Go Back   The Ford Barn > General Discussion > Early V8 (1932-53)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 11-02-2020, 01:33 PM   #1
Daveyjonez
Member
 
Join Date: Nov 2015
Posts: 52
Default Piston to Head Clearance Input

Hello All:

I have read through a few of these threads, need some input on what I have:

4 inch stroke, 3 5/16 bore w/ Ross Pistons, Brand New Navarro Heads and New Best Graphtite Gaskets. New ARP Studs.

Aluminum Foil at sides and center of piston- torque to 40 lbs:

Clearance Middle = .120
Edge of Piston = .075

It seems compression would be way down. How much should I take off the heads??

Thanks Guys,
Dave
Daveyjonez is offline   Reply With Quote
Old 11-02-2020, 03:00 PM   #2
Bored&Stroked
Senior Member
 
Bored&Stroked's Avatar
 
Join Date: Jan 2011
Location: Central Ohio
Posts: 2,893
Default Re: Piston to Head Clearance Input

That is a little bit funny, seems the chamber design of these new Navarro heads (from H&H???) doesn't have a consistent radius over the dome - or the radius is very different from the standard Ross .187" high radius. Hmmmmmm . . .

If the head chambers had a consistent dome radius (that is very similar to the Ross pistons), then your clearances should be the same across the whole top of the piston. (Or at least quite close)

Lets find out a bit more about the chamber radius before you decide to do anything else.

Note: I have NOS Navarro heads on my 284 stroker - but I custom matched the chambers to the piston Domes (via a CNC mill). I tend to pop the piston up a bit (custom compression height pistons) - then "tune" the chamber to match. If I have to mill the heads to get the final squish, then this is what I do.

In the end, I would like to see a consistent .040 to .045 over the pistons - this gives you the best performance (squish is super important - maybe even more than compression ratio). If you can send me a couple hi-res pictures of the heads, would like to see the chambers. eMail: daleohays@gmail.com.
Bored&Stroked is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 11-02-2020, 03:01 PM   #3
Ronnieroadster
Senior Member
 
Ronnieroadster's Avatar
 
Join Date: Dec 2010
Location: East Coast in CT
Posts: 882
Default Re: Piston to Head Clearance Input

Quote:
Originally Posted by Daveyjonez View Post
Hello All:

I have read through a few of these threads, need some input on what I have:

4 inch stroke, 3 5/16 bore w/ Ross Pistons, Brand New Navarro Heads and New Best Graphtite Gaskets. New ARP Studs.

Aluminum Foil at sides and center of piston- torque to 40 lbs:

Clearance Middle = .120
Edge of Piston = .075

It seems compression would be way down. How much should I take off the heads??

Thanks Guys,
Dave
Before considering how much to take off the heads you should understand there's lots more to compression than just the measurement you have. The entire combustion chamber characteristics also need to be considered. Valve size and cam type. Also the actual use for the engine-as well as the number and type of carbs as well as if there a power adder involved {blower} the list can go on and on. The answer to your question at this point cannot be adequately given until a bunch more information is know.
Ronnieroadster
__________________
I use the F word a lot no not that word these words Flathead , Focus and Finish.
"Life Member of the Bonneville 200 MPH Club using a Ford Flathead block"
Owner , Builder and Driver of the First Ford Flathead bodied roadster to run 200 MPH Record run July 13, 2018 LTA timing association 200.921 from a standing start in one and a half miles burning gasoline.
Ronnieroadster is online now   Reply With Quote
Old 11-02-2020, 03:13 PM   #4
GOSFAST
Senior Member
 
GOSFAST's Avatar
 
Join Date: May 2010
Location: Long Island, NY
Posts: 1,052
Default Re: Piston to Head Clearance Input

Lots more issues with the "new" Navarro's than what's apparent, including cooling hole misalignment?

Do a search, I checked these out very closely for a recent blown build here?

Thanks, Gary in N.Y.

