T & D shaft rocker ratio
#2475313
04/01/18 12:57 PM
04/01/18 12:57 PM
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Joined: Aug 2009
Posts: 2,056
Mooresburg, Tn
'72CudaRacer
OP
top fuel
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OP
top fuel
Joined: Aug 2009
Posts: 2,056
Mooresburg, Tn
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Finally got back in the shop this week and mocked up the B-1 heads on this 622 CI RB that I have been repairing. I checked the rocker arm ratio and was surprised to find the ratio is not what I expected.
These are T & D shaft rocker, on B-1 MC heads, and are marked 1.7 ratio. By my calculations, they measure very close to 1.8:1. Solid roller camshaft, .500 lobe lift (advertised & measured), WITH correct lash (in .026", ex .022"), valve lift measures .880" at valve spring retainer.
Is this normal, or am I missing something? This is using light weight checking springs, but I wouldn't expect that to make a difference.
The only real problem that this is causing is the valve spring retainers are very close to the valve guide seals, to the point of just "kissing" the seal, but not moving it.
With the cam installed "straight up"(113.5*), I have enough valve to piston clearance, but when I try to advance the cam, things get real tight as the piston starts back down. (At TDC it's OK, but the valve is opening faster than the piston is moving down).
Again, is this normal, or am I missing something?
Thanks, Brian
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Re: T & D shaft rocker ratio
[Re: '72CudaRacer]
#2475350
04/01/18 01:35 PM
04/01/18 01:35 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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You might want to send them back to TD all my TD rockers measured right on or real damn close (way closer than your measuring).. that .1 is messing up your build 
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Re: T & D shaft rocker ratio
[Re: MR_P_BODY]
#2475360
04/01/18 01:53 PM
04/01/18 01:53 PM
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Joined: Aug 2009
Posts: 2,056
Mooresburg, Tn
'72CudaRacer
OP
top fuel
|
OP
top fuel
Joined: Aug 2009
Posts: 2,056
Mooresburg, Tn
|
You might want to send them back to TD all my TD rockers measured right on or real damn close (way closer than your measuring).. that .1 is messing up your build These are not new rockers Mike. This engine has been running (running well at times, with a lot of problems), and was brought to me to fix prior builders mistakes. I am not trusting anything at this point. At this point, I think that a cam change would probably be the easiest and least expensive fix. Brian
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Re: T & D shaft rocker ratio
[Re: '72CudaRacer]
#2475510
04/01/18 06:54 PM
04/01/18 06:54 PM
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Joined: Sep 2003
Posts: 1,049
San Jose Ca.
boatracer572
super stock
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super stock
Joined: Sep 2003
Posts: 1,049
San Jose Ca.
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Finally got back in the shop this week and mocked up the B-1 heads on this 622 CI RB that I have been repairing. I checked the rocker arm ratio and was surprised to find the ratio is not what I expected.
These are T & D shaft rocker, on B-1 MC heads, and are marked 1.7 ratio. By my calculations, they measure very close to 1.8:1. Solid roller camshaft, .500 lobe lift (advertised & measured), WITH correct lash (in .026", ex .022"), valve lift measures .880" at valve spring retainer.
Is this normal, or am I missing something? This is using light weight checking springs, but I wouldn't expect that to make a difference.
The only real problem that this is causing is the valve spring retainers are very close to the valve guide seals, to the point of just "kissing" the seal, but not moving it.
With the cam installed "straight up"(113.5*), I have enough valve to piston clearance, but when I try to advance the cam, things get real tight as the piston starts back down. (At TDC it's OK, but the valve is opening faster than the piston is moving down).
Again, is this normal, or am I missing something?
Thanks, Brian T&D adds a little ratio for deflection.... some alum rockers deflect more than others depending on RPM and spring load... most of all the pro stock teams now days run tool steel rockers to combat this...
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