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Author Topic:   Stock valves or should i upgrade?
CrazyT
Dirt Forum Racer

Total posts: 81
posted December 04, 2005 09:40 AM  
I have a set of 462 double humps that i ran last year. My machinist put stock type vavles in these heads and i didn't know it the other heads he has done for me he put descent valves in.....i guess thats why it was so cheap.lol Anyway should i replace them with better valves....i guess what i want to know is how much difference does a swirl polished undercutt valve make?

Thanks

Raz_900
Dirt Forum Champ
Total posts: 645
posted December 04, 2005 08:25 PM  
Undercut valves will generally flow up to 10 cfm more than a standard stem. Also, flat faced valves can cut down on chamber size a CC or two which raised compression a touch. Nothing earth shattering, but it's one of those things that add up to make more power.

Also, if they're true stock replacement valves, they could be 2 piece where the head is welded to the stem. These are common for coming apart and 'dropping a valve'. There's no place for a 2 piece valve in a race engine when 'cheap' 1 piece valves can be had for $6 a piece for a SBC.

johder
Dirt Maniac

Total posts: 148
posted December 05, 2005 05:06 PM  
how exactly do you know if they are 1 or 2 piece?

Raz_900
Dirt Forum Champ
Total posts: 645
posted December 05, 2005 05:24 PM  
If a 2 piece valve is completely cleaned, sometimes you can see the mark where the pieces are welded together. It'll be on the radius area where the face attaches to the stem. It won't be a clear straight line and may wave back and forth a bit since it is a weld that was ground down to make it smooth. Sorry I can't be anymore descriptive.

johder
Dirt Maniac

Total posts: 148
posted December 05, 2005 08:17 PM  
Ok im running the sealed power valves...i can see a line but this line is completely straight the whole way around.

zeroracing
Dirt Forum Champ
Total posts: 1914
posted December 05, 2005 08:30 PM  
I think some titanium or all are welded also. I seen a thing on CV products about it. Of course these are very pricy valves so High High quality. I would not try to get a cheap welded one.

Eljojo
Dirt Forum Champ
Total posts: 994
posted December 06, 2005 04:28 AM  
Raz, my machinist steers me away from the $6 valves because of the chrome on the stems. (or lack of it) The cheapest he'll allow is the Ferreaa 5000. You don't have galling issues with the el-cheapos?

outlawstock17
Dirt Forum Champ
Total posts: 1374
posted December 06, 2005 06:34 AM  
as long as the guides are clearanced correctly, they're getting oiled and you're using leaded racing fuel, you shouldn't have any galling issues.

i don't like the tight fitting teflon seals because they wipe too much oil off of the valve stem...

Raz_900
Dirt Forum Champ
Total posts: 645
posted December 06, 2005 05:07 PM  
Actually, I generally use the Ferrea 5000 or 6000 valves or Manley street flo. Only tried a set of 'cheap' valves once and that's in my partners backup motor. He hasn't raced it since the rebuild. So far they're holding up well to the idling up and down the driveway.

I've heard that Ferrea makes some of the best valves out there. The engine shop I worked at used them in all the hi performance heads. Great bang for the buck, especially the 5000s.

James Ott
Dirt Maniac

Total posts: 163
posted December 06, 2005 05:15 PM  
how long does it take to break in the motor going up and down the driveway? Does the motor break in as fast with the car in reverse or do you turn around

zeroracing
Dirt Forum Champ
Total posts: 1914
posted December 06, 2005 05:41 PM  
Ferrea does have the best valve out there.
What do the 5000 series cost on average? The are great valves, but ferrea does have some sets of valves that will give you a heart attack when you go to buy them

tlkdlw
Dirt Full Roller

Total posts: 47
posted December 06, 2005 06:33 PM  
We use One Piece Stainless Racing Values 21-4N from Competition Products $6.99 each for SBC
We replace them each year as part of are freshing program. They Probly dont need it that soon but for $112.00 it not worth the risk of dropping one. Thats big money WWW.Competitionproducts.com 1-800-233-0199

Terry

Raz_900
Dirt Forum Champ
Total posts: 645
posted December 11, 2005 03:48 PM  
quote:
Originally posted by James Ott:
how long does it take to break in the motor going up and down the driveway? Does the motor break in as fast with the car in reverse or do you turn around


His driveway is about 150 yards long and blacktop. Breakin is about 5 holeshots with a 1 legger metric rear and 3 with the locked 9".

2.02" and 1.6" stock length Ferrea 5000s generally go for around $8 or $9 each. 1.94s and 1.5's are about a buck more.

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