Forum Index
Jeep Horizons HomeLinksJeep Horizons Tech Write-upsJeep newsLand useContact

 Watched TopicsWatched Topics   FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

1976 CJ 7 with a 360 motor that surges at low rpm


 
Post new topic   Reply to topic     Forum Index -> CJ Forum
View previous topic :: View next topic  
Author Message
ironjack
Member


Joined: 20 Oct 2005

PostPosted: Thu Oct 20, 2005 7:49 am    Post subject: 1976 CJ 7 with a 360 motor that surges at low rpm Reply with quote

I just found this forum so please bear with me if this has been asked in the past. I just bought a 1976 CJ 7 that has had a 360 motor installed at some point. It has and Edlebrock manifold and a Holly carb. My problem is two fold. First, I don't have a clue as to the year of the motor, so I don't know where to start to look for specifications like the timing of the motor. I saw one article that alluded to 5 deg BTDC, but it was not much to go on. Do most of the 360's have the same timing?

The second part of my question is that my son and I don't have a clue why this motor runs so smooth at idle but seems to surge at low rpm. We can' t find any vacuum leaks, have replaced the fuel pump as precaution, put in new plugs, spark plug wires, new pcv and grommet, and still no change. Could this be a timing issue, or is it bigger - like a slipped timing chain? Any advice or help would be greatly appreciated.
Back to top
View user's profile Send private message
chappy
Member


Joined: 13 Sep 2005
Location: Indiana

PostPosted: Fri Oct 21, 2005 9:19 am    Post subject: Reply with quote

A guy on the forum told me that the holley carbs have a screen on the fuel inlet that can become plugged. You may check that. Is your high RPM's or or does the problem get worse?

I have a 86 cj7 with a 360. It soulds like the same set-up (holley truck avenger, alum intake. I have had to put on a high flow electric pump to keep up with my carb. But that effects higher rpm's. not low.
Back to top
View user's profile Send private message
ironjack
Member


Joined: 20 Oct 2005

PostPosted: Fri Oct 21, 2005 11:23 am    Post subject: Reply with quote

My problem is only at lower rpm trying to cruise slowly along. I will look for this screen this weekend. Is it where the fuel line connects to the carb? Thanks for any help on this setup.
Back to top
View user's profile Send private message
chappy
Member


Joined: 13 Sep 2005
Location: Indiana

PostPosted: Mon Oct 24, 2005 5:29 am    Post subject: Reply with quote

Mine is a new carb so I did not take mine apart. But I was told it is were the fuel inlet screws into the carb body.
Back to top
View user's profile Send private message
ironjack
Member


Joined: 20 Oct 2005

PostPosted: Mon Oct 24, 2005 11:09 am    Post subject: Reply with quote

Thanks for your replys Chappy. I did take both fuel inlets out and that is where the filters are located. Mine were really plugged with junk. I changed them, but my low end engine speed is still a problem much like a vacuum leak. I don't have any misfires like a timing problem would give you, but it definitely surges when trying to cruise in second or third gear at a constant lower rpm. Anyone else have any ideas, I would love to hear them, because this thing is giving me fits.
Back to top
View user's profile Send private message
Bockwinkle
Member


Joined: 11 Aug 2005
Location: Parsippany, NJ

PostPosted: Tue Nov 15, 2005 6:10 am    Post subject: had a similar problem Reply with quote

on my 360....surged/sputtered at idle thru mid range in each gear....culprit was worn distributor shaft that was wobbling ever so slightly but seemed to run true at higher rpms. Just something you might want to check out...don't no if it relates to your problem.
_________________
Bockwinkle
84 CJ-7
Back to top
View user's profile Send private message
tomthbomb
Member


Joined: 22 Mar 2006
Location: Deep East Texas

PostPosted: Wed Mar 22, 2006 6:09 pm    Post subject: Reply with quote

chappy wrote:

I have a 86 cj7 with a 360. It soulds like the same set-up (holley truck avenger, alum intake. I have had to put on a high flow electric pump to keep up with my carb. But that effects higher rpm's. not low.

I have the same problem with a holley truck avenger on a 401. Where did you mount the pump?
Back to top
View user's profile Send private message
AZ_Mopar_Man
Member


Joined: 17 Jun 2006

PostPosted: Sat Jun 17, 2006 11:10 am    Post subject: Reply with quote

I hope by now you got it ironed out if not then you might want to look in to a few things. To answer the question you have regarding the motor, Mopar put the casting info on the block to make it easy to find. On the side of the block you will find not only the cubic inch but the date is part of the long number as well. Second thing is on the carb. Is this a four barrel or two? if it is a two barrel you probably are not getting enough fuel from the primary idle curcuit the same issue can be happening with the four as well. Another culpret is the fact that Mopars build vacume if you don't account for this in the carb build it will cause all sorts of issues. I would suggest a power valve change to a 8.5 instead of the 6.5 it all has to duee with the idle and just off idle throttle response. another thing is jetting as these days with vacume secondary carbs having a venturi type system it will adjust the secondary side automatically the primary still needs to be done by you. depending on the plugs and ignition system as well as if the camshaft was replaced with a beafy one you may need to try several different sizes. I will look back to see if you get it cleared up.
Back to top
View user's profile Send private message
ironjack
Member


Joined: 20 Oct 2005

PostPosted: Thu Jun 22, 2006 5:06 am    Post subject: Reply with quote

Thanks for your reply AZ_Mopar_Man

I have not checked out the replys in a while, and am glad you offered some additional advice. I still am having the problem, but will try the power valve changeout. This is a four barrel carb. Will I have to order the power valve directly from Holly or is this something an auto parts place should carry? I bought the jeep with this engine in place, and with no visible changes I have to assume that everything save for the carb is stock. I recently replaced the distributor with a new stock distributor to try and alleviate the problem. It helped a little, but the surging and erratic firing still exists at a low cruising rpm.

I will check back in a day or two for your response and any more help you may offer. Thanks
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic     Forum Index -> CJ Forum All times are GMT - 8 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Visit links4jeeps.com for write-ups, forums and clubs




Jeep®, Wrangler, Cherokee, Liberty and Grand Cherokee are copyrighted and trademarked to Chrysler LLC.
jeephorizons.com is not in any way associated with or endorsed by the Chrysler LLC.
All other content is copyright Jeep Horizons 2004-2008.
Tech write-ups Links Discussion board Land use News Site Map Terms of Use

Powered by phpBB © 2001, 2005 phpBB Group