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331 hemi in a 55, 56 Plymouth or Dodge
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halosoldier
Posted 2015-02-24 5:36 PM (#470834)
Subject: 331 hemi in a 55, 56 Plymouth or Dodge


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Location: ocala, fl
What is the best way to install an early hemi in these cars. I know PAW made motor mounts for this but PAW has been out of business for awhile. I hear stories about using poly head 318 motor mounts with a slight modification. Butch's cool stuff has a swap kit for a small block Chrysler. Hot Heads has a motor mount kit for the early hemi. Or should I save myself a headache and just put in a small block Chrysler?
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Rodger
Posted 2015-02-24 7:15 PM (#470847 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge


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Hola John

Is the vehicle an Manual or an Automatic ?

Does it still have any parts of this ?



Rodger & Gabby
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hoodinki
Posted 2015-02-24 8:22 PM (#470859 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge


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Dodge and Plymouth changed their motor mounting designs from 1955 to 1956. Up until 1955, they had a single point mount under the water pump and wide rear mounts on bellhousing ears for standards and a special wing for automatics. In 1956 they flipped and put wide mounts on the front corners of the blocks of V8's and a single point under the bell housing for standard or under the tail of automatics. The rear cross members of automatic cars are removable, and far more aft of the standard transmission. The rear cross members for standards are welded to the frame.

Why not just get a 1956 Dodge 325 hemi and bolt it right in? Fits in 55-56 Plymouth real good. A 331 offers not a whole lot more than a lot of weight. The 325 has dual quads available, and a rebuild can punch it up to 350 ci and a 9:1 compression.
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wayfarer
Posted 2015-02-26 12:42 PM (#471029 - in reply to #470859)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge



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hoodinki - 2015-02-24 5:22 PM

Dodge and Plymouth changed their motor mounting designs from 1955 to 1956. Up until 1955, they had a single point mount under the water pump and wide rear mounts on bellhousing ears for standards and a special wing for automatics. In 1956 they flipped and put wide mounts on the front corners of the blocks of V8's and a single point under the bell housing for standard or under the tail of automatics. The rear cross members of automatic cars are removable, and far more aft of the standard transmission. The rear cross members for standards are welded to the frame.

Why not just get a 1956 Dodge 325 hemi and bolt it right in? Fits in 55-56 Plymouth real good. A 331 offers not a whole lot more than a lot of weight. The 325 has dual quads available, and a rebuild can punch it up to 350 ci and a 9:1 compression.


Extreme over-boring any of the EarlyHemi engines is a recipe for disaster. You simply will not gain enough to compensate for the
weaker cylinder walls. Period. You want more power ? use forged pistons and 10:1 c/r.
Always, always, always sonic check each cylinder before doing any cutting.
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wayfarer
Posted 2015-02-26 12:48 PM (#471030 - in reply to #470834)
Subject: RE: 331 hemi in a 55, 56 Plymouth or Dodge



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halosoldier - 2015-02-24 2:36 PM

What is the best way to install an early hemi in these cars. I know PAW made motor mounts for this but PAW has been out of business for awhile. I hear stories about using poly head 318 motor mounts with a slight modification. Butch's cool stuff has a swap kit for a small block Chrysler. Hot Heads has a motor mount kit for the early hemi. Or should I save myself a headache and just put in a small block Chrysler?


The EarlyHemi has virtually the same ears on the block as all of the pre-62 A series engines. The later LA ears only vary slightly so mounts can be made to fit the block w/o much hassle. If the subject car has side mounts then an EarlyHemi (except the 51-53 33) will be an easy bolt-in...as far as the mounts go. Clearance around other stuff will be another issue.

