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Bolt In SBC Motor Mounts & Car Muncie

Bolt In SBC Motor Mounts & Car Muncie
H

hawgn68

Jeeper
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Location
Warrensburg, MO
Vehicle(s)
84 CJ 7 Trailer of Parts
Greetings CJ Experts,
I've been lurking the forum since trading a motorcycle for a trailer full of '84 CJ parts a couple years, now I'm retired and it's time to get to building. I've finished the frame, both axles and brakes. I'm a Chevy muscle-car guy, so naturally I'm planning for a SBC conversion, specifically the drivetrain left over from my '67 Camaro, 327 and Muncie M20. Two lead-off questions for my first post I haven't been able to find through the search functions here:

1. Is there a source for bolt-in motor mounts with adjustability? My frame was galvanized prior to my acquisition, and welding on it will be problematic, so looking for bolt-in mounts. I'd like to be able to adjust the motor placement for firewall clearance or driveshaft angle. All the mounts I've seen appear to be fixed position

2. Is there an adaption difference between the Muncie SM465 and a passenger car M20? I'll need to adapt this tranny to my T300 TC of unknown internal condition. It looks like the SM465 adapter is close to $600. Would I be better off sourcing a GM 4x4 truck tranny and Transfer Case combo? I know either way, there will be plenty of fab work.

Thanks for any insight. Any forum dwellers here in the KC area? I bring beer for practical advice?


Jimbo
 
Weclome to a great site.
Novak Conversions and Advanced Adapters are good sites for conversion info and parts. MORE offroad has bolt in engine mounts which use the bolt holes already in the frame.
Most use the sm420/465, ax15, nv3550 or a gm automatic. The difference besides the beef in the Transmission is the bigger front bearing which will require the bellhouseing opening to be larger. So if you use the m20, a car bellhouseing could be used without opening up the Transmission hole. The Dana 300 Transfer Case is a well respected unit and will stand up to a V8.
 
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Thanks R&S,
I've got the bellhousing and clutch assembly for the M20, so my only concern is the output area and the conversion kit to mount the Dana 300 . I'll check with Novak and AA to ensure their kits will work for the M20. Have you used the MOORE motor mounts (I see you've done this SBC swap a few times)? I guess I can drill more frame holes if I need to adjust the placement.
 
The mounts were already in when I got the jeep. I have found in my research that the mounts most likely came from MORE.
I have seen one swap using the m20, but it was only 2x4 no Transfer Case .
 
I have used several sets of the MORE bombproof motor mounts, amc6 amcv8 and sbcv8 mounts and they have all been perfect. No grinding, beating, cussing, etc. just bolt in and go.

The MORE mounts position the SBC really well fore and aft, leaving enough room at the firewall for a large cap HEI, although clearance is much better with a small cap setup. The SBC mounts also have 2 sets of holes to allow for positioning the engine higher than would be normal in the frame. They are worth every penny and then some.

If you are going to use your jeep for typical offroad duty, i would ditch the relatively close ratio M20 for an SM465 as has been mentioned. Wide ratio transmissions are much better for offroad use generally speaking. If its just a street cruiser or a big horsepower dune machine the M20 would probably be fine, assuming you can find a kit to adapt it to the Dana 300 .
 
Also, this is off topic, but if/when you start looking at GM conversion radiators, be aware that some of the ones on the market will interfere with the power steering lines where they enter the steering box in some applications.

I used this radiator:

https://www.cgj.com/store/product/jp-3009/

except i had them custom make it with a notch in the bottom corner to clear my power steering lines. If you are interested, they probably still have the pattern on file. This mod added about 50$ to the standard price. Very nice unit that works exceptionally well.
 
Thanks Dave, great info. Based on both recommendations, I’ll press with those motor mounts. It’s a little ways down the road, but which power steering pump do you use? Adapt a bracket to mount the Jeep pump to the SBC, or adapt the lines from a GM pump to fit the Jeep steering actuator?
 
If you already have brackets and pump from your sbc it will work with the jeep steering box, it is a saginaw and should be metric with orings instead of flare type hose fittings.
On edit: I used a combination of the jeep pump and a tank from a gm C/K truck to get the right return angle.
 
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I used the SBC p/s pump. I installed a Vanco Hydroboost brake setup

Jeep Hydroboost Kit

at the same time, and it came with all new lines, but as has been mentioned, the pump on the SBC is essentially the same pump that many CJ's came with so it ought to be easy to adapt.
 
What tire size do you want to run? What axle ratio?

Not sure exactly which ones, but I know that there are adapter for some Muncie car transmissions to the Dana 300 . It think made by Advance Adapters. A buddy of mine found a cheap adapter used (well, it was bought, never installed and had been sitting a guy's garage for a while) and he looked into it, but they were very close ratio and 1st gear was horrible (somewhere in the low to mid 2s). By the time you get a low enough axle ratio to be usable, you would really need o/d for it to be streetable.

In other words, I think you'd be better off with a different Transmission
 
Thanks fellas. Good to know that the PS systems are compatible. Once I get the engine mocked up with my MORE motor mounts, I'll look at the bracket options based on my pile of chevy and jeep parts.
 
JP360,
Yeah, the more I read, the less I think the M20 is the right option. I may just press the easy button and put in a 700R4. Of course I'll have to hide my face when offroading...
 
hawgn68 said:
JP360,

Yeah, the more I read, the less I think the M20 is the right option. I may just press the easy button and put in a 700R4. Of course I'll have to hide my face when offroading...
Click to expand...
If you plan on rock crawling automatics are the best and nothing to be ashamed of.

Sent from my Pixel 2 using Tapatalk
 
Welp, based on info here, I'm gonna go with the 700r4. I put one in my wife's '67 Camaro with 396 and 3.73 gears, the best mod I've done. Now trying to find a 4x4 Transmission candidate in order to adapt the TC vs the tranny. I figure the OD will be pretty useless until I change the gear ratios, currently 3.31 with 33" tires, but I like the low first gear vs the TH350. I did install the 1-piece axles that came with it so a little more strength there. What's the highest ratio you can put in a Dana 30 and AMC20 rear?
 
Highest gear ratio you can put in a Dana 30 is 4:88 but it gets pretty weak at that point and you have to be careful not to strip the gears. I've done it once. Not sure about the AMC20 .

Sent from my LG-LS777 using Tapatalk
 
I've heard that someone makes a higher ratio for the D 30 but don't remember who. It has to be pretty weak with that small of a pinion.

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A 350 with 33s isnt gonna need super steep gears. As cheap as you can get them these days I'd put an LS in it, run the gears you got and see how they feel and go from there.

Sent from my Pixel 2 using Tapatalk
 
I would definitely stay away from the car muncie tranny in your Jeep. They are great for drag racing but terrible for offroading. Go with the SM-465 muncie truck 4-speed so you have the granny gear. They are extremely cheap, plentiful and bulletproof.
 
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