daddyo
Need a Spot
Reged: 10/08/08
Posts: 2
Loc: Mt Idaho, Idaho
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I have an '81 CJ7 with the 258. It was originally a California vehicle. The time has come to get rid of all the spagetti under the hood. I plan on putting in a HEI, new carb and exhaust manifold. I plan on removing my cat as well. This is daily driver so I want reliability. What's the best combination?
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DBL_DTY97TJ
Rock Warrior
Reged: 01/18/07
Posts: 534
Loc: Wilmington, NC
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Is there a problem with the way it's running?
I don't think you'll find many people on this board who take kindly to the removal of polution control equipment. Myself included. If it's got a mechanical problem, you'll get all the help you ask for.
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97tj, Shaved Ford 9 rear, 4:10's, New 35x12.5 BFG KM2's to test!, Warn x8000i, ARB's, Quick Disco's, Hand Throttle, & it's my DD. :)
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daddyo
Need a Spot
Reged: 10/08/08
Posts: 2
Loc: Mt Idaho, Idaho
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My apologies. I guess I should have been more clearer with my intentions as well as chosen a better topic title. Early '80's california emmisions was incrediably inefficient. The mere act of turning the smog pump not only robs horsepower but robs mpg. With the current set up I have never gotten better than 12mpg's and that is with 31's. By replacing the current underpowered ignition system with a newer, modern HEI, and exchange the stock carb with a better designed model, I hope to greatly improve my mpg's as well make a much cleaner burning engine. I have to replace the exhaust manifold because I am unable to find replacement air injection tubes and the brass plugs I'm using now to fill the holes don't work all that great. The engine as a whole is in excellent condition, no leaks, doesn't burn oil, etc. The only downfall is the fuel delivery system. I'd appreciate any kind of help that someone with a similar experience/situation could provide.
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jstritec
Mudrunner
Reged: 10/22/02
Posts: 466
Loc: Grand Junction, CO
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If you're gonna spend cash on the HEI and carb, you might as well spend a few more bucks on a TBI fuel injection system. Howell makes a good system for about 1200 bucks that is easy to install, and for what i heard has great customer support. they have a CARB approved model which will be in compliance with both CA and Federal law. The HEI wont get you better gas mileage despite what the ads say.
Good luck,
Josh
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80 CJ-7.
It runs
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BigJim
Web Wheeler
Reged: 10/07/03
Posts: 7724
Loc: Central Texas
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Quote:
My apologies. I guess I should have been more clearer with my intentions as well as chosen a better topic title. Early '80's california emmisions was incrediably inefficient. The mere act of turning the smog pump not only robs horsepower but robs mpg. With the current set up I have never gotten better than 12mpg's and that is with 31's. By replacing the current underpowered ignition system with a newer, modern HEI, and exchange the stock carb with a better designed model, I hope to greatly improve my mpg's as well make a much cleaner burning engine. I have to replace the exhaust manifold because I am unable to find replacement air injection tubes and the brass plugs I'm using now to fill the holes don't work all that great. The engine as a whole is in excellent condition, no leaks, doesn't burn oil, etc. The only downfall is the fuel delivery system. I'd appreciate any kind of help that someone with a similar experience/situation could provide.
Daddyo I am the happy bearer of news about that HEI. As long as the dist setup that you are using lights the fire in the cylinder NOTHING you can put in there will do BETTER!
Hei dists are for engines that have fuel injection and can burn a LEANER mixture. As the mixture got leaner it was found that the .032 point gap sometimes didn't have enough fuel in it to LIGHT when the spark occured. So the engine MISSED and jumped a bit.
The CORRECTION for this miss was to widen the gap in the plug to .045 or so and that ASSURED enough of the lean fuel to LIGHT! So as long as you are using ANY carb the mixture will be rich enough to light in the smaller gap..There is NO NEED nor is there any USE for a larger gap or hotter coil setup!!
TRUST ME putting a hei in there is throwing good money AWAY!
If you want more response put them 26 inch tires it came with back on there and it should be a lot better! OR change the gearing to accomadate the height of the tires.
As for the smog? If it is in working condition leave it in there... Taking it off won't get you even ONE mile per gallon.
