Thread: Early HEMI

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Just got my 331 hemi pulled out of 52' Chry. wagon. Have some questions on trans. adapters? this is an extended block, and I would like to run mopar 4-spd. Any one out there have suggestions or ideas on getting them to mate up?

There doesn't seem to be a whole lot out there (for either stick or automatic). One alternative that has been done is to have the bellhousing extension cut off.

Before you dismiss the idea out of hand, consider that to mate a SB Chrysler bellhousing to the non-extended early hemi (the early hemi and small block Chrysler bellhouings bolt pattern is almost identical) you need a spacer that is about 1" thick to get the correct depth for the tranny input shaft. Commercial adaptors kit run in the area of $500. I don't know what it would cost to have the extension cut and retapped but by cutting less off of it you might be able to eliminate the cost of a kit.

Another area to watch out for is the pilot bearing. A lot of the early Hemi automatic cranks were not drilled for the input shaft of the tranny This one is pretty easy to get around however. You can either find a sealed bearing with the right OD for the torque converter pilot hole and ID of the input shaft, or if that's not available have one custom cut from a piece of bronze bar stock. Then all you have to do is shorten the end of the input shaft so it dosn't bottom in the hole.

If you go this route, a flywheel from a 57-59 Ploy stick car can be cut down to SB Chrysler ring gear size. It's only 6 bolt compared to the Hemi 8 bolt, but basically they just didn't drill 2 of the holes.

I'm currently doing a 4 speed conversion on a 56 354 (non-extended block) and I built my own adaptor for the swap. I can pretty much walk you through this if it's the way you want to go.

Check here, http://hothemiheads.com/ I read that they had some adaptors for the extended block 331's. If not it may have been one of the links from that site. I remember reading it but didn't pay much attention, I've go5t a '55 331. It's not extended. Good luck, lots of cool stuff out there once you get to lookin'. Have fun.

Thanks, I don't care what I have to do to make it work as long as it will work properly and safe. I am a machinist so anything in that area doesn't bother me at all. I would love any help you would be able to give me! I read in a book about machining off the extension, but I can't find out how much? I have the original setup so getting the length from trans to bellhousing surface at block shouldn't be difficult. Like you said Mike P, maybe I don't need to take as much off the block so I don't need an adapter.

Wilcap http://www.wilcap.com/webdoc3.htm has an automatic adapter. Don't know about a four speed. Send them an email and see what they say.

I have made a few posts in the past regarding the early extended block 331's and my advice has generally been to avoid them. There are 2 main reasons for my opinion.


1. Compared to the latter (54-56) non-extended bellhousing 331/354s they have smaller ports and valves, and the water crossover was in the intake manifold rather than at the front of the heads. This limits the choice of intake manifolds to a large extent. This in and of itself is not a show stopper, a simple head swap can cure this and there are a bunch of latter 331/354 heads out there. (Avoid the 57/58 392 tall deck heads for the 331/354 low deck engines. They physically fit, but are wider and unless you are planning on running a 2 piece log manifold your not going to find an intake that will work).


2. A VERY limited availability of transmission adaptors to allow the use of a more modern tranny. The adaptors for most automatics require the cutting off of the tranny bellhousing, and the stick setups I've seen are limited to Ford top loaders. This to me is the main reason for the average hotrodder to avoid them. The trimming of the bellhousing (either on the block or the tranny if the automatic adaptor is to be used) if NOT for the faint of heart or mediocre machine shop. With access to a good machinist it is doable and the parts to convert to a SB Chrysler bellhousing and stick are not really all that expensive but IT"S GOING TO BE LABOR INTENSIVE!!!!! ($$$).

In a lot of cases many machine shops would not want to tackle this for a customer due to the time involved. Where this is not an issue in this case, here's what's going to be involved.

The first step is to collect your parts:

Transmissions: The A 833 Chrysler tranny have been around since 1964 and are a good heavy duty unit that are more than enough for the most early Hemis. The MOPAR Performance Chassis Manual pretty well spells out the differences between the different units. Here are a couple of the major variations you will need to keep in mind when looking for one. The basic 833 could either be found in either a basic 4 spd configuration (1:1 Fourth) or an overdrive unit (.74 OD fourth). There were 2 different tail housing lengths and between the 2 there are a total of 3 different shifter locations possible (1 on the short tail shaft and 2 on the long tail shaft). The 833s came with 3 different pilot bearing retainer sizes (4.30", 4.80" and 5.125"). The Bellhousing must match the pilot bearing retainer used.

Bellhousing: Besides the input bearing retainer size the other major difference between the small block Chrysler bellhousings is they are made of either aluminum and cast iron. Although I'm running an aluminum bellhousing on mine (it was all I could find) I prefer the cast iron units as I feel they are more rigid and less likely to crack. You must also get the fork that corresponds to the bell housing your using.

