General Hemi Info Part 5

General Hemi Info Part 5


The builds:

Well, since I covered finding the parts required to put an early Hemi together, I figured I’d go ahead and talk about actually building one or two.

I’m be covering the 2 early Hemi’s I’m building, a 354 for the 57 Plymouth and a 331 for the 37 Dodge pickup.


The 354 has been bored .060 (which happens to be the same size as a standard bore 392 Hemi). Using stock 392 pistons yields a 10:1 compression ratio which with the Hemi heads is still streetable on pump gasoline. Displacement on the 354 is now at 365 cubic inches. The cam is a .450 lift/290 duration which is actually a reasonably stout grind for an early Hemi street motor.

The 331 is also bored .060 over and now displaces 341 cubic inches. It is receiving a set of aftermarket pistons and with the milling on the heads and block will be running a 9.5:1 compression ratio. The cam choice is a bit milder at .440 lift/280 duration. I chose this cam due to the smaller displacement and the plan to run an automatic and relatively high gears behind the engine instead of a 4 speed like the 354 will be getting.

The 354 will be getting cast iron manifolds (which actually flow very well) and at this time it’s up in the air whether the 331 will be getting manifolds or headers.

Both of these engines are build as basic street motors, nothing fancy or “race only”. They will both require premium fuel, but intended to be driven long distances and have a lot of miles put on them.

The prep:

Building a Hemi is no more difficult than building any other American V8 engine (a good deal more expensive than doing a SBC, but no more difficult). That being the case, I will not necessarily go into all the different aspects of engine building that would be common to any engine rebuild, but rather try to concentrate on those areas that specifically relate to building an early Hemi.

Like any other engine the first step is the tear down and inspection. Due to the weight of the heads, I prefer to remove (and re-install) the heads on the floor dollies I have built to move these engines around on. Once the heads are removed the short block is put on an engine stand and the disassembly completed. Don’t be shocked once you get the heads off, as impressive as the engine looks when assembled once the heads are off you’re got a basic MOPAR small block poly motor!!!!!!

During the inspection/tear down you’ll be looking for the same things you would in any other rebuild. This will include condition of cylinders, pistons, rods, crank etc.

Two things that you will want to remove prior to sending the engine off to the machine shop are:

The intermediate shaft bushing (the bronze bushing the intermediate shaft goes through. You can see this bushing in the picture that shows removal of the galley plug).

The oil by-pass valve located under the rear main cap. This is removed by pushing it out by using a 1/8 rod through the oil pressure sending unit hole.

Once the engine is stripped, it’s time to send it off the machine shop for all the standard procedures that take place during any engine rebuild.

For a “normal” street motor this should include vatting, polishing/grinding the crank, re-sizing the rods if necessary, boring, valve job (including guides and seats if necessary) decking the heads/block and any of the other things you normally would have done.

Unless you have already removed them, one thing to stress to your machine shop is to remove the galley plugs in the back of the block prior to it going into the vat (or however your machine shop cleans them. While the two larger outside plugs are not necessarily real critical to remove (they go into the water jacket), the smaller 2 plugs and the “hidden” one go into the oil galley and their removal is crucial to proper cleaning of the lifter oil galleys. The smaller of the 2 plugs the goes directly into the right side (passenger side) oil galley. The larger left hand (driver’s side) plug goes into the lifter valley, but needs to be removed to access and remove/install the oil galley plug in front of the intermediate shaft bushing.

The machine work can as simple as a “standard” rebuild or as extensive as prepping a full blown race motor. That will depend on what your plans for the engine are and your budget will allow.

If your building a normally aspirated street engine that will be operated at a reasonable RPM range, you really don’t need a lot high buck race prep as your starting out with a pretty stout motor to begin with.


Just because it’s a Hemi, the actual machine work should cost no more than having it done on any other engine, nor are there any other “special hemi steps” necessary required (based on the performance level your building for).

The crankshaft:

The early Chrysler Hemi’s all come with a steel crank that is more than adequate for street applications. If your going to go racing with one or building the engine to handle a blower/turbo they lend themselves to all the normal race prep procedures of any other quality crank.

One of the things you should spend a few minuets looking at however is the crank flange, primarily the pilot bearing area. I have come across 3 different pilot bearing configurations over the years and think I should bring this up. While the pilot bearing may not be a big deal if you are planning on running an automatic, it is critical if you’re going to run a stick (or if somewhere along the line you decide to convert from an automatic to a manual)

If the engine you are building came from an automatic equipped car chances are the crank has not been drilled for a pilot bearing at all. (See picture 1). The crank going in the 331 is an automatic crank, and while the engine was apart I had it drilled for the standard Chrysler pilot bearing just in case at some point I want a stick behind it.

