Intake Valve not seating

[bmwillia]

I just read that clearance for intake valves is .012. If that is the case then I should be able to use Don T's manual method to take .001 off to get to the .012.

So should I be at .012 or .015?

[Bored&Stroked]

Truth be told, won't matter one bit whether you're at .012 or .015. If I was you and you're sure the lifter is on the base of the cam . . . and I had .012 clearance, I'd put it back together and be done with it.

I've never had a case where my valve clearance got tighter over time . . . they always seem to increase, so you should be good to go.

[aussie merc]

so the intake clearance is less than exhaust due to the difference in operating temps when engine is actually running exhaust will be hotter so they expand more so in theory both clearances wind up the same [perfect world] Valve clearance will decrease especially on exhaust valves Not due to valve growth but to seat recession this takes time and is often caused by high temps. bad fuel. and cheap valves [ask anyone with a C15 cat engine what happened when they took the Sulphur out of diesel fuel ]

[Mart]

If this is a 59A motor the clearance for an inlet valve should be .010" to .012" So at .011" you are RIGHT ON THE MONEY.

Only the later 8BA types with the rotator valves got the bigger clearances.

Mart.

[Tinker]

I know the time is pasted for suggesting a good used mushroom valve from folks here that pull them and throw them in a reuse bucket. Fixed my 36 burnt valve for 15$ that way. Lapped and go.

[48-710]

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Aussie merc, being a auto machinist i'm hearing ya mate.

[bmwillia]

Originally Posted by Tinker

I know the time is pasted for suggesting a good used mushroom valve from folks here that pull them and throw them in a reuse bucket. Fixed my 36 burnt valve for 15$ that way. Lapped and go.

The valve I ordered from Mac Vanpelt cost around $15. So I’m right there with you in terms of cost and it looks like a lap and go here too!

Going to attempt to get it buttoned up and running today. I’ll update this post if I do.


Sent from my iPhone using Tapatalk

[Bored&Stroked]

What condition is the valve seat in? Have you cleaned it and can you post a picture? If the seat is in bad shape due to a bent valve beating on it in a strange manner, lapping won't resolve the issue. But it will tell you a lot! I'd use fine lapping compound . . . it should be all that you need.

Given that your year engine will have hard seats, the seat may be in good shape - but it is worth checking into. Valve lapping is not regrinding the seat - it is only done to deal with very small imperfections and to validate that you have a good concentric seat, that it is at the right place on the valve and that it actually will seal.

[bmwillia]

The seat appeared to be in good shape. I didn't see your post until after it was all buttoned up so I didn't get any pictures.

When I lapped the valve in, I got a nice even surface on the valve and seat. There didn't appear to be any damage to the seat.

Once I buttoned it up I got 70lbs on the compression test.

I have read that compression on these early engines should be in the 70-100lb range. Is that correct?

All other cylinders are 80lbs.

[aussie merc]

so what caused the valve to bend

[bmwillia]

It may have been bent when it was installed. I don't know but I don't see any evidence that it was hitting anything to make it bend.