401 swap into my CJ7

After playing with the choke and never getting it to work right, I decided to just switch to a manual choke. I bought a manual choke conversion kit from Holley for my 670 Truck avenger and installed it, wasn't hard, but instructions were a little vague.

Before, with the electric choke, to get 750 rpm and 8 DBTDC, I had to back the idle screw all the way out. Now it seems that I have the exact opposite problem. Idle screw all the way in and it will only idle around 300 rpm, sounds like an old tractor. I played with the timing and got it up to 500 rpm at 18 DBTDC, decided to put the timing back where it was. If the throttle is opened a little, it idles perfectly at 700 to 800 rpm, but that's only while holding the throttle. I reckon I could adjust the throttle linkage a little to hold it open, but that doesn't seem like the right way to fix it. Anyone got any ideas whats going on here?
 
Don't think it matters, but I also changed to a 9.5 power valve and changed the see through bowl sight glasses that broke to a solid screw type at the same time, but don't think that would have anything to do with it.
 
New symptoms - I pulled the primary sight glass plug, could not see any fuel. I ran the adjustment way out and ran the engine, still could not see any fuel. I pulled the entire carb and found that the secondary bowl was full, and the primary bowl had almost nothing. I pulled off the front bowl and cleaned the bowl float adjustment to make sure the spring and needle were not clogged. I then set the float back to parallel dry like the instructions say to.

Next thing I thought was fuel pressure. I read that a Holley likes 4 to 7 PSI incoming. I unhooked the fuel line from the carb and hooked up my HF vacuum/fuel pressure gauge. With just the starter turning it over, kinda slowly, it would bounce to 2 PSI then down to 0, then back up to 2. I re-installed carb, primed it and it fired right up, went to 1000 rpm for about 5 seconds, then back down to 300 rpm and still no fuel seen in the primary bowl.

I pulled the fuel line from the carb again and hooked up the pressure gauge, poured a little fuel down the carb, just enough for it to run a few seconds, and fired it up, it ran for a few seconds, the fuel pressure read 3 PSI.

I then pulled the fuel line from the fuel filter, return style, oriented so that the return line is at the 12 o'clock position like its suppose to be. Hooked up the fuel pressure gauge, poured a little more fuel in the carb and fired it up. It ran for a few seconds, found that I have 7.5 PSI going into the filter.

So I have 7.5 PSI going into the filter and only 3 PSI coming out of it and going to the carb, so I am assuming that I might need a new fuel filter, this one is brand new, has less than 200 miles on it. Anyone know of anything else that could cause the low fuel pressure? Something wrong with the return system perhaps?
 
I'm not sure my answer will help but I'll tell ya what I'd do.

First, I'd change the filter and see what happens. It could be the filter or it could actually be the fuel.

You could put another carb on it and see if it does the same thing. If so, then it's def. the fuel system. If not, then it's prob the carb. I'd check the idler scrrew??? I'm not too good with carbs. But I seriously hope you figure it out.

BTW, that video is awesome. Thanks.
 
I'm glad that video helped you.

I don't have another carb to put on it and try, but a new filter is cheap, will probably try that first. The idle screw is all the way in, the idle mixture screws are 1 1/2 turns out, should run as far as I can tell. The primary bowl should be full up to the bottom of the sight glass, so as far as I can tell, its not getting enough fuel. But I'm not good with fuel systems either, I don't know how much pressure should be coming out of the pump, or how much the return style filter should drop that pressure.
 
So I went out and tinkered with it some more this morning. I noticed that when it is running, it is blowing out blue smoke and stinks, then it started blowing fluid out of the exhaust......gas......I think maybe this thing is getting too much fuel, the primary bowl isn't filling because its dumping into the engine and flooding it. So I pulled the front bowl and found some trash in the power valve. I put the other power valve back in, put it all together, thinking it'll run for sure now, I found the problem......I was wrong, still runs like crap, still no fuel in the front bowl :confused:...... What else could it be???????????
 
I took this directly off thier page. thier is a link in the paragraph below to How-To tune for Holley's. Maybe that'll help.

