Looking for a fast answer on this one, trying to order valves tomorrow .

I am getting ready to order valves for my Dart 220 race heads. They take a .200 long 2.08/1.6 valve to get the installed height I am looking for.

Basically here is the question:
I am looking at Manley race series valves- the Race master and the Race flow valves are both about the same cost. The race flow valves are undercut and the Race masters are not, I am assuming for strength?

My valvesprings are Isky 9965's which spec at:
1.56OD, 245lbs on the seat @ 1.950, 585lbs open @ 1.270 and will be setup at 1.950 installed height.

Basically, am I running too much spring pressure for an undercut valve like the Race Flows, or does it really matter?

Thanks guys!

 

This is obviously, in 'hindsight', but...no, for flow.

Basically, am I running too much spring pressure for an undercut valve like the Race Flows...?
No, but could have contacted Manley, to confirm.

 

Obviously an undercut valve is beneficial to flow. I was curious as to the strength difference between the two.

I called Manley and talked to a technician who said the undercut valves are mainly for people who are running in classes who arent allowed to do any porting, and that since I am going to have portwork done on my heads I should just stick with the Racemaster valves.

 

A wise man told me a couple days ago that the Race-Flo valves are like 9 grams lighter than the Racemasters. That is a considerable difference in valvetrain weight if you ask me....I would get the race-flo's.

 

Thoughts before purchasing springs:

You've quoted .680 lift and a lot of spring. How fast are you planning to turn this engine? How aggressive is the cam? Does you valvetrain designer know about the u/c valves, and were the heads ported/flowed for u/c valves?

If the answers don't add up, you might be a little premature in ordering springs.

 

I have already purchased the springs. I found a deal I couldn't pass up ($50.00 with titanium retainers), they are the Isky tool room springs.

The guy doing my headwork knows they will be non u/c valves, they have not been ported yet. They will be ported for the racemasters and flowed. As long as I am happy with the results they will go on the car, or else they will go back under the grinder and then be reflowed. I would like to see 310/210 @ .700.

I plan on shifting the car at 7000 rpm, maybe less if it doesn't effect ET a great deal. The camshaft is as follows:

262/266@.050, .667/.625 w/ 1.5's (which is what I will be running), 106LSA.

If I find the motor wants to peak above 7000 rpm, I plan on advancing the cam timing a few degrees.

This is my fast street car. Extremely limited street use, driven to the track (7-10 minute rural highway drive) and downtown occassionally on weekends.

Any constructive input you would like to give would be appreciated .

 

LOL I was just going to write that..... Thanks.

I would take 9g out of a valve any day I could.

Bret

 

Well I already ordered the valves after I talked to the Manley tech on Friday, so its a done deal. Any other suggestions are welcome.

 

I have had the undercut stems break on both the intake and exhaust.
Won't run them anymore.Makes a mess @7000 RPM's.
A little Flow and Weight don't make up for a new block and pistons and heads.

 

That is exactly what I am scared of. That is why I didn't skimp on valves either, spent the $200.00 on a decent set . What kind of spring pressure were you running?

 

Now is 260# on the seat and 660# on the nose. Nasty mech roller in my shop car. Have run different pressures in customers cars from 125# on the seat to 280# on the seat. Also saw the undercut stems hurt air flow in some heads.