".....i believe the valve covers with adjustable rockers had "bumps" in them to clear the adjusters......"

Yeah they did on the ones with adjustable rockers. I didn't know if Dodge did the same thing, so I looked it up in Tex Smiths HEMI book (bought a copy back when they were affordable) and they show the covers with the dimples.

After talking with them they have a process to relive the adjusters allowing them to be used with regular valve covers. I’ve talked with several HAMB members that had their valvetrain converted. They said that their valvetrain clears their valve covers. Only complaintI heard was the cost however given what you get it’s worth it for me.

any pics of what was done to the adjusters to clear the covers ?

“…….After talking with them they have a process to relive the adjusters allowing them to be used with regular valve covers……”

Cool. I saw where Hot Heads sells a 1” valve cover spacer kit for the Chrysler HEMIs but they don’t seem to offer one for the Dodge HEMI’s. Their pricy though, I suspect in part because they also include a set of longer spark plug tubes. By the time you buy the spacers you’re most of the way to what a set of aluminum covers cost.

I dont have them back yet. I called them today to verify they got my cores. It will take around 8 weeks to get them back.

All the machine work is done on the block. The “month or so” I expected it to take to get the backordered cam in turned out to be closer to 5 months, but it finally made it last week. My machinist likes to have the cam on hand when he installs the cam bearings (so he can make sure there won’t be any binding issues).

With that done the block finally came home and I chased the threaded holes, painted it and installed the freeze plugs and pipe plugs. It’s lot nicer looking than the ball of rust I brought home 3 years ago.

354 block by M Patterson, on Flickr

The crank’s out to be ground and then it and the rotating assembly will be balanced. So back to waiting .

it has been years since I work on a Chrysler Firepower hemi block, I'm thinking the pushrod holes in the block are not round like in your block picture.
Maybe now is the time to make sure the exhaust pushrods will clear oaky in your block

“……I'm thinking the pushrod holes in the block are not round like in your block picture…..Maybe now is the time to make sure the exhaust pushrods will clear oaky in your block …….”

Cab, frankly if this hadn’t started out as a potential POLY build I probably would not have understood what you are talking about. You are right about the pushrod holes on the late 55 and up HEMI blocks not being round.

My block as an early 55 HEMI block, hence the round holes . From late 1955 on the “HEMI blocks” had drilled/teardrop shaped pushrod holes as shown below.

Y valve Relief 2 by M Patterson, on Flickr



Y Valve relief 1 by M Patterson, on Flickr

Reshaping the pushrod holes was necessary when the blocks were fitted with Poly heads because of the different pushrod angles required for the single rocker-shaft and rockers they used.

1955 was the first year for the Poly engine (in the Windsors and Saratoga wagons) and was a 301CI one year only engine. In 56 Chrysler used the 55 331 CI blocks with Poly heads for the Windsor/Saratoga and in 57 and 58 they based the Windsor and Saratoga Polys on the 354 blocks. By reshaping the holes the blocks could be used with either HEMI or Poly heads. Some of these engines in both Hemi and Poly form also found their way into Dodge trucks (but I’m not real sure on the years or models).

I had been planning on doing the pushrod hole mods to this block for the poly heads until I figured out the 301 Poly heads I have wouldn’t work with the bore size we went with. For now it’s just going together as a HEMI and the factory holes will be fine. As far as building a Poly, I may have a line on a complete 57 354 Poly…….what’s another engine sitting around the shop

.

Dodge started offering a V8 for the Dodge trucks in May of 1954. I happen to have a 54 Dodge truck factory service manual here. That manual listed repair info for two different Hemi V8 motors and two different flathead 6 motors. One Hemi motor listed was a 241 Hemi, and the other Hemi motor listed was a 331 Hemi. The only thing that make sense would be that Dodge offered both a Dodge version of the flathead 6 and the Dodge 241 Hemi, and may have had the longer version of the Chrysler flathead 6 and the larger displacement Chrysler 331 Hemi as options over either of the smaller Dodge motors.

I remember seeing or reading that Dodge also offered a poly V8 in the trucks as well as the Hemi, but the 54 service manual doesn't have repair info on a poly motor at all, but the poly may have been offered after 54.
Got nothing covering Dodge cars. Gene

My 55 Dodge truck had a poly head in it when I bought it. It was still all original when I got it.

Chrysler call their poly motor Spitfires is what I remember now
I'm almost positive that Plymouths had V8 in 1956 in the Furys and maybe in 1955 also
I think they were 301 C.I. poly motors in both years, 1957 was the first year for the Plymouth 318 poly motors

Yeah Cab it can get a bit confusing trying to keep track of all the engines Chrysler, DeSoto, Dodge and Plymouth produced during the 50’s. Here’s a pretty good breakout of the 50s Plymouth poly engines.

https://en.wikipedia.org/wiki/Chrysler_A_engine

The Chrysler 301 Poly (Spitfire) engine shares nothing with the Plymouth 301 other than the displacement.

The Spitfire 301 is based on the 331/354 HEMI block (with smaller bores) and the blocks are externally (dimensionally) the same.