P.S. Had words with H&H back then will NOT use or sell them here no matter what! Here's a few shots, with your short stroke and assuming they are also 80cc heads be a bit tough on the final C.R.
Attached Images
File Type: jpg Flathead Navarro Heads-Gasket Fit D.JPG (87.4 KB, 106 views)
File Type: jpg Flathead Navarro Heads-Gasket Fit A.JPG (75.4 KB, 98 views)
File Type: jpg Flathead Navarro Heads-Gasket Fit B.JPG (85.6 KB, 93 views)

Last edited by GOSFAST; 11-02-2020 at 03:21 PM. Reason: Add photos
GOSFAST is offline   Reply With Quote
Old 11-02-2020, 03:40 PM   #5
Daveyjonez
Member
 
Join Date: Nov 2015
Posts: 52
Default Re: Piston to Head Clearance Input

Thanks Ronnie:

Stock size valves- 1007b camshaft. Looking to run two 48’s. Just looking for a zippy street motor. In terms of compression, I guess I should be asking- with a stock deck and a given gasket, what should my compression be with those pistons and heads?? (Shouldn’t HnH be able to tell me)? I would think the radius should be consistent over the dome as commented above. Do I have a bum set of heads??

Thanks Again
Daveyjonez is offline   Reply With Quote
Old 11-02-2020, 04:01 PM   #6
Bored&Stroked
Senior Member
 
Bored&Stroked's Avatar
 
Join Date: Jan 2011
Location: Central Ohio
Posts: 2,893
Default Re: Piston to Head Clearance Input

Sponsored Links (Register now to hide all advertisements)
Nobody can tell you what your CR is - you'll have to CC the heads (on the engine is the easiest) - making sure there is no air in the chambers - with piston at TDC and determine the final compression area volume.

You can also do it by measuring everything separately, but you'll find it is a bit more work (needing a plexiglass plate) - measuring the head, measuring the block valve/relief area, the head gasket area and then subtracting the dome area.

Good luck!
Bored&Stroked is offline   Reply With Quote
Old 11-02-2020, 04:46 PM   #7
Daveyjonez
Member
 
Join Date: Nov 2015
Posts: 52
Default Re: Piston to Head Clearance Input

Quote:
Originally Posted by Bored&Stroked View Post
That is a little bit funny, seems the chamber design of these new Navarro heads (from H&H???) doesn't have a consistent radius over the dome - or the radius is very different from the standard Ross .187" high radius. Hmmmmmm . . .

If the head chambers had a consistent dome radius (that is very similar to the Ross pistons), then your clearances should be the same across the whole top of the piston. (Or at least quite close)

Lets find out a bit more about the chamber radius before you decide to do anything else.

Note: I have NOS Navarro heads on my 284 stroker - but I custom matched the chambers to the piston Domes (via a CNC mill). I tend to pop the piston up a bit (custom compression height pistons) - then "tune" the chamber to match. If I have to mill the heads to get the final squish, then this is what I do.

In the end, I would like to see a consistent .040 to .045 over the pistons - this gives you the best performance (squish is super important - maybe even more than compression ratio). If you can send me a couple hi-res pictures of the heads, would like to see the chambers. eMail: daleohays@gmail.com.
Thanks Bored Stroked- i sent you some photos
Daveyjonez is offline   Reply With Quote
Old 11-02-2020, 05:22 PM   #8
JSeery
Senior Member
 
JSeery's Avatar
 
Join Date: Nov 2012
Location: Wichita KS
Posts: 15,452
Default Re: Piston to Head Clearance Input

You might gain some insight by reading the thread GOFAST started on the H&H heads.
JSeery is offline   Reply With Quote
Old 11-02-2020, 05:39 PM   #9
Ronnieroadster
Senior Member
 
Ronnieroadster's Avatar
 
Join Date: Dec 2010
Location: East Coast in CT
Posts: 882
Default Re: Piston to Head Clearance Input

Quote:
Originally Posted by Daveyjonez View Post
Thanks Ronnie:

Stock size valves- 1007b camshaft. Looking to run two 48’s. Just looking for a zippy street motor. In terms of compression, I guess I should be asking- with a stock deck and a given gasket, what should my compression be with those pistons and heads?? (Shouldn’t HnH be able to tell me)? I would think the radius should be consistent over the dome as commented above. Do I have a bum set of heads??

