Used Aftermarket Aluminum heads.

[ken-r-mer]

If a set of rare used heads have minor corrosion around a few water jacket openings and some pitting in the piston dome area of two pistons, is that a set of heads to avoid? The top side is near pristine. Can those defects be remedied? I know everything cost $$$, but can the water corrosion be deck machined and using a thicker head gasket to offset the machine cut, if the cut is no more than 0.10"? It's also hard to get machining estimates without having the heads in hand. So any feed back on recent machining work would be helpful when negotiating a price to minimize overall risk. As far as the piston dome pitting, that is another issue. Seen some epoxy's with a 1,000 degree temp range.

[tubman]

Since I prefer Edmunds heads, I am becoming an expert on used heads. The best thing you can do is to temporarily test fit the heads to an engine and check the clearances using aluminum foil balls and a used gasket. Amazingly, every set of used Edmunds heads I have checked (except the last set that I haven't gotten to yet), required additional milling to bring them into a nominal clearance of .045"-.050" over the piston heads. I check 8 or 9 places on the piston and each valve. Typically, I have needed to take .020"-.030" of the heads to get them close. Generally, this is enough to greatly reduce the pitting and corrosion around the water openings. They need a little attention with a die grinder after that to bring everything into spec.

Maybe I'm just lucky, but then again, I probably need it. I've gotten so I can see if a set of heads has been milled too much by judging the diameter of the circle round the combustion chamber.

[Bored&Stroked]

Post some pictures of the head surfaces and chambers.

If the heads have been milled quite a bit already, you might be able to redome the area over the pistons. Also, if you have not ordered your pistons as of yet, then you can get all the head work done, drop the crank and a rod in the engine and figure out the exact compression height (pin location) needed to achieve a .040 quench above the pistons. Then, you can have Ross make pistons with the exact pin location. So, there are lots of ways to skin the cat and get things correctly setup.


As far as the erosion goes, it depends how much and how close to the sealing areas of the head gaskets. I've had plenty of heads welded up and some guys have used DevCon and other epoxy to fill in the pitted areas.

[ken-r-mer]

They are a set of stock uncut Weiand heads. Came across them a few days ago in my ongoing obscure global searching. The Joe Abbin Performance Handbook has the stock heads flowing the most cfm (intake and exhaust) than all other general name brands (not including Navarro or other more exotics) on his Tables 4.3 and 4.4 for valve lifts between 0.05 -0.40". The head volume is 69cc, and max lift of 0.455" (intake) and 0.425" (exhaust). The Schneider P-3/8 lift I'm contemplating on is 0.375". No data (yet) on the clearance above stock pistons using a stock compressed head gasket thickness of 0.055". Also have no data (yet) on the wall thickness above the valve or piston dome areas.
Just worried the machining might get exorbitantly $$$ to address the flaws.
Also found that Cometic has head gasket compressed thicknesses in roughly 0.10" increments from 0.055" to 0.090" (non-copper).
Preliminary calcs: with the relieving should bring the CR to just below mid 7's with the Weiand heads. So with either 5-6 lbs boost and 91 octane gas (street use), and a general use area of 1,200' altitude, no pre ignition or detonation worries for a safe blower combo...even if I (accidently) hammer it HARD on the freeway on-ramp.

[19Fordy]

Make sure the person that does your heads DOES NOT run them on a belt sander.

[ken-r-mer]

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Originally Posted by 19Fordy

Make sure the person that does your heads DOES NOT run them on a belt sander.

Belt sander? NEVER! Too high tech. I have some old time settler tools (wooden mallet and chisels) that were used to hand hewn logs.

[Bored&Stroked]

Originally Posted by ken-r-mer

Also found that Cometic has head gasket compressed thicknesses in roughly 0.10" increments from 0.055" to 0.090" (non-copper).

I run Cometic gaskets in my 284 cube stroker motor. One thing to note, they are MLS gaskets and the surface finish of both the block and the head needs to conform to the RA spec (which is much smoother than most stock blocks and many older heads). If the RA finish isn't good enough, you're asking for leaks to occur.

They've ran fine for me . . . though they are twice as expensive as everybody else. The most important thing is to tune the squish --> .040 to .045. This makes a big difference in performance (blown or NA).

Above the valves you only need .060 or so . . . so if you need clearance, don't fly-cut them more than you need to (and the flycut should be at an angle to match the valve angles).

[ken-r-mer]

Here are the worst areas of wear on the Weiand heads.

[tubman]

They make some amazing epoxy these days; look at Dev-Con and Belzona. The variety offered is amazing; actually making it hard to chose what to use.

