tubman
Well-known member
Actually, it depends more on whether you use bolts or studs. That's the heads, sometimes the gaskets themselves can be a bear to get off.
Aluminum heads
- Thread starter 30-9
- Start date
Actually, it depends more on whether you use bolts or studs. That's the heads, sometimes the gaskets themselves can be a bear to get off.
tubman
Well-known member
Aluminum foil balls and a caliper.
Check this discussion out. I think I got a little deeper into this than I should have, but we all know : "Knowlege is Power". Here's a link : https://www.fordbarn.com/forum/showthread.php?t=199642&highlight=clearance.
Check this discussion out. I think I got a little deeper into this than I should have, but we all know : "Knowlege is Power". Here's a link : https://www.fordbarn.com/forum/showthread.php?t=199642&highlight=clearance.
Ok thanks. Knowledge is power, I agree. Unfortunately, it’s all way over my head. As previously mentioned, I’m 86, I like turning a wrench and was looking for a somewhat easy winter project to keep me moving and off the couch. I do like the look of aluminum with dual carbs and thought I could just swap out the cast for aluminum. If I need to worry about all the details you went into, I don’t want to create a issue.
JSeery
Member Emeritus
If you mainly like the look of the heads and your not wanting to squeeze out the extra horsepower, most of this is not a concern, you can basically just bolt them on. It is always a good idea to do a quick check for piston and valve clearance. An easy way to do that is to place the new heads on the block with a couple of bolts loose and no gaskets. Turn the engine over slowly and see if anything tries to lift the head up. If not, you have at least the thickness of the gasket clearance when it is installed. That is plenty. A high performance engine build takes a lot of checking and modifying to get things just right. A street engine just built for the fun of it, not so much.
19Fordy
Well-known member
30-9 Smart decision. Spend your time detailing your engine and engine compartment so it looks brand new - one part at a time - a little each day. You will be very pleased with your new look. You can paint your engine with Bill Hirsch paint and it will look newly born. Brushes right on. Leaves no streaks, Just take you time.
Thanks Jerry, that I can handle.
Metal gaskets IMHO are the best, steel or copper but both liberally coated with copper coat prior to installation. The composition gaskets are a bear to get off and again in my opinion subject to non uniform clamping. A little more compression is a good thing. Try driving a T with a stock head and then with a Z alum HC head over the same hills.
tubman
Well-known member
"30-9" - Like "JSeery" said, everything I did is nice, but not necessary. I will tell you that, while I am a few years younger than you, I am still getting on in years and am not able to do everything I used to be able to do. Once you have the heads off and the block cleaned up, all of the hard work is done. The rest of it comes under the heading of "puttering", especially with aluminum heads which are not nearly as heavy as the stock iron units. You put some grease on the tops of the pistons and then roll a bunch of of "BB" size aluminum foil balls and stick them on the tops of the pistons, install the heads without gaskets, snug up 4 or 5 bolts, and turn the engine a couple of times. Take the heads off and measure the thickness of the foil balls to first, determine if the overall head needs to be milled (all balls over .060" thick), and second, determine whether any of the combustion chambers need to be ground to provide minimum clearance. I find it an enjoyable process, one that takes minimum physical effort, and is even fun to do. I can't throw engines (or even transmissions) around any more, but I can take the heads on and off a couple of times, do some grinding, and maybe even take a leisurely drive to the machine shop.
It's the kind of a task specifically suited to us "old guys".
But if you like the look, it's worth while doing for that reason alone.
It's the kind of a task specifically suited to us "old guys".
But if you like the look, it's worth while doing for that reason alone.
Bored&Stroked
Well-known member
Note: As I mentioned to him in a message, there are two distinctly different piston dome shapes that I frequently see:
1) Has three different radii, a "pointy" crown center and was used in many stock engines as well as in some cast pistons (like some of Egge's and old 4-ring Jahn's).
2) Consistent radius type - which matches the piston crown shape of many aftermarket pistons - like Ross, like the old Jahn's 3-ring. etc..