Thanks Again
Your welcome
There's really no way for the radius of the dome to be identical to the top of the piston unless both parts were made by the same company that way they would actually match. Back when Barney Navarro was making the heads he no doubt had the dome matching similar to what ever piston was popular at the time. It may have been the shape of the stock Ford piston or at the time the popular Jahns pistons. Heck when i made my doming tool back in the last century we used the Jahns piston dome as our model that was way before Ross pistons. The fact the radius is not consistent will not effect how well your engine will run its certainly something interesting you discovered but really nothing to worry about. The one area I pay very close attention to on original older heads and todays new production heads is the water hole locations in relationship to the brand of head gaskets being used. That by far is extremely important.
Ronnieroadster
__________________
I use the F word a lot no not that word these words Flathead , Focus and Finish.
"Life Member of the Bonneville 200 MPH Club using a Ford Flathead block"
Owner , Builder and Driver of the First Ford Flathead bodied roadster to run 200 MPH Record run July 13, 2018 LTA timing association 200.921 from a standing start in one and a half miles burning gasoline.
Ronnieroadster is online now   Reply With Quote
Old 11-02-2020, 05:50 PM   #10
Bored&Stroked
Senior Member
 
Bored&Stroked's Avatar
 
Join Date: Jan 2011
Location: Central Ohio
Posts: 2,893
Default Re: Piston to Head Clearance Input

FYI: As a side note, there are TWO different Jahn's piston domes - the one on the 3 ring "racing pistons" used a consistent radius, the one on the 4-ring stock-style pistons used a multi-ellipse pattern - essentially two different elliptical profiles on the same dome.

There are a variety of different piston crown/dome styles - some with a consistent radius, some with the multi-elliptical radius. I've seen different chamber/dome shapes on various Navarro heads over the years (original sets) - but I have no idea as to what H&H is doing these days.
Bored&Stroked is offline   Reply With Quote
Old 11-02-2020, 09:45 PM   #11
Charlie ny
Senior Member
 
Join Date: May 2010
Posts: 2,588
Default Re: Piston to Head Clearance Input

Dave,
I've mention my method of matching chambers and domes & determining
valve clearance.......
I'll use alum foil balls to begin the process to determine how much to mill the heads. Part of that is to attach the head without the gasket to the block and turn
it over by hand a few times. If the average crush on the balls is .060 I'll have head
milled that much. Now comes the multi hour massage.....using prussian blue on the

piston domes and the heads of the valves, it's messy. The head is hung on the block with 4 studs and using arm pressure to hold the head down I spin the motor over
a few times. Removing the head and flipping it over I can plainly see areas of

contact and patiently blend those areas away using my trusty high speed air grinder. In most cases a head is off and on 20 times and the process per head is usually 10 to 12 hours. You must take your time.
I'm on my 6th motor using this process and interestingly while it's not CNC it surely
fits the head to the block perfectly. Something that comes to light is one bank will
be off to the front the other side will favor to the rear. With this proceedure the head
gasket is out of the equation until final assembly...this is where the .040 piston to head clearance is addressed....a crushed BEST head gasket is .040.
I will tell you when I wind either motor up to 5000 plus I think about that .040
and rod stretch but so far so good.
Charlie ny
Charlie ny is offline   Reply With Quote
Old 11-02-2020, 10:17 PM   #12
tubman
Senior Member
 
tubman's Avatar
 
Join Date: Dec 2013
Location: Minnesota, Florida Keys
Posts: 6,996
Default Re: Piston to Head Clearance Input

I agree with everything "Charlie ny" said above. I have been through the heads off and on 20 times as well. Although cast iron heads can be made to perform as well as fancy aftermarket finned units, I only use the aluminum heads because they're not nearly as much work as the iron ones. I guess I'm just lazy, though I do like the looks of the finned units.

Again, this is probably the cheapest and most important thing you can do to improve flathead performance. It sounds like you may have bit of a problem with the larger than normal variation in the clearance in various areas. This is where judgement comes in to decide between the amount of grinding you do versus the amount initially milled off the heads.

