Valve Spring Reference

[greg brillus]

I actually don't see why anyone should hide engine tips for gaining horse power on these engines, what are you really up against 10 other Vincent's out on the track..........hardly these days. It really comes down to how much money one can spend, that is the limiting factor for most of us.

 

[vibrac]

I actually don't see why anyone should hide engine tips for gaining horse power on these engines, what are you really up against 10 other Vincent's out on the track..........hardly these days. It really comes down to how much money one can spend, that is the limiting factor for most of us.

So true, plus the ACU regs for those of us in UK wanting to do a championship, however I suppose if I had the cash I could build a Vincent to chalenge the 1962 cut off rather than the 1949 so yes it all comes down to money

 

[Deleted member 3831]

The PAC1223 spring is well known to me, it being a progressively wound spring of ovate wire section, and is favored by many Classic racers for fitment in their Norton Commando engines, but is not used in any of the top performing, 2 valve big single engines, where valve lifts are approaching 15 mm.
In these engines, springs often used are RD10034 or PSI1536 - seriously strong when compared to PAC1223, but found necessary to maintain control of the valve train at the engine speeds where maximum power is developed. These two springs are doubles, and are progressively wound round wire items.
For use in a Vincent engine where standard cams are still used, the PAC1223 would most probably be a spring that would be hard to better

 

[bmetcalf]

I don't suppose the standard ET37 & ET40 or PAC parts will work without modification?

 

[davidd]

The PAC 512 titanium retainer is what I wanted to use.

There does not seem to be a big reason to use all the extra weight of the stock item. It was difficult to find the correct valve locks as the Ford uses tripple radius locks to keep the valve spinning. I did find a single radius lock, but it is not listed in their catalog, so it took me a while to find it: L8087. This means that you can turn a single groove into the top of the valve for a single radius lock.

For the top valve guide I turned down a stock one. I will have a few made up to fit the much smaller diameter of the valve spring.

I did all of the above as a test fit to determine the design of the valve.

The titanium retainer, 512, is $15 from PAC. I had to buy a new valve height micrometer to adjust the seat height and a new valve spring compressor due to the small diameter of the valve spring.

David

 

[bmetcalf]

turn a single groove into the top of the valve for a single radius lock.

Is this a mod to a standard Vin valve or a modified alternate? With the new spring being shorter, what is the groove height above the shoulder?

 

[eglijim]

I actually don't see why anyone should hide engine tips for gaining horse power on these engines, what are you really up against 10 other Vincent's out on the track..........hardly these days. It really comes down to how much money one can spend, that is the limiting factor for most of us.

With you completely Greg, even if you tell all, very few people will have the skill to anything with the information. Just for interest but no science, I have just found I can (just)push the valves off their seats with the heel on my hand, Gold star springs. The Comet engine build notes are also attached. Now we have to build the bike and try to persuade the DVLA to register it as a reconstructed classic in a 30+ year old unused Egli Comet frame I have.

 

[davidd]

Is this a mod to a standard Vin valve or a modified alternate? With the new spring being shorter, what is the groove height above the shoulder?

The valve that I have in the photo for the mock up is a Vincent valve that I cut a groove right at the top of the stem to see how much more height I would need. The beehive spring is taller than the Vincent spring when installed. I need a valve that is slightly longer and has a taller shoulder by .080". I also have to step it down to 5/16" to fit the retainer.

I will use a Mopar small block valve for the next mock up. The hope was to use off the shelf performance parts for the mod, while restricting most of the changes to the valve, which needed to be custom made anyway to run the cam. As it turned out, the top valve guide will probably have to be made and it is possible that the valve cap itself may need to be modified for the new height of the valve.

I used the two above ending in 196 and 198.

Greg used Chevy big block valves and Toyota Corolla retainers and locks to make his racer valves.

I don't have the position of the top groove on the valve here with me. It is at the shop on my notes.

David

 

[bmetcalf]

I'm thinking I'll "Keep 'em standard!", to quote One Track. My bike is just a humble Rapide anyway.

 

[Robert Watson]

We made new valves for my A's using big block chevy valves. Worked just fine.