I have a very nice 1981, all stock, automatic. I'd like to have 300 plus hp, but retain the cruise and a/c.

So the question is, pull and modify what I have, as well as a trans refresh, or is there a later model engine and trans that would drop in with out too much modding that would be better?

This car is a driver, not a "gotta keep it original" machine. I want quiet smooth power and shifting, and the creature comforts.

It's winter storage time, so either this powertrain is coming out for a refresh / upgrade, or I will get a newer efi engine / trans and drop that in.

Thanks for any and all suggestions.

 

If money is no limit....

The stock 350 can be rebuilt...plenty of books, posts, threads, etc on what can be done.
Many will say the CCC is a restriction...and it is to some extent...due to using engine vacuum from the MAP sensor as an input to the ECM.
Simple to remove the CCC system, just get a different carb and distributor.

If the engine retains the stock heads, they are cracked. New heads are a must have; much better flow...but will require headers....the ole air in...air out...rule applies. Then true dual exhaust...which is always a bit of a challenge on an '81 due to the stock routing..but there are systems available.

Machine the block, all new internal parts, heads, exhaust, and you will have your hp goal.

As far as the transmission, I have no input as you have an auto and my '81 is a 4 speed manual...but I would think there are better auto transmissions.....700R4....available. But this requires modifications of the crossmember, driveshaft.

As i started....if money is not limited......

Good luck.

 

Thanks. I have true dual exhaust already, no cats. Did that last year.

You say the "heads are cracked"...it does not leak coolant, are you referring to another place?

 

My heads are original and are not cracked...

Here's what I did with my '81, It was bone stock when I bought it:

Adjusted the timing to 14* base timing
Summit brand long tube headers and a true dual 2.5" exhaust with magnaflow mufflers.
swapped the automatic out for a Richmond 5 speed transmission.

I can spin the tires up pretty good from a stop now and the car is much more fun to drive. My stock carb and computer work perfectly though, so I had no drive-ability issues to begin with.

My next item on the list is to remove the mechanical fan and install an electric one.

Whens it time to think about the engine, New heads are a MUST. The stock heads don;t flow very well at all, and like said already, are prone to crack.

If I were you, and wanted to mess with the engine I would install a roller cam, and some 170cc-185cc heads, and anything else that goes along with it (new timing chain etc.) don't go too crazy on the cam, otherwise your stock carb and Distributor will need to be replaced, as the stock ECM doesn't like low vacuum situations. The stock aluminum intake will work well and fit under you hood (obviously)

A 700R4 transmission has a lower first gear so that will help with your crappy 2.87 rear gears. You can get all the parts from an '82 to do an easy install. Or you could go with a TKO500 manual transmission or a Richmond 5 speed like I did.

When the time comes, I'm going to just replace my engine, Since it has 100K on it. Roller cam Crate motors are cheap enough now that I don't see a point and spending the time to rebuild the original block.

 

That's my dillemma...if I pull the L81 for a rebuild, and put all that new stuff in it / on it, aren't the dollars better spent just getting one all done already and dropping it in? I'm all for keeping the ECM, E4ME carb, etc.

Perhaps an alternative is to leave the engine in, pull the heads and replace those, cam, lifters/rockers etc and see how it performs? Or is this transmission the real problem?

Thanks for the inputs.

 

Keeping the stupid POS ECM AND carb on a crate motor would just be folly. It really is a pain in the **** when it has issues, if originality is no issue, I would can the ecm and associated crap especially with a crate motor. I canned mie when I got my car and have had no need to touch anything since.

 

I pulled the original engine on my 82 and replaced it with a ZZ4 turnkey crate engine, gained a bunch of HP and torque. The only minor issue I had was getting the TV cable right for the lock up torque converter but I got that figured out. My car is a everyday driver and I take it on trips a couple times a year. I have no regrets, never looked back. My ECM is still in the car but disconnected. One less thing to fail.

Andy

 

Did the ZZ4 fit under the hood?

I assume you kept the TH350 trans, if you keep the ECM hooked up for just the trans lockup that would be a great option. What carb and exhaust manifolds / headers did you go with?

Thanks!

 

maxmachz,

This is a few notes I wrote up for another forum member a couple of years ago. This should answer some of your questions:

I know my 82 very well but I have little knowledge of the 81 so what I had to do may differ from your install.

Engine: This is the engine I bought http://paceperformance.com/i-5145964...e-package.html and I am well pleased with it.

Headers: The ZZ4 has “D” shaped exhaust ports on the heads. You will need to get headers designed for the engine. I bought Hedman long tube headers for mine. I do not remember the part number right off hand but I can get it for you if needed. Changing spark plugs with these headers is a bit of a pain but manageable. It helps if you have a daughter with small hands to reach in tight places.

Water pump: The engine comes with a long pump, I needed a short one for my install. The pump from your old engine may work, but generally they will interfere with the plastic timing cover GM uses. Sometimes you can make a cast iron stock one work if you replace a few of the rear cover plate bolts on the water pump with button head allen screws and if you grind 1 or two of the heads of the bolts used on the plastic timing cover. Using the special Edelbrock pump is usually easier, but its up to you.
Swapping the plastic timing cover for your original timing cover is also a possibility, but generally every other bolt hole in the block is missing for an old style cover and will need to be drilled and tapped - The new blocks can be either way as far as the timing cover bolts are concerned, no way to tell for sure without pulling the plastic cover and looking. .
I bought a Edelbrock 8812 water pump to make my life easier which bolts right on with no problems.

