A few engine questions.

[JOeyKnapp]

I had to replace the bypass water fitting on my head because the original one was rusted and wouldn't come out. I took the head off this afternoon (will post the fitting pictures later).

When I got it off and started cleaning a little I noticed a few things and wondered if someone had any answers about them.

The first is a "U" stamped on the head, near the thermostat. Did that ever happen to designate unleaded? Or is that normal?

The second is on the underside of the head 080 is stamped. Bore change?

The third is that 3 pistons were P17 and one was P19. Don't know if that means anything? Just curious..

 

[Gerard]

I don't believe those are stock markings, rather probably done by the shop that rebuilt it. The U could indeed be for "unleaded". The number 080 on the head is probably how much has been removed (which is a LOT).

 

[JOeyKnapp]

So, you are saying it's a high compression race motor!!??

Thanks for the insight. Looking at the minimal amount of buildup on the valves I was thinking it had been apart before.

Is there a "best practice" for doing anything before the head goes back on with an engine you don't know anything about? For instance, should I take it to a machine shop to have them check to see if it is warped or anything? (I have only had experience with aluminum heads, due to my Honda and Type1 VW experience..)

 

[Talonaer]

if they've take that much off it it shouldn't be hard to measure the depth of head and see that its far from stock....

 

[Whitephrog]

I have a 948cc engine which was modified by Howard's Machine Shop in Huntsville Alabama in the early 1970s. At the time they were building NASCAR engines. I don't yet know what all they did to the engine. The only obvious modification is that the pistons are 30 over.

I have the same but smaller "U" stamped on the head. On the block near the front I have stamped a small "P" and a bit larger "JF".

 

[Gerard]

So, you are saying it's a high compression race motor!!??

Thanks for the insight. Looking at the minimal amount of buildup on the valves I was thinking it had been apart before.

Is there a "best practice" for doing anything before the head goes back on with an engine you don't know anything about?

The pistons do look like they have a very small dish as well.

It would probably be a good idea to check for any warpage. I would also check the valves for any leaks. A shop can do it at the same time, but you can do your own little self test by inverting the head and pouring enough solvent (i.e. lacquer thinner) to form a little pool around the valves and see if any leaks/drips develop.

Another indication of how fresh the rebuild might be is to look at the cylinder walls. Can you see or feel a ridge at the top of the bore (where the piston rings don't reach)? Can you see any cross hatch pattern still remaining in the bore? These would both be indications of low milage.

 

[Spridget64SC]

The 'U' on the head is a rather common stamping. I've got A-Series heads of all types and there is usually a letter code on the head.

What is your head casting number? And, is this a 948 or 1098 engine? Usually found between the 2nd and 3rd rocker stand location. If it is a 12G206 or 12G295 head, then 0.080" off the head is a typical cut to get the compression back to where a 948 engine started. Remember that the 1098 heads have a few more cc's in them that the original 948 heads.

From what I see with the exhaust valves being pocketed as much as they are, the head has not been converted to un-leaded fuel use, that is, hardened valve seats. The valves would stand a lot more proud and there would have been a seat insert circle/seam visable.

The 3 with the cap means that the bore finished out at BMC to fit size code 3 pistons. In the very early days, size codes went from 1 to 4. A bit more displacement with the 3's. There should be a 3 in a diamond near one of the tall head studs opposite each cylinder. Also, all cylinders may not have the same size pistons. I've seen different sizes in a single cylinder before. The 2013 is the part number of the piston. Front is front meaning the pin is offset for noise reduction with the amount of stroke in the engine. These are shallow dish, high compression (9.0ish, IIRC) pistons.

As long as you weren't having any sealing issues with the valves or head gasket, I would put it back on and torque to spec's.

HTH,
Mike Miller