Most modern aluminum heads are designed for a consistent radius type of profile - type #2 up above. The potential challenge is that the piston crown shapes of #1 do not fit all that well on many of the aluminum heads. What happens is the "pointy" crown area at the top wants to hit the center of the dome shape in the head - as not only is the shape different, but the center sticks up a lot higher than a Ross type piston.
The other issue is that you cannot get a correct squish dimension above these pistons - as you have to use too MUCH clearance to stay above the pointy crown - leaving way too much clearance above the rest of the piston . . . and a lower compression ratio as a result. Flatheads REALLY like to have a consistent .040 to .045 squish above the piston.
Due to this issue, I don't like to run the "pointy" style of pistons (if I have a choice). If I'm working with an engine that has this type of piston crown, then I have the chambers in my heads reworked on a CNC to match the piston shape, then mill the heads to achieve the final squish/clearances that I want above the dome. I like a consistent .040 to .045 above the dome.
See the attached 'section' images and a sketch of the piston crown that I designed for the older Jahn's pistons - 3 5/16 diameter. I had a brand new set of Edelbrock heads reworked to fit these piston crowns. Notice how much DEEPER the piston pocket needs to be for the crowned piston shape:
Here is a sketch form my 3D Model of the Egge style dome:
Here is a cross-section view of the Egge style dome:
Here is a cross-section view of the consistent radius style dome - Ross pistons:
I've seen some engines where the installer ran into this issue and then took a big file or grinder to the tops of the pistons to "remove the crown". I'd not recommend this method . . . I believe it is best to modify the chambers - but I'm a bit of a perfectionist! LOL I've also seen folks reshape the piston tops in a lathe . . . just another way to skin the combustion chamber cat!
1) Has three different radii, a "pointy" crown center and was used in many stock engines as well as in some cast pistons (like some of Egge's and old 4-ring Jahn's).
2) Consistent radius type - which matches the piston crown shape of many aftermarket pistons - like Ross, like the old Jahn's 3-ring. etc..
Most modern aluminum heads are designed for a consistent radius type of profile - type #2 up above. The potential challenge is that the piston crown shapes of #1 do not fit all that well on many of the aluminum heads. What happens is the "pointy" crown area at the top wants to hit the center of the dome shape in the head - as not only is the shape different, but the center sticks up a lot higher than a Ross type piston.
The other issue is that you cannot get a correct squish dimension above these pistons - as you have to use too MUCH clearance to stay above the pointy crown - leaving way too much clearance above the rest of the piston . . . and a lower compression ratio as a result. Flatheads REALLY like to have a consistent .040 to .045 squish above the piston.
Due to this issue, I don't like to run the "pointy" style of pistons (if I have a choice). If I'm working with an engine that has this type of piston crown, then I have the chambers in my heads reworked on a CNC to match the piston shape, then mill the heads to achieve the final squish/clearances that I want above the dome. I like a consistent .040 to .045 above the dome.
See the attached 'section' images and a sketch of the piston crown that I designed for the older Jahn's pistons - 3 5/16 diameter. I had a brand new set of Edelbrock heads reworked to fit these piston crowns. Notice how much DEEPER the piston pocket needs to be for the crowned piston shape:
Here is a sketch form my 3D Model of the Egge style dome:
Here is a cross-section view of the Egge style dome:
Here is a cross-section view of the consistent radius style dome - Ross pistons:
I've seen some engines where the installer ran into this issue and then took a big file or grinder to the tops of the pistons to "remove the crown". I'd not recommend this method . . . I believe it is best to modify the chambers - but I'm a bit of a perfectionist! LOL I've also seen folks reshape the piston tops in a lathe . . . just another way to skin the combustion chamber cat!
