I have been trying, without much luck, to find out how to tell if a head from a 300 I6 has been resurfaced.The head is not installed. Is there someplace that I can measure to tell if it has ever been cut? Maybe from the deck to the valve cover rail? If that is a reasonable place to check it, what should the dimension be? Any help that you folks can give me is surely appreciated.
Thanks.

 

That's a tough one. I was suprised no one at fordsix was able to help out. My gut feeling is that Ford would grind the block side then use that as a datum to determine what distance to machine the valve cover ridge and spring seats. The trick here is to figure out how much should be there. I know this isn't as accurate as you'd like, but I checked my performance head (sitting in the spare room waiting for the block to be machined) and it's at 3 11/16" from the valve cover ridge to the block side -I'm not sure how much has been removed, but it has been cleaned up. It'll be a while before I take it into work and get it on a surface plate to check it accurately. I think you may be best off getting everyone that has an extra head laying around to take measurements and then compile the data. I'll try to remember to check my 240 head that sitting in storage the next time I go.
Why do you ask? You should have the head CC'd to help figure where you want to go with it. -that's my next step. I got my hands on a set of early 300 rods with the small pin size hole (.912) to use 351W pistons. There is quite a selection of them, even if the chamber size is a little small for what I want, I can use dished pistons to make up for the loss. You may want to look into it.

 

Why do I ask? Last month I bought a '75 E250,4.9L, C6, 3.73 Dana60 for $200. Drove it on the trailer. I am planning t use the 4.9L in a '68 F100 that I've been working on for about three years. In the interest of completing it in my life time, I intend to install the engine stock for now. Like most motorheads, I can't seem to leave things alone for long. Last week I traded a set of mini truck wheels for a "rebuilt" head, however I don't know the extent of the rebuild. Plans call for more compression, better flow and increased carburation (probably either a two BBL or two Carter YF's). In addition to being able to do the performance mods to a head that I am not using at the time, it also presents me with a fairly stable work platform for fabbing intake and exhaust systems. I have heard that these heads can be cut up to .060", but with out knowing if the head has already been cut, it makes it exceedingly difficult to know how to proceed. I'm under the impression that the D2TE-BA heads have 76cc chambers, but what is the volume after it has been cut .010?,.020? .030? I really am not sure where to go from this point, I suppose I could call Cylinder Head Exchange, they ought to be able to tell me where to dimension the head.

 

Castings are what Castings are.

There is no way to accurately say what size your chambers are even if you knew if or exactly how much it has or has not been milled. The factory castings aren't going to be accurate enough for anything more than a rough approximation. In addition things like re-grinding seats and valves will change the chamber volume also.

If you want to know for sure you will have to directly measure the combustion chamber volume. You can sorta do this with a large syringe and a plexiglass plate by measuring the volume of a liquid required to fill the chambers. However to be very accurate you'll need to use a Graduated Buret instead of a syringe. Don't be suprised if every chamber is slightly different.

If you want good pictures/instructions on measuring them, I would suggest picking up one of those "How to Blueprint you Engine" books you can order from Summit, Jeg's, etc.

 

I'm enjoying the discussion and really would liek to hear how the 351 piston use come out. Here's a less than scientific way to tell if the head has been milled (its alittle work too), place the head on the block with the gasket and see where the exhaust lines up. If its higher, then its been milled.

 

Believe it or not I already know how to check combustion chamber volume. The problem that I have is that I really don't know how much volume I should have after a 60 thou cut on the head, not to mention that I haven't been able to ascertain a dimension for the stock unmolested head, so that I can determine if the "rebuilt" one I just got has ever been cut. What would be the consequence of cutting the head a greater amount than .060? Piston hit the spark plug?,valve to piston interference?,loss of sealing ability?, or would I just have to replace all of the pushrods?

 

>What would be the consequence of cutting the head
>a greater amount than .060? Piston hit the spark plug?,valve
>to piston interference?,loss of sealing ability?, or would I
>just have to replace all of the pushrods?

I wouldn't worry about hitting the sparkplug. But it wouldn't hurt to mock it up and check it with everything else.

Pushrods are probably going to have to be changed if milled. This dim. also changes when valves and/or seats are reground. If you had a head that you absolutely knew was uncut then you could put them on a perfectly flat surface one at a time and measure the height to the valve stem tip with a mag based indicator and compare them. I would still recommend that you check pushrod installed length with the head on the engine.

Comp Cams reccomends that you check it by the following method on non-adjustable valvetrain. 1 install head with all valvetrain. 2 rotate motor until both intake and exhaust are closed on the cylinder you will be checking and allow to set for a few minutes so lifters will bleed down. 3 using pencil or equivalent make a mark on the pushrods at some known repeatable spot such as level with valve cover gasket surface. 4 loosen valvetrain to allow the lifters to unload. 5 remark pushrods. 6 compare both marks, should be between .020 to .040 preload. Or you could put a mag-based indicator on it as you loosen it up. Just be carefull not to knock it around.

Stock size valves aren't too likely to hit the piston. But it's just a matter of putting a little play-doh in the valve reliefs and checking it. That's probably the only way to know for sure. Especially if you're running a non-stock cam or oversize valves.

As for .060 being the max that you can mill a head that's just a generalization. Each and every casting will have a different deck surface thickness. If you want to know if it can take more/or has been done too far, you'll have to take it to a machinist and have the thickness measured with an ultrasonic probe. Acceptable thickness will vary by intended usage and what areas of the head are thin. Obviously a small isolated thin spot won't be as much of a concern as an entire head that's thin. You should be able to get an exact recommendation from your machinist.

 

heathdaily;
Thanks for the info, I think that I'm finally making some progress.