Britbike forum

Classic British SparesKlempf British PartsBaxter CycleBritBike Sponsor SteadfastCyclesThe Bonneville ShopLowbrow CustomsGirling Classic MotorcycleLucas Classic MotorcycleHepolite PistonsIndustrial tec supply

Upgrade Your membership! Premium Membership Gold Membership Vendor Membership

New Sponsor post
5% Off Everything for Brit Bike Users
by The Bonneville Shop - 12/30/21 4:54 pm
New FAQ post
Manuals on DVD - Buy 4 for 3
All 4 DVD Manual
Member Spotlight
Gary Caines
Gary Caines
Hiawassee, Georgia USA
Posts: 109
Joined: October 2014
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Top Posters(30 Days)
Lannis 63
Top Likes Received (30 Days)
Lannis 25
NickL 24
Newest Members
Vincent in LA, Lil Dave, OWhatAThrill, Mountain Rider, ToddK
11,996 Registered Users
Who's Online Now
6 members (Wilfred, ducati2242, Fin_Hannu, Rohan, quinten, DavidH), 22 guests, and 16 robots.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums35
Topics75,326
Posts758,926
Members11,995
Most Online14,755
May 5th, 2019
Previous Thread
Next Thread
Print Thread
#657825 06/21/16 7:42 pm
Joined: Oct 2008
Posts: 7,500
Likes: 198
DavidP Offline OP
Britbike forum member
OP Offline
Britbike forum member
Joined: Oct 2008
Posts: 7,500
Likes: 198
Lapping in new Black Diamond valves in my A65. One cylinder is done, no bubbles seen in the soapy water when I blow air into the ports.
The other side is trouble. I've lapped those valves four times, but I still see bubbles when using this test.

I've read this thread about cutting seats at 46 degrees. http://britbike.com/forums/ubbthreads.php?ubb=showflat&Number=610086
General opinion is that the metal will deform until the valve seals.
I don't suppose that will happen in my case, so I guess I need to have the seats cut and lap some more.


It's not a bug, it's 'character.'

72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
92 BMW K100rs "Gustav"
BSA on eBay
Joined: Oct 2001
Posts: 1,973
Likes: 242
Britbike forum member
Online Content
Britbike forum member
Joined: Oct 2001
Posts: 1,973
Likes: 242
Yep, they're definitely good gear.

Joined: Apr 2005
Posts: 2,933
Likes: 64
M
Britbike forum member
Offline
Britbike forum member
M
Joined: Apr 2005
Posts: 2,933
Likes: 64
I bought an old seat cutting set that uses stones and they work very well. I never lap the seat, and also make sure they are not overly wide. I use a black texta so I can see the angles and seat width easier.

[Linked Image]

Last edited by Mark Parker; 06/26/16 1:39 am.

mark
Joined: Oct 2007
Posts: 1,409
Likes: 12
W
Britbike forum member
Online Content
Britbike forum member
W
Joined: Oct 2007
Posts: 1,409
Likes: 12
I bought a set of valve seat cutting tools set years ago for about a hundred ( apparently made in England ) but have never used them. However, I have had the local machine shop machine the head seats to match the new valves and had to lap two of the valve/sets in anyway and that was after they had seriously created deep pockets in the head which had to be eased down to get rid of all the hard edges they left behind. Perhaps I should try using the seat cutting kit next time. They are not stones but cutting edges of steel.....

Cheers, Wilf


"It's about the ride..."
Joined: Dec 2004
Posts: 11,505
Likes: 211
Britbike forum member
Offline
Britbike forum member
Joined: Dec 2004
Posts: 11,505
Likes: 211
The steel cutters if they are the same as mine don't work, they blunt too quickly. The Neway cutters however are a pleasure to use and make me very popular locally wink

1 member likes this: lemans
Joined: Mar 2009
Posts: 126
Likes: 3
Britbike forum member
Offline
Britbike forum member
Joined: Mar 2009
Posts: 126
Likes: 3
Kommando,which type of blade do you recommend for the neway cutters ? I have serrated but other types are available.

Pete.


'74 T140V,'83 XR1000, C&J FLATTRACKER T140,
Joined: Dec 2004
Posts: 11,505
Likes: 211
Britbike forum member
Offline
Britbike forum member
Joined: Dec 2004
Posts: 11,505
Likes: 211
I have serrated on 30 and 45 degree, and on the 60 partly serrated. The instruction book shows you the cutters they recommend for the end uses and my blades follow that recommendation.