RLTW
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halosoldier
Posted 2015-02-26 5:15 PM (#471056 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge


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Location: ocala, fl
The car in question has an auto.trans thanks for the all the replies. The 331 hemi will have 10:1 comp.ratio, Isky cam, Arias pistons. The heads have been rebuilt using all Hot heads parts (good bunch of people in Low Gap, NC.) I used a 331 poly bock from a 56 Chrysler Saratoga. That means the block wasn't beaten to death. I've heard of people over boring these blocks to 354 cubic inch, doing this you end up with an expensive boat anchor. The Chrysler Hemi has a decent parts train behind it not so much for Dodge and Desoto. Oh yeah, I will be using a hot heads single4 barrel intake manifold, I will be using the chevy water pump adapters so the weight will be somewhat reduced. Msd billet distributor, Edelbrock carb I haven't eaten for weeks oh well hobbies can do that!
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Handygun
Posted 2015-02-26 6:16 PM (#471065 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge


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Powerflite has a post on putting a 700r4 in a 56 Ply in the Hot Rod section, he would be a good source on putting a Chrysler in a 56 Plymouth
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hoodinki
Posted 2015-02-26 6:54 PM (#471072 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge


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These engines were thick wall castings, there is a stupid amount of meat in the cylinder walls. The way machine shops handle the risk of an overbore is to bore it and measure the wall thickness. If too thin, then that cylinder gets a sleeve. But staying stock at 325 ci is better in any event. The 354 was a bored out 331. But I see you're stuck on using the 331, so never mind.

I had a 55 Chrysler 331 hemi with a 56 Imperial Torqueflite on it and used an engine hoist to experiment with positions in the chassis of a 56 Plymouth when I had its body off. Not a good fit, it was happy nowhere. Too much weight, too wide, too long. Trouble with a Capital "T".

So I wound up getting a stock 277 poly and finished it that way.
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Handygun
Posted 2015-02-26 8:16 PM (#471080 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge


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Machine shops around here usually sonic check the clock to check for wall thickness prior to boring, probably 180/120 max/min, something around there. Different builders have different preferences. Core shift is another issue. 331's and 354's are different castings. Personally I would bore to whatever cleans it up, leave as much material for ring seal and cylinder stiffness. 325 vs 331 the Chrysler will make more power because the head is better.
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wayfarer
Posted 2015-02-27 12:44 PM (#471145 - in reply to #471072)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge



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hoodinki - 2015-02-26 3:54 PM

These engines were thick wall castings, there is a stupid amount of meat in the cylinder walls. The way machine shops handle the risk of an overbore is to bore it and measure the wall thickness. If too thin, then that cylinder gets a sleeve. .


More internet fallacy.
The walls are not 'stupid thick' and they DO have terrible core shift issues. You best sonic check the walls before cutting unless you own stock in one of the sleeve companies.
There is simply NO performance advantage to huge overbores but you are entitled to believe what you want to.
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Shep
Posted 2015-02-27 1:18 PM (#471156 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge



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Well over boring will increase compression and free up some airflow but in daily drivers this is not a big deal, especially risking thin cyl.
walls.

Edited by Shep 2015-02-27 1:19 PM
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58coupe
Posted 2015-02-27 4:15 PM (#471174 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge



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What is a safe overbore for these early hemis (assuming little or no core shift)? I have a 55 331 hemi that has already been bored to .040 over. Unfortunately, the previous owner did not take care of it and let water rust a couple of cylinders, I believe one cylinder will not clean up at .060 so I could have it sleeved. I also have a 57 354 poly that I believe has never been apart and would rather build that as a hemi.
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hoodinki
Posted 2015-02-27 8:40 PM (#471192 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge


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Some of us here don't know what we're talking about. I hope it isn't me.
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halosoldier
Posted 2015-02-28 3:41 PM (#471251 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge


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Location: ocala, fl
Well if you're talking about me so what. I saw this swap done on a 56 plymouth , guy dropped a stock 392 Chrysler Hemi with some minor mods
I wouldn't use an Imperial transmission. I forget what issue of Mopar Muscle , some person dropped a nicely done 392 Hemi into a 56 Fury and it looked factory. As far as overboring a 331 hemi just do it. A few guys I llistened to said if you want a 354 hemi get one. Those guys I'm talking about are Don Garlits and Gene Adams. I probably will use stock car exhaust manifolds rather than the truck manifolds. The manifolds will hurt power , that's ok I want to build something reliable and have fun.
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halosoldier
Posted 2015-02-28 5:03 PM (#471253 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge


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Posts: 17

Location: ocala, fl
Hoodinki, have you ever been on the Hot Hemi heads internet site? Some guy dropped a 354 hemi into a 71 Dodge Dart. You will find all kinds of stuff that seems impossible possible. Hot hemi heads, Lowgap, NC. Talk to Bob Walker and the good folks there.
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d500neil
Posted 2015-03-01 4:22 AM (#471275 - in reply to #471253)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge



Exner Expert 19,174 posts. Neil passed away 18 Sep 2015. You will be missed, Neil!

