Rebuilding An Early Hemi

Part III



With the short block assembly completed its time for assembly of the long block. Before this happens however there is one item that needs to be addressed.


-------------------------------------------------------------

The first is the distributor. In my case I want reliability so I've decided to go with an electronic ignition system. The easiest one to convert is the standard 340 electronic distributor. With this system you can run any of Mopar's electronic boxes based on the kind of performance you're going to need. In this case the standard orange box will be just fine.


In this picture you can see that the standard 340 electronic distributor doesn't quite fit the early hemi block. Although it fits the hole perfectly, it just isn't quite long enough to fully engage the intermediate shaft (arrow).





The solution is to lengthen the shaft so it fully engages the intermediate shaft. HotHeads has an adaptor that does just that and it is very easy to install. The kit consists of a sleeve and two pins. All that is required is to cut the shaft about an inch up from the bottom and then drill a hole through either the lower section or upper section and install the sleeve with one of the press fit pins. Then all you have to do is insert the distributor in the block with the sleeve on the shaft and mark where the sleeve needs to be to fully engage the intermediate shaft. Once this is completed just drill and install the pin in the shaft to hold the sleeve in the proper position and you’re done. Simple and effective. Here's a picture of the distributor with the sleeve installed. You can see how both pins hold the sleeve in position and how it lengthens the shaft.





In this picture you can see the stock 331 distributor (left), the stock 340 distributor (center) and a modified 340 distributor (right). You can easily see the difference in length between the stock and modified 340 distributors.





Here is the modified 340 distributor installed in the block. Notice that it now fully engages the intermediate shaft.





OK. Time for some serious assembly. Here you have a basic set of big port '54 heads fresh from the machine shop. There is nothing special about the heads except to say that it is my preference to use the stock cast iron valve guides rather than brass. If set up with the stock clearances they will give thousands of miles of trouble free use.





The valves I used were stainless steel HotHeads 392 replacements. For the cost it is almost always better to go with new valves. The fact that most of these motors have been sitting for years will usually mean that at least some if not all the stock valves are damaged anyway its best to replace them while you have everything apart.





Here you see the rebuilt rocker assemblies. For performance applications where high spring pressures are run it's a good idea to have the shafts hard chromed, but in this application a simple stock rebuild was all that was necessary.





Be sure to follow the recommended tightning sequence for the head bolts and torque them to 85 ft. lbs.





With the heads installed we can turn our attention to the valve train.


*** NOTE ***

It is always a good idea to use adjustable pushrods whenever you have installed a performance or reground camshaft. You will also need them if you have the heads shaved or block decked. Failure to use adjustable pushrods in these situtations can damage your engine. Standard hemi rocker shafts have no provisions for adjustment so any differences from stock dimentions must be compensated for with adjustable pushrods. Adjustable rocker shafts were used on factory high performance engines as well as industrial and some marine applications but they are expensive and hard to find. In most cases it is much easier to simply use the adjustable pushrods



When it comes to adjusting valves on an early hemi it is the same procedure used on any small block Chevy motor. Simply adjust the pushrod to take the "play" out of it and then continue one full turn on the adjustment and lock it down. Since the firing order on an early hemi is the same as the small block Chevy the same valve adjusting sequence can be used as well. Adjustable pushrods can be a bit of a pain to work with and you'll sometimes feel like you need smaller hands but with a little patience it can easily be done. The exhaust valve is almost always the easiest to adjust but sometimes the intake can be a real pain as the following pictures show.







When I build an engine I like to pressurize the oiling system to ensure oil is getting where it needs to be and to prime the oil pump. There are a couple techniques for this but because of the need to remove the intermediate shaft on a hemi in order to spin the oil pump, I like to use an engine pre-oiler.





This engine oiler system consists of a tank and hose hookup. All that is required is pressurized air. Simply fill the tank with 4 quarts of oil, pump the tank up to about 100 psi. and turn the valve. The air pressure forces the oil into the engine and pressurizes the entire oiling system. While the oil is being forced into the engine I rotate the crankshaft a quarter turn at a time just to make sure everything gets completely oiled. On the day I did this it was 20 degrees in the garage and the oil was so thick I could only get about 25 psi. on the guage (see the following picture) but even that was more than sufficient to do the job. I also like to repeat this senario a few times. You can never be to cautious and oil is the life blood of an engine.





With the oiling system checked out and the heads installed and valved adjusted we can now button up the rest of the engine. I used a HotHeads aluminum valley cover on this motor. This is not necessary but since I want this to "look" like a 426 I'm using oil breathers in the valve covers and I don't want the oil fill tube to show. I like the HotHeads valley cover since it has a cap at the rear (where the old road draft tube used to be) that can easily be removed to add oil.

Because I'm useing pre-"55 heads without provisions for a water crossover manifold it will be necessary for me to use the stock 4 bbl. intake manifold. I could use a later version without the integral thermostat housing and modify it to use a remote housing but the "look" wouldn't be right. Below you can see the biggest problem with the stock manifold. This manifold was designed to use the Carter WCFB 4 bbl. carburetor. As you can see by the scribe marks the difference in the diameter of the WCFB and a modern Holley or AFB 600 cfm carb is pretty dramatic. In order for this engine to perform at all these holes will have to be opened up.





A quick trip to the machine shop and walla... we now have a manifold that can breath.





Here is the carb adaptor I'm using. It adapts the stock "small" mounting holes to the later Holley / Carter / Edelbrock square flange bolt pattern. The center section was made from a 1" plastic riser and simply fit in place.





One last item. When mounting exhaust headers or when installing studs for stock manifolds you need to know that the top three holes go all the way through to the inside of the head and will leak oil if you don't use a high temp sealer on the threads (arrow).





Now that the engine has been buttoned up we need to look at the transmission adaptor. I'm using a GM TH-350 and a Wilcap adaptor. This basically adapts the GM trans to the back of the hemi but it also allows you to specifiy (at the time of purchase) if you want the starter on the drivers or passengers side. I chose the passenger side to make more room for the steering hookup. This unit also uses the late model Chrysler small block high torque starter which is a plus. A flexplate is provided with the adaptor that will mate both to the hemi crank flange and the small block Chrysler starter.

One other thing to think about are the flexplate bolts. The stock flexplate uses bolts and nuts. With some adaptors, like this one, there is no room to use these. While the crank was at the machine shop I had the holes tapped for 1/4" X 20 bolts which make it much easier to mount the flexplate. Here is the adaptor and flexplate installed.





There are a couple things to take into consideration when using any adaptor. First is that although they work well sometimes slight modification may be required. This case was no exception. As you can see in the next photo there is almost no room to get a bolt through the flexplate to mount the torque converter. This would not be a problem if I were using a standard transmission since the pressure plate would bolt directly to the flywheel but on an automatic flexplate you need nuts and bolts for the torque converter installation.





In order to remedy this situation I simply drilled a small hole to allow a bolt to be installed through the front of the adaptor.





So there you have it. A complete hemi ready to install. The following pics show the Hemi in its final resting place. It won't be long now!









----------------------------------------------------------


Remember, several steps in this entire assembly process have been left out because they are the same as any other engine assembly. To help the novice hemi builder, I've tried to point out some of the more unique procedures and techniques that are peculiar to this engine. Also please keep in mind that my techniques are by no means the only way to do things, just the way that works best for me.



I hope you have enjoyed this little exercise and that it has provided some insights for your next rebuild.





BACK