So, I picked up a BP head from a 91LX a few weeks ago to get a few things going: (1) obtain an extra exhaust cam for the exhintake conversion and (2) get a head rebuilt / ported for the eventual BP swap into my tired DX chassis. I've decided to go NA for a while, just because I can build it slower (cash-flow wise). So the plan for the motor is:
exhintake, with modified stock timing gear (save cash on adjustable)
ported head & matched intake
required overbore on block (0.020?)
Genie header + cat back
RX7 VAF & cone filter
Possibly mill head and / or block for compression
2001 Miata pistons
Since the wife was out of town, the kitchen counter was chosen for head disassembly & cleaning. Spread the newspaper, tub of degreaser in the sink, onward. The cam bearings all looked okay, the ones down by the drive end seemed a bit more "polished" than the others. Some showed almost no wear. Cleaned them all & put them in labeled baggies with their hardware.
The hydraulic lifters were about the same. Mostly looked new, with a little extra polish in a few places. These did NOT go in the degreaser soup, they were just hand-wiped down, verified that the internal springs still worked, and individually bagged & labeled. They will get cleaned & manually pumped (have fun with that) in 10-weight oil before they go back in the motor.
Started to take out the valves, when I discovered that my spring compressor that worked on my Buell will NOT work on the BP head. After some gymnastics with an 18mm socket, I got the retainers out on one intake valve, and removed the valve. It looked like a 100,000 mile valve; lots of carbon on the valve both back & front. Chambers are all black.
So, after the valve was out I started looking at the ports. The short side radius looks like it could be blended, and maybe some other light blending around the rest of the seat looks okay too. The ports are filthy, so they'll get polished up too.
Looking at the combustion chambers, I think I see some flow waiting to be had. The sides of the chamber are right next to the intake valve, the walls have GOT to be shrouding the valves. It looks like cutting those areas back will allow for better flow into the chambers. I guess that means I'll have to cc the chambers to get them all the same, that should be fun. I'm hoping to get an ending compression ratio about 10.5:1 or so.
Has anyone tried that mod to the heads?
exhintake, with modified stock timing gear (save cash on adjustable)
ported head & matched intake
required overbore on block (0.020?)
Genie header + cat back
RX7 VAF & cone filter
Possibly mill head and / or block for compression
2001 Miata pistons
Since the wife was out of town, the kitchen counter was chosen for head disassembly & cleaning. Spread the newspaper, tub of degreaser in the sink, onward. The cam bearings all looked okay, the ones down by the drive end seemed a bit more "polished" than the others. Some showed almost no wear. Cleaned them all & put them in labeled baggies with their hardware.
The hydraulic lifters were about the same. Mostly looked new, with a little extra polish in a few places. These did NOT go in the degreaser soup, they were just hand-wiped down, verified that the internal springs still worked, and individually bagged & labeled. They will get cleaned & manually pumped (have fun with that) in 10-weight oil before they go back in the motor.
Started to take out the valves, when I discovered that my spring compressor that worked on my Buell will NOT work on the BP head. After some gymnastics with an 18mm socket, I got the retainers out on one intake valve, and removed the valve. It looked like a 100,000 mile valve; lots of carbon on the valve both back & front. Chambers are all black.
So, after the valve was out I started looking at the ports. The short side radius looks like it could be blended, and maybe some other light blending around the rest of the seat looks okay too. The ports are filthy, so they'll get polished up too.
Looking at the combustion chambers, I think I see some flow waiting to be had. The sides of the chamber are right next to the intake valve, the walls have GOT to be shrouding the valves. It looks like cutting those areas back will allow for better flow into the chambers. I guess that means I'll have to cc the chambers to get them all the same, that should be fun. I'm hoping to get an ending compression ratio about 10.5:1 or so.
Has anyone tried that mod to the heads?
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