Sbc In Cj2-a

I would suggest you download a copy of DynoSim from Comp Cams-it isn't a free app but well worth the expense. This is way more than a cam selection program and in fact, if you have all the actual engine component data, it is actually quite accurate with the output. I basically designed the current sbc in my 3B using that. The actual cam specs and head flow are important for accuracy. I was blessed with an actual dyno test done by Hot Rod magazine about 15 years back on an engine using nearly the same bore and an identical stroke as I used. When running the specs on that engine, I came within 2% with Dyno Sim. Any engine is going to involve a number of compromises and you just have to determine which are the most important to what you are trying to accomplish. In my case, whatever the HP came out to be was totally incidental to the bottom end torque I was aiming for. If the Dyno Sim numbers are close to reality, the sbc in the 3B should be producing over 400 ft lbs at 1000 rpms. The caveat is that was by no means a cheap engine to put together. But it was a bucket list item.

 

The relatively inexpensive way to make torque is to “stroke” the crankshaft, in other words, increase the stroke. Back in the day, this meant find a Chevy 400 small block, or use the crank from one to use in your 350 block. In the ‘80s, the aftermarket started producing the 3-3/4” stroke cranks ( 3.48” is stock 350) or “383 stoker kits”. You had to buy pistons to match for either 5.7” or 6” rods to make things work, as well as appropriate cams. These kits were very effective at building big low and mid-range torque.
Small block Chevy engines mixed and matched various bore and stroke combinations for different applications, but cam timing also contributed greatly to either high-end horsepower or low end grunt. The 305 was a lazy long stroke (same 3.48 as a 350) engine that produced decent torque, as opposed to a 307 (3.25 stroke) that wasn’t as well respected. Both the 305 and 307 are kind of turds in the SBC family, but were built for their respective purposes.
Even a 283 (3” stroke) with a good “RV/towing cam” can produce decent torque for the engine size. This engine was used in the early/mid-60’s in many full-sized cars.
Remember that high torque is what starts breaking things like T90 transmissions or two-piece D44 axles in our old Jeeps.
-Donny

 

The other way of coming up with a "383", using all GM parts, is to use the 400 crank in the 350 block and the short 400 rods with 350 pistons. Maybe something not to do if high rpms is the goal but it worked well for me for 3+ decades in the 3B. I put that together before there were any 383 kits. That engine would pull clear down to 300 rpms and still produce enough torque to get over just about all obstacles without having to hit the clutch.

 

It's really complicated.
But in short...
A long stroke gives a longer lever for the rod to push. But there is a given speed for the explosion inside the cylinder.
So with the same displacement you can have a range of v8s.
Think of a piano and it's notes...
Then if you want to drop an octave, you add a cylinder or two. Now you have a high revving small v10. Or a big lumbering v6 (whichever way you look at it)

 

Thanks for all the insight ^^^
Hopefully @stevecres is getting his SBC sorted in his flattie. Having owned a 2A with a 327, I will say the sooner you get rid of the T90 the better

 

I recall my ' Big Brother's ' building a 1970 CJ5 with a 327 SBC , W/ a Posi rear & front . I did not know 'nutin' about tranny's back then, but it was a thing of wonderment & beauty to this ' Kid '. Jack always satirically laughed that he really loved it too........He just couldn't afford to keep the Rubber on it .

 

IME, a 327 with the 538 gears would burn rubber in 3 rd gear, not that I would have done anything like that---

 

The first CJ2A I saw with a SBC was at a deer camp around 1968, I was just a kid then, but I sure was impressed with what that Jeep could do.

I built quite a few Chevy small block engines in my youth for various hot rods, but I never put one in a Jeep. Not yet anyway.

The 305 is a good engine, even if it is not as popular as a 350. I had one in a 1968 Nova, just a mild built engine with a high lift short duration cam and that thing had great bottom end. Would be more than plenty enough power in a little ole Jeep.

As to a distributor, were it mine I would go with an early breaker points distributor, or, if you don't like to deal with that, you could do as already mentioned and convert an early distributor to electronic ignition. I think either would give you the smallest size distributor without spending a whole lot of money.

Personally, I prefer a breaker point ignition, but that may partly be due to my age and familiarity with that.

 

And break axles... but like you I wouldn't know anything about that

 

Thank you for the positive input

 

There is absolutely no reason to use a V6 radiator if you can fit something larger-which will always be the case here. Aluminum? Absolutely with welded tanks. I ended up using a GM app 19x26x3 in my 3B (Summit item). I had to reclock the outlet but that isn't a big deal. Not sure you have that height to work with a 19" tall version in a low hood. The radiator will need mounted very close to the front of the grill with all the stock "extension" removed. You can tilt the top of the radiator back so it is parallel to the face of the fan-that buys you more room for the headlight buckets. And you can lop off the backs of those buckets. There are a near infinite number of fan/spacer combinations for radiator/belt clearance. Fans are available with both forward and rearward offsets-check the manufacturer's sites for dimensions. Also, all "short" small block water pumps are not the same length so also look up the specs for what you plan to use. I've found the aftermarket pumps can vary more than a 1/2" which can totally screw things up when working a tight clearance. And I'm no longer much impressed with FlowKooler pumps. Things kind of went awry when they shifted production to china.

I'm looking forward to a build thread on this!