When we decided to build a street gasser there were only a few things we knew for sure: The car would have a straight axle, a blown Hemi, and fenderwell headers. Granted that wasn't much of an initial plan, but after finding our '50 Plymouth three-windowv, the concept of RamRodder-a car loosely based on the Ram Chargers altered from long ago- started to come together.
As most projects go this one is lumbering along. So far we've added a Fatman stub to the front of the stock frame and have a Speedway straight axle mocked up. In the rear, a Currie 9-inch is attached to Morrison ladder bars. We've modified the firewall to accommodate our supercharged 392 and now it's time to put it in place.
The Chrysler Gets A GM Trans
Several years ago when we first got the itch to build a gasser we collaborated with Hot Heads and Pro Machine and built a blown Chrysler Hemi. Unfortunately other projects got in the way so, other than being cranked over on a regular basis, our 392 has been sitting in the shop gathering dust. Built as a driveable, reliable street engine it made peaks of 604 hp and 580 lb-ft torque, but what's really impressive is the 560 lb-ft torque average from 2,500 to 6,000 rpm-and that's with 91-octane pump gas and the blower under driven with the biggest pulley available.
To reliably transfer the power this engine is capable of producing, we needed an equally stout transmission, so we turned to Gearstar for their recommendations. Their response was in the form of the King Kong of automatics: a Level V 4L85E. Thanks to a laundry list of improvements, including a Yank converter, Alto Redline frictions, Kevlar band, and a host of Gearstar's own high-performance hard parts, this transmission is capable of handling dragstrip launches with 1,000 hp yet, with the lockup converter, and specially programmed computer it's civilized on the street (we'll get more into that when RamRodder is on the road).
To bolt the GM transmission to the Chrysler block an adapter would be required and Pat McGuire of Wilcap handled that. One of the oldest names in the adapter business, they supplied the adapter plate, flexplate, crankshaft spacer, and the necessary hardware to bolt the engine and transmission together.
Three of the things we wanted...
Three of the things we wanted in our street gasser are in place; a blown Chrysler Hemi, fenderwell headers, and a straight axle.
Making Mounts
As we said, fenderwell headers were planned for this project before we even had a car, they're just part of the gasser package. The ceramic coated set we used came from Hot Heads and we basically positioned the engine based on how they fit, as luck would have it they allowed the engine to fit closely to our modified firewall, cleared the frame without having to position the engine unreasonably high, and still provide plenty of tire clearance.
With the engine supported on blocks and positioned where it needed to be, we fabricated a pair of motor mounts and a transmission crossmember. In most cases, engines are installed at an angle, with the rear lower than the front, to help align the driveshaft. As a result, intake manifolds normally have the machine at an angle to keep the float bowls level. However, blowers typically mount the carburetor's level, parallel to the crankshaft, so that's how our Hemi is oriented in the chassis.
To make the front mounts we used engine brackets from Chassis Engineering and fabricated mounts to attach to the frame, the transmission mount was made from a combination of round tubing and flat stock.
Step by Step
It's probably apparent that we're taking a somewhat unorthodox approach to assembling our gasser by building it around a few specific design elements, however we're sure it will pay off in the end. Now that the engine and headers are in place we can finish the suspension and install the steering, which we can tell you will be done differently than most, but then given the car we're building and what we've done so far that shouldn't come as a big surprise.
While fabricating the engine...
While fabricating the engine mounts and positioning the suspension we left our Plymouth attached to our rack/frame table. We had temporarily installed the radiator support, but we removed it to make installing the engine easier.
The original transmission...
The original transmission crossmember was riveted in place as was the shifter, clutch linkage, and brake pedal brackets.
A fresh blade in a reciprocating...
A fresh blade in a reciprocating saw made removing whatever stood in the Hemi's way quick work.
Before the Wilcap transmission...
Before the Wilcap transmission adapter was bolted to the block the mounting surface and guide pins were thoroughly cleaned and deburred and a tap was run through all the threaded holes.
In stock form Chrysler Hemis...
In stock form Chrysler Hemis use 7/16-inch bolts to secure the flywheel/flexplate to the crankshaft. When using an adapter, these special bolts with thin heads are necessary to clear the torque converter, they're available from Wilcap.
Another option is to tap the...
Another option is to tap the crankshaft flange for eight conventional 1/2-inch flexplate cap screws. The holes are the correct size for threading, Wilcap can supply a fixture to ensure the tap runs true.
The transmission adapter slides...
The transmission adapter slides over the stock transmission guide pins, and it's secured with five counter sunk socket head cap screws from the transmission side, and one hex head cap screw from the engine side.
Included with the adapter...
Included with the adapter is this flexplate spacer. Note the raised center register to accurately locate the flexplate.
Another unique feature of...
Another unique feature of these engines is that the flywheel is located by the outside diameter of the crankshaft flange. The flexplate spacer is recessed on the engine side for that purpose.