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3.0litre stroker crank set, k-jet fueled?

Been busy on the 531 head
 

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Question, I have been cutting the seats. The valves are the same size as the seat. So when doing 3 angle valve job the outer edge of the seat would be 30 degrees. But can it do any harm when it is already within the size of the 45 degree angle of the valve itself? Do I need to cut the first of three angles outside the seat? Then the valve would be deeper inside the head as well?
 
Question, I have been cutting the seats. The valves are the same size as the seat. So when doing 3 angle valve job the outer edge of the seat would be 30 degrees. But can it do any harm when it is already within the size of the 45 degree angle of the valve itself? Do I need to cut the first of three angles outside the seat? Then the valve would be deeper inside the head as well?
What tool are you using to cut the valve seats? There seems to be a lot of vibrations and poor cut quality, and these will not seal. Lapping compound is not the way to make them seal either.

As far as valve seat diameter: You need to place the transition of the 45 to 30deg a bit in from the edge of the valve. Otherwise the valve face may be sealing on the aluminum, this is not good. If you place the edge of the valve seat all the way out at the edge of the valve, you will have to "sink the valve" to get your top cut (the 30deg) in. This isn't a big issue, except you will have to correct it with removing material from the tip of the valve. It is very easy to go too deep with the valve and then you have to grind so much of the tip that the bucket will hit the spring retainer (very bad).
Total width of the 45deg valve seat in the head should be ~1mm.

I also see that you ground the exhaust guide flush with the port. If you are using a tapered pilot system you will have a really hard time getting a concentric valve seat. With a Mira or Serdi system you will be ok with a lot of fiddling.

If you're using a 3 step cutter system:
1. Cut the 45 so it's OD is just under the diameter of the valve. Try very hard to have the face of the valves all the same distance from the deck surface of the head.
2. Use a 30deg cutter to add a top angle and to set the total diameter of the seat. The total width of the top cut should be about 0.5-1mm.
3. Use the throat cutter (are you using a 60?) to then set the seat width to ~1mm for intake and 1.5-2mm for the exhaust.
 
Thanks a lot for the extensive advise!

My eyes see nicely cut valve seats. My phone camera sees shitty ones for some reason.
They really aren't that bad at all.

Edit: about the valve guide on the exhaust side, this is how I also did it on my b20 head. How should I correct this?
 
Thanks a lot for the extensive advise!

My eyes see nicely cut valve seats. My phone camera sees shitty ones for some reason.
They really aren't that bad at all.

Edit: about the valve guide on the exhaust side, this is how I also did it on my b20 head. How should I correct this?
What valve seat cutting system are you using?
 
OK, so that is (should!) use a tapered pilot for the cutter. When the pilot is installed a guide with an angle cut on it, the pilot will deflect to the "low" side of the pilot. So you will need to side-load the cutter the other direction. A flashlight and a straight valve will help you see how concentric the valve seat is.

If it's a Neway cutter, you might have good results but you have to be careful. If it is the brazed and machined cutters from China/India... good luck!
 
Yeah so it is a brazed one from China. That's why I said I cannot say this in public.

So it is cutting through the hardened seats quite well I must say. It also comes with a kind of surfacing tool for after the cutting. But it doesn't work that well.

So the finishing needs to be done either by lapping or I need to find another way.

How about the valve guide? Do you think it will be an issue?

Edit: but the pilot is straight and fits nicely in the guide. So that shouldn't be to much of an issue right?

Edit2: this is what the thing looks like
 

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Yeah so it is a brazed one from China. That's why I said I cannot say this in public.

So it is cutting through the hardened seats quite well I must say. It also comes with a kind of surfacing tool for after the cutting. But it doesn't work that well.

So the finishing needs to be done either by lapping or I need to find another way.

How about the valve guide? Do you think it will be an issue?

Edit: but the pilot is straight and fits nicely in the guide. So that shouldn't be to much of an issue right?

Edit2: this is what the thing looks like
Volvo seats aren't what I would consider "hard", they are relatively soft in the grand scheme of valve seats.
I don't think the valve guide will be an issue.

I DO think that the pilot clearance (pilot to guide), and the pilot deflection (how much it bends) will be a big issue. It's very very easy to cut a seat that's 0.25-0.5mm non-concentric with a loose steel pilot. Serdi and Mira type machines use a straight pilot with ~0.005-0.01mm clearance to the guide bore, I doubt the pilot you have is that tight.