[Bored&Stroked]

They will obviously need to be surfaced. I don't believe you'll have any water jacket issues as the erosion isn't bad enough to get past the head gasket. I could have the chambers re-domed as these have had a lot of corrosion. When you get them re-domed, make sure the pistons you're going to run have the same shape as the doming tool.

Depending on the cam, you may need to rework the TOPs of the valve pockets (remember, the valves are canted - that is the place they will hit if you have a clearance issue).

If it was my engine, I'd get the heads done first, then have your block work done (decks, etc) - such that you can put a crank, rod and pin in it to determine the compression height you'll need. Make sure the new domes are a consistent radius profile - then you can work with Ross to set the pin location to get the correct squish (obviously taking into account the gasket thickness of whatever head gaskets you'll run). I prefer to calculate with a .050 to .052 head gasket . . . even if running Cometic gaskets as if you ever need to replace a head gasket and don't have a Cometic one handy, you can put in a Felpro, Best, etc.. It is good to have flexibility for the future.

I believe Andy at Kohler Kustom can re-dome your head - you might check with him and also see if he can resurface them with a fine RA finish (50 or less they quote, but I'd be looking for 40 or better).

[email protected]

[Cool Kat with Hot Car]

Bored&stroked, For the uninitiated like me please define RA and MLS?

[cjshaker]

Originally Posted by Cool Kat with Hot Car

Bored&stroked, For the uninitiated like me please define RA and MLS?

RA is the surface finish (average roughness), which is really important for MLS gaskets. MLS meaning multi-layer steel.


Cometic makes some of the best gaskets. Pricey, but worth it. Like mentioned though, surface finish MUST be adhered to.

[ken-r-mer]

The way I understand it:
Vertical clearance over the valves at the backside (towards the intake): Assuming the angled valve at the high end (backside) is flush with the block deck, as I won't know till I remove the current head. The proposed Schneider P-3/8 cam has a 0.375" lift, then factor in a 0.055" compressed head gasket thickness. The valve then extends into the head a total of 0.320". The Abbin Tables 4-2 and 4-3 has the stock Weiand head pocket heights at 0.425" (exhaust) and 0.455" (intake). So a top clearance of 0.100" above the exhaust an an extra 0.030" more above the intake valve. I can see cleaning out clearance on the backside walls of the head, but not knowing the thickness of the ceiling material above the valves, I'd be hesitant to take away anything, other than to smooth out the surface...unless I had a scrap head to do a cutaway to know the thickness at the valves and the piston dome for sure.
At the heads and using a dial indicator, measuring the maximum piston rise above the deck and the depth below the deck at the piston edge (center to edge) for each piston, then with a cleaned head surface, measure the head depth at the center for each piston dome, then adding in the compressed head gasket thickness will tell the squish height. To get a uniform squish gap, having a custom cutter bit made from another same-make piston dome would be the only realistic solution for a LOCAL shop to do the work. Keep in mind changing head gasket thicknesses in the future changes that squish gap.

Now to get a uniform 0.040" gap between the piston and head while using a 0.055" compressed head gasket thickness, the piston edge needs to rise above the block deck 0.015". Is that correct?

[Bored&Stroked]

Couple things to note: The top-edge of the valves are usually NOT flush with the top of the block - especially on the Driver's side. Of course, it all depends on the valves, seat depth, deck, etc . . . I have to measure each engine.

Given that the valve angles are not the same (side to side), it is the Driver's side that I always check first. If the block has not been decked before, usually the Driver's side top valve edge is about .040 or so higher than the passenger's side and will be above the deck surface. Bottom line, you just have to check with a dial indicator or depth gauge.

On the heads, you have it about right - though it depends on the depth of the dome cuts. On Ross pistons, they show the dome sticking up about .187 above the edge of the piston. Of course, it depends on the diameter of the piston (overbore), but that is close.

On my last set of custom pistons, the final compression height (measured) was 1.387 (this was for a 4 1/8" stroker crank). I moved the dome up .010, so I had the pistons made with a 1.397 compression height. So, the pistons popped up about .010 over the deck. My heads were new Navarro heads, I had the domes redone on a CNC mill to match the Ross shape. Final squish/quench (measured after final assembly) was .041.

Standard 4 1/8" Stroker Pistons: If I had just ordered "stroker pistons" from Ross for this combination, the compression height would have been their standard 1.374. This would cause the pistons to be .013 "down in the hole" and my quench would have been about .065 or so. This shows exactly why one has to work with the specific block, heads, etc - to determine what is needed to achieve the proper quench.