On some of the industrial engines, the pilot bearing hole is VERY large. The good news is these are set up to use a sealed bearing and all that is required is one with a right inside and outside diameters. (See pictures 2 and 3).

Some of the cranks are just right and will take a standard 60’s-80’s Chrysler pilot bearing. I have also heard of some cranks having a pilot bearing hole that is just slightly larger that the common Chrysler bushing, in this case they do make an oversize bushing that will fit the crank with the proper interference fit (I picked up one of these some time ago “just in case”).

If you’re going with an aftermarket transmission adaptor is should come with the required pilot bearing/bushing.


Finally, when you have your block back and you put in on the engine stand, take a few minuets and make sure the crankshaft will actually go into the block with the engine stand head on. The Early Hemi cranks have a pretty good overhang, and it may be necessary to add some spacers between the engine stand head and the block so the crank will sit in the journals.

Short block 2:

The next step is laying the crank in. This is very straight forward. Personally I always check the bearing clearance for myself. I’ve used the same machine shop for many years and never had bearing clearance problems, but all it takes is one time on one bearing to ruin an engine.

There are 2 things you must remember to do in the rear main cap area prior to installing it for the final time:

Oil bypass valve or plug: If you are going to use the original style filter and originality is important then the original valve is the way to go. With this system, only a portion of the oil going to the engine is directed through the oil filter prior to going to the rest of the engine. This type of filtering was used for years, and as long as you change oil on a regular basis it generally does fine.

If you go to a more modern spin on type filter and a full flow type system (such as I’m doing) then you will need to use the by-pass plug. This goes in o-ring end first.

Whether using a bypass valve or plug it is critical that the slot be aligned with the oil passage that goes through the block to the oil filter boss. The line on the block corresponds to the oil galley that feeds the filter, and this is the direction the slot in the bypass plug must be oriented to.

Finally you also want to make sure that alignment dowel is in place between the block and the rear main cap. In many case these dowels have been lost if the engine has been taken apart before, but replacements are available. You can also see the rear main-cap dowel in the block. It simply taps into the block prior to the rear cap installation.

Short block 3:

The early Hemi’s have full floating pistons with the piston pins being retained by snap rings. As the pins are not a press fit they can easily be assembled by you rather than the machine shop (saving a few dollars). They are assembled on the rods so that:

1. The arrow, notch or hole (depending on the piston) will face the front of the engine.

2. The bearing alignment tabs on the connecting rod bearing face the OUTSIDE of the block.

3. The oil “spit-hole” is pointed to the inside of the block.

4. As on most engines with snap ring retainers the opening on the snap ring should be either at the top or bottom of the piston, not the side and the retainer should be tight in the groove, not loose and able to spin around..

When you get through you should have 4 piston/rod assemblies of the right bank and 4 for the left bank.



Once the piston/rod assemblies are assembled and rings installed they go in just like in any other engine.

Short Block 4:

Oil Pans, Windage trays, and oil Pumps:

There are basically 2 types of stock oil pans for the early Hemi’s, a rear sump pan and a center sump unit. If your using a stock pan which one you choose will depend mainly on which one you have/which fits the car best (A center sump is REQUIRED if the engine is going into a 57-62 full-size MOPAR).

The use of a windage tray on a street engine is really a matter of personal preference and budget. Over the years many of the big 3 factory high performance engines came from the factory with them but an even bigger number didn’t. In the case of Chrysler’s early Hemi’s the factory installed a windage tray for the first few years and then dropped them. Personally I do believe they do some good at higher RPM and I am using them on both motors.


There are also 2 different styles of windage trays that can be used with these pans. The first is the 4 legged original early Hemi style. These were used on the early 331, but were dropped by 1955. The 4 necessary holes to mount these can be easily drilled into any of the early Hemi’s if you choose to run one on a Hemi that wasn’t originally equipped with one. Sitting on the engine they don’t look like they would be very effective, however once you look at how they sit in a stock rear sump pan you can see that they will be pretty effective.

The second style you could run with a stock pan is a modified Small Block MOPAR unit. These require the use of four special main cap bolts used to retain the tray, which has also been slightly modified by enlarging the mounting holes. This windage tray looks like it will work slightly better in the center sump pans.

