Motor swap + more

1941 - 1945, MB, GPW modifications, sugestions, and ideas, official MWO's and unofficial WWII field mods NO EBAY or COMMERCIAL SALES.
scheinerj
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Motor swap + more

Post by scheinerj » Sun Sep 17, 2017 12:29 pm

Hi, I am currently in beginning stages of building my second military vehicle. My first was an MB, second is a 42 GPW.

I want to go a different route with this one and make it more of a rat rod style, slightly lower than stock.

I am fairly new at restoring cars so I will need some guidance.

Motor - I know of some people that have turbod the F head (which I have a spare of, and it turns over but a rebuild will he needed). Would a small block chevy fit? Would a v8 work? What other options are feasible?

As far as the frame goes, I currently have it stripped and primed. Will I need to make any additions to strengthen it?

For suspension can I utilize the original leaf springs or will I have to modify the suspension and go a different route?

Does anyone know of any other builds similar to one I am thinking of ?

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Re: Motor swap + more

Post by Bart1015 » Sun Sep 17, 2017 9:09 pm

Vortec V6 is the easiest. Pull it from an Astro van (fuel injected with 200hp), including the electric control unit. The bell housing is the same bolt pattern as the 350. Advance Adapters should have the required adapter to a T90, or Turbo350 transmission. Put the electronic control module in a 1st aid box and mount it under the dash like the late WW2 jeeps have.

The vortex is a 350 V8 with two cylinders cut off. Its a short engine that will require less cutting of the grille and firewall.

This is a very common swap in a CJ and this is the way I would go if I were to re-power my jeep. I would also have a good radiator shop address the cooling end of things.

Brett
1942 Matching numbers GPW, capstan winch, BC-659
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Re: Motor swap + more

Post by Chuck Lutz » Mon Sep 18, 2017 5:23 pm

There was a good web post about trying to make a jet plane out of a Sopwith Camel...if you get the similarity. The guy had a souped up engine and driveline, big tires and had modified a tub on an original jeep chassis...except by then he twisted up the frame and cracked it so he needed a tube-welded frame to take the Rubicon or wherever he was going...then he needed a complete roll-over enclosure attached to the frame, not the tub.

Bottom line was...by the end of the exercise he had ruined a rebuildable WWII jeep to satisfy his fantasy and after all was said and done...he could have started with a CJ tub for a lot less and let some G503er purchase the MB and restore it.

So....while a Buick V6 was always the easy engine swap, you can probably stuff a blown and injected Chrysler Hemi in there if you wanted to but the question would remain....WHY?

You will destroy the frame or crack it...the suspension isn't really up to the kind of horsepower I think you are looking for either...

Why not find a cheap CJ tub, build your own frame, get some axles & suspension from a modern vehicle with proper gearing and go that route?
Chuck Lutz

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GPW 108552 4/17/43 Louisville, KY. USA 20371278 (DOD est./Tom W.)
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Re: Motor swap + more

Post by Bart1015 » Mon Sep 18, 2017 10:04 pm

"Why not find a cheap CJ tub, build your own frame, get some axles & suspension from a modern vehicle with proper gearing and go that route?"

Because it's his jeep. With some simple reiinforcements, the frame would be fine. Yes, I have personal experience to justify this.

The axels/brakes will need some upgrading.
1942 Matching numbers GPW, capstan winch, BC-659
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Re: Motor swap + more

Post by Chuck Lutz » Tue Sep 19, 2017 9:33 am

My point is...why tear up a restorable G503 to make a rock crawler when the G503 would provide funds to build a better vehicle in the long run?

I cringe when they take a WWII duck and turn it into a bay cruise vehicle in the same way or someone posts a pic of a WWII jeep one the gee from Ebay or some place that was turned into a rock crawler...its messing up a restorable WWII vehicle to make it into something it isn't designed to be.

But you are right, it is his WWII jeep to destroy.
Chuck Lutz

GPW 17963 4/24/42 Chester, PA. USA 20113473 (USA est./Tom W.)
GPW 108552 4/17/43 Louisville, KY. USA 20371278 (DOD est./Tom W.)
Bantam T3 4582 10/29/42 USA 0173499 (est.)


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Re: Motor swap + more

Post by scheinerj » Tue Sep 19, 2017 1:13 pm

I had a feeling I was going to get this response.

I am not turning it into a rock crawler. I just enjoy the thought of customizing it a little more. I already have restored an MB so I wanted to go a different route for my second one.

I don't plan on ripping the whole thing apart. I plan on keeping it looking similar to what it was originally, just with a beefier engine, original axles, 10 inch brakes, original leaf suspension, and stock steering.

One of the thoughts of going a different route was because the majority of places I travel to in CT, require highway driving and merging with the L134 is not the easiest thing especially with CT drivers who do not pay attention.

I want to be similar, but not the same to the original.

As far as strengthening the frame...what areas should I focus on?

I was planning on putting a SBC 195 HP in it.

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Re: Motor swap + more

Post by Chuck Lutz » Tue Sep 19, 2017 5:16 pm

Put in overdrive so you don't get run over by semi's on the highway.

