1987 Jeep J20 build with 454 Big Block

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JeepManiac
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1987 Jeep J20 build with 454 Big Block

Post by JeepManiac » Mon Apr 08, 2019 7:33 pm

Here is my baby!
Image

So I have received some assistance on here and now my build is truly starting. I love this truck and the compliments I get. I have had quite a few people ask if I'd sell it. And I have even looked around online and there are not many J20's around for sale.

I had a 12V cummins for her, NV4500 and 241. I traded that to a local gentleman for his 2000 K3500 with vortec 454. I took the engine, 4L80E and Borg warner transfer case (4401 I believe)

I tore the big block down to a shortblock and it looks good. 100K miles, but I'm going to run it. L29 vortec 454's are all 4 bolt mains and factory roller cams. Chris Straub cut me a cam and in a similar combo he makes 430 hp/553 lb ft of TQ at 3200 rpm. I have acquired most of my parts recently and spent close to 8K. Part of that expense is living in Alaska and getting burned on shipping. I had planned to do this slowly and then the stock 360 lost oil pressure and died hard. So now I'm moving quickly to get it running and back to DD duty.

I felt like starting this thread tonight, but will begin updating it with pictures later. Today I built my seat brackets for my new corbeau seats. Going to run these in tan https://corbeau.com/reclining-seats/sport-seat.html

For the trans shifter I'm running a RAD designs winters shifter. Makes installing an electronic trans a breeze and it's a pleasure to drive for me personally. I have one in my "race jeep" XJ with the AW4. The engine will be carb'd and will sort of have all the fixings. Planning for power from idle to 5500. So the whole engine build is geared toward that. Long tube headers 1.75" primaries, performer intake etc. Heads are mostly stock L29 vortec heads, milled and gasket matched by me with a little cleanup behind the valves. Valves have been cleaned and lapped. With my .030 head gasket I'll have a 9.8:1 static compression ratio.

You should see the parts piling up in my garage! Got motor mounts from Novak, so on and so on

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derf
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Re: 1987 Jeep J20 build with 454 Big Block

Post by derf » Mon Apr 08, 2019 10:34 pm

Very interested in this build as I'm beginning the plan for a big block swap in my J10.


rocklaurence
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Re: 1987 Jeep J20 build with 454 Big Block

Post by rocklaurence » Tue Apr 09, 2019 6:27 am

That truck will be Fun and Thirsty


ScramblerCJ8
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Re: 1987 Jeep J20 build with 454 Big Block

Post by ScramblerCJ8 » Tue Apr 09, 2019 9:21 am

Awesome J20 project, I will be following your build so as to get ideas for my 66 j200.
Are you able to get it done in that huge hangar?


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JeepManiac
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Re: 1987 Jeep J20 build with 454 Big Block

Post by JeepManiac » Tue Apr 09, 2019 9:42 am

I found a guy a while back selling a J20 with a BBC in it already. I got these pics from him.
Image

Image

I was hungry for higher HP, but my budget and cylinder heads would not allow it haha. I'll take that TQ though. Good thing it's a dana 60 rear.

I can only do very limited things in my hangar. But we have a nice wash rack for our birds and we're allowed to wash our vehicles on the weekend. It's perfect because it's filtered water, must be a PH between 6-8 and a temp of 120°-140°. Your car won't even water spot if you don't dry it off. We had the same thing in San Diego, you could wash your car/truck and let the sun dry it with no water spots

I agree she's going to be thirsty! I already found the fuel tank to be a bit small with the stock 360. 18 gallons or so?? Anyone have "cheap" simple ways to upgrade somehow. Whether adding another tank or replacing the stock tank with a bigger one? I though about using a hotrod style spun aluminum fuel tank mounted in the bed connected to the main tank. Then I would just fill the system by filling the top tank in the bed.

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Stuka
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Re: 1987 Jeep J20 build with 454 Big Block

Post by Stuka » Tue Apr 09, 2019 10:57 am

Looks like that guy mounted the engine pretty low. Lower than the stock AMC anyway.

For a fuel tank, you can add a tank into the spare tire area using a tank from a suburban or the like. Much larger capacity.
1981 J10 AMC 258 with HEI and Weber 32/36 DGEV Carb, T176, NP208, D44/M23 with 4.56 gears and Detroit Locker, 6" lift, 33x12.50 Cooper STT's, BJ's Offroad Rear Dozer Bumper.
2017 JKU Rubicon Lifted and stuff
Pevious Jeeps: 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ


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JeepManiac
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Re: 1987 Jeep J20 build with 454 Big Block

Post by JeepManiac » Tue Apr 09, 2019 12:00 pm

I think I've seen some of those installs online of those style tanks.

I agree about how low the engine is. I like it. The dumb ass air cleaner that was on the 360, the PO put on, hit the damn hood and dented it. The 1" spacer under the carb isn't helping either. With the little bit of suspension lift I have I plan to attempt to sit my big block down fairly low as well. I don't want to have to use a drop base air cleaner or anything.

