+1mm valves & 10:1 CR clearence questions
#1
Senior Member
Thread Starter
iTrader: (6)
Join Date: Jun 2010
Location: San Rafael, CA
Posts: 1,421
Total Cats: 95
+1mm valves & 10:1 CR clearence questions
Looking for some valve clearance data from those who have run the 10:1 stock pistons with +1mm valves on 99 head.
I am trying to get a rough idea what kinda cam lift I can get away with.
I am trying to get a rough idea what kinda cam lift I can get away with.
Last edited by k24madness; 07-14-2013 at 04:04 PM.
#2
well im running +1mm valves on 9:1 pistons. I dont know who your piston manufacturer is but im gonna assume that the valve pockets are gonna be cut to the same depth on all miata pistons by that manufacturer. The material around it is what creates the change in compression.
If that is true, I am running .490 lift and 295 duration on my intake side with no modifications to the piston. But the only way to know for sure what you can run, is to assemble one piston in the engine, clay it up and check your clearance.
If that is true, I am running .490 lift and 295 duration on my intake side with no modifications to the piston. But the only way to know for sure what you can run, is to assemble one piston in the engine, clay it up and check your clearance.
#4
Senior Member
iTrader: (1)
Join Date: Jan 2011
Location: Chattanooga, Tn
Posts: 1,234
Total Cats: 283
With the 10:1 wescos, a block and head that hasn't been machined too extreme and the +1mm supertechs....my motor is still non-interference. I clayed the motor when I built it and measured the actual clearance but don't have my notebook with me....but I think I stil had something like .060" all the way around.
#5
i would be more cautious with big dome pistons, but a 10.0:1 is gonna be flat top if i had to guess, the valve pockets should be just as deep as a 9.0:1, But every piston manufacture will be different and cams change alot as far as open and close timing. And head and block machining can change alot too. my pistons are around .003 in the hole and my head was cut .010"
#8
Moderator
iTrader: (12)
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 20,652
Total Cats: 3,011
Yeah, if I recall, he had almost enough depth with the valve reliefs but they weren't cut with a large enough diameter for the oversize valves. He had a bad day. But, yes, definitely ask him for details including piston brand and cam lift info. I know he is running some pretty big cams compared to stock.
#9
My camshaft is actually pretty mild, with lift not much bigger than a stock 99 cam.
The valves touched the corners on the valve reliefs on each piston's intake side. The valve reliefs were not cut large enough. I simply made the reliefs larger with sandpaper. Ironically there was no visible damage to valves or cylinder head. I think some valves were slightly bent, but they were all repairable.
Pistons were JE, but I bought these pistons years ago, and obviously JE has since made a change to the valve reliefs.
The valves touched the corners on the valve reliefs on each piston's intake side. The valve reliefs were not cut large enough. I simply made the reliefs larger with sandpaper. Ironically there was no visible damage to valves or cylinder head. I think some valves were slightly bent, but they were all repairable.
Pistons were JE, but I bought these pistons years ago, and obviously JE has since made a change to the valve reliefs.
#11
Senior Member
Thread Starter
iTrader: (6)
Join Date: Jun 2010
Location: San Rafael, CA
Posts: 1,421
Total Cats: 95
I am just looking for overall input on stock size valve reliefs with 2001+ 10:1 pistons with +1mm valves. Knowing the pockets are smaller than than most aftermarket pistons I am trying to get an idea of potential troubles.
The real struggle is hearing Andrews voice telling me to go VVT.
#13
Senior Member
Thread Starter
iTrader: (6)
Join Date: Jun 2010
Location: San Rafael, CA
Posts: 1,421
Total Cats: 95
With 99 head. +1mm valves and .396 lift / 216 duration at .050 cams we had to notch the pistons more using the 10:1 stock style pistons.
I had the block zero decked and the head shaved some so maybe that's why you were safe and I was not. It could also be the cams themselves. The ones I used have very aggressive opening ramps.
I had the block zero decked and the head shaved some so maybe that's why you were safe and I was not. It could also be the cams themselves. The ones I used have very aggressive opening ramps.
Thread
Thread Starter
Forum
Replies
Last Post
bigmackloud
Miata parts for sale/trade
19
01-08-2021 11:24 AM
stoves
Suspension, Brakes, Drivetrain
5
04-21-2016 03:00 PM
JesseTheNoob
DIY Turbo Discussion
15
09-30-2015 02:44 PM