86 CJ7 no engine power - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep CJ Forum > 86 CJ7 no engine power

Jeep Wrangler Bushwacker Flat Fender Flare Sale at BaselinAlloy USA and Posi-Lok Cable Axle Disconnect Kits Dana 30 Stainless Steel Door Hinge Pins

Reply
Unread 11-07-2010, 10:42 AM   #1
chieffatboy
Registered User
1986 CJ7 
 
Join Date: Jun 2010
Location: Maxton NC
Posts: 22
86 CJ7 no engine power

I hava a 4.2 in line 6. I just put a new engine in it, changed the exhaust system, and put a new webster carbuertor on it. It had 17" wheels , all terrain, and it would not pull it. I changed the wheels to a smaller 17. It has a dana 44 rearend with a 3.31 gear ratio. I still don't have the power I want. What should I do? How can I boost the power?

chieffatboy is offline   Reply With Quote
Unread 11-07-2010, 10:50 AM   #2
Cherokeester
Registered User
1980 CJ7 
 
Join Date: Jun 2004
Location: Utah!
Posts: 710
Time for a 360 or a 401! On the best days my old 258 never did the job especially on hills and headwinds. You should probably go to 4.10's or lower but you did not mention your tire size.
__________________
1980 CJ-7 with a AMC 401, RE 4.5" Lift, 4-1 Dana 300, Holley TBI Projection, 35" Goodyear MTR's
2010 Rubicon Unlimited
1997 TJ with various enhancements
Cherokeester is offline   Reply With Quote
Unread 11-07-2010, 12:51 PM   #3
jeepcj258
Registered User
1980 CJ5 
 
Join Date: Dec 2009
Location: Vicksburg MS
Posts: 63
If you really want more power...a cam and mild head work, header, exhaust etc.... to the 4.2l but it will never feel like a built v8 (some may argue this).

I built a 4.2 years ago, with the same results... good motor but less power than I expected/wanted. I later found a 360 and built it....was fortunate enough to re-coupe a little of the $$ I had spent on the 6cyl.


Either build a new motor or sell the jeep and look for one that already is set up like you like.
jeepcj258 is offline   Reply With Quote
Unread 11-07-2010, 02:13 PM   #4
chieffatboy
Registered User
1986 CJ7 
 
Join Date: Jun 2010
Location: Maxton NC
Posts: 22
Right now I have 235/65R17 tires with a dana 20 rearend. Where can I find a 4.10?
chieffatboy is offline   Reply With Quote
Unread 11-07-2010, 06:51 PM   #5
Cherokeester
Registered User
1980 CJ7 
 
Join Date: Jun 2004
Location: Utah!
Posts: 710
Quote:
Originally Posted by chieffatboy View Post
Right now I have 235/65R17 tires with a dana 20 rearend. Where can I find a 4.10?
4.10 differential gears is what I am refering too.
__________________
1980 CJ-7 with a AMC 401, RE 4.5" Lift, 4-1 Dana 300, Holley TBI Projection, 35" Goodyear MTR's
2010 Rubicon Unlimited
1997 TJ with various enhancements
Cherokeester is offline   Reply With Quote
Unread 11-07-2010, 06:52 PM   #6
Cherokeester
Registered User
1980 CJ7 
 
Join Date: Jun 2004
Location: Utah!
Posts: 710
You did say in your first post that it had a Dana 44 rear, which do you have the AMC 20 or Dana 44?
__________________
1980 CJ-7 with a AMC 401, RE 4.5" Lift, 4-1 Dana 300, Holley TBI Projection, 35" Goodyear MTR's
2010 Rubicon Unlimited
1997 TJ with various enhancements
Cherokeester is offline   Reply With Quote
Unread 11-08-2010, 11:01 AM   #7
chieffatboy
Registered User
1986 CJ7 
 
Join Date: Jun 2010
Location: Maxton NC
Posts: 22
I have a Amc 20. Gear Ratio 3.31
chieffatboy is offline   Reply With Quote
Unread 11-08-2010, 02:18 PM   #8
CJay7
Registered User
1985 CJ7 
 
Join Date: Oct 2001
Location: IN
Posts: 131
Is it lacking power for your liking or is it down on power for a 258? If you want to get good power for a 258 there are options to look in to. If you want good power in general then you will most likely need a V8. You have to remember that these engines stock put out around 115 HP give or take depending on the year, however, torque was over 200 ft. lbs and at a nice low RPM. A nicely modified 258 can be fun with decent power and torque but you are not going to get whiplash from hitting the gas pedal. A better carb and exhaust will wake it up a bit and give you some power you can feel but it isn't going to be a huge increase, even a 20% increase over stock is only going to get you a little over 20 HP.

Take a look at your ignition system, there are many options that will give you better performance and driveability. TFI or HEI upgrades are common as well as MSD upgrades. Make sure all the supporting systems like fuel delivery and spark are operating correctly and you are getting the most out of those. If you can't find the power you need there, you may need to dig into the engine with a cam or head work.

Plan out what it is you want and go from there. If you want V8 power than a V8 is what you need. If you want a nicely powered 258 than start modifying with an idea of where you want to end up at to make sure everything works well together.

My engine is decently modified and runs strong. Compared to a stock 258 it feels like a V8, compared to an actual modern V8 it feels like a six cylinder. Hope that makes sense.

Good Luck
__________________
'85 CJ-7 - 258 bored .030 w/ mid level cam, 4.0 head, Clifford intake and header, Weber 38, TFI w/ MSD 6, Black Diamond 3" lift, Daystar 1/2" lift shackles, 33x12.5 Goodyear Duratracs with stock 3.31 gears.
CJay7 is offline   Reply With Quote
Reply
Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.