[PAUL K]

Factory Super Duty springs are easy to identify. They are conically wrapped and the tight coils install at the bottom. Test pressures inner 40# @ 1.75 rate 111 outer 70# @ 1.812 rate 261. They are excellent springs. Our "go to" springs are Comp 987 & 988 (I think) pick the one that will work with your cam profile. We stock them both if you can't find them. You will need to machine the inside locator. Very hard to find a HFT spring that will fit over the factory guide boss.

[johnta1]

As Paul said, mine were 1.81" installed. When I put a roller in I used CC 999 springs which did not need any work to install. That cam ran great. (HO-Racing used in their SD SS TA)

[PAUL K]

Originally Posted by steve25

Here’s what I get from looking at the specs for the springs on these heads.

Closed = 117 lb

Open = 292 lb, but this was stated with what was the original cam that had .470” lift, which is not what the production 323 cam had.

The 323 cam only had .406” lift!

Now with no info on what the actual springs rates where my best guess is a open pressure with the .406” lift of 260 lbs .

This to me would be marginal with with the valve weight of even the 4.980” length valves, no less the longer heavier valves in the SD motor.

Just to make a comparison the 1968 428 HO motor had springs that provided 129 on the seat and and 272 open @ .414” .

What do you folks think?

Mike do you still have the stock springs to do a check on?

I think the SD valves are 4.980 long. The exhaust valves are made from Inconal so they are fairly heavy. The intake valves have some mass due to their tulip shape. I don't think you need more than the factory springs to keep up with the RPM capabilities of the factory cams..... and the Super Duty 455 is an all around Bad Azz engine.

[mgarblik]

Originally Posted by PAUL K

Factory Super Duty springs are easy to identify. They are conically wrapped and the tight coils install at the bottom. Test pressures inner 40# @ 1.75 rate 111 outer 70# @ 1.812 rate 261. They are excellent springs. Our "go to" springs are Comp 987 & 988 (I think) pick the one that will work with your cam profile. We stock them both if you can't find them. You will need to machine the inside locator. Very hard to find a HFT spring that will fit over the factory guide boss.

Thank you Paul for great information. The springs installed on the heads DO NOT appear to be OE springs based on your description. They are a dual spring without a damper. They do not appear to be conical and look to have the same spacing on the coils top and bottom. I need to measure and test what I have and go from there. Good information.

[sdbob]

The SD springs I have and from shop manual say/or painted- 'purple' on spring I remember goes against the seat.

[mgarblik]

I have had some time to evaluate what I have for valve springs on these heads. The installed heights without shims varied quite a bit unfortunately. 1.840" was the shortest and 1.870" was the tallest. This was of course due to the valves and seats being ground at least once or possibly twice in the life of the engine. The valves have usable but pretty thin margins, but not overly concerning. The seat work looks OK but I haven't had a chance to run a pattern yet. Setting the springs back to factory height of 1.810" yields a seat pressure of 90-109 lbs through the set. Open pressures of 245-270 lbs at full lift. By reducing the installed height to 1.750" and using a pile of shims to equalize the installed heights I can get to 125 lbs. seat pressure. This would require a set of billet 7 degree keepers @ -.050. I have decided against this set-up. Although it would work, the cost of the new special keepers is 75% the cost of nice new springs that would give me the desired stock installed height and they are a known spring I have had good luck with. Decided to go with Howards Cams 98447 spring. This spring is a dual without damper, micro polished wire. 145 lbs. @ 1.750 and a spring rate of 283 lbs. Setting these springs up at the stock 1.810" installed height should give me 125-130 lbs. on the seat. Other Howards springs I have used lose 5-10% of their seat pressure after the first heat cycle and then settle in. The springs have the right dimensions and don't require any guide machining. Other sets of Howards springs have been pretty consistent pressure wise. I think these springs will be pretty gentle and close to stock SD specs. Only drawback to these springs is the wide distance from coil bind when fully open. But with the RPM limits of a 455, not overly concerned with spring surge. The OE SD springs were a very sophisticated spring design with inactive coils at the bottom. Way ahead of their time.

[mgarblik]

Originally Posted by johnta1

As Paul said, mine were 1.81" installed. When I put a roller in I used CC 999 springs which did not need any work to install. That cam ran great. (HO-Racing used in their SD SS TA)

That's a serious spring for sure. 278 lbs. seat pressure at 1.800. 595 lbs. open with a .500 net lift cam.

