Rebuilding An Early Hemi
The following pages show how I bult the engine for my truck. The techniques shown are not necessarily the only way to do things, just what works for me.
If you are new to rebuilding engines I recommend you not try a hemi as your first rebuild. Not because they are harder to rebuild than other engines, just that they are rather expensive and rare and one simple mistake can forever ruin what could have been a valuable engine.
Generally if you have ever rebuilt a small block Chevy or Ford you can rebuild an early hemi. They're pretty much like all other engines with just a few minor differences. The biggest of course is the expense. Hemis are expensive and even a stock rebuild will cost as much as a performance rebuild on an adverage big block. Also some parts can be difficult to find. Thankfully business like Hot Heads Research and Racing (aka PowerPlay Hemi), Kanter Auto Parts, Egge Machine, and Performance Automotive Warehouse (PAW) have come to the rescue.
The subject of this exercise is a 1954 Chrysler 331. The block was purchased from a fellow who had disassembled and cleaned the block years ago. It was stored in a warehouse for years but was not oiled so the entire block inside and out was covered with surface rust. The heads are the large port '54 models purchased used from Bob at PowerPlay. The rest of the rotating assembly came from a '53 extended block hemi that was cannabolized and the block given to a friend who runs the this type block in his '34 Ford. The intake manifold is a stock '54 single four barrel with an adaptor to mount a 600 CFM Holley. Stock exhaust manifolds from a '55 C 300 Chrysler will be used with accompanying dual exhaust.
This will be a basic stock rebuild, however some modifications will be made and different parts adapted to increase reliability and performance. Since it will be used in the "Hemi Hauler" and will see many miles of both fun driving and long distance hauling duty, reliability is paramount.
Here's the block on the boring machine. Total machine work included cleaning, boring, checking the line bore and ballancing of the rotating assembly. The crank was turned -.010 both rods and mains and it was tapped for 1/2 by 20 bolts. While the block was at the machine shop I had them install a new set of cam bearings. Total cost for the machine work on the block, crank and rod reconditioning was right about $1000.
Prepairing the Block
Prior to assembly there are several things you need to do. The first thing is to thuroghly clean the block. This step is missed by many people when rebuilding the motor simply because they assume because they had the engine cleaned that it is clean. Not so. The block was cleaned prior to machine work so trust me, its dirty. I mounted mine on the engine stand and wheeled it outside where I used a plastic brush, dishwashing liquid and hot water to clean the bores till I could wipe a paper towl up and down the bore and have it come out clean.
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While cleaning the block temproarily install the block plugs and put a hose to the oil supply ports. This will allow you to check for obstructions in the oil passages throughout the engine. If water flows freely your oil passages are clean and free of obstructions.
Once you are convinced the block is clean remove the plugs and hit it immediatly with the air hose to dry it off. Make sure you get all the water out of the block and it is dry. Then take a paper towl soaked in oil or even 3 in 1 spray oil and coat the cylinder walls and lifter galleys. Don't forget to oil the cam bearings if they are installed to protect them as well.
Now that the block is clean and dry and the important machined surfaces an installed bearingas are protected from rusting we can turn to a few other tasks that must be done prior to assembly.
All early hemis used a bushing for the intermediate drive gear. This bushing is located in the block directly under the distributor mounting hole and is not usually removed by your local machine shop.
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You may have noticed that I painted the lifter valley. This is not necessary but does promote the free flow of oil back to the pan.
This bushing needs to be removed and replaced with a new one. The only way I've found to get it out is to turn the block over and find a socket that fits in the hole. It needs a little slop since you don't want it to wedge in there but also needs to fit pretty well. Then using an extension and the socket drive it out with a brass hammer. It will probably take several hard hits to break it loose but hang in there and it will come out.
Here you see the difference between the old (taller) bushing and the replacement. The new one is for a 340 but will work just fine. It must be driven in from the top of the block with a drift or if you don't have one a socket and extension will also do the job.
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Take care when driving this bushing in since its made of relitivly soft material.
Now is the time to remove the ball check valve in the main oil supply galley. The check ball is located in the oil supply hole near the rear main cap bolt holes. It must be driven out from the top using a piece of 1/8" steel rod. Just insert the rod in the oil pressure sensor hole at the top of the block until it contacts the check ball mechanism and using a hammer simply tap it out.
This is what it looks like when removed. There is a spring that isn't shown in the picture only because my spring was destroyed during the removal process. Make sure all remnants of the spring are removed from the block if it breaks as mine did.
The final thing you need to do is install all the block plugs. This includes freeze plugs, rear cam plug, and oil passage plugs. Here you can see that I opted for the mechanical type freeze plugs. These are simple to install and if they ever need replacing are again a simple installation. If you have ever tried to replace an expansion freeze plug in a tight engine compartment you'll understand why I went with the mechanical type.
The rear cam plug must be an expansion type plug and is installed using a ball type hammer or if you don't have one a smooth rachet extention will work. Simply insert the plug into the opening and "dimple" the center with the hammer. This expands the plug and seats it in place.
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Use a little High Tack gasket maker in the opening to provide a little extra insurance.
The last thing you need to do is install the oil filter bypass plug which is a must if you're using a modern filter. The plug diverts oil from the pump and sends it through the filter so the bearings only receive filtered oil. The plug installs in this hole with the little rubber -O- ring going in first.
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Use a little oil to lubricate the -O- ring prior to inserting it in the block.