FAQ |
Members List |
Social Groups |
Calendar |
Search |
Today's Posts |
#1
|
|||
|
|||
Valve and spring choices
Looking for suggestions for SS-valves and springs for a set of 6x heads .. running a RA3 cam and 1.52 roller rockers
|
#2
|
||||
|
||||
I would use Ferrea 5000 Series F5082-8 Intake valves and F5062-8 Exhaust valves(these are standard 4.98" length for factory Installed Height in those 6X heads, with stock 30° Intake seat and 45° Exhaust seat), along with a set of Crower 68404 springs set up at the stock 1.600" installed height for that application.
__________________
1978 Trans Am Pump Gas 461 Stroker Last edited by TransAm 474; 09-15-2019 at 01:50 PM. |
#3
|
|||
|
|||
Opinion. The popular 68404 often used as a "stock replacement spring" rated at 1.600" installed height. IF it's at or near that IH with some popular Pontiac flat tappet cams the distance from coil bind can be a lot !
.
__________________
'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
#4
|
||||
|
||||
CC 988-16 springs should be plenty of spring for that cam, and a lot cheaper.
https://www.ebay.com/itm/Comp-Cams-9...ss!71251!US!-1 Paul Spotts also sells some cheaper springs that will work. https://www.ebay.com/itm/Pontiac-V8-...AAAOSwmrlU0mJ9 SI Valves sells a short 1.66 SS exhaust valve, in case you don't wanna have the seat cut out for 1.77 valves. Part # looks like a 6001SG. http://sivalves.com/flipbook/2016-SI-Catalog.html#p=43 Butler lists these F5080 1.66 exhaust valves as being for 389 & 421 heads. Just looked 'em up on the Ferrea site. It says they will also work in 400 & 455 apps that came with a short 1.66 exhaust valve. I figure most all these guys will recommend cutting the factory seats bigger & going with 1.77 valves. Some say that removes the hardened seat area, requiring hardened seat inserts. Some say it don't matter. I'll leave that argument for the experts. https://butlerperformance.com/i-2445...tegory:1400522 https://www.ferrea.com/Pontiac-Engin...ect_motor=6982 Last edited by ponyakr; 09-15-2019 at 04:56 PM. |
#5
|
||||
|
||||
From what i have read 135# on the seat, #300 over the nose, and .060" from coil bind is the reccommended set up. I plan on using Crower 68404 springs with an 068 cam. Looks like I'll need about 1.550 installed height, any shorter installed height and I think I'll have too much seat pressure. The max distance from coil bind is reccommended to be .150 ". Also from what I have read the springs should be measured for actual pressure as this varies from the factory specs. The seat pressure should also be measured after break-in. and adjusted. https://www.crower.com/valve-springs...oy-dual-1.html
__________________
One test is worth a thousand expert opinions |
#6
|
||||
|
||||
"...i have read 135# on the seat, #300 over the nose, and .060" from coil bind is the reccommended set up. I plan on using Crower 68404 springs with an 068 cam..."
IMO 135/300 spring pressure is way more than is needed for an 068 cam. I think Paul Carter recommends similar pressures for some of the Voodoo cams. But that's because they have steeper ramps & more lift. An 068 does not have steep ramps & has very low lift. The cheap Paul Spotts springs should be plenty good for an 068, unless you just wanna spend more, or are planning a bigger cam in the near future. IMO, there is no reason to put more pressure on the valve train than is necessary. Seems to me that it could possibly produce faster wear of cam & all valve train parts. So, why run stronger springs than needed ? Anybody know the exact specs for the springs that came on 068 cam D-port head equipped engines ??? Is there an online factory spring spec chart of some kind ? Last edited by ponyakr; 09-15-2019 at 05:09 PM. |
#7
|
|||
|
|||
Just keep in mind the Crower 68404 coil bind is rated at 0.950".
0.3134" lobe lift x 1.52 rocker ratio is 0.476" lift in theory. Less pushrod flex This for interest: https://www.hotrod.com/articles/how-...rance-is-safe/ Now I'm sure there are some who feel the farther from coil bind you keep the springs, the longer they will last ! . .
__________________
'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
#8
|
||||
|
||||
The valves I will be using are 2.11" with 30 degree seats. My understanding is that 30 degree seats being "flatter" need more seat pressure. I expect the spring pressure to drop after break-in too. I have the springs and should probably measure the pressure before anything else. I might run 1.65 rockers later. The lift on the 068 is the same as the original posters RA3 so the set up should be the same, right. Thanks
__________________
One test is worth a thousand expert opinions |
#9
|
||||
|
||||
Quote:
https://www.ebay.com/itm/Pontiac-V8-...AAAOSwmrlU0mJ9 I think Paul has built lots of Pontiac engines & is well respected in the Pontiac community. At least I don't remember ever reading anything negative about him. But hey, everybody can buy whatever parts they want. |
#10
|
|||
|
|||
Off the internet I read the 1969 Ram Air IV 400 heads (casting # 722 ) had the valve springs at 1.812" installed height. And the 41 cam used with it was at .517" lift w/1.65 rockers. From my limited reading I get the impression the factory valve springs used with that set up had a 1.220" coil bind number.
