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81azcj7 05-17-2013 08:18 PM

Installing Howell / 4.0 head swap w/summit cdi
I'm installing my 4.0 head and howell TBI this weekend. I've been reading up on the many threads on this for the last few months and finally have the time to get it done. I had already done the rush, nutter upgrades a while back. Then I installed my summit cdi a couple of months ago. One question I have that I'm not to sure on is how the summit cdi will match up with the howell tbi. Some threads say I will need a tach filter and others say it's not needed. Anyone have some helpfull input before I get started. Thanks

SLO_Ken 05-17-2013 08:40 PM

Does your Summit CDI have a tach wire? If so, run that wire directly to pin B5 on the Howell computer. See this thread for more details...

81azcj7 05-17-2013 09:01 PM

Yes, it has a tach wire, thanks I'll check out that thread.

81azcj7 05-26-2013 08:28 PM

I've got a good start on my 4.0 head swap and howell tbi. This has turned into a pretty interesting project so I thought I would make a few notes and take pictures along the way just in case anyone else has the same idea of doing this to their jeep.

Parts so far in getting started:
#7120 4.0 rebuilt head - ebay
4 centering washers (P/N 17-2001 Centering Washers ) - Clifford Performance
4.0 exhaust manifold - ebay
4.0 valve cover - salvage yard
4.0 valve rockers and bolts - salvage yard
4.0 valve lifter push rods - (p/n rp-3180 from sealed power- ACTUAL LGTH (Inch) 9.68) orielly's auto parts
4.0 lower exhaust section (mounts to exhaust manifold) - salvage yard
JB weld - autozone
1992 4.0 head gasket kit - autozone
1 bag of bio degradeable packing peanuts - U-Haul
1 pint of denatured alchohol - ace hardware
1 pack razor blades - ace hardware
Howell Throttle Body Fuel Injection - off road (used) w/ aluminum air filter intake - Ebay
1 flat bar stock 1/4" - Home depot
4 - 3/8 16 Bottom 3/8 24 top automotive studs, lock washers, 3/8 24 hd grade nuts - ace hardware
cleaning rags - autozone
brake cleaner - autozone
small parts stainless steel cleaning brush - autozone
1 roll 1" blue painters tape - ace hardware
permatex high tempreture thread sealant - autozone
2" hole saw - ace hardware

81azcj7 05-26-2013 08:34 PM

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This is what I'm starting with, a 1981 258 4.2 with ca smog, it has a mc2150 carb, summit cdi, nuttered, rushed.

81azcj7 05-26-2013 09:07 PM

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I've stuffed as much packing peanuts into the water jackets as I could, leaving about 1/2" to 3/4" of space for the jb weld. I then mixed up and filled in the water jackets that weren't needed with the jb weld. I took some blue painters tape and taped over the jb filled jackets and set the head back in the normal position so there wouldn't be any seepage into the head. I waited a few hours and removed the tape, I then took a razor blade and shaved the jb weld off as evenly I could. It came off nicely with a little bit of effort, I then took some denatured alcohol and cleaned up the head of any of the excess jb weld.

81azcj7 05-26-2013 09:34 PM

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I've taken the advice that I've read from others that have done the 4.0 head swap and decided to put the intake and exhaust manifold on the head before I installed it. I'm using the stock intake manifold, I've had to carefully dent the exhaust manifold and grind a little bit of the intake manifold to make it fit. I decided to make my own washers since the originals wouldn't work. I made them out of 1/4" flat bar stock. I've also used 2" automotive studs replacing the top 4 original mounting bolts.

81azcj7 06-02-2013 11:34 PM

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I've prepped the block for re-installing the head, cleaning the top off with a razor blade then taking a 7/16 -14 tap and running it up and down several times until it runs smoothly. I also make sure there is no left over oil or debris in the bolt holes with my shop vac, making sure the surface is clean and dry.

81azcj7 06-02-2013 11:48 PM

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I've taken some time to get a start on my new exhaust made from the yj exhaust I picked up at the salvage yard. I like the way the yj exhaust bolts together between the front and rear pieces instead of using clamps like my old exhaust did. I hope to elimenate any exhaust leaks in that area.

FamousJerry 06-03-2013 09:37 AM

nice work so far, cant wait to see it done and hear how much of a difference it made.

81azcj7 07-11-2013 11:43 PM

Thanks... it's taking more time and money than I thought it would.

81azcj7 07-11-2013 11:58 PM

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Since I have the head and exhaust off, I decided to take care of any other needed repairs.

81azcj7 07-12-2013 12:28 AM

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When I put the new #7120 4.0 head on I found that the passenger side bolts were about 3/4 inch to long for the head, I had read this in other posts so I wasn't too suprised. I went down to the auto supply shop but they didn't have any, also, I went down to the local ace hardware they had some hardened bolts, I had read where some guys had used grade 8 bolts and didn't have any problems. But, just to be safe I ordered some new arp head bolts from and also some centering washers from clifford performance since my 258 head had used the 7/16 head bolts and the #7120 head had used 1/2 bolts.

81azcj7 07-12-2013 01:17 AM

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I followed the tightening sequence from the haynes manuel (be sure to use the thread sealant on bolt #11, it goes into the water jacket). I used the torque values from the invoice. "70 ft pounds done in 30 55 then 70 with arp lube included in the kit". I had used a click style torque wrench before but broke a head bolt with it when it failed, so I am using my ever faithfull 35 year old beam style torque wrench.

81azcj7 07-12-2013 01:37 AM

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I'm using all of the rocker arms and carrier retaining bolts from my #7120 4.0 donor at the salvage yard. I was lucky to find it all still intact. The lifter push rods I bought new from orielly's. (p/n rp-3180 from sealed power- ACTUAL LGTH (Inch) 9.68). The preload came out perfect. I tried to use all my rocker arms, bolts and push rods from the 4.2 but there wasn't enough preload on the lifter and valves. I'm using the champion rc12lyc spark plugs listed for the 1992 4.0 head, gap set at .035

The time now is 09:50 AM.

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