On a side note it’s amazing how many 1957 Plymouth 301s are misidentified as 318s by their owners.

Figured as long as I’m waiting on the rotating assembly to get back I’d take care of some small things.

I’m going to be running a Hot Heads dual plane intake on this one with an eye on eventually adding fuel injection.

HHI1 by M Patterson, on Flickr



I ended up doing a little relieving on some of the runners so it would be easier to get the cap screws to start straight when it gets bolted to the heads and also drilled and tapped the passenger side water port for a heater hose fitting.

HHI2 by M Patterson, on Flickr


When I got the 301 Spitfire heads I also salvaged a couple of 301 distributors out of the engines. They are the right length to fit the 331/354 HEMIs and Polys.


Dist 1 by M Patterson, on Flickr


They are also pretty easy to convert over to Electronic Ignition using stock SB Mopar parts. One was set up with mechanical and vacuum advance and the other has the advances locked out (for use with the fuel injection). The lockout was pretty easy to do using parts from a Lean Burn/Electronic Spark Control distributor.


Dist Conv by M Patterson, on Flickr


I went thru a swap meet AFB I’d picked up a while back, it was a little corroded on the outside but beautiful on the inside so it got a kit. It’s only 600 CFM but will do fine on the test stand to break in the cam and run occasionally.


carb 354 by M Patterson, on Flickr


and I got a few other parts painted.


misc parts by M Patterson, on Flickr


I still need to build an Air Cleaner, PS Pump Bracket, Alternator Bracket and AC compressor bracket, but that will all have to wait until I get the engine assembled.

i enjoy builds of uncommon engines.
thank you for the update !

Doing similar with my flathead 6 distributor, using /6 parts.

“……Doing similar with my flathead 6 distributor, using /6 parts……”

Cool. Have you figured out cap and rotor? On the conversions I did on the V8 distributor I had to use the later Mopar rotor and the 56 and up cap. The 56 distributor cap is taller than the 55 and earlier cap which allows room for the taller upper shaft and rotor.

The engine is going together. The rotating assembly got back from the balancer. The first order of business was getting the crankshaft in the block.


crank 354 by M Patterson, on Flickr


For the last few decades I’ve used Plastigauge for a quick check on the Mains and Rods when I assemble an engine. Normally everything’s fine. I’ve had a couple over the years where it did catch some problems……making me a believer that it’s important to do on every engine I build.

When I was checking the mains the clearance was coming out a little loose (as in about a thousands bigger than it should be).

So I pulled the crank and torqued the caps and bearings back in place. I pulled out the gauges and everything was right on the money (I did the rods the same way). Don’t know if I just got a bad stick of plastigauge or what. I don’t think it goes bad with age, even if it does, I just picked this batch up a couple weeks ago and it was about 65 degrees in the shop when I was doing the checking. When I posted this on another site I found out I’m not the only one who has run into this recently.

With the crank, rods and piston in, I installed the Hot Heads SB MOPAR oil pump, adapter and pickup. The instructions say a bit of fitting might be needed to get the neck on the drive to fully seat in the main cap (and on mine there was).


354 OP by M Patterson, on Flickr


There are 2 basic styles of passenger car oil pans for the 331/354/392 Hemi’s and Polys; the rear sump pans (foreground) used from 1951thru 1956 and the center sump used in 1957-8. For now I’m setting this engine up with a rear sump pan (and this became a bit of an issue a little later).


2 oil pans by M Patterson, on Flickr


I normally like to run a windage tray. Back when I built the 331 (in my 37 Dodge truck) and the 354 (in my 57 Plymouth) there were a couple of options available.

If you can find one, the factory actually used a windage tray the first couple of years of the 331 HEMI with the rear sump pan. The tray was bolted to the pan rail area on 4 legs. I used this setup with on the 331 I built with the rear sump pan.


3 0il pickup 331 Cap by M Patterson, on Flickr


When I built the 354 for the Plymouth they (can’t remember if it was Hot heads or PAW) offered a modified SB MOPAR windage tray for the early HEMIs’.



4 SB windage tray by M Patterson, on Flickr


Basically they relocated the tabs that bolt to the main cap bolts to move the windage tray up a bit for counter weight clearance. This setup worked great with the center sump oil pan on the 57 Plymouth.



5 Oil pickup 354 cap by M Patterson, on Flickr




I had a SM MOPAR windage tray and bolts set aside and figured modifying it should be fairly easy. This is when I discovered that the front section of the rear sump oil pan is a little shallower than the center sump pan. Basically I couldn’t get the windage tray high enough to clear the counter weights on the front throws without interfering with the oil pan.


340 WT by M Patterson, on Flickr


I looked up the windage tray Hot Heads sells to see how theirs looked. Basically their windage tray is shorter and stops just shy of the #2 main cap. The windage tray main cap bolts are now bolted on the #3 and #4 main caps.