Joined: Sep 2002
Posts: 7,731
Likes: 1
Britbike forum member
Offline
Britbike forum member
Joined: Sep 2002
Posts: 7,731
Likes: 1
Yes, the Neway cutters are the [***], but as kommando says: beware, you will get lots of new friends. I've now done everything from Ariel square four to Morini to Rudge with them... I can think of very few better investments I've made.


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
Joined: Oct 2008
Posts: 7,500
Likes: 198
DavidP Offline OP
Britbike forum member
OP Offline
Britbike forum member
Joined: Oct 2008
Posts: 7,500
Likes: 198
I need some new friends. Just can't see buying these things for something I rarely do (lapping has always worked in past.) I'll just go see Charlie, he probably has the stones and will cut mine for chump change.
Besides, if I had a set I wouldn't be able to find them the next time I needed them . laughing


It's not a bug, it's 'character.'

72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
92 BMW K100rs "Gustav"
Joined: Mar 2011
Posts: 255
Likes: 15
L
Britbike forum member
Offline
Britbike forum member
L
Joined: Mar 2011
Posts: 255
Likes: 15
the biggest problem with the Neway-cutters is keeping track of to whom you've lend them last time.
but they are a great source of single malts
reg A

2 members like this: BSA_WM20, kommando
Joined: May 2013
Posts: 8,358
Likes: 212
A
Britbike forum member
Online Happy
Britbike forum member
A
Joined: May 2013
Posts: 8,358
Likes: 212
I bought some Sykes picovant valve seat cutters and they did help to remove the step in the seat, however they took a lot of lapping in of the valve afterwards. Maybe from a worn guide or the pilot wasn't quite the right size. In the past I have put sheets of emery paper over the valve head to take the worst off then lap with an old valve then lap with a new valve ( that way I am not putting a bur on the new valve head) that seems to work better than the steel cutters.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (now rebuilt)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Joined: Apr 2005
Posts: 2,933
Likes: 64
M
Britbike forum member
Offline
Britbike forum member
M
Joined: Apr 2005
Posts: 2,933
Likes: 64
Shops that have expensive machines that cut 3 angles at once can really sink the valves and put big recesses that are not good. I prefer doing my own seats, and if they are recessing too much I have new seats put in, then blend and cut them myself, so I can control the widths. Overly wide seats are not good.


mark
Joined: Mar 2005
Posts: 10,781
Likes: 145
J
Britbike forum member
Offline
Britbike forum member
J
Joined: Mar 2005
Posts: 10,781
Likes: 145
Quote
Shops that have expensive machines that cut 3 angles at once can really sink the valves and put big recesses that are not good.


Whether you own a $300,000 Newen valve machine or an old orbital Black and Decker seat grinder you still have to know what you are doing. Is the person doing the work qualified? Few shops today are when it comes to working on Hemi type heads.

Mark, sinking the seat to get that top 3rd angle was the practice with many shops using seat grinding equipment long before the form tool machine (Serdi and others) or computer computer controlled single point machine (Newan) even had been thought of. I have shops ruin heads using Neway cutters. It isn't about the equipment being used but the qualifications of the person doing the job. Remember that Michaelangelo did his best work in stone using a hammer, chisel and file. Burt Munroe did all of his work in a "rose shed" with fewer tools than most of you have in your workshop.

With the fuel available today it is important to toughen your engine against detonation. This starts by using wide valve seats. Those narrow seats are great for performance engines using race fuel, but on the street an engine with narrow seats will eventually suffer from detonation or pre-ignition. Often sooner than later.

Pocketing valve seats on a Triumph typically starts with the removal and replacement of the valve guides. Because of the structure of the head casting surrounding the valve guide is minimal at best, and does not support the guide equally around its circumference, when pounded in the head often goes in at an angle. If you don't want pocketed valve seats insist that the guides be drawn into the head with a proper tool. Also insist that the old guides be machined out of the head to insure oil wont be leaking down the grooves left as you bang the guide out of the head.

Joined: Mar 2005
Posts: 10,781
Likes: 145
J
Britbike forum member
Offline
Britbike forum member
J
Joined: Mar 2005
Posts: 10,781
Likes: 145
One of the things I have learned is an awful lot of the power available is to be found in the head. A lot of this is in the placement and shape of the valve seat. While it was a lot of work to find in the first place, with hand equipment it was even more frustrating to repeat.