TV cable bracket: The TV cable bracket from my old engine with TBI’s would not work with the ZZ4 which is carb’ed. Summit Racing has one that fits well and allows for adjustment. I used http://www.summitracing.com/parts/TCI-376715/ if memory serves.

Air cleaner: The air cleaner that come with the ZZ4 stood too tall so I have to replace it with a low profile type. I think they called it “deep dish”

Fitting the engine in: The 82 has some sort of ram air injection where a small butterfly plate (controlled by the computer) is built into the hood and opens under full throttle. It is supposed to force cold air into the carbs. There is an air channel built into the hood for that reason. I do not know if your 80 has this or not but I had to cut out that part of the inside of the hood in order for the hood to shut. It was really no big deal and the hood is still rigid and has no problems with fit. I repainted the inside of the hood and you have to look close to see this has been done. This modification and the different air cleaner allowed the hood to close with about 1.5 inches of clearance.

My 700R4 transmission mounted right up, no problems.

The ZZ4 comes with a mechanical fuel pump which I wanted to keep, eliminating any fuel pressure issues going from TBI’s to a carb. I disconnected the wiring from the original electric pump and just left it in place.

The AC compressior bolted right up but lost the cruse control which did not work anyway.

The issues I ran into may or may not apply to your 81 model. I was just trying to remember as much as possible what had to be done for my install. I hope this helps.

Andy

 

The ZZ4 is a great choice of an engine. I would still try to keep the stock computer though, Maybe send the carb to Lars and have him rejet it to work with the ZZ4, if that's possible.

I'll most likely be going ZZ4 with mine when the time comes.

 

If I was buying today I would go with this, and slap on the factory intake, carb, distributor, etc.

http://paceperformance.com/i-5146074...ck-engine.html

 

Mike V Here...Happy New Year! I've recently swaped my original motor and dropped in a rebuilt earlier block that we rebuilt.Had some issues with harness reaching certain areas for temp sensors etc as for I used edelbrock intake along with performer carb. Motor runs good but there is an electrc draw on battery???All electric connects not used anymore are taped up.Considering new wire harness...Any suggestions .Motor is set up for "74 specs...Vacuum adv dist,elec choke etc!

 

I've had my '81 f/ quite awhile. IMO, the 2004r transmission is a better choice than the 700 by far. I did away w/ the computer and went w/ an Edelbrock carb and manifold and long tube headers w/ a full dual exhaust and Flowmaster mufflers, no cat on it anymore. You can either rebuild your engine or get a crate engine, or whatever. I'd just go w/ another/or the same "small block" (rebuilt) and the 2004r. It's a very simple fix overall.

 

Texas Jim - just curious, why do you prefer the 200r4 over the 700r4?

Have heard others express similar sentiments - I have a 700r4 behind a 383 in a modded 79, but am considering a change; so not to distract from the OPs original question... But wondering why?

 

The the gear ratios in the 700R4 work better with the '81's rear gears then the 200R4 IMO

 

With the assortment of rear end gears the '81 'Vette came w/, why would you feel that the 700 works better? The 200 gearing is alittle better than the 700, 1st. to 2nd. gear shift is closer (the 700 has a 46% rpm drop from 1st. to 2nd.), less rpm drop, and an over-all more friendly ratio spread. The 700 valve body also prevents over drive access at full throtle and the 200 doesn't. You can use the same drive shaft and yoke (and most of the time, the same cross member if you spin it around or w/ a slight mod) if you go from the TH350 to the 2004R, as they are both the same length. I'm not knocking the 700 trans, as there is nothing wrong w/ it, but from everything I've read over the years, the 200 is a more over-all friendly swap and better choice.

 

The '81 auto transmission only came with one rear end choice, 2.87. the 700s first gear ratio is better for off the line acceleration. That's why GM used the 700 in the '82 instead of the 200

 

Then the RPMs drop 46% when the 700 shifts into 2nd. gear, and 1st. gear is plenty low enough in the 200 then you get a closer ratio shift into 2nd. Please explain how the 700 gearing is better w/ the 2:87 rear gear ratio. Didn't know you were refering to only automatics. Not all of GMs ideas/decisions were the best. Like I said, I'm not sayin that the 700 is junk, but only that the 200 is a better choice, and I've stated the reasons. Please state your reasons, and not that GM used the 700, as also in the '82, the cross fire injection wasn't a great set up either.

 

How many miles on the orig. engine? Its pretty easy to get 300 hp out of a stock motor, heads and cam change would do it, I also put flat top pistons in my 81, it has plenty of power for under 2 grand.

 

You can get 300 crank horsepower with light mods; keeping your engine, AC and Cruise.

recurve your distributor
re-jet your carb for performance (1981 is electronic q-jet. You should be able to make this mod without forfeiting the electronics)
headers
dual exhaust
super turbo mufflers

If you want 350 crank hp:
refresh the valvetrain with a nice retro roller cam/lifter kit
upgrade to a nice set of cylinder heads to match
rebuild your TH350 and add gears to match. Your Dana 44 will run 3.31's, 3.55 and 3.73 without issues. You will forfeit gas mileage with deeper gears. A good compromise is 3.31's. I have 700R4 trans with 3.54 spicer gears.