308 bore spacing?

super651 · July 2007

The was a picture showing the 308 bore spacing ? and the Valve Off-Set ports in each cyl. Please post that info . Needed for a Test on 55-56 blocks.

Thanks To all Rudy

[Deleted User] · July 2007

What measurements are you looking for Rudy? I have a '55 and a pre '55 engine in the shop to compare.

I believe you are thinking about the "Building the 308" thread not so long ago. I posted some pictures, but not any measurements.

A link that that thread;

http://www.classiccar.com/forums/showthread.php?t=10084&page=5&highlight=mark+7x+relief

I have some pictures in my gallery here at Classicar, also some pics of your stuff as well.

Here are cylinders 1&2 '53 308

3&4

5&6

The red lines are the gasket location. Where the red stops to the outside, the gasket starts. Kinda gives you an idea of how dissimiliar the valve locations relative to the cylinders actually is.

A link to my gallery here at Classicar.

http://www.classiccar.com/photopost/showgallery.php/cat/500/ppuser/69

Mark

[Deleted User] · July 2007

You can kinda get an idea of the intake port bias relative to the intake valve position from this picture. This is a '53 308.

Mark

464Saloon · July 2007

Hey that Fluorescent tube looks familiar in that shot. You weren't by any chance checking deck height were you?

[Deleted User] · July 2007

Yep, how in the world did you know? LOL

It works, hard to find a good standard straight edge that long that doesn't cost as much as a set of pistons!

Mark

super651 · July 2007

Mark, thats the Pictures we are looking for.

Thanks so much. Pal Rudy

We will also use your wbe-page.

[Deleted User] · July 2007

I'm even more curious about what you and the local boys have up your sleeve?

Mark

super651 · July 2007

Mark, one of the locals has a wild card up his sleeve so, we will see in the future.

Is it true that the 55-56 308 blocks have very little or no nickel in the cast blocks? Saw it printed few years back ?

Thanks Rudy

[Deleted User] · July 2007

This is true. AMC cost savings. And we all know how that went.

bob ward · July 2007

Getting a little off topic here, but while we are looking at nice clear pictures of the top of a 308 block, what exactly is the fabled "7X valve relief"? Is it the removal or the refining of the shape of the 2 pointed parts of the deck that stick out from the gasket line?

[Deleted User] · July 2007

it is removing and smoothing firstly the pointed sections between the piston and valves and adding a nice radius into the deck area around where the valves open. imagine a radius cut inside of the lines mark has put in there. it allows air to flow in from around the back of the valve as much as the front. im sceptical about its efficiency

[Deleted User] · July 2007

Guys,

the whole deal about the 55-56 blocks being cast with no nickle content

I believe is BS. I went thru several carbide cutting tools doing my roughing in work and about 10-12 expensive shapped cutting tips doing the fine work in the air powered die grinder. With the other cylinder heads I ported I could

do several heads with one shapped cutting tip no problem.

This got me thinking about what several guys were saying about the

cheep cast iron AMC used in these. I used a small shop vac and saved a

box of shavings and had them analized. (It helps when friends work

at places that can get that done for free!)

The nickle content was high & the guys in the lab wanted to know what

it came from. They were use to checking the cast iron in their own diesel

blocks but their material used a small ammount of nickel.

Some place I have the sheet from this for comparison to a early block. If its

less than the early block I would be amazed that any machining could be

done to the pre-55 block!

I'm just glad I didn't need to bore mine oversized as our cutters may not

cut this stuff.

PacerRacer50

[Deleted User] · July 2007

on the other hand i am having no trouble cleaning and smoothing the ports in my 55 block, the first cutter is doing fine. though i did have to make sure my drills were nice and sharp when it was time to drill the dipstick boss to suit the 48-54 sump. cant help wondering about the difference it would make when you machine it right out to the limit

[Deleted User] · July 2007

super651 wrote:

Mark, one of the locals has a wild card up his sleeve so, we will see in the future.

Is it true that the 55-56 308 blocks have very little or no nickel in the cast blocks? Saw it printed few years back ?

Thanks Rudy

If he's wanting to know the bore spacing, I'll bet its the same wild notion I've got.

Only thing holding me back is money.

I can't say the 55 blocks are any softer, they are all tenacious. The cylinder heads seem really soft compared to the blocks, definitely not the same cast metallurgy as the blocks.

Mark

[Deleted User] · July 2007

Depends on what block you had tested. The early 55 engines were still the Hudson plant castings of the blocks before it switched over to the plant in Wisconsin.

bob ward · July 2007

I have read, and I can't find my source at the moment, that the AMC blocks were actually superior to the Hudson blocks.

[Deleted User] · July 2007

The 308 I am running is a very late 1956 casting that we believe was orginally sold thru JC Whitney as a crate engine. The numbers stamped in

the serial number pad on the drivers side deck surface is the highest

number some of the old Hudson Gurus have seen.

I do have the head off of this engine as well. Its a 1/2" stud hole 262 cast

iron head. There is a Clifford head on this engine now so the 262 head is

holding up a wall in my garage. I plan on using it on a future project thats

in the works. Can't say if the material is the same on this or not as I didn't

want to do anything machining work on it now.

There are several items I noticed on this 56 308 block. One was that it

still had the CWC casting logo in it from Detroit. Another was the main caps

were very tight fit, even the center two and they did have alignment dowls

in them contrary to what several people have said. The last thing was that

the core shift in the intake & exhaust ports was pretty bad. The front three

cylinders were shifted back about .125" and the rear three cylinders were

shifted foward about the same ammount. This looked to take place right at

the core parting line in the ports just below the valve seat area.

All I know is that it took me 4 weeks of grinding and smoothing working 6 to

7 days a week for 6 to 12 hours a day to clean it up. Getting the shap exactly

the same from port to port took the longest. I made stainless steel templates so I could check my work.

Like Hudsonator said the port placement is in pairs, 1 & 6, 2 & 5, 3 & 4 match each other but all 6 do not match. There were little differences and I tried

to keep those differences in the basic shapes. I went thru 12 filters for my

mask and two pairs of swimming goggles (they seal all the way around

the eyes completly). Since I wear glasses this was a total P.I.T.A. as I had

to stop every few minutes, pull off the goggles and put the glassses back

on to double check my work.

Both my patients and air grinder was completly worn out after this!

PaceRacer50

464Saloon · July 2007

Something that comes to mind for me,is that if these blocks are so tough and hard,why do I have so many cracks in the chamber area. I purchased all my parts for my build from Randy Maas so he has been coaching me thus far. He said the cracks are normal and once I cut in the 7X valves and do the 7X relief, the cracks will be gone. Fair enough but I still wonder if these are such good blocks,why do I have so many cracks?

308 bore spacing?

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