TR2/3/3A valves and guides

[sp53]

I am not sure what valves and guides to buy for my tr3 head. Should I was the bronze guides or the stock. Should I use the larger 3/8 or the 5/16 exhaust valves. Should I use the stainless steel valves with the stellite tip? And should I use the double or triple spring set. My dyslexia is probably kicking in when I read those spring foot notes in the Moss book so any suggestion would are helpful.

 

[CJD]

How will you be using the engine?

For street use, I'd personally go 3/8" valves (strength), lighter springs (longevity) , steel guides (longevity). With the 3/8" valves you may be able to just ream the old guides, which is their main purpose for being.

For performance, I'd pick 5/16" valves (for flow), bronze guides (easier on stems), strongest springs available (allows higher RPM before floating), and stainless exhaust (for higher temps).

 

[TR3driver]

My recipe would be a bit different : cast iron guides even for a street performance build; and if you are going to replace the valves anyway; 5/16 stems even for the street. Use triple springs with the 3/8 valves; double with the 5/16. Note that the triple springs need a special collar that fits between the inner springs and the cylinder head. Although Moss doesn't mention it, I believe that collar is different for the later double valve springs. (108242 for triple springs; 105803 for double springs). The later collars don't have a step for the 3rd spring.

Stronger springs than stock are a waste of money, IMO, unless you are building an engine that will turn over 6000 rpm. They also cause a lot of extra wear on other components, like the camshaft & valve seats, all the time (not just when using that extra rpm). However, the lightweight alloy retainers might be worthwhile.

Note that the bronze guides need to be reamed after installation, and just a bit larger than the cast iron ones; as the clearance between the guide and stem closes up when the engine gets hot.

 

[sp53]

That is good point John. I do not plan on Hot Roding. Anywaysit looks like to me the exhaust valves are the ones that need to be thought out.I guess the intakes are 5/16 and the exhausts can be 3/8 or 5/16 either basic stainlessor something special. There does not seem to a big difference in exhaust springprice if I went triple spring or double spring, but collars have a differentpart number. The 5/16 SS valves are cheaper, so I guess the cheapest deal is5/16 SS valves and cast guides and perhaps the triple exhaust springs could bebetter, but it looks like they went to double springs on the tr4 for somereason.

 

[sp53]

Thanks Randall I just saw your post and that is the partthat confused me could I use the double springs with the same collar and whywould they change the tr4 to a double spring if the tr4 motors had more HP.

 

[CJD]

It can be confusing looking just at the number of springs. I am not familiar with the Moss offering, but many performance springs I have used only use a single, very strong spring. Conversely, I have seen many stock set ups use more springs for damping, but still have a lower total force. You really have to read the data sheet to know the difference. Look at the pressure at the installed height, and the pressure at the projected valve lift height to compare.


For comparison, the stock springs are rated in the service manual at:

Outer springs 38 lbs seat pressure at 1.98" compression
Inlet inner spring 33 lbs at 1.5" compression
Inner exhaust "aux" spring 10 lbs at 1.54" compression

The pressure at full valve opening is not listed, but would be easy to find out with a scale and a press.
The only advantage to more pressure is being able to turn a higher RPM. The disadvantage to more pressure is shorter valve train longevity, including the cam, lifters, pushrods and rocker shaft.

 

[charleyf]

There are times that a knowledgeable sales person is a real delight. In my case the last time that I rebuilt a head ( that had triple springs) and I wanted only double springs , I contacted British Parts Northwest( 503-864-2001 near Portland ORE.) and told him what direction I wanted to go. They responded by saying they understood exactly what I wanted and would put together the parts that I needed. I need to add that their prices are competitive with Moss and TRF. They can also answer any of those questions regarding the types of guides. To get that level of knowledge from Moss or TRF you will need to contact their special line and then try to figure out the right parts from what they tell you.
Charley

 

[TR3driver]

The only advantage to more pressure is being able to turn a higher RPM.

However, there is an advantage to multiple springs in that it helps suppress resonance at certain rpm. Presumably they are there because the factory found a tendency for the valves to float at certain rpm.

The factory switch to double exhaust springs happened at the same time as the switch to 5/16 exhaust stems. I believe the change in springs was because the lower mass valve reduced the resonance and the third spring was no longer needed. But I could be wrong, of course; maybe it was just a cost-cutting measure.

Many racing spring setups use only double springs, but the diameters are such that the springs rub against each other. The extra friction also helps dampen the resonance. A good idea, IMO, but shortens the life of the spring. For more information on valve spring design (although he doesn't really address resonance), see Larry's page at
https://www.tildentechnologies.com/Cams/CamSprings.html

 

[bobhustead]

I recall that when I built my engine there were also new harder valve seats to help cope with the unleaded gas.
Bob

 

[sp53]

Wow you guys are good. I am starting to learn toward 5/16 SSthe less expensive ones on all valve with cast iron guides. If I am reading the foot note correctly in Moss about831-500 and 831-000 with respect to 3/8 valves and triple exhaust springs, I wouldneed to purchase different collars for the 3/8 triple exhaust valves becausethe stock springs are N/A and their aftermarket springs need a differentcollar. Is that correct.