One thing you might want to consider when deciding on whether you want to run a windage tray is the extra hassle they create if you ever have to remove the pan with the engine in the car. It’s one more thing that will have to be cleared if the pan has to come off and in some bodies this could be a real hassle.

Oil pumps: There are basically 3 types of oil pumps available that can be used in the early Chrysler Hemi. The type you use will depend in part on the type pan you choose to run.

The first is the stock type pump for the rear sump pan. It is necessary to use the correct original style pickup (either floating or fix depending on the pump style. I’m using the floating pickup on the 331.

The next style is the stock 392 pump which takes a threaded pickup and is necessary when using the stock 1957/8 passenger car pans.

At one point the supply of original style oil pumps appeared to be drying up (fortunately I had already bought my pumps before that happened). With the perceived need for replacement pumps due to the growing demand to build these old engines and design of some of the aftermarket pans, one company started building an adaptor to use a 340 high volume oil pump. Use of this pump and adaptor is largely a matter of choice partially dependent on the oil pan you are running. It should be noted that I have read in several places that the “high Volume” 340 pump only moves approximately 3% more oil than the stock 392 pump.


(One little side note on windage trays; around 68 or 69 when I was working in a Chrysler/Plymouth dealership I remember that Chrysler recommended running their factory Big Blocks that were NOT equipped with windage trays 1 quart low on oil at the drag strip. It was worth 1/10 second allowing non-windage tray cars to run a quickly as the windage tray equipped cars.)

Oil filter adaptors come in 4 basic flavors, the stock by pass style filter canister such as you likely got with the engine. An adaptor for a spin on filter (full flow) that positions the filter in the same position as stock (the filter sits upside down making for messy filter changes, but is some times required for clearance such as my 57 Plymouth). An adaptor that goes straight down, and finally a plate that allows you to run hoses and a remote filter setup.

Short Block 5:

Cams: Cam selection will be based primarily on what you want the engine to do. Sources for new on the shelf non-stock cams presently seem to be limited to PAW and Hot Heads. There are also still a few services such as Egge that can also re-grind you original cam. For exact selection of grind to meet your specific needs I would highly recommend talking to the manufacture/sales reps.

There are few other things that you should be aware of. As I understand it when the raised block 392 was produced, the angle of the lifter bores was changed slightly requiring a different spacing on the cam lodes in relation to each other and while the cams physically interchange, installing a 331/354 cam into a 392 or the other way around it will result in a very poor running engine.

There were also early and late style cams, the early style with the long snout and the latter style (55 and up) that is shorter and uses a single cam bolt. All of the aftermarket cams to my knowledge are the later style which can be installed in the earlier blocks by using the latter style cam thrust plates (available through the aftermarket).

If you using the shallow aftermarket timing cover and short BB water pump there is also a recessed cam bolt that must be installed in order for the cover to clear.

Lifters:

If you’re using a hydraulic cam, the supply of OE lifters has just about dried up. A suitable replacement is the 58-65 BB Chrysler lifters. These only have 1 of the 2 grooves found on the stock lifters, but they work and if you order the lifters listed for the early Hemi, these are the ones you get. You might find like I did that they are cheaper to buy locally than to special order.

Timing Chains and covers:

A few years ago you could still by the original style wide timing chains for the early Chrysler Hemi’s (which I am using on the 331) but I don’t know if they are still available. Fortunately these engines can use Small Block (LA) style timing chain sets. The 354 is getting a double roller set. As they can use the timing chain sets, I also suspect that a SB MOPAR gear drive could also be installed if you are so inclined.

For the timing chain cover you have a couple of options. If you use the short BB Chevy water pump your pretty much have to use the shallow aftermarket timing cover. Besides the recessed cam bolt, you also have to flatten the oil slinger in order for it not to rub on the inside of the timing cover, and you cannot use a fuel pump eccentric with it. It will provide a bit more engine clearance through.

If you going with a long BB Chevy water pump you can use the stock timing cover (and have a fuel pump eccentric if desired). If you can use this style pump you may be better off in the long run. Besides not having to have the special timing cover, the long pump is more common (and cheaper) and in smaller towns the long pumps are generally stocked on the shelves of most part stores as opposed to having to special order the short pumps. The availability of the long pumps can lead to a lot of piece of mind if you take your Hemi on a long road trip (unless you plan ahead and throw a spare pump in the trunk (like I’ll be doing when I go to Tulsa).

