? for the engine builders.
Thread Starter
Melting Slicks
Joined: Dec 2000
Posts: 2,130
Likes: 1
From: mesa,az
? for the engine builders.
I have never done this before. I set a degree wheel on my crank, got 0* TDC with the head of and got the wheel dialed in. I replaced two of my valve springs with lighter ones from the hardware store and bolted on the head with no gasket. Then I set a dial indicater on the valve retainer and zeroed it every ten degrees before and after TDC on both the exhaust and intake valves on there opening cycle. every ten degrees I pushed down on the valve to bottom against the piston and recorded the distance. I got
Intake
0* TDC .077"
10* BTDC .156"
20* BTDC .228"
30* BTDC .296"
10* ATDC .072"
20* ATDC .108"
30* ATDC .248"
Exhaust
0*TDC .120"
10* BTDC .10"
20* BTDC .30"
30* BTDC .48"
10 ATDC .084"
20* ATDC .10"
30* ATDC .17"
sound about right to you fellas?
Intake
0* TDC .077"
10* BTDC .156"
20* BTDC .228"
30* BTDC .296"
10* ATDC .072"
20* ATDC .108"
30* ATDC .248"
Exhaust
0*TDC .120"
10* BTDC .10"
20* BTDC .30"
30* BTDC .48"
10 ATDC .084"
20* ATDC .10"
30* ATDC .17"
sound about right to you fellas?
Race Director
Joined: Apr 2000
Posts: 17,676
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Originally Posted by blctalon
For some reason I can't find my book. I seem to recall the recommended minimum values of .080" intake, .100" exhaust at full valve lift.
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
You can do it without the gasket, that's how I did it, just add in the compressed gasket thickness. I ended up being very close or actually less than .100" on the exhaust, these are just ballpark figures, I would not stray to far from them though
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Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Originally Posted by panchop
yep I'll add .028". Chevelles.com says i messed something up as the numbers don't make sense. I'll try again tommorow.
Thread Starter
Melting Slicks
Joined: Dec 2000
Posts: 2,130
Likes: 1
From: mesa,az
Wolfplace says ( and he is worth listening to )
"Just went back & looked at your numbers.
The ex should be closest at about 10° BTDC, the intake ATDC??
The ex numbers at 10, 20 & 30° ATDC seem incorrect??
The valve should be almost closed here??
You need to do this again."
"Just went back & looked at your numbers.
The ex should be closest at about 10° BTDC, the intake ATDC??
The ex numbers at 10, 20 & 30° ATDC seem incorrect??
The valve should be almost closed here??
You need to do this again."
Thread Starter
Melting Slicks
Joined: Dec 2000
Posts: 2,130
Likes: 1
From: mesa,az
Well I think I'll use the indicator, and then tommorow buy some clay and do that also. What the hell. I'll learn something. Anyhow I just degreed the cam and it is within a degree of the cam card. So I figure that could be within tolerances on my high quality harbour freight tools. Now I think I'll run the clearances again. Who needs to sleep.
WTH no where near my last numbers.
Ex BTDT 5* .073", 10* - .068" , 12* - 065", 15* - .073", 20*- .093 ", 30*- .181"
Ex ATDC 5* - .110" , 10* - .154" , 12* - .178", 15* - .209", 20*- .260"
Intake BTDC 5* - .145", 15*-.218", 30*- .3+"
Intake ATDC 5*- .125". 10*- .125". 15*- .128", 20*- .164".
WTH no where near my last numbers.
Ex BTDT 5* .073", 10* - .068" , 12* - 065", 15* - .073", 20*- .093 ", 30*- .181"
Ex ATDC 5* - .110" , 10* - .154" , 12* - .178", 15* - .209", 20*- .260"
Intake BTDC 5* - .145", 15*-.218", 30*- .3+"
Intake ATDC 5*- .125". 10*- .125". 15*- .128", 20*- .164".