Here's some pictures of Dad's speedster engine going back together. I have dummied it up with a head gasket and plastecine to find about .260" is the minimum clearance.
Can anyone tell me what the nominal volume of a Reeder alloy head is? I'd like to sort out the compression ratio on a .060" over and otherwise standard T engine. Is there a good estimate as to piston crown volume?
I'm a little concerned about facing lots off the head owing to it's thinness(?) around the center water hole. Has anyone removed a good deal of metal from these things?
See "Modeling Clay Test" last visited 01/03/08 (or, in your case 03/01/08). Charles provided some volumes in his post on New Year's Eve (31/12/07).
You can measure the volume by lying the head on its back and filling it with water. Your pharmacy should have graduated cups. I used to get them with Kwik Poly kits.
Subtracting the volume of the piston popup is a fun exercise in math. Where did those pistons come from?
You can measure the volume by lying the head on its back and filling it with water.
Ok, Brent, you could use ATF, and dump it in the gas tank when finished.
Or, you could put a drop of detergent in the water.
Or, you could consult the Okie T Club website. They've already done it.
BTW, .060 overbore is inconsequential. That's .030 squared x Pi.
I used to work in an engine machine shop and if I had the time I'd go bother them for the sheet of perspex and burette they used for cc'íng.
With the head on a slight angle, the perspex sealed down using grease you can fill the chamber (thru a hole in the perspex) with kerosene/degraser with great accuracy.
I'll look up the threads listed
Seth(?) I might bother you about valve timing when I have the figures nailed down. I think I need .028"!! intake clearance but I'll explain later
Cheers for your help.
"Bother" me anytime you like though I'll warn you in advance that I'm not a proponent of gross valve lash to satisfy valve timing....:-(
To further clarify I have done the numbers on Dad's speedster. My figures are as best as I can get seat to seat. I think intake duration of 236deg is too great?
The unspecified reground cam with .012" lash works a little like this...
Intake Opens 79deg ATDC
Intake Closes 45degBTDC
Duration 236 Lift .249"
Exhaust Opens 34deg ABDC
Exhaust Closes 81deg ATDC
Duration 227deg Lift .247"
Now looking at all the information I can find on camshafts they tell me that 220 or 225 intake duration is the best...
The engine has a tube steel exhaust header but is standard aside from 1912 intake, tickled straight Holley NH, Reeder head and Tru-Fire, because there are no flywheel magnets.
So by giving it .028" lash I can trim the intake timing (and lift I know) and I was interested to do the experiment so to speak. It would be noisy but I guess the valve will really boogie off the seat!
at .028" it looks like this...
Intake open 8deg ATDC
Intake closes 50deg ABDC
Duration 222deg Lift about .221"
So what do you all think??
I had a Porsche 914 with factory EFI, and a high lift cam. . It would not idle down to the specified 1000 rpm, so to pass a smog check I had to open the valve lash to about .030. It clattered awful, but burnt clean at the required rpm. I readjusted the valves after the check.
That engine is never even going to start timed like that.
For 236 degrees of intake duration, the valve should begin to open at like 5 BTDC and get closed at 51 ABDC.
For 222 degrees of exhaust duration, the valve should begin to open at like 37 BBDC and get closed at 5 ATDC.
Duration figures usually mean at a certain lash but also a certain amount off the seat.
If my cam, I'd check overlap first, using 0.010" lash on the intakes and 0.014" on the exhausts. If that is more than about 20 degrees (crank) from "just open" on the intake to "just closed" on the exhaust, expect rough idle. Flathead engines are very sensitive to valve overlap.
Then I'd time it to where the center of the overlap was just before TDC - yes, this means new holes in the gear!
Then I'd build it, using 0.010" lash on the intakes and 0.014" on the exhausts. Then I'd run it to see what I thought of it.
If in my 3:1 rear axle car with no auxiliary transmission I might be unhappy with the low speed torque but more than happy with the top speed. I'd then drill another cam gear to advance the valve timing maybe 6 degrees (crank). Low speed torque would improve at little expense in top speed.
For a light car like a speedster, 236 degrees intake duration doesn't seem excessive to me, especially with more compression. It will be a benefit to hand cranking because it steals compression stroke.
A centerdoor with a stock 3.98:1 compression ratio head would not like your cam - no amount of valve timing advance would give you adequate low speed torque.
That's what I would do. Others may disagree.
Yeah you're right Seth...
Embarassingly I was just writing down the first raw figurs I got off the engine without remembering, with the engine vertical for convinience, I had laid the degree wheel flat on the flywheel... backwards they are!!!
Anyway I thought the intake figures using .028" lash were somewhere in between the specs listed by the Tulsa site for the ďmproved standard and "280 super power"
I will go and do some more measuring, perhaps print off a cheapie degree wheel, and do the figures at .050" as well
At least (unlike my 351Boss) we don't have rocker geometry to play with here!
Ricks I know what you mean about the happy chatter of valve gear. My Morris Mini used to run .022" clearance and though that did seem excessive gee did it go, all the way to 8000rpm.
