PTV clearance
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PTV clearance I have searched and read many posts on PTV but i would like some feedback...first off here's my build stock shortblock with a torquer v2 cam on a 112 with 2 degrees advance installed straight up. My heads are 62cc AFR 205's with 202/160 valves. I am going to be running a .045 head gasket. For testing purpose i used a stock .051 head gasket while im waiting on my .045 to arrive. I used the hydraulic lifter with zero preload and a checking spring on the heads. I then placed the clay on the top of the piston and rotated the engine 3 complete revolutions. i then took off the head and measured the cay where the imprint of the valve was to at the thinnest point with my digital caliper and cam up with .124" i know my .045 gaskets will be lower that the testing gasket by.006 so will .118" clearance on the intake sound right for my setup?? I just want to make sure im doing this right..or do i need to flycut??
Thanks
Thanks
Two suggestions. First, I had the same issue. If you have your stock MLS gaskets (old ones), drill out the rivets and remove one of the thin layers. The remaining layers come it right around 0.042".
Second, I don't like compressing the clay with hydraulic lifters as it can push the plunger down some and give a false large reading. Have you tried the dial indicator method of measuring PTV?
Second, I don't like compressing the clay with hydraulic lifters as it can push the plunger down some and give a false large reading. Have you tried the dial indicator method of measuring PTV?
Excellent advise!
+1 to Vettenuts suggestions. Taking the old MLS head gasket apart for a mock up is a great tip. Thanks!
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Is there any risk on that? Which layer do you take off, the one in the middle?
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Verdad Gallardo This is done on your old gaskets that are no longer any good (the ones that you removed). Remove the thinnest layer of the MLS gasket. You are only using them to get the thickness correct based on your new thinner gaskets. If you do this, check the thickness and see how close it is to your new gasket. Mine were very close to the 0.040" Cometics I installed.
Yes and no. The issue is you have to squeeze the clay and that will take some force to do this. The rocker arm also provides a force multiplier back to the lifter. This could result in compression of the lifter plunger giving an error. I would double check with using the dial indicator method if you have one. If not, it can also be done with a feeler gauge using a similar method. I would double check your measurements though as this is one thing you don't want to be off.
This is done on your old gaskets that are no longer any good (the ones that you removed). Remove the thinnest layer of the MLS gasket. You are only using them to get the thickness correct based on your new thinner gaskets. If you do this, check the thickness and see how close it is to your new gasket. Mine were very close to the 0.040" Cometics I installed.
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ok, i just checked my clearance using a dial indicator..can someone look at these numbers and tell me what you think.
Intake Exhaust
30 deg - 0.496 30 deg - 0.551
20 deg - 0.327 20 deg - 0.375
15 deg - 0.263 15 deg - 0.314 BTDC
10 deg - 0.219 10 deg - 0.269
5 deg - 0.194 5 deg - 0.243
0 deg - 0.188 0 deg - 0.237
5 deg - 0.200 5 deg - 0.248
10 deg - 0.229 10 deg - 0.280
15 deg - 0.279 15 deg - 0.330 ATDC
20 deg - 0.343 20 deg - 0.391
30 deg - 0.521 30 deg - 0.571
Let me know your thoughts, i installed the gasket and head with 2 checker springs on cylinder 1... engine was at TDC and i installed the degree wheel and set the pointer to 0 degrees i then set up the dial indicator on the top of the valve stem and pressed the valve spring down until i felt it touch the piston and then took the reading. i then rotated the engine to 5 degree and then did the same check....does this sound right?
Thanks
Intake Exhaust
30 deg - 0.496 30 deg - 0.551
20 deg - 0.327 20 deg - 0.375
15 deg - 0.263 15 deg - 0.314 BTDC
10 deg - 0.219 10 deg - 0.269
5 deg - 0.194 5 deg - 0.243
0 deg - 0.188 0 deg - 0.237
5 deg - 0.200 5 deg - 0.248
10 deg - 0.229 10 deg - 0.280
15 deg - 0.279 15 deg - 0.330 ATDC
20 deg - 0.343 20 deg - 0.391
30 deg - 0.521 30 deg - 0.571
Let me know your thoughts, i installed the gasket and head with 2 checker springs on cylinder 1... engine was at TDC and i installed the degree wheel and set the pointer to 0 degrees i then set up the dial indicator on the top of the valve stem and pressed the valve spring down until i felt it touch the piston and then took the reading. i then rotated the engine to 5 degree and then did the same check....does this sound right?
Thanks
Let me know your thoughts, i installed the gasket and head with 2 checker springs on cylinder 1... engine was at TDC and i installed the degree wheel and set the pointer to 0 degrees i then set up the dial indicator on the top of the valve stem and pressed the valve spring down until i felt it touch the piston and then took the reading. i then rotated the engine to 5 degree and then did the same check....does this sound right?
Thanks
Thanks
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Sounds like you are doing it correctly. However, start at 20 degrees before TDC and check every 5 degrees. Exhaust is usually closest just before TDC and intake just after (depends on the cam valve events though). My lowest reading was the intake at 10 degrees after TDC.
So i guess im ready to go?
My lowest readying was at 0 degree TDC with 0.188 on the intake and 0.237 on the exhaust...
Thanks for the replies