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And, FWIW, in the early 80's, during an engine overhaul, had my 325 '57 Hemi bored 40-over (to 330/331?) due to discovered
corrosion in the cylinder walls, from the car's having been dead-stored, in Indiana, before I bought it.

Absolutely no subsequent operational issues have ever occurred, from that overhaul work.


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Beltran
Posted 2015-03-01 10:23 AM (#471290 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge



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John there is a happy medium somewhere. I think folks are just giving you the heads up that there are limits. Any overhauled engine is going to get some cylinder cleaning. I had my 354 overbored .30 to accommodate new pistons and clean up a tired old block. I also strongly recommend having yours line bore checked. Due to the fact that my block was a boat motor in a previous life, I had egg shaped mains. This was fixed by the machine shop (my second one).

I have used a similar plan in my engine, same companies. I have extra parts for various reasons. If you care to bounce your plan off me for lessons learned, feel free to send me a PM and we can chat about it. I will be travelling the next couple of week but will try to check in on the web site.

Edited by Beltran 2015-03-01 10:25 AM
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Mopar1
Posted 2015-03-01 2:20 PM (#471315 - in reply to #471290)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge



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Somewhere on one of the sub-forums here there is a fairly lengthy thread on putting a 331 into a 55 or 56 Plym. Seems to me the OEM tranny cooler on the W/P had to be deleted, maybe a 392 center sump oil pan(needed that when I put a 331 into my '60 plym), The HH verticle oil filter adaptor won't work you need their OEM up angle one. A generic comment is most 331 can be bored to 354 std., but should only be done with a sonic check. As was said I'd go minimum overbore. "Wayfarer" is Quality Engineered Components, I've used his tranny adaptor to put modern 727s behind my 331 projects & really happy with them
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Mopar1
Posted 2015-03-01 2:21 PM (#471316 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge



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Used "A: Poly uppers & fabbed the lower mounts.
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halosoldier
Posted 2015-03-05 1:50 PM (#471692 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge


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Location: ocala, fl
Here's another question on a 56 plymouth can a baby hemi front engine mount be used? The kind that is sold by Speedway motors part #135-5355.
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wayfarer
Posted 2015-03-06 12:29 PM (#471802 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge



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Assuming that you are dealing with a 241-260-270 with the oem front mount (and oem trans arrangement) then you can use the oem mount without
spending money on the aftermarket piece. assuming.....
If you are adapting a different trans and lose the bellhousing mounts then you have more work to consider. I'd be a bit hesitant to rely on the
small timing cover bolts on the speedway mount if the rear mount is at the back of a TF or something.
Just me.......
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halosoldier
Posted 2015-03-06 12:49 PM (#471803 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge


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Location: ocala, fl
I know. I'm just trying to get some "education" by asking the good folks on this forum, because they have been there and done that. I saw a cool 55 Dodge on ebay with an injected 392 hemi that looked pretty boss. Like I have stated before my Hemi will be a 331 Chrysler Hemi with a trans adapter from Hot Heads for small block 727/904.
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hoodinki
Posted 2015-03-06 6:52 PM (#471833 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge


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Here's a Dodge V8-270 hemi that way installed in a 55 Plymouth convertible. Notice how in the later pictures the early hemi has been fitted with a crank vibration dampener from hemi hotheads and a later crank pulley of the bolt-on type.