It was a pretty simple mod so what the heck. Now do I NEED windage tray on a street motor that may at the most might see a drag strip once or twice…..NO. If I didn’t have the windage tray would I spend the money to buy one for this motor…..NO. Would it really bother me not to have a windage tray in this motor…..NO. Basically I had the windage tray laying around so all I had tied up in it was some time.


Mod Tray by M Patterson, on Flickr



So at the end of the day I now have a 354 short block.


354 SB by M Patterson, on Flickr



.

Those pistons look like Hemi pistons to me in a poly block, correct?
Will the hemi pushrod clear in that block without grinding?

“…..Those pistons look like Hemi pistons to me in a poly block, correct?
Will the hemi pushrod clear in that block without grinding?......”

No those are HEMI pistons in a HEMI (only) block.

The grinding would only be necessary if I was running POLY heads on this block.


Cab I think you probably missed the post I made back in September.


“…….Shortly after the last post I ran into a show stopper on the Poly portion of the build. Something I should have thought about when I started doing my initial measurements was whether there would be interference issues between the combustion chamber in the 301 Poly head and the size of the cylinder bore on a 354 block (there is .3125 difference between bore size on the 301 and 354). Basically the head overhangs the cylinder bore. I’ve got some feelers out for 354 Poly heads/a complete motor but so far not a lot of luck.

For now we’re going to go ahead with the hemi portion of the build. We got the block sonic checked to be sure it will safely go out the .125” to standard bore 354……….”

So basically the engine is going back together as a plain Jane old HEMI.

This is probably a good time to recap what I’ve learned so far so I’ll do that in the next post.

RECAP



This whole project started because of

“….A while back there was a thread “…..Chrysler,Dodge and Desoto early Hemi, what interchanges…..” and the discussion got around to whether Chrysler Poly (Spitfire) heads could be swapped onto a HEMI block……”

The part of that discussion that intrigued me was if a “sleeper” Poly motor could be built by swapping POLY heads onto a 392 block. That’s what started me down this road.

Doing the 331/354 instead of the tall deck 392 would still prove if it was possible or not. When I hit the show stopper of the head overhang with the 301 heads on the 354 bore and not having a pair of 354 POLY heads I decided to go ahead and built it back as the HEMI it originally was.

I only have access to the 301 heads I started with so some of this is still supposition. I still think it’s possible….with the right POLY heads.

Chrysler lists different part numbers for the 301, 331 and 354 Poly heads and based on what I ran into on the 301 heads I suspect the chambers are larger on the 331 heads and even more so on the 354 heads.

As far as just swapping a pair of Hemi Heads on a Poly or vice versa without any other changes other than the pushrods, it might be possible on a low compression engine without any problems. High compression pistons, high lift cam and/or larger valves would probably create issues and require a piston swap due to the location of the needed valve reliefs. One of the things I was going check was the feasibility of was just cutting a second pair of valve releifs into the stock 354 pistons.

As far as gaining or loosing compression with a head swap that will depend entirely on what you’re starting with and what you’re changing to. One of the things that really surprised me was that the 301 Poly heads and the triple nickel HEMI heads had virtually the same volume (about 101-102 CCs). I suspect the 331 and 354 heads have a larger chamber but without having the heads to measure that is still up in the air. The volume of the HEMI heads are also all over the place depending on the casting (for instance the 354 HEMI truck heads we measured have a larger chamber volume than the 55 passenger car heads).

On the combustion chamber overhanging the cylinder (the show stopper I ran into), I’m sure the heads were designed to accommodate a potential overbore of probably at least .060 oversize or so. So say 354 Poly heads on a .060 over 354 HEMI block should not be a problem. The issue might become using a 354 Poly head on a 392 HEMI block. The standard bore on a first gen 392 is approximately .062 larger than a first gen 354. At that point there should be no issue, but if you bore the 392 .060 over you’re now talking about a total of .122 total oversized and may run into the same combustion overhang into the bore problem.

Pushrod holes in the block going from a poly to a hemi head are a non issue. Going the other way may be. The angle of the pushrods when using poly heads required notches to be drilled/ground in into the block. 1955 was the first year of the POLY head and some HEMI blocks got the notches and some didn’t. If you’re going to the Poly heads on hemi block you will have to add these notches if they are not already there. Pictures I’ve seen of 392 HEMI blocks do not show the notches so going to the POLY heads will require they be added. On the plus side, modern composite head gaskets already are cut for either POLY or HEMI heads.

As far as pushrods, on the low deck 331/354 engines, the stock POLY pushrods are only about .065 shorter than the intake (short) pushrods on the HEMI, which is within the adjustment range of the adjustable pushrods Hot Heads sells. I suspect the same would be true for pushrods Hot Heads sells for the 392 tall deck motor.

So there are still some questions to answer that I can’t really do without having the parts in hand to check. I do believe that doing a HEMI to POLY conversion is still a possibility without having to do a lot of custom one off parts sourcing, just coming up with the right parts.

Why? I suppose just to have something a little different……and it would still be interesting to see what the difference in performance level really is…..remember the factory rated the 354 HEMI with more HP than the 354 POLY, but according to the factory manuals the POLY actually produced more Torque than the HEMI.