; burn it with fire. "

Given the labor and expense of anti-freeze, when you pull the OptiSpark to remove the timing cover, that is the best time to see what you have. If it's OEM, get a cap and rotor kit or consider the Bailey LTCC kit. If it's not, now is the time to get that Petris Unit installed. Otherwise, you may end up stranded, need to be towed, then have to disassemble the thing to the timing cover, refill with anti-freeze, etc.

Good Luck!

I will absolutely check all of this above, thanks for the reply and info.

 

[chris.linkous]

Define “great pressure up to the engine”. Does the pump prime for 2-seconds, and shut down, showing at least 40 PSI. Does the pressure drop after the pump shuts down? How fast does the pressure drop?

Honestly I didn't read the pressure yet. Before I wasn't getting anything at all. I replaced the pump and it did prime and stop. When I walked up to the fuel test port and pushed the valve in it came out pretty good.

I realize I could still have other issues and may even a fuel issue; however, at this point my main concern is figuring out why it had two floated valves. Please keep in mind that I have no good background on this engine. The guy I bought the car from told me it had a bad starter and that is why it wouldn't turn over lol. I'm not a genius but there is no way he parked the car with it running fine and it had two valves floating without him noticing something was wrong.

My train of thought is this. Originally, it would not turn over. I took the drivers side valve cover off and found a bound pushrod stuck in the valve pan. I put the pushrod back in the lifter and tightened the valve down to a safe starting position. After that I turned the engine over and discovered it was not getting fuel. I removed the pump and tested for voltage which was present. Zero fuel at fuel rail and good voltage so I decided to replace the pump. Installed new pump and cycled the key. Pump primed and shut off. I installed pump all the way and connected fuel lines. Started the car and it was knocking pretty good so I shut it off. I removed the passenger side valve cover and found another floated valve. I installed it to a safe starting position the started the engine again. Engine runs but is still making a knocking sound from the lower end. Throughout all of this short starts and engine cranking I have not seen a single ounce of oil come up to the valves. I am concerned that the pickup tube is off and in the pan or the oil pump is bad! When the car is turned over the oil pressure gauge maxes out so I am leaning toward the pickup maybe. In either case I feel like I should pull the pan and see what is going on down there if for nothing more than piece of mind.

After reading all of the replies I will check all of the items you guys recommended to include fuel pressure. I will check the Opti to see if it is good and hopefully figure out this oil issue. If anyone thinks I am on the wrong track please feel free to let me know what you would do after reading this recap. I am all ears and do not want to make this harder than it has to be.

 

[ZumpTA]

...my main concern is figuring out why it had two floated valves. ... The guy I bought the car from told me it had a bad starter and that is why it wouldn't turn over lol. I'm not a genius but there is no way he parked the car with it running fine and it had two valves floating without him noticing something was wrong.

Thing is, the LT1 has so much low-end torque right off idle, that he truly might not have known. Not saying the guy was or wasn't being truthful, but I could buy into it myself. I'd have to be looking him in the eye to even start to determine the truthfulness of the statement.

Both times I lost a cylinder, the only 2 indicators that I was down on power was a very slight stumble within the first second or two of letting out the clutch when easing away from a light; which many might simply attribute to "180,000 miles". The other was when trying to break the tires loose above 45MPH, it wasn't nearly as "easy". The engine seemed sluggish to revv to the level it previously did, and felt like it was struggling a little. Couldn't keep the rear lit-up nearly as long either.

So, the first time, when the sparkplug boot came off, there was a serious sounding knock which got my attention. I never even noticed the little bit of lost power. I got home and parked it. The second time, when a plug actually came out, I drove around for a couple months thinking I had a leaking exhaust header gasket. No big deal.

It wasn't until I noticed the near inability to put my car sideways at highway speeds that I realized something wasn't right. I'm guessing I'm a "rare 'bird" in this respect. If I wasn't intimately familiar with my powertrain and it's limits, and occasionally took it to those limits, I'd never known and likely continued driving even more months or possibly years until I broke down and tried to replace the header gaskets.

One cylinder is only 12.5% or 35-ish HP/TQ give or take. Lose one and you're definitely still leaving the line with traditional v8 power levels, so I buy it. ...been there as they say.

2 cylinders or a 25% reduction in power, definitely a bit harder to swallow. The sluggishness off the line should be noticed; but I can also understand how someone who doesn't drive their car often and to it's limits could overlook the problem. You're still looking at nearly 200TQ right off idle, and that much torque has no problems getting these cars rolling. Probably feels more like a late 70s or early 80s V8, but still a V8 none the less.

I couldn't imagine it sounding right though. My T/A's exhaust burbles and coughs just idling and firing on all 8, so it's not a smooth or consistent note and one cylinder missing was completely inaudible to me. I suspect if my C4 (also an LT1) dropped a cylinder, I'd hear it. I definitely think I'd notice 2 missing because it does idle smooth and consistent. ...but again, we're back to knowing you car. I know for a fact my wife wouldn't notice if her car lost 50% of it's power and the exhaust note went from bang-bang-bang-bang to bang- - - bang. My father (grandfather), although a massive proponent for big V8 power and torque never really "got on it" because you really never have to with these power levels available just off idle.

So, yeah. Might be the truth.

...or, he could have been lying through his teeth.

¯\(ツ)/¯


You're definitely on the right track in my opinion.

I'm not an "engine guy", but I might be considering renting/using a bore-scope to inspect the cylinders, heads, and pistons. As I don't exactly understand the mode of your top-end failure I'm unsure if there was a possibility the valvetrain could have interfered with a piston. So that's my concern. Without a clear picture of what you faced, my mind goes to "he bent/broke the valvetrain, something may have intruded on the piston, and when the engine wouldn't fire because of this, he cranked it over-and-over-and-over-and-over until the starter gave up and he did too. ...and in the process; damaging the heads, pistons, chewing up the cylinder walls, etc.".

My ignorance of the situation leads me to "worst case". Hope what you found isn't what I imagine.

A LT1 is certainly worth a rebuild to stock specs if need be. ...at least to me. I personally feel that even in todays environment it's a respectable powerplant. You're certainly going to have a hard time finding another stock V8 that lays down 80% of it's torque off idle, and that's where the fun really is. Under the speed limit, light-to-light, never exceeding 2,500 RPM and lazily blowing everyone off the line.

There are refurbished Aluminium head LT1 long block crate engine out there for under $3,000, and Golen Engine Service sells a "turn-key" 440HP/480TQ LT1 for $7.5k, and a 500HP for $8k. Their engines come with a 1 year no mileage warranty too.

Should you need to do a rebuild with machining, consider these prices when you get estimates.

Good Luck!

 

[Injuneer]

Correct way to set rocker arms/valves:

4th Gen LT1 F-body Tech Articles

What do you mean by “floated” valves? Valve float generally refers to what occurs at high RPM when the valve train loses control of the valve, most likely weak springs, and it's not closing. You seem to be describing finding the rocker arms losing contact with the push rods and valve stems. Collapsed lifters due to no low oil pressure?

And when the starter is cranking the engine, the oil pressure gauge pins at 80 PSI? The early production 94’s had the oil pressure sensor on the driver side of the block, above the oil filter. Later production the oil pressure sensor moved to the back of the block, just behind the intake manifold. Which does your 94 have?

EARLY:

http://shbox.com/1/aux_oil_port.jpg

LATE:

http://shbox.com/1/oil_pressure_sensor.jpg