Thread: Early HEMI

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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.