"Also, make sure you're not exposing too much of the 'idle transfer slot' at idle (primary throttle blade adjustment). Common problem. If so, you'll need to open the secondary blades a little bit, in order to close the primary blades (without altering the idle speed). Holley has a good video pertaining to this: http://www.holleytv.com/featured_landing.php?reset=true (Click "carb tuning" & "sec idle speed") View all their carb tuning videos!"
 
well, I don't know what I did, but I put it all back together, and it fired up and ran like a champ, except now I'm back to the old problem, it won't idle below about 900 rpm unless i manually pull the throttle closed a little. I ran the idle mixture screws all the way in while it was running, it slowed down but did not cut off, this is a symptom of a blow power valve right?

Thanks cricket, I'll take a look at that
 
So I double checked the timing, pulled the advance line and plugged it, set the timing to 8 DBTDC, still idling around 900 rpm, When I re-hooked the advance line back to the dizzy, it jumped to 1500 rpm and about 28 DBTDC, so it looks like I'm pulling vacuum on the ported vacuum at idle, which means that I'm not really at idle and the throttle plates are open, I think, and I don't know why. I really starting to think I may need to just go ahead and take this thing to a professional.

going to check out cricket's link and see what I can find there.
 
Have you tried any adjustments with the throttle linkage un hooked, I have found that the bracket holding the accelarator cable needs to be modified so that it has some front to back adjustment because it will not allow the throttle to completely close causing the idle ot remain high. Especially with aftermarket intakes and 4bbl carbs.
This is ofcourse assuming that you are using the stock bracket for the accelerator cable, I cannot tell for sure in the pictures.
 
Did I figure it out - No. Is it working great now - Yes. I took it apart and put it back together several times, I reckon one time I did it just right and it started working great, and I don't know why. That carb was on my 304, now on the 401, for the first time since I've had the jeep, I can adjust the idle with the screw like your suppose to, the choke is opening all the way and the primaries are closing all the way.

I set the float levels, set the idle mixture screws to where I had the highest vacuum - around 1 1/4 turns out and 17 inHG, set the timing to 8 DBTDC and the idle to 750 rpms and it runs like a champ. It has a little hesitation if you stomp it, may play with the pump shot some later, but for the most part, it is running strong.

Cooling system seems to be working good, getting to about 200 degrees and staying there. I am still a little concerned about my oil pressure, it sits around 12 PSI now at idle, about 30 or so cruising when it is hot, which is a little less than when I first fired it up. I may switch to a 40wt oil and see if I can bring it up some. I'm not sure why the pressure is lower now, I just hope it didn't loose some bearing clearance when it over heated on me one time when the electric fan quit working.
 
amcjeepman said:
Have you tried any adjustments with the throttle linkage un hooked, I have found that the bracket holding the accelarator cable needs to be modified so that it has some front to back adjustment because it will not allow the throttle to completely close causing the idle ot remain high. Especially with aftermarket intakes and 4bbl carbs.
This is ofcourse assuming that you are using the stock bracket for the accelerator cable, I cannot tell for sure in the pictures.
Click to expand...

I am using the stock bracket on the after market intake, and that was part of the problem at one point, but not all of it. Once I got everything set on the carb, I adjusted the bracket to where there was very little play in the throttle cable, so it would have the most throw as possible. I then set the cable for my hand throttle and choke cable, final choke adjustment will have to wait until it cools off some.
 
TKFireman said:
I am still a little concerned about my oil pressure, it sits around 12 PSI now at idle, about 30 or so cruising when it is hot, which is a little less than when I first fired it up. I may switch to a 40wt oil and see if I can bring it up some. I'm not sure why the pressure is lower now, I just hope it didn't loose some bearing clearance when it over heated on me one time when the electric fan quit working.
Click to expand...

Its more common for the oil pump gear housing (than loose bearing clearance) to distort when an AMC is overheated and open up the clearance between the gear and housing causing lower oil psi. Ive talked to alot of guys who run 20w50 oil to help with psi. I am one of them. hot idle is about 20 and cruising is between 30 and 40.
 
I'm thinking about changing the oil this weekend anyway. I used to run the Rotella 15w-40 in the 304 and got 20 psi at idle. I'm planning on going with a 40wt, but is there any disadvantages of going with 50wt? Is there a brand of oil or oil additive ya'll recommend? Any brands of filters to go with or to stay away from?