Last edited by tubman; 11-03-2020 at 10:04 AM.
tubman is offline   Reply With Quote
Old 11-02-2020, 11:36 PM   #13
Ol' Ron
Senior Member
 
Ol' Ron's Avatar
 
Join Date: May 2010
Location: Chester Vt
Posts: 7,742
Default Re: Piston to Head Clearance Input

I still can't believe their still putting the sparkplug in the same place they did back in the 30's. The original reason was to clean the spark plug. Modern designed combustion chambers place the spark plug where it will doo the most good for a complet combustion of the AF
Considering the fact we are so concerned about piston to head clearance, there is a reason why! The large area of the piston diameter contains the majority of the AF as the piston reached the top of the cylinder it pushes all this mass at the spark plug, and the ideal place would be in the center of the transfer area. With all the money and time people spend on improving the old flathead, you'd think they would consider something a trivial as this. But changing patterns are expensive.

Just had to get this off my chest
Gramps
Ol' Ron is offline   Reply With Quote
Old 11-03-2020, 08:30 AM   #14
JWL
Senior Member
 
Join Date: May 2010
Location: Fitzgerald, Georgia
Posts: 2,050
Default Re: Piston to Head Clearance Input

If you read my book you will find the Navarro-H&H clearances in your post are typical of the problems I pointed out. There is no easy path to perfection. However, that does not mean your engine will not run just fine. I suggest setting the minimum clearance at .050-.055 when using new Ford rods and a little tighter with used Ford rods but not less than .045.


And, I agree, the sparkplug should be moved.
JWL is offline   Reply With Quote
Old 11-03-2020, 10:05 AM   #15
tubman
Senior Member
 
tubman's Avatar
 
Join Date: Dec 2013
Location: Minnesota, Florida Keys
Posts: 6,996
Default Re: Piston to Head Clearance Input

Well, they are moved, just a little, on Edmunds heads (at least the 8BA versions).
tubman is offline   Reply With Quote
Old 11-03-2020, 10:06 AM   #16
Charlie ny
Senior Member
 
Join Date: May 2010
Posts: 2,588
Default Re: Piston to Head Clearance Input

Ron & John,
For my education where do you guys consider the transfer area to be ?

AND
How proper would it be to bore 1" dia holes in each transfer area and press/
furnace braze steel 'bushings' (with SP threads) in those holes ?
I'm getting ready for long winter.
Charlie ny
Charlie ny is offline   Reply With Quote
Old 11-03-2020, 10:58 AM   #17
JSeery
Senior Member
 
JSeery's Avatar
 
Join Date: Nov 2012
Location: Wichita KS
Posts: 15,452
Default Re: Piston to Head Clearance Input

Quote:
Originally Posted by Charlie ny View Post
Ron & John,
For my education where do you guys consider the transfer area to be ?

AND
How proper would it be to bore 1" dia holes in each transfer area and press/
furnace braze steel 'bushings' (with SP threads) in those holes ?
I'm getting ready for long winter.
Charlie ny
I would like to see some actual test results on this modification. Seems hard to believe all of the common heads (including OEM) would keep the plug located over the edge of the ex valve if there is an advantage to moving it. The normal plug location puts a lot of restrictions on plug selection, you would think it would be moved if there was even the slightest advantage, or at least no loss in performance. Test data would sure be interesting.
JSeery is offline   Reply With Quote
Old 11-03-2020, 11:02 AM   #18
flatjack9
Senior Member
 
flatjack9's Avatar
 
Join Date: May 2010
Location: Oshkosh, Wi
Posts: 3,855
Default Re: Piston to Head Clearance Input

The obvious advantage is spark plug selection, if nothing else.
flatjack9 is offline   Reply With Quote
Old 11-03-2020, 11:16 AM   #19
tubman
Senior Member
 
tubman's Avatar
 
Join Date: Dec 2013
Location: Minnesota, Florida Keys
Posts: 6,996
Default Re: Piston to Head Clearance Input

I am able to run extended tip spark plugs in my engines and I believe it helps a lot.
tubman is offline   Reply With Quote
Old 11-03-2020, 12:00 PM   #20
Daveyjonez
Member
 
Join Date: Nov 2015
Posts: 52
Default Re: Piston to Head Clearance Input

Thanks for the information guys, I appreciate it.
Daveyjonez is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 08:49 AM.