It was just as frustrating to copy what you found in one head to an other. By drawing in the guide, thus starting with it perfectly aligned with the valve seat, you could remove a few thousandths from the seat rather than cutting away a lot of metal just to get to the point where you had a full seat. By trying to correct what you did installing the guide there was little chance of repeating the location of that seat that was giving you that increased performance.

Also the shape of the hemi-head itself becomes the basis for the top angle. See Mark's picture above.

Joined: Mar 2005
Posts: 10,781
Likes: 145
J
Britbike forum member
Offline
Britbike forum member
J
Joined: Mar 2005
Posts: 10,781
Likes: 145
Quote
Shops that have expensive machines that cut 3 angles at once


When it comes to pre-ground tool bits you cannot use a "one type fits all" approach. Most shops will not go out and buy a "properly" ground tool bit to work on just your Hemi-head. You are not looking for someone who is calling himself an expert, but someone who is qualified to work on the type of head you have and has the proper equipment and EXPERIENCE.

The selection of cutting bits used in Serdi type machines (cut three angles at once) for various heads is extensive (although do not cover all applications), and are expensive. Some one with a Serdi type machine who works on a lot of Hemi-type heads would often have a special tool ground for the application.

Someone with a Newan machine, and is qualified to use it (owning one does not mean you are qualified to use it), is computer controlled single point technology and uses a tool similar to what you would use in lathe. The operator programs in the angles, and diameters (including the shape of the Hemi combustion chamber) so there is no need to sink the area around the seat.

Joined: Sep 2013
Posts: 73
Likes: 1
P
Britbike forum member
Offline
Britbike forum member
P
Joined: Sep 2013
Posts: 73
Likes: 1
John,

I've been wondering about the top angle cut on our hemi chambers for awhile. The 30 degree traditional top cut just digs into the chamber, making a mess. Is there a steeper angle that would work better, closer to 45, or just allow the chamber itself to be the top angle? And if so, should we be adding more angles below the main angle instead?


1970 Triumph Tiger
Joined: Aug 2001
Posts: 217
Likes: 12
M
Britbike forum member
Offline
Britbike forum member
M
Joined: Aug 2001
Posts: 217
Likes: 12
if the 30 cutter is digging into the chamber, the diameter of the cutter is too big. it needs to be no bigger that the diameter of the seat

for the record, the 45 (major angle) freshens the seat, and trues the surface to the guide. removing seat material makes a bigger hole. the valve drops in farther and that often makes the valve contact line too near the valve margin

the 30 cutter removes the top part of seat new face, and that moves the line of contact on the valve face. the more 30 you cut, the farther the contact line moves down the valve face, toward the stem

once proper contact is established the width of the seat must be checked. if it is too great, a 60 or 75 is used to narrow the total seat width. this is removing material from the inside diameter of the seat and does not affect the line of contact

if the valve is a 30 degree major angle, everything is the same except the cutters are 15, 30, 45

yes, some manufacturers use cutters that are one or 1/2 degree "off" the seat angle to create an "interference" fit. it produces "line contact" that quickly makes the valve and seat match without lapping. the (much) easier way to achieve this is by grinding the valve face to 44.5 or 29.5 degrees. I've worked 3 different brands of valve grinder (I own one), all have the 1/2 degree line scribed into the table for this purpose.

but... you don't grind coated valves, thats why we see Neway and others making 46 degree seat cutters for instance

the 3 angle cut is pretty much required when doing repair, though sometimes you only need 2 cuts to bring it to spec. there are other angles, and additional cuts that are made for performance reasons

I have (and love) Neway cutters. I dumped all my stone seat cutters & tooling 20 years ago. no regrets. the Neway valve cutter though.... meh, not so hot. I had two (old style and new style) Gizmatic. it works but you get a much cleaner face with a stone wheel type valve grinder. if you don't have space, don't cut valves often, and don't mind lapping, the Gizmatic works well enough

heres some good stuff about valve seats, etc

http://www.newaymfg.com/cutters


Moderated by  Allan G, Jon W. Whitley 

Link Copied to Clipboard
British Cycle SupplyMorries PlaceKlempf British PartsBSA Unit SinglesPodtronicVintage MagazineBritBike SponsorBritish Tools & FastenersBritBike Sponsor






© 1996-2022 britbike.com
Powered by UBB.threads™ PHP Forum Software 7.7.5