1.6 rockers vs 1.7
#1
1.6 rockers vs 1.7
http://www.summitracing.com/parts/TFS-51402000/
im considering getting this cam with a stock block and these heads
http://www.summitracing.com/parts/TFS-51400004/
if i get 1.7 rockers will that change PTV clearance with the cam?
That seems like a decent cam for my setup so far i just need to decide rockers and lifters...parts i have now is
75mm TB 75mm MAF calibrated for #24 injectors trick flow upper and lower intakes, full length 1 5/8 headers....what do you think of the setup?
im considering getting this cam with a stock block and these heads
http://www.summitracing.com/parts/TFS-51400004/
if i get 1.7 rockers will that change PTV clearance with the cam?
That seems like a decent cam for my setup so far i just need to decide rockers and lifters...parts i have now is
75mm TB 75mm MAF calibrated for #24 injectors trick flow upper and lower intakes, full length 1 5/8 headers....what do you think of the setup?
#2
1.7 rockers basically make the cam act like it has a bit more lift and duration. Remember that cams are spec'd at the camshaft lobe and not at the valve. The bigger advantage of using higher ratio rockers is that you can run a milder cam lobe and still good good valve action...and since the lifter has way more mass then the rocker/valve, it can help with high rpm stability and prevent valve float. That's why a lot of high rpm pushrod engines run larger rocker ratios.
#3
It will definitely change PTV clearance.With the 1.7 rr it will change lift on the intake from 499 to 530 and on exhaust from 510 to 542.The way you get the lift numbers is divide the lift by 1.6 and that will give you actual cam lift. 499 divided by 1.6 =311.88.Take 311.88 multiply by 1.7 and it give you 530.40
#5
It will definitely change PTV clearance.With the 1.7 rr it will change lift on the intake from 499 to 530 and on exhaust from 510 to 542.The way you get the lift numbers is divide the lift by 1.6 and that will give you actual cam lift. 499 divided by 1.6 =311.88.Take 311.88 multiply by 1.7 and it give you 530.40
#6
Total valve lift has nothing to do with the possibility of PtV issues. If a setup clears with 1.6 ratio rockers, it will clear with 1.72 rockers 96.9% of the times. Total valve lift happens at 102°+ ATDC, when the piston is over 1.9" down he hole, how can they become intimate? It's during the overlap (exhaust-to-intake changeover) TDC cycle that they can hit the piston.
Here's a comparison using the X-303 cam with both ratio rockers.....
Here's a comparison using the X-303 cam with both ratio rockers.....
#8
I think there won't be a problem with the rockers.
But
If you are using headers that are 1 5/8 O.D. they are only 1 1/2 I.D.
You'll need 1 3/4 O.D. headers for the new heads with 1.60 exhaust valves.......
But
If you are using headers that are 1 5/8 O.D. they are only 1 1/2 I.D.
You'll need 1 3/4 O.D. headers for the new heads with 1.60 exhaust valves.......
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