Nitro Don

I tore down my heads yesterday and noticed on many of the exhaust valves that the damper springs had broken a damper coil off the top of the spring.One spring even had broken off twice cause there was 2 pieces of the damper spring inside the outer spring.I did notice that "ALL" damper springs had grooves worn in on the top and bottom of the damper.I thought that maybe they are made this way,but quikly notice that some of the broken dampers had worn in a new groove where it had broken off. It seems to be the exhaust side that had broken dampers.Maybe cause the lift is .544,but both intake and exhaust have worn damper springs.
The heads are WP 305 torquers that I bought fully assembeled.The teck guy ate WP said that these heads would handle this cam and had a max lift of .560
I guess this is why I dont really have any power in the upper RPM.It was falling flat on its face at 5000 RPM.
Was I having severe valve float to bust the dampers? Or was this coil bind?
The pushrods are straight and the valves do not look like they contacted the pistons.
I dont have the spec on the WP springs,but a quik check shows they were installed with a 1.830 installed height.
Any Ideas?
Thanks guys,
Don


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1990 Trans Am WS6
305TPI 700R4

ENGINE:
150hp NOS kit
March underdrive pulleys
Edelbrock headers(JetHot)
Mac off-road pipe
Flowmaster exaust
Jacobs ultra coil
K&N filter
Fulley ported base,
runners,& plenum
Crane AFPR
Hypertech airfoil
Crane 1.6 rockers
210/220 .533/.544 Cam
W/P Torquer heads
Edelbrock TPI Base
Edelbrock TI Runners
Edelbrock 52mm T.B.
TRANSMISSION:
Richmond 3.73's
Auburn posi
B&M Mega shifter
TCI shift kit
Vette servo
B&M 3-4 upshift kit
TCI Trans Rebuild
2800 stall 9.5" TC
Nitto Drag radials
FUTURE MODS:

BEST RUN:
12.48 @ 109.23 MPH
(with stock heads,cam,intake,and crappy Pep Boy's tires)



[This message has been edited by Nitro Don (edited March 17, 2001).]

ede

if i was selling parts i'd say they fit the widest application range i could too. i thing you should of went with larger springs from the start ,springs that matched your cam, or ere recomended by your cam grinder.

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ICON Motorsports

1st & 3rd

AlkyIROC

Crane 1.6 rockers
210/220 .533/.544 Cam

Are those the cam specs on the cam card or with the 1.6 rockers? If they are on the cam card then the valves are actually lifting .568/.580 No wonder you're breaking springs.

According to the WP catalog, the springs have a max lift of .560 as the tech guy said. They also only have a spring seat pressure of 100#. I'd say your springs are way to small for your cam choice.

Even if those cam specs are using the 1.6 rocker ratio, the springs are too small. You should still be using a 1.460 diameter dual spring.

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Follow my racing progress on Stephen's racing page
and check out the race car

87 IROC-Z Pro ET Bracket Race Car
383 stroker (carbed) with double hump cast iron heads and pump gas
461 Big Block installed and ready for the 2001 racing season

Best results before the 383 blew up
Best ET on a time slip: 11.857 altitude corrected to 11.163
Best MPH on a time slip: 117.87 altitude corrected to 126.10
Altitude corrected rear wheel HP based on power to weight ratio: 476.5
Best 60 foot: 1.662

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

RB83L69

I agree with ede and Stephen, you have WAAAAYYYY too much cam for those springs. How many miles did they make it? If those are 1.25" springs I'd be surprised if they've gone 15,000 at that lift.

Ever take a coat hanger and bend it back and forth until it breaks? Then feel the ends of the wire? Notice how hot it is? Well, valve springs are pieces of wire, that get bent back and forth every time the valve gets opened. They generate heat in themselves as a result. That's what kills them. The heat kills their temper and fatigues the metal. I'd bet money that if those springs had 100 lbs of seat pressure new, not one of them has 75 lbs now.

1.45" springs have a 15% greater outer diameter. So each time they get bent, each unit length of metal bends 15% less. On top of that, to get the same pressure, you can use 15% thinner wire; and alot of the stress induced in the wire during bending is the resulkt of the part of the wire on the inside of the bend being in compression and the outside of the wire being in tension, and since metal doesn't compress, ALL of this energy goes into trying to tear apart the metal on the outside of the bend. So the thinner the wire, the less of this force there is.

If there is any one place in a motor that you can cheaply improve reliability, the valve springs are it. Get the spring pockets cut for bigger springs and put a set of Comp 987s or some one of the other first-line cam mfrs. equivalent in there. BTW, Comp changes from calling for 1.25" to 1.45" ones at .500 lift; and they go from the first level of 1.45" to the higher level at .550". Crane and Lunati make their breaks in their product line at similar points. You are far beyond the real-world limits of the springs you have, no matter what the guy on the phone told you.

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"So many Mustangs, so little time..."
ICON Motorsports

Nitro Don

Although I put the heads on last June.Im lucky if I put 3,000 miles on them.Ive been hunting down a problem for a while now.I just felt that I should be putting out alot more power.Based on the fact that it isn't possible to run the same ET's after swaping out the stock heads,cam,and intake.
I thought that the WP springs were to weak so I ordered 1.265 K-Motion springs with 10 degree retainers and locks a week ago.I didnt think I was going to pull the heads. Well I did anyway,and Im stuck with the springs.
The K-Motion springs spec out pretty good.They have 130# at 1.700 installed height,380# at 1.150,coil bind at 1.050,450 rate,and are good up to .610 lift.
These spec are far greater than the 1.440 springs that Comp recomends for my cam and there larger 230/244 .544/.576(1.6) cam that I might be putting in.
Just to be safe,since I have the heads out I will get them machined for larger springs and just use a spring locator.
I also want to get these heads fully ported and machined for guide plates.
Don

AlkyIROC

Those K-Motion springs will be a big improvement. Although they're not double springs they will still be better than the springs that WP used.

Since you have TPI and a 700R4 I can't see you reving it much past 5500 so those springs should last for a while.

Since you're getting the pockets enlarged now, you can always install dual springs later on down the road.

david auster

iTrader: (10)

I am in the market for some valve springs myself. What is the advatage of using a double spring? I have L98 aluminum heads going on a 305 with a ZZ4 cam. What springs do you recomend for this application. Thanks