That would be closer to .140 in the hole, but either way, it is a bunch. And I must say, it wasnt from a previous owner. It was done when I had a machine shop rebuild the motor. They said the 312 rods wouldnt make much difference. Ha! That was back when I knew less than rebman.
My suggestion is use the G heads. Youve got them. However, as indicated previously, the heads, cam, and 4v carb are going to need compression. Hence the attention to the quench. Most I have read indicates .040 quench as a target. .035 can become too small, especially if the motor sees high rpm. I think it was Ted Eaton who was running a .035 quench in his drag motor, and when he tore it down the imprint of the piston oversize was visible on the bottom of his head. But he was shifting at around 6100 rpm.

http://www.campbellenterprises.com/R...o%20calculator
This is a link to plug in some numbers which yields compression. It calls for a value based upon whether or not the valve faces are dished or dome, and I used a value of .001 since my heads were cc'd with valves installed.

This was discussed in another thread, but Mummert told me that a total of .040 can be removed from the heads and deck in total before problems with intake manifold alignment occurs, FYI.

 

Well...not much I can say on Ted's deal. I don't know him personally, but he seems like a nice guy and knows his stuff, and if he said .035 doesn't work for his engine, then it doesn't work. However, here's a few things to ponder when setting a quench distance.

Rod material & design play a large part. Aluminum rods stretch a lot more than steel, and .035 would be a BIG problem there. In addition, any engine using aluminum rods is presumably intended for drag racing or possibly sprints (yeah, I know, there's always the odd exception...) and therefore a higher RPM.

Higher RPM demands more clearance (for example, if Ted (or anybody) is shifting at 6100, conceivably it's going to 6500 or more depending on the trans, driver ability, traction, etc., etc.)

"Cast" rods, like Pontiac ARMASTEELs, need a little more distance.

"Skinny" rods, like a typical six cylinder, often need more, as a rule.

Gasket compression & design make a difference, too. If the gasket starts at .042 and compresses to .032, not unheard of with old design compositions, again, it has to be factored in.

Piston design is a factor, too. If you are using old Jahns pistons or something else made forty years ago (again not uncommon with vintage engines like the Y, nailhead, etc.), they grow in every dimension, not just diameter. Not necessarily bad...just something to keep in mind. Modern slugs are much more stable in the piston top as a rule. Piston WEIGHT makes a difference, too; and old designs are HEAVY. More rod stretch. 30-40 year old forged pistons often specify .008 or more wall clearance, too.

Piston to wall clearance and pin location are big factors as well. Both may contribute to piston "rock", which will demand more clearance. For ex., in a 4.440 bore BBF with .007 skirt clearance, even at, say a 6500 rpm limit, you would open it up a little.

I will say, though, that I use .035-.037 as a target for steel rod street engines, with an assumed rpm limit of 6500, and never had a problem (including things found upon disassembly ). Most of the engine builders I converse with, doing SBC, SBF, BBC, & BBF, look at .035 as a good figure to hit (assuming modern components, that is). In a Y, with its limited bore size, I would think .040 is just fine. I wouldn't go much more, though, with G heads, a 030 or more 292, and a relatively mild cam.

Hey Mike, I couldn't recall who did the engine, but I knew it wasn't you, anyway. Tryin' to keep you "anonymous"....

 

Homespun, all good and instructive points. If .035 works, so much the better. It is surprising the effect that .005 less will have on the compression. I am eager to put all this info to use and hope the checking account keeps up it's end.

 

Hey, speaking of hitting things...ever seen the FE Ford valves (OE) with the center bump on them? From the early '60s 352/390/406, intended to hit the piston top in case of valve float....so the valve would tend to close rather than bend.

Glad we have better springs nowadays.


My wallet's attitude toward me lately....

 

Homespun, very well done.

Your comments about pistons and pin location hit particularly home with me. As my screen name suggests, Im well into high performance flatheads. It sometimes becomes a chore trying to unteach a lot of SBC habits to a new crop of young flatty builders. Ive built many SBC's back when the 327 was king.

Of particular concern with a flatty is that the crank is offset in the block a few thou (about 10 of them). This causes a slight bias in the way the rod forces the piston against the wall. It becomes particularly critical when a builder feels he has to go with 3 ring forged pistons for a mild street build without realizing that the stock style 4th ring way down on the skirt is a primary stablizing force. It also contributes to longer engine life before oil consumption becomes excessive. Then add the longer stroke Merc crank with the same rods and the pin a full 1/4" higher and you wonder how that engine ever stays together.

There is absolutely nothing wrong with G or comparable big valve small chamber heads; Im using them on the engine Im building for nostalgia dragging. You caught my reasoning perfect for why I prefer C heads on a truck that is used as a truck and are certainly more eloquent than I !! Out here in the hills and mountains of NH many of my customers use their F100's and larger as daily drivers in good weather, hauling stuff, towing a camper or boat, etc.

 

One of these days I've got to do a flathead. Never have; worked on a few though.

I keep pondering doing a '32 highboy with something different for power, a Y, or maybe a MEL. I had kind of decided on a flathead, but now I keep seeing them in Deuces all the time. I'm kinda pumped up about somebody's 430 MEL powered wrecker (hint, hint).

