Differences between 51 and 55/56 308 engines

Hienkel429

Hey all.

I started wrenching on the engine in my 51 Hornet in earnest and discovered something pretty quick.  I am almost 100% certain it is not the original engine to the car.  The car still has its single range automatic but the 308 in the car has some "different" characteristics.  #1  The engine has a faded grey paint job.  #2 The vibration damper has two grooves.  #3 It has the later style intake manifold with the balance tube cast into instead of on the outside. 

So... questions would be 

#1  Should I really care as long as it is solid?

#2  Does the second grove in the damper give me any ability in the future (besides power steering, I've heard they're rare((both the pulleys and power steering parts)) )?

#3  Any parts not compatible between early and later 308s?

#4  Overall opinions or thoughts? 

Thanks all... getting the timing cover cleaned up over these next few days.  

- Ray

Ol racer

FYI
The most common difference is the Block will have 1/2" Head Bolts, but someone may have drilled & Tapped  them larger ...
 The other things are Valve Relief is a little wider, the Crank is a little shorter requiring a spacer when using earlier trans, the Crank Flange uses 1/2" SAE Bolts to retain the Flywheel.. Additionally, they have Hyd Lifters, different cam,  and the rear Main Seal is Neopreme instead of the old Rope style............ Many prefer the '55 - '56 Motor..
 Only negative ive ever heard is some say they are not as 'High Nickle' Alloy as earlier blocks...Dont matter though...

Glowplug

The following link located on my website is an excellent explanation of the Hudson 6 cylinder engine differences.

http://hudsonrestoration1948-54.com/Demystifying HudsonStepdownL-Head6CylinderEngines_RalphAlden.pdf

Nevada Hudson

The following link located on my website is an excellent explanation of the Hudson 6 cylinder engine differences.

http://hudsonrestoration1948-54.com/Demystifying HudsonStepdownL-Head6CylinderEngines_RalphAlden.pdf

Seems there is a fee to enter that site.

Hienkel429

Thanks all, I did find the write up after some digging.  

Hey Ken,

Hmmm.... It might be a replacement engine.  There is a weird tag attached to the head.  I will get a picture of it when I get home.  The beer in question is Hohenthanner.  You definitely want the the dark.  Will prob be difficult to find outside of the Munich / Bayern area.  Enjoy!

- Ray

super-six

Don't all later Hudson engines have the cars serial number stamping?

Glowplug

Sorry, to access the content of my website the index page must be used.
http://hudsonrestoration1948-54.com/

The initial notice is my way of reminding users that I do not use advertiser revenue to provide the technical information, the full cost is borne by myself and the generously of those who donate.

Hienkel429

Here's some more pics... some red paint peeking out from under the grey but might be some sort of primer?Serial number on the nub of the block near the head is mostly obliterated and looks to begin with a F13_____ .  Also weird tag of H-315 on the coolant neck.

super-six

The location of the serial number on the block looks to be of a '55 or '56 engine.

TwinH

My 55 engine was red under the gray too. Looks like it was primed with Glyptal before any machining was done as every unmachined surface on the block had the red,even the edges of the water jackets on my never run 55 motor. The hot tank removed the gray in short order but didn't touch the glyptal,so I left it.

dougson

Hydraulic lifters were used only in '56, lessons learned from Hash bodies being too narrow to adjust solid lifters. The '56 cam was a redesigned "7X flat top" with slightly higher lift and longer duration than the '55, which was a basic, standard issue Hudson cam. Both '55 and '56 engines had 1/2 " head bolts and better flowing coolant manifold than earlier engines. Both '55 and '56 engines had the equalizer tube on the intake cast into the manifold because of, again, space issues in the Hash engine compartment.