Cheers for your time guys
This last week I milled off .120" from a high head to boost compression. I also had another high head that I previously milled off .100" and a Z head that had .020" milled off. In addition, I also had a stock low head. I decided to do some volume comparisons and here are my findings:
Z head milled .020: 208 ML
Low head (stock): 286 ML
High head milled .100": 290 ML
High head milled .120": 270 ML
Method used for measurment: I supported and leveled each head on a mill table using a machinists precision level in both X and Y planes. I placed a precision parallel bar across the combustion chamber (Approx. Centered) and filled each chamber with water until the water maniscus just touched the bottom edge of the parallel bar. I used a graduated lab beaker (ML) for measuring the amount of water required to fill each chamber measured. This may not be the most accurate method for measurement.....however, I do feel my numbers are interesting when comparing head volumes.
Visually comparing 3 Z heads, I am not impressed with the Z head registration (centering) of the bolt holes and water inlet openings or locations in relationship to the combustion chamber compared with stock heads.
One of my friends had to fly cut out several combustion chambers on a Z head in order to gain sufficient piston clearance. His engine is bored only .030" over. On one high head that I was experimented with, I milled off .120" on half the head then cut the head in both directions in order to see how much combustion chamber material was left stock vice milled area.
It is only my opinion....but I do not recommend removing more than .120" from a stock high head. Has anyone milled much off a low head and how far can you go? Have any volume measurements on a milled low head? Just sharing my findings and not suggesting that others follow in my steps. I have reviewed the cam project & Tulsa web site for their findings which were interesting but did not answer all of my questions. "Les"
Your numbers jibe with what I remembered, Les; the stock low head is indeed higher CR than stock high head.
"Low head (stock): 286 ML"
"High head milled .100": 290 ML"
Is yours the later low head with the script?
My Reeder head measured as follows, Anthony:
CR calcs .06 over
Displacement = 45.34 cu. in. = 24.94 oz.
Reeder head = 14.55 cu. " = 8 oz
Popup = -3.54 cu. " = 1.95 oz Egge/Chevy pistons
Gasket .75" = .41 oz
CR 57 / 11.75 = 4.85:1
Les -- I just had .125" milled off a low head. I haven't assembled the total engine yet, but nothing touches the head without a head gasket. I showed some pics of modeling clay on the pistons to test clearance in another thread a couple of weeks ago. That was before milling, to see how much I could have removed. I'll do another modeling clay test with the milled head when I get back to it. (The engine has .040-over domed pistons, and a Stipe 250 cam with the valves set at .010 and .012, solid lifters.)
The low head that I used for this compairson had rased lettering. The word "Ford" was centered with "Made" and "In USA" along one side. In addition, I have several other low heads that are cracked....one only has "Ford". The low head that I am running on our 13 also has rased numbers at the back of the head...."7 2 11". Another low head has "11 1 25" have no idea what these numbers mean. If it were a cast date "11 1 25" does not agree for a low head?? Mike, I would still like to know what your low head chamber volume measures with .120" milled off? With that much milled off a low head, how would it compair to a Z head? I know that the chamber shape....as in "Squish" area also has a lot to do with performance beside just compression. Any education on this subject as it applies to T's is appreciated. Thanks, "Les"
Right well I havn't done the compression measurements yet but here is the final word on valve timing... advertised and (.050" figures)
Intake with .012" lash gets .260" lift
Intake opens 9deg BTDC (19deg ATDC)
Intake closes 63deg ABDC (44deg ABDC)
Exhaust with .014 lash gets .255" lift
Exhaust opens 57deg BBDC (32deg BBDC)
Exhaust closes 6deg ATDC (13deg BTDC)
Overlap is 15degrees.
Having looked at all this I don't know what adjustment I can make anyway... it appears Dad has fitted a fibre timing gear so I am a little reluctant to try putting a scotch key in that!
Compression is the next issue. I'm pretty sure there is some scope for improvement there.
I'll post as many head volume measuremens as I can get...
Looks good by me. Get all the CR you can, button it up, and enjoy!....Seth
I've not spent years with Ts, have been told to buzz off twice now with no forum participant having enough of a problem with it to even mention it, so you might want to check with a real expert before you go much further.
My opinion? The car should run like a scalded-a$$ ape. If it does, just keep it to yourself.
Have a fine week.
Are those high dome aluminum pistons in the top photo of this thread? Can you run high dome aluminum pistons with a Reeder (high compression?) alloy head?
Domes are round, that one looks beveled. The short answer is no, you can't mix them out of the box. The other answer is yes, you can do anything if you put enough effort into it.
But, go over about 7:1 and your beyond what I consider safe to use with the original babbitt bearings. I've done two with 100psi compression (we're at 50ft above sea level here), one worked ok (new babbitt), and the other one beat the babbitt(75 year old babbitt) up enough to require adjustments every few hundred miles, forcing me to change to a 6:1 Z head.
These pistons are a direct replacement chamfered/flat top T pistons. I'm unsure of the brand but they aren't Australian made JP pistons.
I have heard, and hand cranked myself a speedster that had was fitted with both alloy head and domed pistons. It certainly seemed to go well
It had some noticeable but not unreasonable comp when swinging it over. I dont know what the compression ratio was or if the pistons had been profiled or head reshaped?
Might be able to find the bloke if you need to talk to him.
Thanks Anthony, your answer was enough for me.
Which aluminum head has 20 - 27 Ford cast in the #4 cylinder area on the driver's side? I have one of those that I got 2nd hand and am wondering if I should try it on my engine.
My Reeder head has its name stamped inside the water outlet.