I got my 59 short block back from the machine shop And have been working on getting it in my car. I put the heads on, and the Pistons are hitting the heads when I do not have a gasket on. I placed the head on loosely with a bolt holding it and turn the engine over by hand, with a thin layer of grease on the pistons the heads are moving up and down, so I have obvious an issue. when I loosely place a gasket between the block and the head, I do not get contact. I’m assuming that when I torque the head down with the gasket that I will have piston contact still. HnH did what they call a big bore grind on the heads to get more clearance, but the pistons still hit. I can slip a .032 feeler gauge in the gap when the piston pushes the head up (without a gasket in place. What are my options to get my pistons to clear my heads? - Cast-iron and aluminum heads both hit without a gasket. - The head grind did not seem to work. - thicker gaskets???? - Other options? are there thicker gaskets in the world that will get me my clearance? If yes, how do I measure to determine the gasket thickness? any other ideas? I assume the decks are too low after 85 years. I’m tired of hemorrhaging money over this pile of ________! Engine: - 1939 59 - 4” crank - Schneider 270f cam (mild cam per Jerry) - 30 over - I have edmunds heads and stock cast heads
Cometic sells a .018 to .140 compressed thickness head gasket but they aren’t cheap There are different thickness composite big bore gaskets from like speedway, Macs JEGS etc . Ive compared the thicknesses in the past between the brands wish I would have wrote it down.
Did HnH build the shortblock as well as clearance the heads? If so, shouldn’t they have made sure they cut enough? If no, can they cut some more?
This is a perfect chance to get you head fitment right. You want .045-050" clearance between the top of the piston and the head. A compressed regular gasket is .055-.060". Try them bolted down with used head gaskets. If the pistons hit, I think you may have a problem with the heads being milled too much. If they don't, go through the exercise of using foil balls to find out what you really have. If you're close to the desired dimension, the heads can be clearanced with a die grinder to yield optimum quench. In my opinion, getting the quench right is the single most important thing you can do for performance on an unblown flathead. (Since you are using an aftermarket cam, check for clearance over the valves as well.) There is no way in hell that I would build an engine requiring gaskets available only from a single source at that cost.
no they did not do the short block so I’m on my own with the clearance issue. I called Mike, Hopi g he calls me back with advice. Thanks for your inputs.
Thanks Tubman. I agree that those gaskets are expensive but it may be the easiest solution. Tomorrow I plan on checking clearance with clay and then need to make some hard decisions… $300 gaskets, more head machining, new heads…. I believe the deck has been machined too much which is creating the issues. If stock heads and aftermarket both touch, it’s got to be the deck right? I can’t blame the edmunds heads if stock heads do the same.
BTW, the Edmunds heads are really the ones you want. If you look at them carefully, you can see that the spark plug has been relocated just enough so that it is not over the exhaust valve. This means that you can run extended tip plugs that really seem to help. I installed the current engine in my '51 club coupe in the summer of 2016. It has a set of reworked Edmunds heads and a set of Champion 328 (L82YC) spark plugs. I checked the original plugs last summer and they still looked perfect. The car is the best running flathead I have ever had. All other heads I have checked (both stock and aftermarket) have the plug located so that the exhaust valve will close the gap on an extended tip plug. Don't let those Edmunds heads get away, but if you do, I'd be interested.
thanks for the tips. I bought them at a good price recently and check them out. They are “purdy”. After polishing, clear coat, and the HmH grind, they’ve become expensive. .
Yep, they sure are. I can't even see any broken fins from what I can see. It sure would be a shame if they are unusable for some reason. One caveat : I have experience only with the 8BA versions of the Edmunds heads. I have no reason to believe that they would be engineered any different in regards to spark plug relocation and other factors, but you never know. Also, you can expect anything on these old engines. On the last one I built, the block had been decked .040" more on the front to the back. It showed up when I was measuring clearances for fitting the heads. Since the short block was complete, I ended up having one of the heads milled that .040" more on the other end. I now have an engine that has to go together one way with specific parts, but it beats the alternative. It's not too much of a problem with the 8BA heads.
Worst case, do a search either here or on Fordbarn. I seem to recall someone made a fly cutter out of an old spring leaf or lawn mower blade or something like that and was able to redome their heads at home using a drill press. My advice is get accurate measurements, take your time and think it through. As much as it stinks, it's not that uncommon to have this situation.
My 8ba has 4 1/8" stroke and .125 overbore. Previous owner gave up on it cuz it knocked as a new build and they couldn't figure it out. Turns out the pistons are 4" stroke! My old business partner had a machine shop at home so he made a fly cutter to the proper shape and fly cut my 59a style Offy heads to the proper clearance. Been running them for many years. Dave
In the 2nd picture ( cylinder head underside) the finish in the un-machined "dome"portion of the chambers looks mighty odd. I'm guessing all the patterns are etched in the aluminum, not missing material ?.
Your third photo looks like the block has been "decked" and you can see who ever did that didn't bother to chamfer the stud holes. They may have cut way too much off for some unknown reason. Perhaps a set of custom made gasket shaped spacers can save your engine.
are you seeing the light grease I put on the pistons that transferred to the head when the pistons touched during rotation?
Can you zero a dial indicator from your decks to top of stroke at piston? Your favorite machinist with a fly cutter should be able to help you with those specs along with your gasket specs I would assume.
I used clay puddy today to check the piston to head clearance with gaskets in. Clearances range between .01 and .03 so I shipped them down to HnH for a little more haircut. Fingers crossed all goes smoothly.
To close the loop.... HnH gave the heads a little more haircut and all the clearances were clayed and checked out perfect. Big thanks to Mike for turning these around quickly for me so I could trailer the car halfway cross the country.
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