Jeep Engine Build

[bob w]

I've been showing bits and pieces of this engine build on my '29 Chevy roadster PU build but thought it might be of some interest to a few of you. I have a Crosley wagon that has been laying dormant in the back garage for about 3 years now. It has a 406 sbc in it and runs in the 10.30's At my age that is a bit faster that I care to go.

So, I've become interested in Jeep stroker engines. Take a 4.0 liter block and put a 4.2 liter crank in it and you get about 280 cu. in. A very mild one makes 300 horses.

That will propel the 2,200 pound Crosley quick enough for me.

I had to buy 3 different Jeep engines to get the good parts. One 4.0 for the block, one 4.0 for the head, and one 4.2 for the crankshaft.

Here's a pic of the intake that had a throttle body on it. Now converted to carb use.

Been keeping a list of expenses which some of you might find interesting.

3 core engines $300
Pistons $100
Rings $100
ARP rod bolts $55
Sandblast intake $20
JB Weld $10
Grind Crank & provide bearings $305
Clean, mag. bore, hone, cam brgs
Recon rods, install rod bolts
static balance rods, pistons on rods $426
Brass core plugs $20

Total so far is $1,336

I brought the block home so I can fit the crank, and piston/rod assembly to determine how much to mill the block for a zero deck. Then it goes back to the machine shop to be finished.

[old28]

Nice start Bob, going to make a fun 12.50-13.0 second ride. What's the Crosley weight with the Chevy now?

[redidbull]

If you need info on anything Jeep head over to jeep-owner.com. Old friend of mine runs it and there are some hardcore Jeep guys there. Jim

[bob w]

Got the freshly machined block on the stand. Will drop the crank in place and put a piston/rod in #1 hole and measure the deck height. Then put the same piston/rod in #6 hole and do the same. I'll then know how much Ryan the engine shop owner will have to mill the deck. He even painted the block.
In turn, I cleaned and pressure washed the head today so he won't have so much of cleaning job when I have him touch up the valves.
I never built an engine where the rings cost as much as the pistons.

[Torchie]

Originally Posted by bob w

I never built an engine where the rings cost as much as the pistons.

"It's a Jeep Thing."

Torchie

[bob w]

Finally got back to the Jeep engine. Went to drop the crank in and found out I had the wrong main bearings. They were the right size but the tangs were in the wrong place. They were for a 258. Ordered mains for a 242 (4.0 L) and all is okay. I put the crank in and one piston/rod assembly in the #1 cylinder. Measured deck height, the amount the piston is below the deck at Top Dead Center. It is .044". Put the same piston/rod assembly in the #6 cylinder and measured .047". Ideal quench clearance is around .040". I ordered a couple different head gaskets to measure their thickness. Ideal quench is .040". So if the head gasket is .040", the pistons will have to be flush with the top of the block. That means milling .044" to .047" off the block. Unless my engine guy can angle mill the block front to back.

Compression ratio should be 10 to 1. I'd like more so I'll see if milling the head is an option.

[Old Iron]

Measure from the main journal to the top of the block and it'll tell ya if the block is the culprit difference if it is then, the machinist won't have to angle cut the block.

[Burgerman]

Cool engine build Bob. Photos be fun. 🙂

[bob w]

The block is back at the machine shop. Ryan is going to measure the deck height according to OI's suggestion. Then mill for about zero , meaning the piston top will be even with the top of the block.
The bare head is going to be magnafluxed and cleaned. Then I'll do some port matching and a little bowl work, smoothing the valve guides, etc. Nothing very radical The bowls look quite good but like all inline engines the port size is not overlarge. They were built for torque, not maximum horsepower. Stock valve size is pretty good at 1.91" intake and 1.5" exhaust
I'll be looking for max torque around 4,000rpm and max horsepower around 5,000+ rpm.

[bob w]

The Crosley has been languishing in the back garage for about 3 years now. Got to pull the 406 small block Chevy to make way for the Jeep engine. Also going to put an Anglia front axle under it for lighter weight. I've been pulling parts off of it but now it needs to go into the front garage where I can finish the job. The front axle that is in it now will go in my Renault and the small block could very well find its way into the Bantam. Lots of juggling going on around here. All the plotting and planning is great fun.