Strange 292 head problem

If you decide to go that route, check closely for vacuum and coolant leak(s) when you install the intake.

Have you thought of going back to the machine shop and see if they will deck it correctly?
 
metro1 said:
I saw the replies on the other site. I contacted Ted today and he gave me a time to sign up tonight. It's not really off that much so I think I'll use the other guys suggestion and take out a little with a burr grinder in the affected area and hope for the best outcome.
Click to expand...

I would use a sanding roll instead of a burr grinder, being careful to only remove the amount of material necessary. check your progress frequently.
Click to expand...

What the man says. Be very careful here as you do not want to gouge the material possibly leading to material weakening/stress cracks.

I understand it is not a HI-PO build but still ...

ADDENDUM -

More knowledge from TED -

As a general rule, always check the head bolt holes in the blocks for being threaded deep enough. I will install the bolts first without the washers to ensure that the bolts do go deep enough and then reinstall with the washers. The ARP washers have a bevel on one side and that bevel must go up and against the head of the bolt.
Click to expand...
 
Last edited:
ECL-A heads were original equipment on 1955 272 Fords and 292 Mercurys. They have a lower static compression ratio (7.6) than the ECL-B/C heads (8.5) as found on 55 Tbirds and 4-barrel 292 Mercurys. Your ECL-A heads, although having the same valve sizes, must have larger combustion chambers, which would explain the difference in compression ratios.
 
Last edited:
Would the 8.5's happen to also be the ones used on the 312 T-birds THAT LEFT THE FACTORY AS 312'S?
 
Last edited:
Those heads have 73cc combustion chambers, used on 56 272 pickups, and have a static compression ratio of 8.5. They have the same valve sizes as the ECL heads.
 
On a completely stock engine? No. If you have a good quench area (.040-.045), you should get good results running on 87. As originally built, the pistons were about .020 below deck; with the original head gaskets having a compressed thickness of .025, the quench would have been .045. Aftermarket cast pistons can be .035 below deck (assuming the block hasn't been surfaced). Replacing the OEM gaskets with composite gaskets that have a compressed thickness of .046, results in a quench of .081, which could be prone to detonation. The composite gaskets provide a better seal, particularly if the block deck and head surfaces aren't perfect. A zero-decked block with composite head gaskets will provide a decent quench.
 
It may be in one of your other posts, I didn’t see it in this one. This is the link to the head casting number and other info from John Mummert’s site. It’s got a variety of other head info, and if you look around his site much more info.

http://www.ford-y-block.com/cylinderheadchart.htm

55blacktie pretty well covered the compression question.

I’d be getting to the bottom of the question on those heads though. Finding out why they appear to be out of kilter, and getting it all squared away first. If it’s minor, fine. But if it’s off enough that the intake doesn’t seat properly you’re going to be chasing vacuum leaks, or water leaks, or possibly head gasket sealing problems.

This is not the time to say “we don’t have time to do it right, but we’ll have time to do it over”
 
Gene F said:
Would the 8.5's happen to also be the ones used on the 312 T-birds THAT LEFT THE FACTORY AS 312'S?
Click to expand...

You mean original factory assembly before who knows what service/repair/modifications were done to the engine? What year BIRD are we talking about?
 
metro1 said:
I removed the heads from another engine and had them reworked at the machine shop. I was installing them today and ran into something I had not experienced before. On the drivers side head the top holes in the head do not exactly line up with the threaded holes in the block. The bolts drag against the front of the holes in the head. I tried it back on the old engine and the same thing. It must be bored wrong.
Click to expand...

530031

The head was at some point decked incorrectly as it will not fit correctly on either block.

To correct this, the head will have to be re-surfaced square and depending on the amount of material required to be removed to accomplish this will/may raise the CR on that one bank due to lessening CC as cast by the factory. The other head would also have to be cut to match this one are the engine will be operating with different CR from side to side.

Another thing to remember is even though the head has a distinct CASTING ID NO, it may have gone through differing machining protocols to meet the assembled engine needed calibration (may be differing combustion chamber volumes). In short, one would have to CC the combustion chambers to see it it is in calibration for a particular engine or has been possibly previously machined.

Now we are getting into selective fit and/or blueprinting and that equates to $$$. It is going to make a difference whether the car will be a driver, street/strip or especially competition.

Due to the age of these engines and parts, they need to go on the forensics table to verify exactly what you have to work with before spending the big bucks.

Case in point, recently watched a U2 short about a guy with a 396 CHEVELLE (and you respected these damn things back in the day). Somewhere he had lost his take-off heads and was wanting to bring the car back to numbers correct. Finally found a set (CASTING ID correct and DATE CODES within a few days of one another) on FleaPay and when he got them ($$$) they were pure junk.

- !!! CYA !!! -​
 
If you go to the link to Mummert’s site, you’ll see the “factory” compression spec for various heads and the variance from using them on a 292 vs a 312. Keep in mind few if any engines from the factory would actually cc out to meet the advertised compression ratio.

Then you add the over bore, and it changes again. My bored and stroked 292 (320 cid) with the Mummert heads cc’s out at around 10.75 static. Which starts the whole conversation between static and dynamic ratio. We can ignore that here.

I wouldn’t worry much about slight compression variations even from one bank to another. It won’t be a problem on a stock or mildly modified street engine. I would be more concerned about things being “square” as I stated above.
 
KULTULZ said:
You mean original factory assembly before who knows what service/repair/modifications were done to the engine? What year BIRD are we talking about?
Click to expand...

I guess I am asking if a person has a 312, that was shipped out of the factory as a 292 and the heads were put back on it, what compression is that upgraded 292 likely to be? I feel like the 312's that left the factory that way are superior to a 292 that has been punched out. I keep telling people yes they are a 312 CID, but they are not the same engine that you think they are when you refer to a "Thunderbird 312".
 
You must log in or register to reply here.
Back
Top