 

I almost feel embarrassed reading this thread, like I hope no one else is reading is because I'm sure this info is reeeealllly basic....

Of course, I have more questions....

Let me get this straight....if your piston comes to the exact top of the block (zero deck height) and you have a gasket that is 0.040" think, then the distance from the top of the piston to the head is 0.040". But if the piston pops out of the hole by 0.005", then the difference would be 0.035". And 0.005" makes THAT big of a difference ???

Now the scientist in me will come out...I suppose I could convert the inches into centimeters and multiply that by the surface area of the piston (pi*r^2) to get the amount of cc's that the combustion chamber would change due to 0.005"...I take it the combustion chamber is the volume of the space between the top of the piston and the heads, right? Plus, the compression ratio is inversely proportional to the volume of the combustion chamber, so the smaller it is the larger the ratio would be...interesting....

I was thinking of taking the heads and putting them into one of those "space bag" things and vacuuming all of the air out...no oxygen means no rust, right?

 

We've talked before, 46....remember, I'm the Grants Pants guy...

What would be the problem with too small of a quench? For example, say it was something like 0.025"?

 

Sorry rebman, I had forgotton. Forgettfulness comes with age you know? .025 in. would have your piston hitting the bottom of the head. Not a good thing! Remember that as the motor heats up the components expand. Aluminum expands more than steel. Also as Homespun said, with the piston in motion it will have a slight rocking action in the bore, since it is a little bit smaller than the bore. Add a small amount of rod stretch, and you are set for disaster at .025.

There is a thread currently running on another forum about deck height and quench. The original poster had a mistake occur with the machinist and instead of zero deck he got .010 in the hole. His question was whether there were any composition gaskets out there that would measure .031 when compressed. The only ones available come out to be .041-.044 compressed.

He did not like those selections because the quench would be .051-.054. So he is going with a steel shim gasket of .23 thickness, for quench of .033. No one is sure whether he will have problems or not, but everyone agrees it is a gamble. Guess he has the money to gamble with.

He is trying for maximum performance, therefore the **** attitude on quench. Most of us common folk would be far better off if we were faced with his choice and opt for the larger quench. Of course he could have the block milled again, but for some reason he does not want to spend another $100, and would rather gamble his entire motor.

One man did an interesting thing to get the compressed Felpro gasket thickness. He did a test, and put a piece of lead shot into one of the gasket openings after laying it down on the deck. Then installed and torequed the head, which would squash the gasket and the shot to an equal thickness. Pulled the head off and measured the shot, which was .044 thick. This compared to another man's direct measurement of the same brand of gasket after removing it, which was .043.

I tend to consider compression and quench as a means to gain improved performance and mileage, and forget its importence to prevention of detonation. Properly done, your motor should like regular pump gas well.

Did you try out that compression calculator above? It sure beats the geometric formulas. If I plug in my motor's numbers with zero deck height and .040 gasket thickness, a compression of 9.13 results. Cut the gasket thickness to .035, and compression becomes 9.23. Mind you these are funny numbers, and you cant get a gasket that I know of with .035 thickness. I just used them to show what the .005 less can do.

Like you my plan is to do this motor work in stages. When you get to yours, make sure you know and record for future reference the amount the deck was shaved, the distance in the hole of the piston, the amount the heads were shaved (if any) and the cc's of the combustion chambers. If zero decking, or for that matter any accurate decking, rods have to be checked for equal lengths center to center. The machine shop will do that when they recondition the rods. One guy on here a year or two ago was trying to decide what to do about decking, and his current measurements showed 3 or more different deck heights from one piston to another, meaning probably the rods were of unequal lengths due to stretch or wear.

Like stated above, when I started all of this I knew less than you, not even what questions to ask or examine. So hang in there and have fun.

 

I've been looking for some reference to the longer C2AE rods and forged crank diameter, but havent found anything. The C2AE rods came in light duty 62-64 trucks with the regular cast cranks and journals. Therefore I cant see how they can be longer. Didnt the heavy duty forged cranks match up with C1TE rods?
Also have seen recently, somewhere, a statement about the C2AE rods being forged. Is that correct, or are the C1TEs forged, or are none of them?

 

All the Y rods I've seen were forged, & have the wide parting line on the beam which is a sure sign. Not too many cast rods out there; the old Pontiac "Armasteels" come to mind.

So far as I've found, the C1TE rods were shorter to compensate for the increased piston compression height of the HD engines, & are the same length as the earlier 312 ECZ rods; & that the C2AE and EBUs were the same length as each other, .072 longer than the C1TE/ECZ. I just figured this comment was a momentary brain fade. It has, however, been some time since I've gotten my grubby hands on a set of C2AEs.

 

Ive been away for awhile taking turns with my wife helping her 90 yr old mother get into the hospital for a heart pacemaker and get strength back at her home up in Maine.

Somewhere Ive got the rod dimensions written down and the C2AE was the odd man out of the bunch. I'll dig around as soon as I get a bit caught up here. Remember that the C2 was almost the end of Y production and Ford wouldnt have done a new casting for just a few last gasp Mercs! I'll try and dig a bit deeper.