Valve tip height

[Andys101]

So, I had my heads skimmed and the exhaust valves and seats cut.
I lapped all the valves in, rebuilt the heads, fitted them, and when I came to checking the lifter preload I discovered that using the shims i cant get all preloads within 20 to 60 thou.
The reason for this is the tips of the valves are not all level.
Now I know that adjustable push rods would be the best way to go but I just dont have that kind of money, what with all the other work that the Land Pig needs doing.

Some advice on how to overcome this would be most appreciated.

[ChrisJC]

I had exactly the same problem. I compromised with the average, but it always rattled a bit.
The only real way is to take the heads back off and return it to the machine shop and ask for it to be done properly!

Chris.

[Mc Tool]

Yeah ,that is not how you should get them back . How different are we talking , a few thou or a few mm. Did you also get the intakes done , and are the exhausts all the same and the intakes all the same but different to the exhausts. You may have to get the intakes done too just to get everything even .

[Andys101]

Just had the exhaust valves done, the inlet just needed lapping in.
There is enough variation that I can't get all the valve preload within tolerance with any of the shims, one valve will have no preload and another would have too much preload.

[minorv8]

Are you sure that this is all because of valve tip height ? Have you checked the difference by putting a straight edge on top of each valve ? This will show the actual difference between the valves. Sounds like you may have wear elsewhere.

[stevieturbo]

If all the valves are the same length....then whoever cut the seats did a bad job.

They should be all cut the same height.

Good machinists are hard to find

[Mc Tool]

I spose if there was wear on the rocker shafts it would add to the clearances ,specially if they wernt all worn the same. Might pay to have a good look at pushrods too ,I stripped an rv8 once that had a lot of wear on the pushrod ends ,( among other places )

[Andys101]

I am where I am, the valves have been cut and the height of the valves are where they are.
Yes, I put a straight edge across the top of the valve tips, this is how I found out they are not level.
Removing the heads and having further machining isn't an option.

So, what I have come up with is a finger file and level the valve tips.

[SimpleSimon]

Please dont resort to that like suggested above get it done properly do it right

[stevieturbo]

grinding the tops of valves is not uncommon....not quite sure a finger file will do it though.

However....in the case of an RV8 with a rocker tip passing over the valve, the valve tip will need to be of hardened material, and grinding the tip is likely to remove anything that is there.

So go down that route with caution. But a simple linisher type tool can be used to ensure a good smooth and straight tip ( with suitable alignment jigs. )

https://www.axminster.co.uk/axminster-c ... pcEALw_wcB

There are cheaper options ( a friend has used one from Lidl before lol )

But you get the idea...but the engines I've done this on are OHC with buckets acting on the valves. A massive difference to a rocker arm valvetrain.

[Andys101]

It's done now, one bank with the finger file the other draw file.

These heads have been skimmed a little too much for my liking anyway.

But I do have another pair of heads.