You can't assume anything as far as the above numbers for stocking pistons and aftermarket heads and whatever block you have. Also, if you square-deck the block (off of the mains) to achieve equal deck heights, then you've changed it anyway. On the block above, it was decked .010 on one side and .018 on the side (to equal up the deck heights). The decks are usually off a bit - not just in height, but as far as being "square" to the mains. If you have the block decked, make damn sure they are doing it off of the main saddles - it is the only way to get it right and they need to understand that the valve seats on the Driver's side will be higher than the passenger's side.

I've seen machine shops without flathead knowledge deck the blocks so the valve seats were at the same height . . . making one side completely wrong.

[ken-r-mer]

Would the solution be to machine the valve ring seat depth the same (side to side)? Then any variation is taken up in spring shims and the adjustable lifters.

Well, now working on getting the Weiand heads for a decent price. One step at a time.

[Bored&Stroked]

No, the block is designed with the crankshaft offset .265 from the center of the block . . . it is a deliberate part of how the engine is supposed to work. The rod lengths, valve lengths and all components are the SAME from side to side (as they should be).

Do not attempt to alter the decks or valve seat depths to make the valves the same height to the decks - that will ruin the block. There is nothing wrong with the design - it is just important that you know about it and don't attempt to "correct it".

If you're bored, you can look at the drawing that I did for a 4 1/8" stroke crank in the block (based off of Ford's original blue-prints). It is a bit hard to read - lots of details.

Note: This is for the 59A through 8BA blocks - the valve angles were different from 32 - 42.

FlatheadFordEngineCrossSection-59A-8BA.PDF

[ken-r-mer]

So the flathead is asymmetric like most other engines of the time to minimize the "slap" at TDC. I know late model engines use offset in the piston wrist / connecting rod area to accomplish the same thing.

When I pull the head, I'll use a dial indicator to see what the back side of the seated valve is in relation to the deck height. I'd think cutting the valve seats can also affect the valve seat height.

[ken-r-mer]

My understanding FOR MODIFICATION OF THE ALUMINUM HEADS
1) Get the head surface milled

For just the piston dome:
1) Measure each cylinder piston maximum height above the block deck
2) Measure each piston dome center depth of the head
3) Take into account the selected compressed head gasket thickness
4) Have each dome cut to get a 0.040" quench height matching the piston top radius shape (+0.40" added to the piston radius) for the custom cutter shape.

Then for the overhead valve clearance:
1) Measure the high point of the angled valves in it's seated position above the deck surface (all 8 pair sets of valves)
2) Using the selected Schneider P-3/8 cam grind with a max 0.365" lift
3) Weiand stock heads with a head volume of 69 cc, 0.425" max. lift exhaust and 0.455" max. lift intake (Joe Abbins tables 4-2 and 4-3). Followed by a depth gauge measure of each 2 points of the valve areas of each piston for verification and accuracy.
4) Then there is whatever the milling thickness is to clean up the head surface.
5) What is the minimum valve clearance between the valve and the upper head surface measured at the valve back side (highest point) recommendation?

The interpolated combustion ratio using Abbins table 4-1 has my ratio at 7.3-7.4. So on the high side of 87 octane and will probably safely run 91 octane.

Oh and in researching Ross Flathead pistons: in a supercharged setup, the fine print limits the boost to 5 psi. So I'd have to get a smaller pulley to reduce the psi from 6-7 to 5.

[Ronnieroadster]

To reduce boost if the pulley you wrote about above is on the blower. You need to increase the diameter of the pulley to slow down the blower. A smaller pulley diameter will increase the blower drive shaft speed thus producing more boost.
Ross will make a piston that works with more boost on a special order. Been using them for a very long time at boost levels as high as 23 pounds of boost in our little stock block Ford flathead V-8 record setting engine's.
Ronnieroadster

[ken-r-mer]

I'll have to get back to TR Designs to see about a larger pulley (my error in the previous post, had a senior moment) for 5 lbs boost to run on 89 octane or stay with the 6-7 lb boost and run 91 octane.

And if I stay with the current piston that was installed in a professional rebuild, 12,000 miles ago by the previous owner, I can determine the radius by the chord formula method knowing the diameter of the piston and the height difference between the piston rim edges and at the center. Then just add 0.40" to the calculated radius and thus the radius of the required cutter bit for the head cut to be parallel to the piston radius.
Since the cutter bit will flush out the cut to the head surface, to maintain the 0.040" separation at the piston perimeter, Cometic makes 2 compressed thicknesses for piston rim maximum upward heights being below the block deck surface, one being 0.027" and one 0.036". Then one compressed height at 0.040" for a piston perimeter being flush with deck height. Finally,7 compressed thicknesses for piston perimeter heights being above the deck height from 0.051"to 0.140". All gaskets being MLS (multi-layer steel) comprised of 3-5 layers.
I'm learning why the various thicknesses are on the market.