Valve drop @ TDC only .175" WTF
#1
Valve drop @ TDC only .175" WTF
I want a bigger cam but I think I'm screwed, when I put a dial indicator on the top of the valve stem and zero it when the valve is resting on the piston, and then lift the valve up into it's seat I only have .175". I now have a TR224/224 .563/.563. How am I going to fit a bigger cam with that close a tolerance. I have AS 5.3 Stg 2 heads 11/1 CR with 978 springs. The other bad thing is the spring install height should be 1.850, it's only 1.830 on the intake and strangely 1.870 on the exhaust. What could be the reasoning for that?
#2
Originally Posted by bigdsz
The other bad thing is the spring install height should be 1.850, it's only 1.830 on the intake and strangely 1.870 on the exhaust. What could be the reasoning for that?
#3
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Take your .175 and subtract the difference b/w cam lifts new - current and you get your final clearance.
My cam with your specs for example.
Intake Valve (thats all you gave right?)
.6307 my cam
- .5630 your current cam
= .0677
.1750 clearance
-.0677 difference
= .1073 Thats quite excellent still actually.
So you can go with way more cam, but you have to consider the duration and events as well. Above was just a mathmatic representation based off increasing only your lift.
Good luck,
Charlie
My cam with your specs for example.
Intake Valve (thats all you gave right?)
.6307 my cam
- .5630 your current cam
= .0677
.1750 clearance
-.0677 difference
= .1073 Thats quite excellent still actually.
So you can go with way more cam, but you have to consider the duration and events as well. Above was just a mathmatic representation based off increasing only your lift.
Good luck,
Charlie
#5
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Originally Posted by CAT3
Take your .175 and subtract the difference b/w cam lifts new - current and you get your final clearance.
My cam with your specs for example.
Intake Valve (thats all you gave right?)
.6307 my cam
- .5630 your current cam
= .0677
.1750 clearance
-.0677 difference
= .1073 Thats quite excellent still actually.
So you can go with way more cam, but you have to consider the duration and events as well. Above was just a mathmatic representation based off increasing only your lift.
Good luck,
Charlie
My cam with your specs for example.
Intake Valve (thats all you gave right?)
.6307 my cam
- .5630 your current cam
= .0677
.1750 clearance
-.0677 difference
= .1073 Thats quite excellent still actually.
So you can go with way more cam, but you have to consider the duration and events as well. Above was just a mathmatic representation based off increasing only your lift.
Good luck,
Charlie
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#8
GueSSwho, I appreciate your support more than you know, can you give me hard numbers how it will fit ? This is absolutely driving me nuts, Ijust hate to buy the cam to find it Ain't gonna work. My wife is already really pissed at me about the money I've already wasted on mods that produced poor results.
#9
FormerVendor
YOU need to look at the lift at TDC and multiply that by your rocker ration and then subtract that from the free drop data you measured. The valves are closest 10 BTDC on exhaust and 10 ATDC degrees after on intake. Most lobe cataloques show your lobe lift at TDC at at least two centerlines.