Y-Block Rocker Ratio Question
Y-Block Rocker Ratio Question
Elder User
Joined: Jan 2002
Posts: 692
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Y-Block Rocker Ratio Question
I'd go with the 1.54's on both,
but thats just me...
Steve & the Rockette
'63 F100
'68 F100
'72 Capri 2L
'73 Capri 2.6L V6
'73 MG B GT 2.6L V6(Ford)
'98 Contour SVT 2.5L V6 (Mods)
'01 ZX2 (No Mods yet)
but thats just me...
Steve & the Rockette
'63 F100
'68 F100
'72 Capri 2L
'73 Capri 2.6L V6
'73 MG B GT 2.6L V6(Ford)
'98 Contour SVT 2.5L V6 (Mods)
'01 ZX2 (No Mods yet)
Posting Guru
Joined: Mar 2002
Posts: 2,070
Likes: 2
From: Boise, Idaho
Y-Block Rocker Ratio Question
Well, that may be a way to get the intake to exhaust flow into the 80% range (where the exhaust flows 80% of the cfm that the intake flows at a particular valve lift.) This assumes a stock cam. But then the stock cams varied, too.
The intake valves on my (1956 292) engine are 1.78" and the exhaust are 1.51". I can see how a fella would want to bias the rocker arm ratio in favor of the intake.
Cargo Master
Joined: Apr 2003
Posts: 2,389
Likes: 58
Y-Block Rocker Ratio Question
EZmoney,
Are you going for performance or streetability? The 1.43 rockers on the exhaust will decrease duration and lift on the exhaust valves and more than likely cause less flow. The decrease in lift and duration may help with low end torque but hurt top end performance. I would use the same ratio rockers on the intake and exhaust. If you were running some form of forced induction, nitrous, turbo, or supercharger, using different ratio rockers would be valid. But in this case of forced induction you would want the higher ratio rockers on the exhaust valves to help the spent gases get out of the cylinder. The valves would behave more like a dual pattern cam.
Freezeplug,
The pushrod question is interesting. I use the 1.54 rockers on my engine and I purchased new pushrods for it. I just barely have enough thread on the screws to get the rockers adjusted. Just barely. So I would think that the longer ones would be best. I didn't measure mine before I installed them. That probably would have been a good idea. But as long as it works with no problems I am happy.
Are you going for performance or streetability? The 1.43 rockers on the exhaust will decrease duration and lift on the exhaust valves and more than likely cause less flow. The decrease in lift and duration may help with low end torque but hurt top end performance. I would use the same ratio rockers on the intake and exhaust. If you were running some form of forced induction, nitrous, turbo, or supercharger, using different ratio rockers would be valid. But in this case of forced induction you would want the higher ratio rockers on the exhaust valves to help the spent gases get out of the cylinder. The valves would behave more like a dual pattern cam.
Freezeplug,
The pushrod question is interesting. I use the 1.54 rockers on my engine and I purchased new pushrods for it. I just barely have enough thread on the screws to get the rockers adjusted. Just barely. So I would think that the longer ones would be best. I didn't measure mine before I installed them. That probably would have been a good idea. But as long as it works with no problems I am happy.
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