Brodewok80

Hello. (68 olds 98 w/ ps, PB ac, factory everything except 10:1 compression) I just ordered a 400165 cam for my 455. It had a comp 280h and corresponding heavy valve springs. Now I'm looking for springs that correspond with the "stock" 400165 cam. It looks like the GM part # is 411226, Elgin rv1016, melling vs720, sealed power vs721, qualcast 321016....
My question is....
Am I on the right track with those part numbers?
The only one that seems more expensive is the NOS GM ones. So the rest all are similarly priced.
Are any of these brands better or worse than the other?
Recommendations and corrections are greatly appreciated.

BillK

Do you know which springs are on the heads now ? What you need to do before you order a spring is to remove a couple of the ones that you have and measure the installed height and look to see if the heads have been machine in any way that affects the spring. You don't know for certain that it does have heavier springs, do you ??? The springs look like the Comp 995's but you simply do not know without taking one of and measuring. If you don't do that, please dont come looking for help when whatever spring you choose does not fit or wipes the camshaft

The other thing is I am surprised to see that they have rotators on both the intake and the exhaust valves. That is unusual in a performance application. It also significantly affects the valve spring installed hgt and is another reason you really need to measure before you blindly swap springs.

There are many sellers of valve springs. Very few actual manufacturers. I would venture to say that most of the "stock" springs are probably the same exact part in different boxes.

If you pull one of your existing springs and get some measurements I will gladly recommend a spring number for you.

sysmg

Your 280H cam has advertised duration of 280/280 with .490/.490 lift
https://pitstopusa.com/i-23923560-co...c-260-455.html
The cam you ordered 400165 has advertised duration of 285/287 with .472/.472 lift
https://classicoldsmobile.com/forums...0-050-a-96365/

So the GM cam has more duration with slightly less lift. Probably pretty similar cams. Someone with more expertise could tell you what the difference would be. A 442 cam is not a mild 98 cam.

Brodewok80

It being so close and assuming the springs that are installed are correct for the 280h. Why would the 400165 require the stock springs and not these heavy ones?

Brodewok80

I measured the OD and installed height. The OD is 1.43 and the IH is 1.75. After a quick search they seem to correspond with comp 986. Obviously there's more to measure. Do these numbers speak to you at all?

Fun71

Note the differences in how the advertised duration of each cam is measured, and also that the GM cam is around 205* @ .050” lift vs 230* for the Comp cam. That is a huge difference. I have a 217* cam in my 350 and it has a smooth idle with barely a lope sound to it.

Brodewok80

I THINK this is the numbers for my springs. I'm going to keep measuring but so far these correlate. Assuming these are what I have, are they reasonable to keep in there?

Brodewok80

Good to hear. Do you think it's a good choice for a 10:1 engine that won't be driven hard? Also, do you think the comp 986 springs would work for this cam? I'm still measuring them but so far I think that's what they are.

cutlassefi

The way they did advertised duration on the stock stuff decades ago vs the way it’s done today are vastly different. The SU cam should be considerably milder.

BillK

Since you have a spring off can you post a picture of the spring pad in the head where the spring sits ? The 1.750 installed hgt does not sound correct with the rotators unless someone has machined the spring pads down. Also I dont think the 986 spring will fit on the factory rotator correctly.

The VS720 spring is probably not going to work, it will be very close to coil bind. It is listed in the catalog for engines "except W30" If your springss are indeed what you show then they are probably too much spring. Take one of them with the rotator to your machine shop and have them check the installed and open pressures. Anything else is just guessing.

Where are you located ??

Brodewok80

I'm in Seattle
I don't have one off yet. I just ordered a spring compressor and it came in this morning. I took those measurements because I could with them still on there.WHats the most a spring can be shimmed if it comes to that?

Brodewok80

BillK

Thats definitely been machined and has had guides put in it. Not a very pretty job either Does the second picture have a shim under the spring ? Or is it machined with a step in it ?

Your next step is to measure the installed height and then pick a spring.

Brodewok80

I got this (pretty close)
2.00 not installed height, 1.75 installed height
1.43 OD, 1.09 ID
0.72 Inner springs ID, Shim is about 1/16"

Brodewok80

It's a shim

Brodewok80

I almost threw up when I saw the valve guide so rough.

Brodewok80

All the measurements correspond very closely with the 986 springs. The difference is probably just my rudimentary measuring.
IS it possible to just take the inner springs out? Basically I'm asking if these outer springs are the same as solo springs? Or are they totally designed to work with the inner springs and alone they're trash?

BillK

Yeah, would have taken 5 minutes with a spot facer to make them look nice.

Brodewok80

I could have made them look nicer with grandpa's ball peen hammer.

BillK

They do look close but they could be 995's. Thats what Comps calls out for the 280 cam. I have a set of those here and they measure the same as what you are getting.

I have taken inners out before but the only way to know for sure is to have someone check the pressures on a spring checker. I just checked one of the 995 outers and they are too weak by them selves.

I dont think any of the springs you listed before will work because they are for unmodified Olds heads with a very short installed height. Usually around 1.650
You are also stuck with using a large spring because the way they cut the head there is nothing to keep the spring from moving around on the bottom. How does the single outer spring fit on the rotator ? Will the rotator keep it centered ?

A PBM / Erson 3300 spring would probably be pretty close to what you need.
http://www.pbm-erson.com/Catalog/Ers...prings/PBM3300

Brodewok80

There's some slop between the rotator and the spring when not installed. They don't move by hand installed. If it's centered it can move 1/16 "in" and 1/16 "out" total travel 1/8 approx.

Brodewok80

How much slop can the rotator have?

Brodewok80

I just compared the rotator to spring slop to a stock valve spring and "keeper? plate". It's about the same . Maybe less than the stock engine. So I imagine I'm good there.

Brodewok80

Got those 3300s ordered

BillK

Ok, How are you measuring the installed hgt ? Just curios. Hard to do with the rotators.

Brodewok80

IT was hard. But I used a thin piece of metal. Sat it on the shim. Scored a line at the top of the spring. Then measured the metal thing I used. The rotators didn't really affect the measurement. Shoot now I'm second guessing. Lol