engine head ...
06-11-2002, 08:21 AM
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engine head ...
i went to a local tuner shop
they they want to lower my head to increase the compression ratio.
But how much should they lower my head without valves hitting my pistons?
have any of you tried to lower head?
they would bore my IM TB to 57-58 mm for about 100 euro ( about 100 $ )
but i don't know about quality !!!
they they want to lower my head to increase the compression ratio.
But how much should they lower my head without valves hitting my pistons?
have any of you tried to lower head?
they would bore my IM TB to 57-58 mm for about 100 euro ( about 100 $ )
but i don't know about quality !!!
06-11-2002, 08:39 AM
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I have never claytested with the valves open, because my new pistons had deeper-than-stock valve reliefs cut into the domes. Thus, the many-thousandths of an inch I took off the block deck and 25-thousandths of an inch removed from the head were a non-issue with the valves.
The best way to do this is to claytest: using a small blob of hard clay placed on the #1 piston crown right over the intake valve relief pockets. Rotate the engine so the piston is at bottom dead center, then put the head gasket and cylinder head back on. Torque the bolts to about 30 pounds and then (with the timing belt ON) rotate the engine to TDC. Now that it's at TDC, remove the timing belt and reverse the cams very slowly with your hand 180 degrees.
Now rotate the engine so that #1 is again at bottom dead center, pull the head off and check the clay on the piston. You can now measure the thickness of the clay between the valve relief and where the valve actually dimpled against it.
Add about 0.015" for heat and stretching tolerance, and that's your maximum amount that can be shaved off the block deck, head gasket and actual head surface grand total.
Not hard to do, just time consuming and requires a motor that's fully disassembled.
The best way to do this is to claytest: using a small blob of hard clay placed on the #1 piston crown right over the intake valve relief pockets. Rotate the engine so the piston is at bottom dead center, then put the head gasket and cylinder head back on. Torque the bolts to about 30 pounds and then (with the timing belt ON) rotate the engine to TDC. Now that it's at TDC, remove the timing belt and reverse the cams very slowly with your hand 180 degrees.
Now rotate the engine so that #1 is again at bottom dead center, pull the head off and check the clay on the piston. You can now measure the thickness of the clay between the valve relief and where the valve actually dimpled against it.
Add about 0.015" for heat and stretching tolerance, and that's your maximum amount that can be shaved off the block deck, head gasket and actual head surface grand total.
Not hard to do, just time consuming and requires a motor that's fully disassembled.
06-11-2002, 09:45 AM
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I dunno if this helps....
Issued: 5/23/01 Revised: 5/23/01 Version 1
97-01 Hyundai Tiburon Page 2
2001 TECHNICAL INFORMATION FORM
Head Gasket Thickness (compressed): 0.71 mm
Deck Clearance (Min) (above or below): .10 below CAMSHAFT
I will start a new topic and post all the technical data...
Issued: 5/23/01 Revised: 5/23/01 Version 1
97-01 Hyundai Tiburon Page 2
2001 TECHNICAL INFORMATION FORM
Head Gasket Thickness (compressed): 0.71 mm
Deck Clearance (Min) (above or below): .10 below CAMSHAFT
I will start a new topic and post all the technical data...
06-12-2002, 12:35 AM
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A flowbench tool wouldn't tell you jack shyt about valve-to-piston clearance issues when shaving the head or the deck.
Think about it -- FLOW bench. What are flow numbers going to tell you about? The only way I know to test those clearances is to claytest the bastard, or else you can just take very accurate measurements of the head, valve extension from head, radial width of the exterior valve face, piston clearance to deck at TDC, throw it all together in a big-ass math problem and get the answer after about 2 hours worth of micrometer and calculator work.
Clay is just faster smile.gif
BV, where did you find those specs?
If I'm reading that correctly, they're outlining valve-to-deck clearance of 0.100, so theoretically speaking you could shave off quite a bit of cylinder head before you start ramming valves since the stock pistons still have valve reliefs.
Think about it -- FLOW bench. What are flow numbers going to tell you about? The only way I know to test those clearances is to claytest the bastard, or else you can just take very accurate measurements of the head, valve extension from head, radial width of the exterior valve face, piston clearance to deck at TDC, throw it all together in a big-ass math problem and get the answer after about 2 hours worth of micrometer and calculator work.
Clay is just faster smile.gif
BV, where did you find those specs?
If I'm reading that correctly, they're outlining valve-to-deck clearance of 0.100, so theoretically speaking you could shave off quite a bit of cylinder head before you start ramming valves since the stock pistons still have valve reliefs.