I have a 1981 Chrysler LeBaron I picked up over a year ago for literally a song and a prayer. The original owner had the engine and transmission rebuilt at 100K (it now has 124K on it) and seems very solid. The downside to all this is that I feel I got the California version (single barrel carb and a vacuum system from hell) and I'd really like it to perfom and run a lot better in general. Obviously, first of all I'd like to do away with the single barrel and do a 2 barrel setup on it, but I'm not sure where to begin. I can locate a nice Holley 2 bbl setup, for example, but finding the correct intake manifold seems to be an issue. Any help and advice would be greatly appreciated. I'm out......

Hi there

Welcome to the forum!

To give you a quick rundown

Slant 6 engines have a couple of strikes against them all located around the head

Ignition and timing

Induction

Exhaust

Compression

Head flow

Valve lash - if not hydraulic

All can be remedied

From cheapest to most expensive

If you have mechanical lifters get your valve lash sorted

Where I got the best oomf for money spent is on the ignition - I replaced my plugwires with Accel superstock units, distributor cap and rotor from them as well. Plugs NGK ZFR5N.

The only expensive bit was the MSD 6A unit I have installed

I set my ignition to maximum mechanical advance 32 Degrees at 2600 rpm. Vacuum hose disconnected. On my setup it gives me 12 Degrees advance at 750 rpm - search recurve on this site

As you said the dual barrel supersix setup helps a lot! I dont now how rare they are your side of the pond - we used a simmilar setup over here on most of the slants since the late sixties

Exhaust - long tube headers for torque- opinion is devided if you should go 6 into 1

6 - 2 -1 or 6 -2 with an x or h crossover

Or Dutra duals - the main thing is that the slant exhaust system is very restrictive - a 2 1/4 to 2 1/2 pipe to the rear with a freeflow muffler of reputable make will help things along

Now for the expensive bit - the head

You can up your compression quite a bit but this is dependant on your cam

but as a rule of thumb 9.3 to 9.5 is ok

Head flow: Unshrouding the vlaves, have a set of backcut standard valves in stalled - or go the whole hog and fit a set of oversize valves

The most cost efficient is to use the back cut valves, a good blending job, have your manifolds and head port matched, and skim the head for higher compression

Oh yes the cam read up on the ERSON group buy that is going on at this stage


Search all the underlined text it will help
But most important - get a field service manual.

A book that helps me a lot is Mopar Engines, by chrysler and mopar performance

Goodluck and enjoy

_________________
Regards,
Fanie Gerber
It's never junk, it's just a part you're not currently using

http://www.valiant50.co.za
Just say I own a few Mopars

Forget the 2 and go straight to a four barrel. Unless money is tight and car needs to get moving. Here's the reason, assuming you don't switch the engine out for an eight, the four will be effective from 390cfm for a stock engine, to 500cfm for a 13 sec engine. People in the biz call it acting proactive not reactive, at least that's what I heard.

Certainly some strange advice you've had so far ("Forget the 2bbl and go directly to a four"), given the kind of car you have, where you live, and your stated goals of simplifying matters. I didn't read in your question anything about wanting to make a race car or swap in a V8 or any such thing.

You do indeed have a hard situation on your hands (strangled California '81 engine struggling to pull a heavy car around at 5,500 feet above sea level). However, you also have a rebuilt engine, so unless you like spending money, your most cost-effective way forward will probably be to make changes to things like the induction, ignition, and exhaust systems — things that don't require re-rebuilding the engine. Later on, if you still feel you need more, you can get into things like a better camshaft and such.

The factory 2bbl setup works really well and requires a great deal less fiddling and tuning and futzing around than a 4bbl setup. They're not as common in wrecking yards as they used to be, but if you keep your eyes open, one should eventually show up at Pull 'n' Save (off Peoria @ 33rd in Aurora) or Colorado Auto & Parts (@ the end of Radcliffe off Santa Fe Blvd). You'd need the air cleaner, carb, intake, shorter throttle cable, and complete kickdown linkage and bracket assembly. Stock carb is a Carter BBD which, in good repair, is a very good choice. Holley made a 2280 as an aftermarket replacement carb for this setup; in good repair that one's a fine choice, too. Other 2bbls (Motorcraft 2100, Holley 2300, etc.) have been adapted with success.

An ignition recurve should definitely be on the short list of mods — does your California '81 have Lean Burn, with a distributor that lacks a vacuum advance?

But before we get too far into this project: what's the current emissions testing situation in the Denver-Metro area? When I left in '00-'01, 1982 and newer vehicles had to go through the I/M240 chassis dyno test run by Envirocare, while '81 and older vehicles got the simpler FTP75 "idle and 2500rpm" test. If that's still the case, you've got a good deal more lattitude in the modifications you can get away with. If that's changed and '81 vehicles have to have the I/M240 test, you'll have to be much more thoughtful about what you do and don't change.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan's got you covered, especially on the local laws...
If your engine is original then the 1981-1987 slant will be hydraulic lifters and thus no lash required, and the hydro motor only uses the 'BL' style spark plugs (so no ZFR5N unless he retrofits the engine to a pre-74 drool tube head, and a mechanical lifter cam shaft).

I would also check the rear axle ratio for a bit of 'help' many of the late body cars got a 2.45 instead of the better 2.76 or 2.94 rear (let's hope you got a 2.94 to throw that heavy beast, luckily it's not a 318/360 car that may get 2.26's)...

Best of luck, let us know what you 'can' get away with, what your budget is, and we'll get you in the right direction.

-D.Idiot

I apologize, I didn't put together the year and the location that you had to work around emissions. I don't have to pass DEQ where I live. good luck

Not yet, but the powers that be and with all the Californians buying up 'cheap' property here, it won't be too long before the mid valley gets mandatory checks...


On another note, another thing to look for on the 1981 Lebaron is making sure the cat. convertor in the exhaust isn't old and 'plugged', this could free up a whole bunch of power if replaced with a newer/better flowing model (if necessary in your area), or just 'replaced' with a test 'pipe' (if not inspected in your area...

-D.Idiot

Might I recommend a new high flow cat...

Err on the side of our Kiddo's. If the Enviro's are right, you'll be thanked, if not....at least you took the high road...

CJ

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Part of Tyrde-Browne Racing

Sorry Over Here as well - no testing over her

_________________
Regards,
Fanie Gerber
It's never junk, it's just a part you're not currently using

http://www.valiant50.co.za
Just say I own a few Mopars