Big JIm 
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professional bovine relocation specialist
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superdawg
Body Damage is Cool
Reged: 10/13/99
Posts: 2211
Loc: Denver, Colorado
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Quote:
I hope to greatly improve my mpg's as well make a much cleaner burning engine.
What you are hearing here is right, hei is a good ignition system, but what you have works well too.
The 258 4.2 and 4.0 platform are all dirty motors even with EFI if measured against the new technologies. The reason they bagged using the 4.0 in the new JKs is because no matter what they did it simply could not run clean enough.
Other straight 6 engines over the the years were pollution problem kids too. The 300 Ford, the 292 and 250 GM and the 225 slant 6 in mopar. From an engineering stand point I could not tell you why. Those other engines stopped being produced over 10-15 years ago or longer. Does this tell you something? Adding EFI to it saved the 4.2/4.0 until last year. Other than the Cummis I6 diesel I6s have vanished for good.
The feedback carb system you have (when working correctly) will control the metering of fuel better than any non feedback carb ever could. It does more, under load and idle conditions to keep the 14.7:1 closer than any manual carb ever could.
We have seen folks like you try and rationalize why to tamper with fuel systems and emissions controls before.
Just a kneejerk response to looking at the hoses and tubes and electronics and having no idea how it works or worse zero idea of how to repair it.
Other than the suggestion to install a EFI (howell or Mopar)
NOT HOLLEY, there will be no improvment in economy or pollution levels by simply removing the pasta.
A properly working (fresh) cat does more to reduce tail pipe emissions than you would ever imagine.
Smog pumps, A.I.R. systems help clean far more than they rob in HP or MPG. An AC compressor, now that takes HP and MPG away.
SD
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Bigbird79
Rock Warrior
Reged: 09/23/05
Posts: 692
Loc: Connecticut
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Quote:
Other than the Cummis I6 diesel I6s have vanished for good.
I agree with pretty much everything you said superdawg, but I do believe BMW is still using the I6 quite successfully. The main reason most manufactures have left the I6 for the V6 is the dimensions of the engine. Initially there were vibration issues with most V6s, but with modern CAD software the engineers have been able to smooth out the V6s. The biggest issues I see with the “Jeep” (really AMC) I6 is it is based off an engine design that is over 50 years old. IF Jeep was to make a I6 that performed up to today’s standards it would be a complete redesign of the engine, so from manufacture’s standpoint, why start over from scratch when I can take an existing V6 design that currently exists from some other application and modify it to meet the needs of a given application.
Sean
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99 XJ Sport 2 Door, 4.0L, 5 speed, all stock. Daily Driver
79 F150 Standard Cab Short Box, 400ci, NP435, NP205, 35" SSRs
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DBL_DTY97TJ
Rock Warrior
Reged: 01/18/07
Posts: 534
Loc: Wilmington, NC
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Quote:
Initially there were vibration issues with most V6s, but with modern CAD software the engineers have been able to smooth out the V6s.
Educate me here a bit Sean. I thought the whole point of the "V" formation was to reduce vibration over the slant and straight 6's, with a bit of torque sacraficed, but with better overall performance.
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97tj, Shaved Ford 9 rear, 4:10's, New 35x12.5 BFG KM2's to test!, Warn x8000i, ARB's, Quick Disco's, Hand Throttle, & it's my DD. :)
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Brown81CJ5
Body Damage is Cool
Reged: 10/15/06
Posts: 2079
Loc: Arlington, Texas
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It's easier to balance a motor when the pistons only move up and down...in V engines the pistons are moving up, down, inward, and outward....more directional force to have to balance out.
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Gun it and run it!
1981 CJ5,258,T-176,D300,AMC 20,Dana 30,Trxus M/T 31x10.50, Rancho 5000's, GroundPounderFab front bumper, polyethylene gas tank, aluminum dash, AutoMeter gauges
What this country needs is unemployed politicians.
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BigJim
Web Wheeler
Reged: 10/07/03
Posts: 7724
Loc: Central Texas
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Perhaps the balancing would be a bit harder if it were done by hand. But in today's shops, with all the machinery available, Any engine balance should be a pieceofcake.
Also note that only the FIRST engine must be balanced. After the first one all following are built of mimicked parts with the weight of each part within tolerances to stay within the balance required..
Big JIm
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professional bovine relocation specialist
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