My truck has a nice stereo I installed and when I tore out the interior to clean up and repaint the floor I laid down dynamat in place of the wool insulation stuff. I'm trying to make it a nice fairly quiet daily driver. So on that note the induction noise from the 360 and open air cleaner was pretty prominent. So I'm running this and going to route the hoses forward to keep the induction noise down https://www.spectreperformance.com/sear ... x?prod=728

I then bought a dual 3" in and 3" out dynomax X flow muffler https://www.summitracing.com/parts/wlk-17554. It is a muffler and X pipe together. After that I'm running a cherry bomb on each pipe (true duals) to make it quiet. With 3" pipes and performance mufflers it will still sound great.....I think. But I'm not trying to build a loud weekend cruiser. I want to drive it to work everyday. I will also be driving it from Alaska to my next duty station. Upwards of 5000 miles.


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JeepManiac
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Re: 1987 Jeep J20 build with 454 Big Block

Post by JeepManiac » Tue Apr 09, 2019 12:10 pm

Here's something I've thought about, but won't be able to afford until later. My truck seems to have come with maybe 2" or as much as a 4" lift. Still SUA up front and stock shackles in the rear. It was a pretty basic kit. Looks like skyjacker or rancho. Anyway, stock rear leafs with about a 2" block, and replacement lift springs up front. It doesn't ride very nice. Any proven combos out there that ride as good or better than stock? This thing will pull average truck duties, but not wheeling. I have my race jeep for that. I also wish my front shackle angle was a little better.

Truck came with 33x12.50's when I bought it and it did not rub or anything. I swapped those out for 265/75R16's


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JeepManiac
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Re: 1987 Jeep J20 build with 454 Big Block

Post by JeepManiac » Tue Apr 09, 2019 12:15 pm

Here's another question. I wonder if I'll be able to somehow adapt the sensors on the BB to work with and be able to use my stock gauge cluster.

Other gauges I have and will be running are AFR, fuel pressure, vacuum and a tachometer.

One I think will be tricky is the speedometer. I got my drivetrain from a 2000 K3500 and I'm sure the speedo was all electronic rather than a plastic gear like in old tcases. I do have the option of rebuilding and running my friends NP241 he has laying around that was from a '92 chevy, but the borg warner I have has a fixed output rather than slip yoke, and is quite a stout tcase. I absolutely plan on 4wd launches.

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derf
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Re: 1987 Jeep J20 build with 454 Big Block

Post by derf » Tue Apr 09, 2019 12:37 pm

As far as regular gauges:

oil pressure is oil pressure. The sender attaches to a standard NPT port. You might have to use an NPT adapter fitting if they're not the same size but maybe not. Getting the wire over to the gauge might require a splice for a longer wire. Or just shortening it.

Temp is temp as well. It's easy to find a port in the manifold for a temp sender.

Fuel level has nothing to do with the engine per se. The ammeter/voltmeter will work the same as well.

Speedo will be a challenge. It's possible to drive a mechanical speedo from an electric source but that's not cheap. Using the 241 gives you the option of running a mechanical sender and makes the speedometer work much easier. One option is to find an old NP205 and bolt it up. That would be stronger than the 241 and would handle 454 with 4WD launches but also have a mechanical speedometer.


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JeepManiac
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Re: 1987 Jeep J20 build with 454 Big Block

Post by JeepManiac » Wed Apr 10, 2019 5:33 pm

derf wrote:As far as regular gauges:

oil pressure is oil pressure. The sender attaches to a standard NPT port. You might have to use an NPT adapter fitting if they're not the same size but maybe not. Getting the wire over to the gauge might require a splice for a longer wire. Or just shortening it.

Temp is temp as well. It's easy to find a port in the manifold for a temp sender.

Fuel level has nothing to do with the engine per se. The ammeter/voltmeter will work the same as well.

Speedo will be a challenge. It's possible to drive a mechanical speedo from an electric source but that's not cheap. Using the 241 gives you the option of running a mechanical sender and makes the speedometer work much easier. One option is to find an old NP205 and bolt it up. That would be stronger than the 241 and would handle 454 with 4WD launches but also have a mechanical speedometer.
This was all very much in line with what I was thinking and assuming. I plan to buy sensors at NAPA for an 80's truck with a carb'd 454. Should work for coolant temp, oil pressure, volts, fuel should remain unaffected, and I'll probably have to figure out what to do with my speedo


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JeepManiac
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Re: 1987 Jeep J20 build with 454 Big Block

Post by JeepManiac » Sun May 05, 2019 7:22 pm

ALright, got some questions related to this project.

I want it to ride nice, and that involves trying to coerce 10" of suspension travel out of her (minimum). I wonder if the BJ's 2.5" lift springs made by deaver + a longer shackle could result in 10" of total travel up front. I'll most likely ditch my previous idea of air shocks and run custom valved fox 2.0's (remote res) from Accutune Offroad

II have the spectre air intake kit 728 https://www.spectreperformance.com/sear ... x?prod=728

Anyone run an intake like that, with the hoses running up to the round openings inboard of the headlights on both sides (left overs from Rhino grille).


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JeepManiac
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Re: 1987 Jeep J20 build with 454 Big Block

Post by JeepManiac » Sat May 25, 2019 9:36 pm

Here's my big block. Waiting on taller valve covers to clear my roller rockers

Image

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