I currently have a stock 304 size oil filter on it, I bought one for the 401, but it was too big and hit the motor mount, is there a bigger filter that fits in the CJ frame, say from a 360 in some vehicle?
 
No disadvantages Ive seen running the 50wt. Has worked fine for me the year Ive used it. Definatly get a WIX filter. You can order a 360 filter from a late 70s model wagoneer and it will fit with the CJ frame/motor mount. O'reilys sales WIX brand and I belive NAPA Gold filters are made by WIX. Whatever you do do not use a frame, they have a card board anti-drain back flap that if it comes apart (common) will cause the bypass vavle to stick open and loose psi, if you dont have a bypass plug installed.
 
Thanks CJ5walt, I do not have a bypass plug, and their is an O'Reilley's not far from here, I'll check them out, usually go to Advance Auto because its close to the house and a couple of jeep guys work there. Whats special about the WIX filter? Running a Puralator now.
 
From what ive read and researche dthy are the highest quality built filter. And alot of it comes back to the anti-drainback flap (i belive thats the correct name) WIX uses a rubber one (cant come apart). If you take a look around on some AMC forums and even the BullTear forum there are pages of threads discussing just oil filters and pages more talking about the oiling systems.

I also like the WIX becasue they are made in NC, gotta support the local guys!!!
 
I went ahead and changed the oil today with 200 miles on her. The old oil looked good, no shiny specs,looked clean. Replaced it with Pennzoil 10w-40, WIX oil filter and STP oil additive. Idling in the driveway, the oil pressure looked to be higher after it warmed up, but I'll wait until I take it for good drive to see if the oil pressure stays good.

I got an oil filter for a '78 waggy with 360. This filter had the larger diameter of the 401 filter, but the shorter length of the 304 filter and fit perfect.
 
Looks good man. You get the initial stumble start off fixed yet?

Sent from my SCH-I500 using Tapatalk
 
I haven't played with the stumble yet, I have to do some more reading, I'm very much a newbie at playing with carbs, but from what I've read so far, It has to do with the pump shot that is activated by a cam on the throttle linkage, right now I'm just happy to be driving it and getting planted in the seat every time I give it some gas.

I did drive it to work today around 8 to 10 miles, when I got to work it was idling with a little over 20 psi oil pressure, so the 40wt definitely brought the pressure up a good bit, I'm happy with 20 psi.
 
Drove it a ways today, short trip, got some fuel, no problems, went to pick up take-out for the family, no issues, got home, cut the key off, and it stumbled and sounded horrible, has never done that before, almost like it hit a lick or two after turning the key off, what could cause this?
 
Help!!! no oil pressure

It has been running great, oil pressure has been 60 psi cold 20 psi hot consistently since switching to 40 wt oil. A few days ago I fired it up, no oil pressure. Checked the oil level, its full. I unhooked the line from the back of the mechanical gauge and fired it up - nothing. I unhooked the line from the side of the block, probably not my smartest idea, and made an oily mess in the garage.

I then went to advanced auto and bought a copper line to replace the plastic one, thinking the plastic line may have clogged or even melted itself shut. While installing it I crimped the copper line and ruined it, so went back to the store and got another plastic line, got it installed to the block, fired up the engine and got a trickle of oil out of the line at idle. Hooked the line back up to the gauge - nothing. I hooked the line up to an old gauge I had laying around and got about 3 psi at idle, hit the throttle momentarily and it went up to about 20 psi. So I had two gauges, one reading nothing, one reading very low so I thought it could be the gauge, I went and bought another mechanical gauge to try, read same as the spare I had.

I pulled the oil filter, oil filter bypass gate was shut, it moved freely when pushed by a screw driver closing by itself. I cut the filter open, didn't see any debris or shiny specs in there. I unscrewed the bolt holding the pressure bypass and removed the spring. The plunger seemed to be all the way down and I couldn't get it to move, very little access to it to get it to come out of the bore. I re-installed everything, new oil filter, same result.

Where do I go from here? Pull the oil pump cover and check the pump? Drop the oil pan and check the pick-up? I appreciate any suggestions
 
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