L31 to LT1 swap?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

cookseyb

Newbie
Joined
Oct 14, 2016
Messages
39
Reaction score
4
Location
central Texas
The biggest issue with the opti-spark is folks tend to wanna mess with them, Think on this, there are thousands of cop cars and taxis running that engine with little or no problem.. Great engine that makes lotsa power. Just put one in a 1964 Chevy truck, runs like a bat outa hell with a little head and cam work. Get the fresh air vented opti cover ,95 and up and the moisture goes away. I drill and tap the water pump weep hole for 1/8 inch pipe and run a barb and drain hose away from the front of the engine. Good parts are getting hard to find but there are some good books on Amazon about this power train that are worth having
 

Supercharged111

Truly Awesome
Joined
Aug 20, 2015
Messages
12,612
Reaction score
15,235
The opti in my Camaro was installed in 2014. Over that winter, I replaced plugs, wires, coil, ICM, and knock sensor with all factory stuff. Haven't had an issue since.
 

Mark Gilbert

I'm Awesome
Joined
Sep 25, 2019
Messages
105
Reaction score
36
Location
Arizona
The truck posted isnt mine, I have a 96 with a vortec 350, the one I am planning on swapping to an LT1. I knew the TBI chips were considered ECMs, but I was also given information that the black box was an ECM as well. I figured that if the transmission was controlled by the same computer as the engine it would be a PCM, but in that same case a 95/94 TBI would have a PCM, yet are still considered an ECM

You are correct a PCM controls the engine and transmission, and an ECM is only the engine. Some TBI "computers" are ECM and some are PCM. Most people don't really care and we generally know what you are talking about so it is just kind of semantics...

I'm only being obstinate for the sake of accuracy.

Just to mess things up even more. the newer vehicles are back to running an ECM instead of a PCM, they just run a TCM in conjunction with it to control the transmission...
 

Hobie

I'm Awesome
Joined
Oct 1, 2019
Messages
286
Reaction score
225
Location
Missouri
The biggest issue with the opti-spark is folks tend to wanna mess with them, Think on this, there are thousands of cop cars and taxis running that engine with little or no problem.. Great engine that makes lotsa power. Just put one in a 1964 Chevy truck, runs like a bat outa hell with a little head and cam work. Get the fresh air vented opti cover ,95 and up and the moisture goes away. I drill and tap the water pump weep hole for 1/8 inch pipe and run a barb and drain hose away from the front of the engine. Good parts are getting hard to find but there are some good books on Amazon about this power train that are worth having

I wouldn't say there are still thousands of cop/taxis running around with an LT1 or Baby LT still. At least not around here. LTs are extremely scarce, basically only found in a handful of camaros and corvettes. The caprice cars are basically gone, either non running, or just rotted away.

I know these engines have a very nice power capability, and this is why I want to have one, and I will have a 96, so it will be the updated opti, but I still dont like the fact itll be there. I will say it again, this is my opinion, you can argue all you want, but I will continue to dislike the reliability of the opti spark system due to my own experiences. I think this topic is like orange silicone lol, some people swear by it, and some wont touch it
 

Supercharged111

Truly Awesome
Joined
Aug 20, 2015
Messages
12,612
Reaction score
15,235
I see the LT motors in other land barges like Buicks more than Caprices. The iron heads flow better than the aluminum
 

Hobie

I'm Awesome
Joined
Oct 1, 2019
Messages
286
Reaction score
225
Location
Missouri
I see the LT motors in other land barges like Buicks more than Caprices. The iron heads flow better than the aluminum
IIRC the iron heads flow like Vortec heads? But either way, the engine has aluminum heads, and dont really plan on buying another set if these are good.
 

L31MaxExpress

I'm Awesome
Joined
Apr 21, 2018
Messages
5,890
Reaction score
7,539
Location
DFW, TX
I see the LT motors in other land barges like Buicks more than Caprices. The iron heads flow better than the aluminum

The slightly better flow are the iron heads only benifit. I doubt the flow helps as much as the compression drop. The aluminum heads have screw in studs, the iron heads have pressed studs, the chambers are larger on the iron heads, the aluminum heads can be reworked easily to flow much higher. A pair of Lloyd Elliot ported aluminum heads would be a nice upgrade on a cast-iron head engine.
 

gisbradokla

Newbie
Joined
Jun 21, 2021
Messages
3
Reaction score
0
Location
Oklahoma
I got an offer today for a LT1 out of a 96 Corvette. The car had 38k miles, and was wrecked. The engine will include intake to oil pan (I'll try to get the accessories as well,) engine harness, and the PCM.

Now my L31 is on its last legs, oil pressure at idle is around 10 PSI, and leaks oil from about every point possible, and it sounds like I've got some piston slap.

I do have another L31 that I've tore down, but havent given the machine shop the go ahead to start on the block and heads. So since this LT1 has come up, I'm considering the option heavily.

I have a 411 PCM ready to send off, and I'll go with a basic rebuild on the LT1 if I grab it. I will also be swapping it to a 24x setup to get rid of the opti spark ignition.

I've looked around on here, and I'm not seeing anyone who has done this swap, although I have a feeling someone has. What kind of headache would you guys reckon I'll be getting myself into if I go ahead and perform this swap?
Did you do the swap?
I did one from a 95 C4. Problem is the harnes is about 4’ short for the truck. I got a caprice harness and used the long end of it to splice into mine. I am still fighting that battle and also the problem of my 95 K1500 has the range selector and also the C4 has all the cabin convenience center pass side while the truck had it under hood driver side.
Hindsight is 20/20
 

L31MaxExpress

I'm Awesome
Joined
Apr 21, 2018
Messages
5,890
Reaction score
7,539
Location
DFW, TX
I have discovered with an OBD2 LT1 timing cover a LT1 can be run with a Vortec or 0411 PCM without a cam sensor. Use the optispark as a distrubutor for spark and the later LT1 crank sensor, reluctor, coil and ignition module is the same as a L31. L31 will run without a cam sensor connected.

Of course I figure this out; after I sold the LT4 heads and intake manifold I had and built the 383.
 

Supercharged111

Truly Awesome
Joined
Aug 20, 2015
Messages
12,612
Reaction score
15,235
I have discovered with an OBD2 LT1 timing cover a LT1 can be run with a Vortec or 0411 PCM without a cam sensor. Use the optispark as a distrubutor for spark and the later LT1 crank sensor, reluctor, coil and ignition module is the same as a L31. L31 will run without a cam sensor connected.

Of course I figure this out; after I sold the LT4 heads and intake manifold I had and built the 383.

You're not the only one. I put a 4x reluctor and OBDII cover on my Camaro this past Spring. Intent is to 411 swap it this winter to pioneer a rule change for my race class. Intent was to accomplish this all last winter but I ran out of time.
 
Top