Can someone here confirm if in fact that coil bind number is correct ? If that figure is correct then in theory at .517" lift then the distance from coil bind in theory is 0 .075". If all this is correct then it falls right in line with the common statement there should be AT LEAST a 0.060-inch safety margin between the maximum valve lift and the point at which the spring binds. Personally I'd question using the 68404 spring installed at the rated 1.600" installed height and the resulting 0.180" distance away from coil bind with a .470" lift cam ! But I'm sure many will suggest no big deal. "Valve Springs are one of the most important parts of an engine. They control the valvetrain. The spring makes sure the valve opens and closes smoothly. It also keeps the lifter in contact with the camshaft. Despite their importance, they are one of the most commonly overlooked performance parts." And I also feel valve springs because of their importance is no place to cheap out ! .
__________________
'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE Last edited by Steve C.; 09-15-2019 at 05:43 PM. |
#11
|
||||
|
||||
These springs really don't have a lot of specs with the ad. To get the recommended .080" from the 1.00" coil bind height with a .410 lift cam you are going to have to shim them .110" from the installed height of 1.600". This is going to increase seat pressure a lot. They would probably work OK. Looks like apples to apples with the Crower springs specs and less expensive. Really need to measure.
__________________
One test is worth a thousand expert opinions |
#12
|
|||
|
|||
The obvious much of this is just to generate conversation, especially on my part. Example when discussing a specific installed height distance like 1.600" with the Crower spring. An installed height of +/- 0.020" is acceptable according to some sources. And there are springs shims to consider. Similar situation with valve springs and the comments on pressures. Comp Cams considers a variance of +/- 10% is acceptable for new springs.
.
__________________
'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
#13
|
|||
|
|||
If you were going to replace the valves and use positive seal, you could use early length valves and 68405 springs @ 1.75 ih .They would have plenty of coil bind margin and be able to reshim them for more pressure later if you recam.
|
#14
|
|||
|
|||
Going the opposite direction with the 68405 spring ! At 1.750" it states only 92 lbs seat pressure. And with 0.476" valve lift at that height it would be a whopping 0.294" away from coil bind !
Pg 177 https://www.crower.com/media/pdf/valvespring.pdf .
__________________
'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
#15
|
|||
|
|||
Quote:
Last edited by antique69lemans; 09-16-2019 at 10:30 AM. |
#16
|
|||
|
|||
"Depending on the intended use and the spring and cam-lobe design, coil-bind safety margins can now vary from 0.015 to 0.120 inch, with tighter numbers predominating on very stiff valvetrains. Anything more than 0.150 inch may cause spring surge, which can greatly reduce the available spring load needed to close the valve."
https://www.hotrod.com/articles/how-...rance-is-safe/ "Coil clearance is the distance between the valve spring coils when the valve is it maximum lift (fully open). A minimum of 0.060" must exist between the coils at maximum lift. Coil bind is when the valve spring is compressed fully-to the point that all of the coils are "stacked up" on top of each other. For high RPM applications, .100" is recommended." Lunati Tech "WE always do a mock up with loaded valve train to determine actual net lift. As example a 1.100 cam card was actually 1.040 at the retainer, 1.040 cam card was actually .977 at the retainer, 1.085 cam card was actually 1.015 at the retainer. It is never a good idea to take the words on a piece of paper as truth. Bill C. Ceralli Competition Engines Example, not related to this thread but within another involving a Voodoo hydraulic flat tappet lobe Paul Carter suggested to keep the coil bind distance under 0.100" for that specific application. Paul has a lot of experience with these lobes, including dyno testing. .
__________________
'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE Last edited by Steve C.; 09-16-2019 at 10:43 AM. |
#17
|
||||
|
||||
Quote:
Watch this video and you'll understand why spring pressures and coil bind height with certain types of springs is so important. Counterwound dual springs help with spring surge, but most Pontiac springs are not counterwound so being closer to coil bind with them is more important. https://www.youtube.com/watch?v=_REQ1PUM0rY
__________________
Paul Carter Carter Cryogenics www.cartercryo.com 520-409-7236 Koerner Racing Engines You killed it, We build it! 520-294-5758 64 GTO, under re-construction, 412 CID, also under construction. 87 S-10 Pickup, 321,000 miles 99Monte Carlo, 293,000 miles 86 Bronco, 218,000 miles |
#18
|
||||
|
||||
I used Ferrera "regular" D port length in my 6X heads. Got the spring IH a little better for more choices of springs.
__________________
Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#19
|
||||
|
||||
In terms of spring resonance and bounce I whish there was a Beehive spring close enough in size to use in our D port iron heads !
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
#20
|
|||
|
|||
At one time I dug into this and found where someone did use, maybe a late mopar application but it may have been closer to 1.8 ih. If you search around the internet you might find it again. One post listed comp 26995 but they are a little light.
|
Reply |
|
|