HOME MAGAZINE FORUM RULES SPONSORS CONTACT
     
   
   
 
Go Back   CLASS RACER FORUM > Class Racer Forums > Class Racer Builds

Reply
 
Thread Tools Display Modes
Old 04-19-2019, 08:29 AM   #41
Dwight Southerland
VIP Member
 
Dwight Southerland's Avatar
 
Join Date: Dec 2001
Location: Arkansas - In the middle of everything.
Posts: 1,792
Likes: 5
Liked 67 Times in 24 Posts
Default Re: Dumbo The Flying Elephant

Larry -
If you are going to make a flat cut on the head to reduce combustion chamber size, here is an easy way to know exactly how much to cut. Put the head on a stand with the combustion chamber facing up. Shim or adjust the head so the head surface is level in all directions using a level. Then, pour the combustion chamber with the amount specified for minimum volume. Use a dial indicator on a bridge to measure the distance to the surface of the fluid from the head surface. Do that for all cylinders and adjust the numbers to determine how much to cut.
This method will work on any head regardless of combustion chamber shape or size.
__________________
Dwight Southerland is offline   Reply With Quote
Liked
Old 04-19-2019, 12:28 PM   #42
Larry Hill
Live Reporter
 
Join Date: Oct 2004
Location: Hickory, Ky
Posts: 7,442
Likes: 41
Liked 194 Times in 53 Posts
Default Re: Dumbo The Flying Elephant

Thanks Phil and Dwight, I will fill and check to see if 5cc will be .030''
__________________
IHM Used Parts
https://ihmusedparts.com
888-821-1817
Larry Hill is offline   Reply With Quote
Old 04-19-2019, 12:55 PM   #43
Greg West
Junior Member
 
Join Date: Jul 2016
Posts: 16
Likes: 0
Liked 1 Time in 1 Post
Default Re: Dumbo The Flying Elephant

Take a piece of graph paper and trace a outline of the combustion chamber shape on the paper. Count the number of squares on the paper that are within the traced area. Do the math to calculate the area of the squares. From there you can calculate the volume. This method will get you close. Double check the volume with your first pass on the mill.
Greg West is offline   Reply With Quote
Old 04-19-2019, 02:04 PM   #44
Mike Gray
Member
 
Mike Gray's Avatar
 
Join Date: Oct 2006
Posts: 269
Likes: 3
Liked 16 Times in 3 Posts
Talking Re: Dumbo The Flying Elephant

Quote:
Originally Posted by Larry Hill View Post
Pored alcohol all day and only lost 1/2 a qt. The heads are legal right out of the box. The runners are good and the chamber is big 5 to 6 cc. I will run it that way and then recheck before we make an adjustment.

Does anyone how much to cut to reduce chamber size by 1 cc?

Thanks
Hopefully it wasn't the good stuff and by losing 1/2qt do you mean spilling it or drinking it?
Mike Gray is offline   Reply With Quote
Old 04-20-2019, 06:31 AM   #45
Larry Hill
Live Reporter
 
Join Date: Oct 2004
Location: Hickory, Ky
Posts: 7,442
Likes: 41
Liked 194 Times in 53 Posts
Default Re: Dumbo The Flying Elephant

I spilled it, but I did buy a small funnel that fits the burette.

Yesterday was recording day in the "Dumbo" engine book. The engine I got came in several boxes, for me its the only way to get one. Most boxes have the brand name and part numbers. This make replacement parts hunting easier. Other parts are in plane white or brown wrappers without part numbers. Such was case with the spring seats for the head. Exhaust and intake have different seats, valves are not the same length. So I make a drawing of each in case I can't find a vendor. If push comes to shove I will be able to find some in some bar stock.

Since I had the heads out I would see how well the seats fit. They almost fit but would not set flat against the head. The problem was the OD of the chamfer was not large enough to have clearance over the radius on the head. Solution cut chamfer 1/64 bigger than the chamfer on the guide boss. I was surprised as to how soft and easy the spring seats machined.