Edited by hoodinki 2015-03-06 7:02 PM




(P1010219.JPG)



(P1250018.JPG)



(20130323_121327.jpg)



(20130323_121321.jpg)



(20130323_121243.jpg)



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Attachments P1250018.JPG (95KB - 150 downloads)
Attachments 20130323_121327.jpg (92KB - 193 downloads)
Attachments 20130323_121321.jpg (97KB - 144 downloads)
Attachments 20130323_121243.jpg (87KB - 135 downloads)
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halosoldier
Posted 2015-03-07 11:26 AM (#471890 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge


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Location: ocala, fl
Great information with the pix. I do have that mount in my garage. I hope I don't keep throwing dumb questions. With that timing cover mount did you use a traditional transmission crossmember and did you fab the mounts on the frame that bolts to the timing cover engine mount? Thanks.

That's the trouble with the speed of light: it gets here too early in the morning.
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Mopar1
Posted 2015-03-07 12:40 PM (#471896 - in reply to #471890)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge



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halosoldier - 2015-03-07 10:26 AM

Great information with the pix. I do have that mount in my garage. I hope I don't keep throwing dumb questions. With that timing cover mount did you use a traditional transmission crossmember and did you fab the mounts on the frame that bolts to the timing cover engine mount? Thanks.

That's the trouble with the speed of light: it gets here too early in the morning.
The HH adaptor is a full circle design the Bob says is installed before you put the oil pan on. If you can't drop the oil pan when installed, you'd have to pull the engine/tranny together to get either out. The QEC one is a horseshoe style & it works. I'd think I'd cut the bottom off of the HH one to get normal access to unbolt the engine & tranny from each other in there are problems later.
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hoodinki
Posted 2015-03-07 3:04 PM (#471917 - in reply to #471890)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge


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This car needed to have its X-member 1955 Plymouth convertible frame replaced. I also wanted 3-speed overdrive. That car was originally an automatic with the removable rear crossmember. So a standard transmission 1956 frame was available and the X-channels from the original frame were transplanted into the replacement. The rear crossmember was the welded in type and had the single mount under the center of the bell housing. (That supports the engine when the transmission is pulled back for clutch service.

I am unaware of any oil pan issues with this HH mount.

I did fashion the mounting pads on the frame using standard pieces available from Speedway. I choose to bolt them to the frame, but welding them on may have been better.
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Mopar1
Posted 2015-03-08 9:30 PM (#472022 - in reply to #471917)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge



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hoodinki - 2015-03-07 2:04 PM


I am unaware of any oil pan issues with this HH mount.

.
I was talking about the tranny adaptor being full circle
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hoodinki
Posted 2015-03-09 11:24 PM (#472110 - in reply to #470834)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge


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Rear mounts used up to 55. And How 56 was different.

Edited by hoodinki 2015-03-09 11:33 PM




(1955 Rear Mounts.jpg)



(1956 Rear Mount Std Trans.JPG)



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Attachments 1955 Rear Mounts.jpg (99KB - 161 downloads)
Attachments 1956 Rear Mount Std Trans.JPG (98KB - 145 downloads)
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Powerflite
Posted 2015-10-14 4:19 PM (#492273 - in reply to #471251)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge



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halosoldier - 2015-02-28 12:41 PM

... I probably will use stock car exhaust manifolds rather than the truck manifolds. The manifolds will hurt power , that's ok I want to build something reliable and have fun.


Looks like I am really late to this discussion, but... I have done this swap and made it work really nicely with the motor at the stock height, but shifted to the left to center the motor in the engine bay. It is likely that the reason hoodinki couldn't find a good place for the Chrysler hemi to sit in the '56 was because of the exhaust manifolds. You can't use any stock manifolds and expect it to work out well. You need custom headers or modified ones like I did. It is possible to use stock manifolds, but you have to jack up the motor and put the drive train at a lousy angle to make it fit. It isn't worth doing it that way.

Have you made progress on your build?
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Mopar1
Posted 2015-10-18 4:13 PM (#492555 - in reply to #471251)
Subject: Re: 331 hemi in a 55, 56 Plymouth or Dodge



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halosoldier - 2015-02-28 2:41 PM

. I probably will use stock car exhaust manifolds rather than the truck manifolds. The manifolds will hurt power , that's ok I want to build something reliable and have fun.
The 4 bolt truck ex mans will flow better than 2 bolt car ., basically what they used on the 300 cars
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