jmatt82

Hello friends! Its time for this years winter project. I will be removing my bone stock CFI L83 motor and replacing with a 350 carburated engine. I will be running SBC 400 heads, comp cams 286H hydraulic cam, TRW flat top pistons. I havent made the final decision on my headers and intake yet, and probably will go with Holley 650. 700R4 trans. Installed 3.73 gears last winter. My question/concern is Im not sure what I need to do as far as the ECM and any other electrical mods that I may need to do. Any help in this area would be appreciated.

DUB

One thing that you better get worked out...if that if you plan on using an air cleaner...you have to remember that a hood for a 1982 is different that a 1980-1981...which were had carbs. So height of intake manifold and carb and so on will dictate if you are going to have to either get another hood or modify the one you have now.

DUB

Rebelrob

You will lose the ECM. Just leave it or remove and sell it with the rest of the CFI engine.
You can pull the 2 fuses also for each of the injectors.
You will need to install a fuel regulator if you stay with the electric pump to reduce to 5-7# pressure or go mechanical.
Install a new header -exhaust system.
You can reuse all the under hood wiring for ignition, gauges, tach, altenator.
You may have to do some mods to the hood as mentioned above or go with aftermarket.

alconk

Are you wanting to remove the L83 because of issues because even though they get a bad rap you cn make some good power out of those. That setup is what is unique to the 82s. The most thing hindering the power is the intake, it's very restrictive having a 1/3 of the ports closed off. I ported my intake and seriously made a seat of the pants difference, then bought me a Renegade intake. Holy crap is what I say, it turned it into a totally different car. There are alot of things you can do just like any other motor. Not trying to talk you out of it because we all have our reaons but some people don't want to mess with them because they might already be having issues with it and can't figure the problem out. Good luck.

jmatt82

Alconk you make a valid point. You can gain some good HP just working with the top end of the motor. However that will only take u so far. I've found a great deal on new engine that should get me up around 425HP at 9.5:1 compression. I will keep the stock L83 motor after it's pulled. But to build that much power in the stock motor would require about as much money as I will have in the new engine so I figure why not just have 2 motors instead of one.

jmatt82

Rebel rob thanks for the info. That's what I was looking for. I had read that I wouldn't need the ECM but didn't want to take it out of service if it still ran something I might need.

alconk

Sure I see your point and I don't think you could get close to the 425 hp with the L83 with mods, pushing it maybe 350-360. Sounds like you have a good plan, be cautious on your hood though as DUB explains. You can remove the center cold air induction system under the hood if originality isn't a issue.

jmatt82

And yes dub that's good info. Thanks

jmatt82

Was curious as to what all the ECM ran. Is it mostly for engine sensors , engine electrical, etc.? Does it run anything for the interior? Door buzzer,etc.?

alconk

Nothing in the interior but you have a speed sensor in the speedo that helps control the lockup. Also the ECM controls the distributor among the other sensors.

7T1vette

The ECM also provides fuel management, as well as the diagnostics for any problems with the engine system.

qwank

I think a 350hp L83 would be an awesome car.

jmatt82

Has anyone done an engine swap or upgrade and still kept the stock distributor? Sounds like it would require keeping the ECM also!

alconk

If done so yes you would still have to retain the ECM. You could do the engine swap just be careful how aggressive you get with the cam as the ECM can't handle much more lift than factory. If you can find the specs I think the Compucam 2040 is the largest you can run with the ECM unless you change out the ECM to a newer late 80s early 90s Camaro with a ham board sold by DCS.

7T1vette

Just curious....why did you buy a 1982 car if you just wanted to rip out its powertrain??

You could keep all of the engine management system components and just put different heads, cam, pistons and exhaust on the engine. Open up the intake a bit and put larger/modified throttle bodies on it. You would get similar performance, but still get the benefits of EFI and ECM control of your transmission.

hugie82

First 400 heads on a 350 SUCK! they are large chamber, small valve heads.
Second, you can install a mild 350 or small block 400 and keep the CFI system with some minor adjustments.
Third, if you choose to remove the CFI system? The entire car will need a rewire. A lock up converter kit must be used with the trans, the fuel pump must be changed out or an external regulator installed, an HEI non computer distributor must be used and all the original wires will need to be put somewhere and there a lot of them

My advise is if you want a good street runner? Keep the CFI and invest in a nice set of heads (original L83 are nothing special). A mild cam (under 212 duration) and if money allows, find a renegade manifold with some ported Throttle body's.

These engine make awesome torque! So your goal is not rpm horse power but as much torque as possible under 5500 rpm.

alconk

You will love the Renegade if you can get one. Pulls hard to the redline no ****. Feels like a different car with that on.

wilcar

The comp 286 cam has 236-236 duration at .050 on a 110 lsa and will produce about 9 " of vacuum at 900 rpm, pretty radical cam for a mild 350. Will need a big stall converter. Better rethink your cam selection.

scottyp99

'82 'vettes also came with a pretty high diff gear, 2.72 or 2.87. Even with the steep first gear on a 700r4, you're still looking at an 8.78 final drive ratio in first gear, at best. Not bad, but not exactly the stuff that dreams are made of with a cam that big. Especially with a stock converter.

Scott

alconk

A 110lsa will throw that ECM into a fritz. If you had the correct software to run this cam it would be great but your factory ECM won't handle it.