You need to have the valve seat concentric to the centerline of the guide to within the valve stem to guide clearance or less (rough rule of thumb). Otherwise the valve face will be bending to seal on the head. The length of the valve guide also plays into this, a longer guide needs a more concentric seat.

I'm also concerned about the chatter marks that I'm seeing in the pictures. It needs to be perfectly smooth for the valve face to seal. Using a lapping compound to "fix" the sealing issue just destroys the finely ground valve face surface and makes it cupped like a "U". While this may seal, it will wear out a lot faster than two flat cones sealing.

My advice for that nice engine you're spending money on: Take the head to a cylinder head shop and have them cut nice concentric seats for you. Just the seat cutting and valve stem length adjustment will not be expensive. Use the tool you have to refurb the seats on a stock head that you just want to have work.
 
Picked up the engine yesterday!
Looks so nice after boring, honing and decking job!

Fitted one piston to measure the deck hight. Came up with 0.2mm above the deck.
They have a dish of 25cc

So looks like I need to shave the head like a lot!
Measured the head came up with 56ml.
For 1 on 11 I need 43cc.
So looks like I need to cut the head down like 2.5mm at least.
Is this a smart thing to do? Or should I do a bit less?
 

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Why not consider having material added to the combustion chambers so you can also shape them for good flow? That will reduce volume without cutting the head much. Just throwing the thought out there not sure if it's viable for you.
 
I am able to weld aluminum yes, I have everything in my workshop to do it. But I am afraid to warp the 531 head. So I will just shave the head.
Any advise from culbero how much shaving is reasonable?

I brought the head away to the head shop yesterday, my valve job was not too bad only didn't cut the 45 degree angle far enough and throat cut should be also more.
They will finish the head. Then I need to measure it again after they finish it.
After this they will shave the needed amount off.

Started today putting the pistons together and gapping the rings.
Only still waiting a bit for the BMW squirters.
And the head job ofcourse.

Edit: found it already skimming the head more than 2mm is no problemo
 
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Picked up the engine yesterday!
Looks so nice after boring, honing and decking job!

Fitted one piston to measure the deck hight. Came up with 0.2mm above the deck.
They have a dish of 25cc

So looks like I need to shave the head like a lot!
Measured the head came up with 56ml.
For 1 on 11 I need 43cc.
So looks like I need to cut the head down like 2.5mm at least.
Is this a smart thing to do? Or should I do a bit less?
I haven’t ran your combo through my CR calculator, but just check your math and numbers.
With that extra stroke and displacement you should have a pretty high CR even with the dishes pistons.

If it does all come out correct, 3+mm off the head is fine. I like to level the head, pour in some windshield washer fluid to the desired chamber volume, then measure from the deck surface to the liquid. The distance is how much you need to machine the head.
 
Windshield wash liquid it is! Thanks for the tip!

The most horrible part of it all is the waiting :p
Waiting for the BMW squirters, waiting for the machine shop, waiting waiting :p

Got ma rims back from coater too!

And added some pics from piston and rods. Just for the post always being better with pics!
 

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Morning,

It's been a while, block was decked 1.3mm pistons come out 0.2mm.
Installed crank, pistons and rods.
Needed to remove some material from the block at no3 cyl to clear the rods rotation.

Got the head back from the shop, they cut them seats as discussed above. Looks nice, valves are nicely seating and sealing. Didn't spend that much money even.
Took the head back home, assembled the valves and put in the cam, measured the thickness of the shims needed. Ordered some lashcaps to get it right.
The caps delivered with the cam are quite thick.

Then, whilst I removed the freeze plug on the distributor hole, I found that the gear on the aux shaft is missing.
Went to the parts attic and found a b21et with a aux shaft in it with a gear. So compared it, numbers are same. But one has a gear and the other one doesn't.
So I swapped the shaft for the one from the b21et.

Then I also measured the head, I came up with 55cc's a chamber. I need 41cc's for a 10.9 CR.
Put 41cc in the head in two chambers and both measured 2mm to reach the needed cc's. Will go back to the head shop today to get it shaved.

Been busy as well to get a zero setup for the carbs. Will go with 42mm chokes and ordered all the needed emulsion tubes and jets.

Got myself some head studs as well, instead of the bolts. Hope to get the engine running by this month.
 

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Got the head shaved, measured it an came up with 42cc so 1 to 10.8 nice!

Got the head back on too!
 

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