[HWYSTR455]

Might be worth commenting, many aluminum-bodied roller rockers do have a spring psi limit, and it's good practice to know, and adhere to the limits.

Everyone probably knows that, but figured maybe for others who are unaware it's worth noting.


.

[mgarblik]

Cleaned the valves and lapped the seats this morning. Boy, the combustion chambers are just beautiful. The smooth, fully machined chambers are a work of art compared to what the "darling division", Chevy was doing. Is there any way possible to make a chamber with more sharp edges, places to trap liquid, encourage detonation? I guess only the Bow Tie experts know. It's no wonder the Chevy stuff responds so favorably to extensive modifications. In stock form they are crap IMO. I am a little biased!

[johnta1]

The 1st thing I did to mine was a 3 angle valve job. That seemed to work great.

[sdbob]

I in the 60s wonder why chebies needed an air pump and Pontiacs didnt. They were the darling hp division.

[steve25]

Well to be honest Pontiacs back then in CA still needed them until 68 when the open chambered heads came to be.
Makes that used cast chambers had a expensive decision to make, either change there casting molds to achieve a cleaner running motor, or add a air pump, all Pontiac had to do which was easy ( realitivly ) and with little extra cost was to machine the chambers different.

[OldSDGuy]

Originally Posted by sdbob

The SD springs I have and from shop manual say/or painted- 'purple' on spring I remember goes against the seat.

Just a reference pic of the springs from my '74 SD engine. You can easily see the purple dye/paint near the seat.

[steve25]

So the originals look like they have what I hate most, a flat wire damper .

Is that what I see on the inside in your photo?

[OldSDGuy]

Hey Steve25,
No dampers on the SD. Just an inner and outer spring. Not aware of any recent Pontiac V8 with a flat spring damper. I've heard of a flat inner damper spring on early Ram Air motors (before '68) but I've never seen one in person.

[steve25]

Oh good!
The factory info I have is correct then.

[sdbob]

I have a new OEM 67 Ram Air springs,I think 998 inner,999outer nos. both coils. Bought in 68,yes I'm old.

[OldSDGuy]

Thanks for that info sdbob. Was trying to remember where I heard/saw that early ram air heads had an inside damper and then I recalled that I saw it on Wikipedia....for what it's worth:

'Around January 1966 Pontiac took the next step and began offering as a factory option the XS-code engine. It included a new camshaft with duration increased from 288/302 (No. 068) to 301/313 (No. 744) and a new valve spring package with dampers to positively control valve action. Valve lift stayed at just over 0.400-inch with 1.5:1-ratio rocker arms. The tri-power equipped XS-code 389 was shipped with the Ram Air pan in the trunk, and the dealer had to fit it and cut out the underside of the hood scoop to make it functional. The XS-code 389 was still rated at 360 bhp at 5,200 rpm, same as the more common WS-coded Tri-Power 389, but performance was noticeably improved on acceleration runs. Pontiac engine production records report that 190 XS-code 389 engines were built during the 1966 model year. Whether all were installed in GTOs is unknown.'

Did some further searching a few minutes ago and also found this post on the forum some years back:

Bob Eiler
Senior Member

Join Date: Nov 2001
Location: Centerville, Oh. USA
Posts: 208

Early 1967 Ram Air valve spring (670 Head), single with damper.

Like Button Notice (view)
__________________
There is no such thing as too much cam, just not enough engine.

1966 GTO - 11.31@119 (3478 lbs) in 1979

1967 Firebird - 9.73@138 (2940 lbs) in 1986
400 cu in / 295-298 cfm RAIV / Lunati Cam 278/283 - .704 lift/5.13 gears

Again, I've never seen this setup on a stock Pontiac V8. Perhaps they changed the design and dumped the damper mid-year?

-steve m.

[sdbob]

Hmm. You jogged my memory, yes I do remember a damper with a single spring. I have a set of seemingly virgin 670s I traded with Jim Mino. I'll ck. Off subject sorry.

[mgarblik]

I received my Howard Cams 98447 valve springs a few days ago. They look great and that was the extent of the good news. They test significantly weaker than advertised on three different valve spring testers I had available. They were pretty consistent which is good. Through the set, they test about 13-15 lbs. weaker at their specified installed height. They test 130-132 lbs. @ 1.750 instead of 145 lbs. I wanted 125-130 lbs. on the seat and I was able to shim appropriately to get there and 270-280 lbs. open. So they will work fine, but not exactly what I was looking for. Heads will be cleaned and assembled/installed and painted in the next week or so.