3G rocker ratio ?

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ateam

A motor can
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Looks like the 6.1L "billet" cam is big enough base circle to regrind for the hotter, 6.4L crate cam spec's. To do this right, I need the rocker ratio, anybody ? Case hardness depth should be adequate. Regrind is $75. vs $400. for new stick. Will use "Manton" made-to-length, push rods, to get correct lifter preload. Thanks,ateam:thumbup:
 
I have been told it's 1.65:1 and that was what I have baised my numbers off of in the past. If you know lobe lift, and you find the valve lift simple math can tell you what it is. You will have to round your number though to account for the oil pressure in the lifters. As you will slightly compress the plunger in the lifter without the oil pressure.

I'll be doing a cam swap soon and can check it and give you my measurements if you would like. But it will be a few weeks before it gets done. The cam has been ordered and it looks like it will be a little while before it arrives.
 
03ramit1 said:
I have been told it's 1.65:1 and that was what I have baised my numbers off of in the past. If you know lobe lift, and you find the valve lift simple math can tell you what it is. You will have to round your number though to account for the oil pressure in the lifters. As you will slightly compress the plunger in the lifter without the oil pressure.

I'll be doing a cam swap soon and can check it and give you my measurements if you would like. But it will be a few weeks before it gets done. The cam has been ordered and it looks like it will be a little while before it arrives.
Click to expand...

I had heard 1.65:1 somewhere also. I got (1.6:1) from the "New Hemi Builders Guide 2003-present" :---)
Note: Don't waste your money on this book. There is far more and higher quality info right here in the New Hemi Swap Forum if you just spend the time to search and read it all.
 
yeah that book is junk. I got it when it came out. All the info on it is way outdated. I knew more about the motor than what is in the book. And that was years ago. Some of the companys in that book are no longer in business so that would make it fun to try and get the parts from them.

I agree there is better info here than what can be found in that book. My understanding is that most cam companys use 1.6:1 some use 1.7:1 because it's close to the actual rocker ratio. But to me it means you have to know the advertised ratio as well as the actual in order to correctly size up the lift at the valve to avoid coil bind.
 
03ramit1 said:
yeah that book is junk. I got it when it came out. All the info on it is way outdated. I knew more about the motor than what is in the book. And that was years ago. Some of the companys in that book are no longer in business so that would make it fun to try and get the parts from them.

I agree there is better info here than what can be found in that book. My understanding is that most cam companys use 1.6:1 some use 1.7:1 because it's close to the actual rocker ratio. But to me it means you have to know the advertised ratio as well as the actual in order to correctly size up the lift at the valve to avoid coil bind.
Click to expand...
Or even worse,Valve Tag ! Anybody "dial indicate" at the retainer with a known lobe lift. Thanks, ateam.:thumrigh:
 
Couldn't you also just pull a rocker and measure between the pivot point and the tips? Might not be quite as exact though.

Edit: Oh right, I forgot the hemi uses the weird angled ones. Might still be able to get an idea though.
 
ateam said:
Looks like the 6.1L "billet" cam is big enough base circle to regrind for the hotter, 6.4L crate cam spec's. To do this right, I need the rocker ratio, anybody ? Case hardness depth should be adequate. Regrind is $75. vs $400. for new stick. Will use "Manton" made-to-length, push rods, to get correct lifter preload. Thanks,ateam:thumbup:
Click to expand...

Here are the 6.1 cam spec's.
 

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hemidup said:
Here are the 6.1 cam spec's.
Click to expand...
Thanks "Hemidup", very helpfull. I've heard,"no notching allowed", for stock pistons. I haven't clay checked yet, but would like more lift and tighter lobe centers, with stock pistons. ateam:cheers:
 
ateam said:
Thanks "Hemidup", very helpfull. I've heard,"no notching allowed", for stock pistons. I haven't clay checked yet, but would like more lift and tighter lobe centers, with stock pistons. ateam:cheers:
Click to expand...

Yeah, you don't want to flycut a stock piston.
 
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