Hi all,

I plan on installing an Isky VV71 camshaft c/w Isky hi-rev kit, double wound valve springs, new valve, and guides to my 122s B20.
These parts were purchased from IPD and I was wondering what would the wear be like on the camshaft, since the double wound valve springs would exert more force on the camshaft lobes?
A local volvo 'expert' mentioned to me that the double valve springs would cause huge wear on the lobes.

Also, for those who have tried this, is there a noticeable difference in the power with the vv71 cam?

Thanks in advance
Blueb20
Sunny SA

The dual springs that Isky supplies are only marginal stiffer than stockers, so they will not cause any problems. You will want to degree the cam in for maximum performance. What are you using for an intake & exhaust system?

There is a noticeable difference in performance. If you don't have the later exhaust manifold you need one!
I have used that cam with OEM valve springs and not had problems with valve float, either on B20
or with the 6 cylinder version on the B30.
There was a thread about lifter/lobe wear on the 1800list not long ago that concluded that a motor oil
with zinc, "ZDDP", is needed, especially on breakin, or you can get a ZDDP additive for your oil
that will help a lot. More modern engines don't need it so most oil manufacturers have phased it out.
--
George Downs, Bartlesville, Heart of the USA!

George is right about ZDDP in the oil. Use race oil or motorcycle oil that still provides plenty of zink. All current passenger car oils are lacking zink and phosphorous for flat tappet cams.

Those isky valve springs do not have enough pressure to wear the cam if you do everything right. In fact they need to be shimmed up quite a bit to provide enough pressure to work at 7000 plus rpm. If you are running below 5500 or 6000 rpm stock springs or maybe VW springs are OK and you can save your money. I run much stiffer springs in my race car but also use much stiffer pushrods to go with them.

What often kills Vovlo cams, besides the wrong oil, is lifters not spinning in their bores freely. You need to make sure there is plenty of clearance by honing the lifter bore and polishing out any dings or roughness on the sides of the lifters. It may also be helpful to have the lifters refaced with a bit more convexity to the face. This encourages the lifter to rotate. I have had better luck with used refaced lifters then new ones.

Also, read up on properer break in for camshafts and keep the idle speed up to provide plenty of splash lubrication to the cam and lifters.

I have used that cam with OEM valve springs and not had problems with valve float

How do you know that you don't have a problem? I can absolutely guarantee that the stock springs have problems with stock cams once you exceed 4000rpms.

I think you can get more then 4000 rpm of stable operation from stock springs but I agree that Georges probably doesn't realize how much bounce and instabality is going on at high RPM.

Do you need a hammer to loosen the valve keepers when you disassemble the head? ever look at he wear on the retainers or spring seats in the cylinder head. That is the result is insufficient valve springs allowing parts to bang together. I also attribute the commonly seen pitting on the lifter face of my ITB 142 on valve train instability.

Do you need a hammer to loosen the valve keepers when you disassemble the head?

That's is the case with every stock spring head I have seen other than the B20A heads I've come across.

With Isky grey & whites at 135lbs on the seat + the mediocre cam profiles I use I don't have this problem.

ever look at he wear on the retainers or spring seats in the cylinder head. That is the result is insufficient valve springs allowing parts to bang together. I also attribute the commonly seen pitting on the lifter face of my ITB 142 on valve train instability.

I think valve float & spring surge have a lot to do with pitting lifters too, when the lifter parts company with the lobe & then smashes back together again, it surely hurts them since they are at the hardest end of the scale used on flat tappet cams.

Another factor is people don't know that their valve train is out of control, because the B20 will rev through the problem most of the time.

Essentially agree with the above, including the need for stronger than stock springs for aftermarket profiles, or even stock cam for high rpm use. The improved control will actually reduce valve train wear.

But back to the original question.
Given a decent exhaust system the VV71 will normally give you more upper rpm power. But is it a good choice? Its a 30+ year old design, sold because its cheap. There are better designs around.

A question. Has Isky gone back to using a decent pushrod in their
high rev kit? I stopped buying and recommending pushrods from them more than
10 years ago when the dropped the Isky pushrods and went to something cheaper which bent and came apart.

John
V-performance.com

Given a decent exhaust system the VV71 will normally give you more upper rpm power. But is it a good choice? Its a 30+ year old design, sold because its cheap.

I'd pay a little extra for a dual pattern cam, but there isn't that much wrong with those old profiles. Modern profiles are just too harsh to live long in a B20.

Has Isky gone back to using a decent pushrod in their high rev kit?

I've never bought a kit from them. I made my own retainers & pushrods.

I bought a box of Eaton SBC lifters with the intent of making pushrods to suit, but have never actually tried them either. The SBC lifters cost me less than $1 each when new Volvo lifters where $11 each.

Hello,

We once had a problem with Isky pushrods and it turned out to a small batch of pushrods were made by their supplier, Smith Brothers, with the incorrect upper cup on the pushrod.

It is a special cup used only on Volvos.

On our very 1st performance motor that we built back in 1981, we had a failure of an IPD lifter, the top of the NON-ISKY lifter collapsed!!

We have been using Isky pushrods and lifters in our performance motors ever since.
--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502

I think you can get a nicer custom pushrod from Smith Brothers or other pushrod vender for the same money as IPD or Isky and be able to order the exact length you need for that thin HiPo cylinder head.

Hello,

Who do you think makes the pushrods for Isky?

--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502

I think Charlie is saying that you can get custom length ones, if you need them, direct from Smiths, for the same $ as a standard set from IPD or Isky.