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tubman
Well-known member
I am not experienced with Edelbrock heads, but since no one else has chimed in here, I will add my 2 cents. First of all the stock Ford plugs (Champion H-10's or equivalent) are not correct. They do not have enough reach (the threaded length). Most aftermarket heads take 7/16" or 1/2" reach plugs (Champion "L" or "N" series). What I usually do is get a couple of plugs from the FLAPS and screw them into the head. Then check and see if the bottom of the plug is flush with the combustion surface of the head. If it is not, try the next longer or shorter plug until you find one that fits. Once you have the proper reach, select a "regular" plug (not extended tip) with a heat range equivalent to a Champion H10. This will give you a good starting place. You may have to adjust the heat range up or down a step or two after a few hundred miles of driving, but that's part of the fun. Now that I've described how to do it, someone with the right answer will post it.
Let's hope so.DO NOT chamfer the bottom of the plug hole to expose the electrodes on a shorter plug. It will not only shroud the plug to some extent, but will also decrease the number of threads holding the plug. Aluminum is not as strong as cast iron, and those additional threads are there for a purpose.
As an aside, sometimes there is not a common plug that has the exact reach. This has been found to happen with Offenhauser heads. In such a case spacers will need to be made and used. This should not be necessary with the Edelbrocks's.
Bored&Stroked
Well-known member
Yo Tubman: I believe that Edelbrock changed all their patterns (at least on the 39-48 style) to 3/4" reach plugs - so there are a wide variety of plug options as this length is used in just about every type of OHV aftermarket head on the planet.
tubman
Well-known member
Now that you mention it, you're probably right. In any event, I test fit plugs on every set if heads I get to make sure I have the right ones.
Very good points although I don't really understand the first drawing. I went with the budget Eggy "pointed" pistons for my stk build, but down the road will likely switch to aluminum heads, so it would seem if that was the case, I would likely either look at new pistions, or some head machining.
tubman
Well-known member
Please don't get discouraged. I think that this is partially my fault, as a bunch of us have bombarded you with a lot of extraneous information. I think this is partially a desire to allow you to be informed of ALL aspects of adding aluminum heads to your engine, but also a chance for us to show off our "great knowledge". I believe that in particular, my discourse on custom fitting spark plugs and the detailed investigation of piston top profiles by "Bored & Stroked" were particularly not particularly relevant here. The Edelbrock heads probably come with a spark plug recommendation and the chance that your "stock 39" engine has the problematic Egge pistons is quite remote.
What you should be aware of is the potential problems you may encounter installing the heads. You say you have a "stock 39". That means that you have head studs, not bolts. You do not say how long it's been together, but just removing the stock heads can sometimes be a real problem because of corrosion on the studs and other problems. There is the possibility of breaking a off a stud, which really complicates the situation. Even if you get the heads off, you will have 24 obstacles sticking out of each side making clean up and prep for the installation of new heads and gaskets a real chore, especially with the engine in the car.
If the discussions in this thread are daunting for you, the mere exercise of removing the old heads, prepping the engine, and installing the new ones probably will be too. I believe you are making the correct decision in leaving well enough alone. "If it ain't broke, don't fix it".
Bored&Stroked
Well-known member
My buddy has had a set on order since November (for a 302 CI flathead that I'm mentoring him on) - the shipping date has been moving out (multiple times) - now it is in May. Due to this, I'm going to give my friend a set of NOS Edelbrock's that I have (so his build can continue).
He will replace them when his finally arrive . . .
Truth be told, I like the ORIGINAL (vintage) Edelbrock cast chambers better than their modern ones. The chambers are quite different (the vintage ones are much better) - they picked up the valve angles correctly and keep chamber volume to a minimum. In recent years, I noticed that their cast chambers became "worn out looking" from the patterns - the distinct chamber shapes were pretty much gone (in the valve areas and spark-plug transfer slot) - then they started fly-cutting the valve areas (probably to "punt" and increase the clearances so that folks wouldn't complain about valve clearance). None of the modern changes improve performance - exactly the opposite in fact!
I just dug out an old original set of Edelbrock 59AB style heads - they shaped the lower heads like Henry did (to use the short studs), the chambers are the way they should be, the fins are more elegant, etc.. I wish I had a boat load of them! I'm going to rework/restore them for a future project - they deserve to be running again.