Installing the heads: This is very straight forward but as I said earlier may be easier and more safely done with the engine on a floor dolly but it’s up to you. Just make sure you have the head gaskets positioned properly. As the head bolts also retain the rocker shafts, once the head is sitting on the dowels, install the pushrods and rocker shafts. BEFORE you tighten down the head bolts insure the rocker shafts have been correctly assembled and are correctly installed. There is on rocker stand on the intake side of each set of rocker shafts that has a cast in oil passage that must match up to the oil passage located in the head. There are also 5 short and 5 long head bolts per head. The long bolts go on the exhaust side of the head.

Torque the head to specs using a circular pattern and you are done with the head install.



Rockers/push rods: Again a few options also exist in this area. If you are running a stock/original grind cam (and have not milled the heads or block excessively) you can get by with stock hydraulic (non-adjustable) rockers and pushrods.

If you are running an aftermarket/re-ground cam, have done a lot of milling, or are running solid lifters you will need either adjustable rockers or adjustable push rods.

Only a few of the early Hemi’s came with adjustable rockers the 300 letter series cars and SOME on the industrial Hemi’s ( I have torn several industrial Hemi’s down that had hydraulic cams and non-adjustable rockers to include the 354, even though ALL industrial valve covers have the dimples for adjustable rockers). Adjustable rockers do occasionally come up on E Bay both OE and early aftermarket units, but they are pricey.

The other option is adjustable pushrods. These can be a PIA to adjust, but they are a cheap and effective alternative, and they do let you run Stock style non-dimple valve covers if you wish. As I said they are a pain to adjust especially the intakes, but with a little patience it is doable. I have heard of some people installing the adjustable pushrods in upside down (both ends are shaped the same) which would make adjustment considerably easier, but would require the intake being removed is a latter adjustment is required.

Pre-oiling:

Pre Oiling on ANY freshly rebuilt motor is critical and even more so on an early Hemi. The rocker shafts are hollow and are filled with oil to lubricate the rockers. If the engine is started dry it is very likely that you will destroy the rocker shafts. I normally prime these early Hemi’s 3 or 4 times before I start them for the first time to insure that they are completely pre-oiled before the initial start. It’s pre-oiled when you have oil out of ALL the rockers.

A tip here, you will want to put some rags down in the sparkplug wells and bolts in the upper exhaust manifold stud-hole to prevent the oil run off from filling the cylinders or running on the floor.

Odds and ends:

At this point you are basically ready to put the accessories on and start it. A few last things I’ll pass on as general information that might be useful:

Balancers: Something else you have some choices on. You could use the stock one IF it’s in good shape, but any balancer 50+ years old would be questionable. You could go for the Hi Buck SFI approved units, or you could use a replacement stock type balancer which is usually a modified 340 unit. Now the 340 unit IS NOT a bolt on. The keyway is too small on the stock 340 units and chances are the timing marks will not be in the correct place. Hot Heads does sell a modified unit that is a bolt on and has timing marks located for most timing covers. It’s well worth the piece of mind. The first picture shows (clockwise from the top left) a stock 2 piece balancer and hub assembly, stock 1 piece balancer, stock SB Mopar balancer and finally a Hot Heads modified unit. The second picture shows the difference in keyways between the modified and stock units.



Pulleys:

Stock Mopar BB and SB will bolt not only to the modified 340 aftermarket balancers but also to the OE early Hemi balancers.

If you are using a 4 groove lower Mopar pulley, the inner 2 grooves are slightly larger than the outer 2 grooves. A belt on an outer grove and one on an inner groove CANNOT also go over a common 2 grove pulley due to the difference in belt speed.

If you use the short aluminum lower pulleys (such as those sold by Hot Heads) and a short water pump, a 2 groove SBC water pump pulley (stock or one of the chrome aftermarket ones) lines up perfectly.

Bolt Sealant:

Sealant should be used on certain bolts/studs. The upper 3 valve cover bolt holes are drilled and tapped into the water jackets and needs sealer. The upper exhaust manifold bolts are drilled into the inside of the head where the oil collects when the engine is running (you might want to screw some bolts in these holes if your priming the engine if the manifolds are not on yet). The lower exhaust manifold holes are drilled and tapped into the water jackets.


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All in all there really isn’t mush more to building one of these than any other engine, just like any build take your time and do it right.

Great posts and thanks for taking the time to write this up! I know it's helping me out a ton!