Flywheel/ring gear/clutch/starter: The two flywheels that I've found that can be used and are fairly common are the early Hemi industrial/truck units which are 8 bolt and match the crank. They are also rather thick and heavy. I used the thinner and lighter 57-61 6 bolt poly flywheel (which is a bolt on to the Hemi crank) both to have a lighter flywheel and because the depth of the ring gear was better for the starter (the picture below shows the difference in width between the 2 flywheels). As neither of these flywheels will physically fit inside the SB bellhousing, I cut the flywheel down to the diameter of the a SB Chrysler unit and installed a late 60's 318/340/360 ring gear (this was actually done on a brake lathe). The flywheel is already drilled for the correct 10.5" Chrysler pressure plate so thats no problem and with the flywheel cut to SB size and with the SB ring gear, a stock Chrysler starter and throwout bearing are also used.

At this point the next step would be start trimming the extended bell housing. I tried to come up with a good reference point to take a measurement from and ended up using the centerline between the 2 oil holes that are seen when the oil filter housing is removed. My adaptor plate on the non-extended block is 1 1/8" so from the center line for a total thickness of 2 1/2" from the measuring point. I would recommend that you stop cutting at about 3" to 3 1/4" (maybe a little more if your using the thicker flywheel) so you can gradually cut to the correct depth. The key is to cut the depth so that the bellhousing positions the starter drive gear into the proper depth on the ring gear as explained in part 3.

At this point it is time it will be time to attach the bell housing so you can determine the final amount of material you need to remove. The picture below shows the SB Chrysler bellhousing bolt holes that will be used (marked with the Xs). The key is to have the bellhousing centered prior to drilling and tapping the holes (remember to drill and tap the holes deep enough to compensate for the material that will have to be further removed).

To center the bellhousing I used a gutted tranny case with an input shaft, input bearing and retainer.

1. To do this it will also require that you have a pilot bearing in the back of the crank. If your crank is already drilled for a pilot bearing your golden, just use one with the correct OD/ID. If the crank hasn't been drilled you have a couple of options. Drill the crank for a standard Chrysler pilot bearing or build a custom one that fits into the torque converter pilot hole. If you choose the custom bearing you will need to trim to end of the tranny input shaft so it doesn't bottom in the crank.

2. Attach the flywheel to the crank and loosely bolt the bellhousing to the back of the block. Insert and bolt up the tranny case w/input shaft and bearing retainer to the bell housing. Reach inside the case and rotate the tranny input shaft, adjust the bellhousing until the shaft turns without binding on the pilot bearing. Once this is achieved the bellhousing is centered and can be tightened down.

3. Install the starter and apply 12V to the solenoid terminal (the SMALL electrical terminal on the starter). This will extend the drive pinion without spinning the starter. The distance to properly mesh the drive gear to the ring gear is the remaining amount of material that must be removed from the extended bellhousing for everything to properly fit. This final cut will align everything else(clutch disc on the input shaft and input shaft into the pilot bearing to the correct depth).

Once this is all done the final step I would do is to completely assemble everything again (to include the clutch disc) and recenter and tighten the bellhousing as described in 2 above, and drill and place a couple of alignment pins. Clutches/throwout bearings etc do wear out the pilot dowels will greatly simplify clutch changes.

Finally, to add extra support for the bellhousing I built this bracket to catch 1 more bolt when I built my adaptor. You may be able to simply drill and attach this bolt to the remainder of your extended one.

Many of the Chrysler stick cars also used a brace from the lower part of the bellhousing to the oil pan rail to help prevent flex/cracking of the belhousing. I plan on adding one to my setup just as insurance.

I hope this helps. To me this is pure hotrodding, taking a bunch of parts that were not designed to work together and making it happen. With you doing the machine work yourself, I'm sure you'll beat the price of an adaptor. Most of the parts you have to buy you would need anyway to put a stick in. Additionally, the 833 Chrysler trannys are usually a lot cheaper than the top loader Ford units which is the only stick tranny I'm aware of for the extended bellhousing units.

Dude, you are freaking sick. Thank you very much for that very informative lesson. That is the the most info I have seen posted about an early HEMI yet. I've got one at a buddies house and am currently kinda lookin' for a car to put it in. These posts really get me fired up to get to work.

Yeah, you build em long enough on a budget you'd be amazed at how much seldom asked for information you can acquire.

Mike, that's a great compilation of early hemi information. Thanks.

Thanks Richard, I figured that once I got it put down once it could always be refered back to in the future when the question of the 51-54 331s came up.

I shall have to agree with everyone, that's the most info I have gotten on early HEMIs' all around! I've bought books and have talked to some people and neither have much info. I am in agreement with you on the hot rod issue. I admit that I don't know much, but I do love hot rodding. The extended blocked 331 wasn't my first choice(392,354), but it came to me for $150.00. I don't have a lot to choose from so I snatched it up. Anyway the guy was going to scrap the car so I felt like I saved a little HEMI history.