The frames are lightweight to try to make the gov't weight restrictions so they flex in the middle...that is where you need to look for existing cracks as it is.
Chuck Lutz

GPW 17963 4/24/42 Chester, PA. USA 20113473 (USA est./Tom W.)
GPW 108552 4/17/43 Louisville, KY. USA 20371278 (DOD est./Tom W.)
Bantam T3 4582 10/29/42 USA 0173499 (est.)

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Michael O.
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Re: Motor swap + more

Post by Michael O. » Tue Sep 19, 2017 10:33 pm

Why not just buy a new reproduction tub and frame as the base of your project? That way, you can sell your original GPW to someone who really wants to restore and preserve it as it was meant to be (original).
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Re: Motor swap + more

Post by artificer » Wed Sep 20, 2017 2:42 am

This response always happens when so called purists try to get involved in the modification section.
A section meant to help not hinder or ridicule.
The Mustang /Pinto 2.3 litre, I have heard, is a good candidate & I know the Ford Falcon 6 up to 220 in3. with mod of front cross member.

Do what you like but remember the brakes on the original vehicle are totally unsuited to engine/power upgrades.
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Re: Motor swap + more

Post by Bart1015 » Wed Sep 20, 2017 11:26 am

I send the OP a PM.

Artificer, I also sent it to you by mistake.

Brett
1942 Matching numbers GPW, capstan winch, BC-659
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Re: Motor swap + more

Post by Ralph » Wed Sep 20, 2017 3:43 pm

Scheinerj
Since you've asked this forum for advice,here is mine.GPW unsuited in every way for contemplating the torque of a small block Chevy,or any V8 for that matter.The frame would have to be strengthened everywhere.The springs,same deal...
Sure it's yours.IMO,it's more unsafe than unsuited but it's both really...
Ralph

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Re: Motor swap + more

Post by Cyclefreak13 » Fri Sep 22, 2017 9:50 am

Why not do something a little different like a flathead ford v8. They don't make a ton of power (unless you really hop them up) so I don't think much frame strengthening would be needed. Advanced adapters makes a kit to bolt up to a t90. It has been done before I have seen some CJs with them, but can't find the pictures right now.
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Re: Motor swap + more

Post by Marty, SoCal » Fri Sep 22, 2017 1:58 pm

I had a 283 in my '61 CJ-5, ran like a scalded ape! The V8 swap was already done (poorly) when I bought it.

Mods needed:
Cut out front cross member for clearance to the balancer on the V8.

Cut off stock motor mounts, install kit mounts, reinforce frame where they mount to it.

Gut the grille shell, the radiator will need to fit flush with the inside of the grille stamping.

Relocate steering gear to the front of the frame (Saginaw)

Add a second gas tank to the rear after removing the pintle hook reinforcing members., the V8 burns a lot of fuel.

Full float kit on the stock '61 Dana 44, the stock axle shaft broke on me.

11" drums, worked great until they got wet, I would at least put discs on the front.

Box in the whole frame. It ended up cracking bad on mine where the rear springs mount to the frame and the rear spring, front hanger, tore off the frame on me, luckily while going very slow off road.

A late CJ-5 or CJ-7 might be a better candidate for a V8 as most of the mods needed are already done.

I would use a big modern EFI four cylinder, maybe even a 2.5l from a YJ or TJ jeep, lots for sale cheap when people pull them for V8 swaps. Same bolt pattern as a Front Wheel Drive GM. I'd use a T-176 four speed and a Dana 300 with late narrow trac CJ axles. They have 125 horsepower.
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Re: Motor swap + more

Post by pgcf » Sun Sep 24, 2017 6:22 pm

It's your jeep so do what you want but I agree with Chuck. The bigger issue is you would be working with a 75 year old frame and all the related stress and hard life it has endured. There are plenty of these unfinished projects out there but cheap always comes out expensive and there is usually a good reason it is unfinished, mainly they can't fix what the did. To start modifying from square one you will find that you have more questions than answers since you have not done this before.

This has already been done to perfection by Duncan Rolls with a repro body and chassis. He has a Chevy V8 expertly stuffed under the hood with a muncie 3 speed and disc brakes, etc.

Just google Duncan Rolls Willys V8 and check out the youtube video of "Bastardo". I'm a purist but I've ridden in this jeep and it is nothing short of awesome! I also know it is for sale.

I also know that Lloyd White has '45 MB with a blown V8 that he did back in the 60's and as far as I know that too is for sale the difference is it has not run for a while.

In both cases it is money well spent to either buy one that was done by a guy that knows what he is doing or freshen up one that has already had the hard work and modifications done. Lloyd used to show his before we got him back in the purist camp...ha!

Hope this helps,
Peter

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Re: Motor swap + more

Post by scheinerj » Mon Sep 25, 2017 5:42 am

Thank you for all of the advice and info.

Here is where I am at so far:
- Decided not to go with the V8, added torque and the thought of squeezing it in flatty engine bay was not a fun idea
- Did decide to go with the 4.3 Chevy V6, will fit much better
- began boxing in the frame...the front crossmember to the rear is completely boxed in, but I will cut out a few trouble spots where holes are to rebox
- definitely going to do the disc brake conversion

Thanks for the help!
JS

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