I wonder how much unwanted aluminum the seats would have shaved of heads and put in the oil?
__________________
IHM Used Parts
https://ihmusedparts.com
888-821-1817

Last edited by Larry Hill; Yesterday at 05:53 AM. Reason: change retainers to spring seats
Larry Hill is offline   Reply With Quote
Old 04-20-2019, 06:37 PM   #46
Tom Broome
Junior Member
 
Join Date: Sep 2009
Posts: 58
Likes: 6
Liked 5 Times in 5 Posts
Default Re: Dumbo The Flying Elephant

Quote:
Originally Posted by Dwight Southerland View Post
Larry -
If you are going to make a flat cut on the head to reduce combustion chamber size, here is an easy way to know exactly how much to cut. Put the head on a stand with the combustion chamber facing up. Shim or adjust the head so the head surface is level in all directions using a level. Then, pour the combustion chamber with the amount specified for minimum volume. Use a dial indicator on a bridge to measure the distance to the surface of the fluid from the head surface. Do that for all cylinders and adjust the numbers to determine how much to cut.
This method will work on any head regardless of combustion chamber shape or size.
Done it this way for decades.

Use a dial indicator and bridge or a depth micrometer and some ground tool stock for parallels. Once the chamber is filled with the specific amount of fluid, lower the tip a thousandth at a time. Watch the tip of the indicator or micrometer, when the tip touches the fluid the surface tension will attach the tip. You can then calculate the amount to remove.
If your surfacing machine is really level, you can do it right there....you're not going to bump the head out of level after it's bolted to the machine.

Last edited by Tom Broome; 04-20-2019 at 06:42 PM.
Tom Broome is offline   Reply With Quote
Liked
Old 04-21-2019, 08:33 AM   #47
Larry Hill
Live Reporter
 
Join Date: Oct 2004
Location: Hickory, Ky
Posts: 7,442
Likes: 41
Liked 194 Times in 53 Posts
Default Re: Dumbo The Flying Elephant

Since all this gen 3 stuff is new to me I am going to check piston to valve clearance, before I do any cutting. Thanks to you guys I have some direction on doing it correctly.
__________________
IHM Used Parts
https://ihmusedparts.com
888-821-1817
Larry Hill is offline   Reply With Quote
Old 04-21-2019, 04:09 PM   #48
Larry Hill
Live Reporter
 
Join Date: Oct 2004
Location: Hickory, Ky
Posts: 7,442
Likes: 41
Liked 194 Times in 53 Posts
Default Re: Dumbo The Flying Elephant

Just finished cc's on the heads. It should make more power now that I'm done. Growing up I always heard, ''If you want to go fast get some heads that have been cc'd from Racing Head Service.'' Well I sure hope my cc'ing is as good RHS. Time will tell.
__________________
IHM Used Parts
https://ihmusedparts.com
888-821-1817
Larry Hill is offline   Reply With Quote
Old 04-21-2019, 06:44 PM   #49
Tim H
Senior Member
 
Join Date: Jan 2007
Location: Ontario, Canada
Posts: 730
Likes: 61
Liked 11 Times in 7 Posts
Default Re: Dumbo The Flying Elephant

I bet your work is "A-1" and maybe we will say " if you want to go fast, get some heads cc'd from LHS."
Tim H is offline   Reply With Quote
Old 04-22-2019, 06:37 AM   #50
Larry Hill
Live Reporter
 
Join Date: Oct 2004
Location: Hickory, Ky
Posts: 7,442
Likes: 41
Liked 194 Times in 53 Posts
Default Re: Dumbo The Flying Elephant

Today we start checking installed height, seat pressure, open pressure, and adjusting to make equal. It's going to take a while.
__________________
IHM Used Parts
https://ihmusedparts.com
888-821-1817
Larry Hill 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


All times are GMT -5. The time now is 04:51 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Copyright © Class Racer.com. All Rights Reserved. Designated trademarks and brands are the property of their respective owners.Ad Management plugin by RedTyger