Raising the compresion on a 1917 head

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration
Model T Ford Forum: Forum 2012: Raising the compresion on a 1917 head
Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Diederich on Sunday, September 30, 2012 - 09:07 am:

I have my cly head off the block and want to know how much I can machine off? I have a machine shop that will do it but I have to tell them how much. I don't think it has been machined before. I would like to get a little more power for hills. Thank you Bob Diederich MTFCA 22350


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Gruber- Spanaway, Wash. on Sunday, September 30, 2012 - 09:32 am:

I milled .125" (1/8") off a couple heads.
My friend said he could notice a little more power...I didn't see a difference.
Mine cracked after a year or so.
I wouldn't bother.


Top of pagePrevious messageNext messageBottom of page Link to this message  By joe bell on Sunday, September 30, 2012 - 09:37 am:

I have seen 1/4 milled off, you need to shorten head bolts.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary H. White - Sheridan, MI on Sunday, September 30, 2012 - 10:39 am:

I took .125 off and used domed pistons.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Walker, NW AR on Sunday, September 30, 2012 - 10:59 am:

Bob D. -- Since you don't know whether the head and/or block have been milled before, you should use balls of modeling clay on the tops of the pistons to determine how much clearance is there. Like Gary, I have used domed pistons and milled a low head .125, but not before checking the clearance. I put about 5 balls of clay on each piston, to see where the closest point is. After that, you can use just one per piston at that closest point.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Walker, NW AR on Sunday, September 30, 2012 - 11:03 am:

BTW, Using the domed pistons and milled head, I noticed quite a difference in power, similar to using a high-compression aluminum head. (No dyno involved, just seat of the pants experience.)

I'm not sure that milling the head without using the domed pistons would make much difference, but it might help a little.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Diederich on Sunday, September 30, 2012 - 11:10 am:

Hello, I.am the Bob that posted the message about milling the head if any one has any thoughts on the subject either neg or pos please post. I have the head off but if there is no change in performance I'am not sure it will be worth the bother. Thanks Bob


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Scott Owens on Sunday, September 30, 2012 - 12:28 pm:

Bob, Use the money that you are going to pay for milling the head and buy new domed pistons. Its a little more money but lots more power than just milling the head. And you get fresh pistons with tight ring glands. And of course new rings. You will like the power increase. Scott


Top of pagePrevious messageNext messageBottom of page Link to this message  By David M.Saleh on Sunday, September 30, 2012 - 02:55 pm:

.125 is the minimum to mill off a stock head to make it worth the effort and SHOULD make a noticble difference in any Model T , how could in not! 1/4 is about max off a stock head.
Milling the model T head to raise compression is about the single most important serious performance improvement (and a easy one),one can make in stock car . I live in a city of hills and heavy city traffic..Geting a little more peppy off the line and a good head start for the hills is needed. My last Runabout a 24,,with iron pistons..I milled off 1/8" .The car ran cooler,idled smoother,started quicker.added 2 -3 more MPG overall and many of the hills I had to shift into low I was able to pull in high gear! Remember the fuel wasn't to good and lower compression was needed back then but many cars had compression in 5.2- 5.5 range at the time.And Fuel is better as far as knocking.
Some places have trouble milling these old flat heads because they can' t just bolt them up in the new jigs set up for more popular modern engines, 2 machine shops I tried couldn't/wouldn't do it.The head(scrap test head)chattered..The one shop local I found that worked on vintage cars for a high end restore/dealer did it,and actually lightly threaded a head bolt hole on each end of head..(I barely noticed it) to hold it down right. It was 200.00 bucks..Its not a fast process and setting up took time I;/m sure.You may find cheaper .
I'd mill an iron head down before I spend on an Aluminum head...Iron/steel and aluminum don't like each other and it's nice to keep as much period metal on the car if you can!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Nathan Bright on Monday, October 01, 2012 - 05:53 pm:

Can you tell us how much they are doing it for? so we have a ballpark for whats a normal price for such thing? Thankyou!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Walker, NW AR on Tuesday, October 02, 2012 - 06:56 pm:

Hi, Nathan -- I've been trying to answer your question for 3 days now. :-) Thanks, Chris!!!

I've had some iron heads milled 1/8" at two different shops. The charge was $60 at one and $100 at the other. Those are Arkansas prices, so they should be about that in SC, ballpark anyway.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Money - Braidwood, IL on Tuesday, October 02, 2012 - 07:14 pm:

$45 around here for mine to get milled.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry Ostbye on Tuesday, October 02, 2012 - 07:23 pm:

If you want power buy a Z head. Huge difference !
I milled a low head for my car to 680 CCs if I remember right. Look it up on that club in Co. that does all the dinoing. It made a bit of difference but the Z head was amazing.
Note that a milled low head gave me only 4.2 to 1 compression and an unmilled Z Head gives you 5.8 to 1 but the power comes from the much better combustion chamber design. WELL WORTH THE $$


Top of pagePrevious messageNext messageBottom of page Link to this message  By mike conrad on Tuesday, October 02, 2012 - 07:43 pm:

BUT,Jerry!! David said iron/steel and aluminum don't like each other. (Dave you forgot copper) aaand it's nice to keep as much period metal as you can (I know, that second one's out there alittle) Please don't tell my T's, they love their Z heads Over 8 years on the one car But you know me most likily not alot of miles on that car...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry Ostbye on Tuesday, October 02, 2012 - 10:21 pm:

Mike, it might be your imagination that most new cars have cast iron blocks with aluminum heads


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Gruber- Spanaway, Wash. on Tuesday, October 02, 2012 - 10:28 pm:

I just put a P head on my car (along with a new engine).
It certainly has more power than the old engine with a Waukesha Ricardo head.
Yeah, Mike I've seen your car sitting with grass growing up around it!
Yard art?


Posting is currently disabled in this topic. Contact your discussion moderator for more information.
Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration