Building a 99/00 BP head
#1
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Building a 99/00 BP head
Building a Mazda BP Head
If you have not read
https://www.miataturbo.net/engine-pe...pection-70069/
https://www.miataturbo.net/engine-pe...bp-head-70149/
The porting work is done, the head has been cleaned again.
The bronze guides installed.
The guides have an unfinished ID, so the valves will not fit in the guide.
Time to get the guide hone out.
I use one of my pilots as a gauge to set the guide ID.
Hone until the pilot fully seats, I also check the top of the guide this way.
Now the head will be washed yet again.
Now the seats can be cut.
Now there is an issue…
Went to lap a valve in to check valve seat placement.
The valve did not seat. At all!
Here is the issue, the casting hump on the valve is hitting the guide.
The close tolerance of the bronze guide to valve stem was not figured to work with stock valves, Most all quality stainless steel valves will not have this casting hump.
So now to fix this issue, machine the valve, or machine the guide? Machining the guide seems simpler.
A slight taper in the bottom of the guide will do.
Now the valve fully seats, and I can check seat placement.
Now the seats are cut, each valve is hand lapped.
With the valve work done, the head can be surfaced.
A total of .007 was removed from the head.
Now the head is assembled, valve tip height is checked along with spring installed height.
Viton blue hi-temp valve stem seals were installed.
Along with the Brian Crower valve springs for testing on the BP head.
Stock valve spring retainers were used.
Buckets, shim pucks, and cams are installed to check valve lash.
It is a bit easier for me to set lash since I have extra pucks.
What is needed to check lash, feeler gauges and a sharpie
Lash is checked.
It is some simple math and measurements to get the lash set where needed.
Now the head is done!
Placed in a box and shipped back!
If you have not read
https://www.miataturbo.net/engine-pe...pection-70069/
https://www.miataturbo.net/engine-pe...bp-head-70149/
The porting work is done, the head has been cleaned again.
The bronze guides installed.
The guides have an unfinished ID, so the valves will not fit in the guide.
Time to get the guide hone out.
I use one of my pilots as a gauge to set the guide ID.
Hone until the pilot fully seats, I also check the top of the guide this way.
Now the head will be washed yet again.
Now the seats can be cut.
Now there is an issue…
Went to lap a valve in to check valve seat placement.
The valve did not seat. At all!
Here is the issue, the casting hump on the valve is hitting the guide.
The close tolerance of the bronze guide to valve stem was not figured to work with stock valves, Most all quality stainless steel valves will not have this casting hump.
So now to fix this issue, machine the valve, or machine the guide? Machining the guide seems simpler.
A slight taper in the bottom of the guide will do.
Now the valve fully seats, and I can check seat placement.
Now the seats are cut, each valve is hand lapped.
With the valve work done, the head can be surfaced.
A total of .007 was removed from the head.
Now the head is assembled, valve tip height is checked along with spring installed height.
Viton blue hi-temp valve stem seals were installed.
Along with the Brian Crower valve springs for testing on the BP head.
Stock valve spring retainers were used.
Buckets, shim pucks, and cams are installed to check valve lash.
It is a bit easier for me to set lash since I have extra pucks.
What is needed to check lash, feeler gauges and a sharpie
Lash is checked.
It is some simple math and measurements to get the lash set where needed.
Now the head is done!
Placed in a box and shipped back!
#4
So, silly question maybe. I want to swap the lifters from my 99 head with the 949 shim-under-bucket lifters. Any prediction on the amount/size of shims I'd need to get in order to have the lash set correctly, or is it a matter of buying all the thicknesses 4034893 times (at $5 each or so) and build a paperweight from the leftovers? Apparently 949 doesn't take returns on these and I don't want to have my build delayed by ordering more shims because I didn't get the correct ones the first time.
#5
So, silly question maybe. I want to swap the lifters from my 99 head with the 949 shim-under-bucket lifters. Any prediction on the amount/size of shims I'd need to get in order to have the lash set correctly, or is it a matter of buying all the thicknesses 4034893 times (at $5 each or so) and build a paperweight from the leftovers? Apparently 949 doesn't take returns on these and I don't want to have my build delayed by ordering more shims because I didn't get the correct ones the first time.
https://www.miataturbo.net/engine-pe...ere-buy-67555/
#9
You should probably try finding a machinist who does his own lash caps. This would be the easiest for you and would require the least amount of parts purchased.
Another idea would be to order a full set of the shortest lash caps, check your assembled lash, then figure out how much thicker each cap needs to be to get within specs.
Another idea would be to order a full set of the shortest lash caps, check your assembled lash, then figure out how much thicker each cap needs to be to get within specs.
#10
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Join Date: Mar 2012
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I have a couple sets being run, it looks good so far. But I want to get a bit more feedback, and miles in them before I give them the ok.
You can swap the pucks around, just measure the thickness and swap around to get as many in spec, then note what you you need thicker or thinner.
If the valves are ground, and the seats cut, that will close up the lash.
You should probably try finding a machinist who does his own lash caps. This would be the easiest for you and would require the least amount of parts purchased.
Another idea would be to order a full set of the shortest lash caps, check your assembled lash, then figure out how much thicker each cap needs to be to get within specs.
Another idea would be to order a full set of the shortest lash caps, check your assembled lash, then figure out how much thicker each cap needs to be to get within specs.
If the valves are ground, and the seats cut, that will close up the lash.
#12
I had a Taurus SHO with the DOHC V6, and the common knowledge in that community suggested re-using old pucks by flipping them over. The wear is primarily focused on the center of one side of the puck, and flipping them gave you a new wear side and maintained the installed thickness of the shim.
I don't think this would apply with the shim under buckets or shimless lifters. I'd make sure each of those went back into the hole it came out of.
I was under the impression he was asking about shim under buckets, which come without lash caps.
#13
949racing is right down the street from me fortunately, assuming they arent dropped shipped I can always buy a couple of them at a time to find the correct size?
Although I wish this wasnt the only option, in for any other ideas?
#16
Hypothetical Example: Lash with 1 mm cap (~.0394 in) is 30 thousandths on one of the intake valves. Say you want the loose end of specs at 9 thousandths, so you'd need to order a cap that is 21 thousandths thicker. .021 in is ~.533 mm, so you'd order either the 1.5 mm cap (probably too loose in this example), or the 1.55 mm cap.
Also, you're better off doing this with a metric feeler gauge and not dealing with Mazda's unit conversion rounding.
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