1.7 Rockers on a SBC? Will BBC rockers work on a SBC?
#1
Melting Slicks
Thread Starter
1.7 Rockers on a SBC? Will BBC rockers work on a SBC?
Pretty much all in the title. I want to upgrade to some 1.7 full roller rockers. Will the 1.7 rockers cause any kind of pushrod clearance issues? If so, how about the 1.65 rockers? I am using guideplates if that matters.
Also, 1.7 rockers for a SB are hard to come by, and the ones that are out there are pricey. So stupid question, would it be possible to use BBC rockers on a SBC? If so what needs to be done?
*I just read on another forum that SBF and BBF rockers will work without modification on a SBC? Can anyone confirm or deny this?
Also, 1.7 rockers for a SB are hard to come by, and the ones that are out there are pricey. So stupid question, would it be possible to use BBC rockers on a SBC? If so what needs to be done?
*I just read on another forum that SBF and BBF rockers will work without modification on a SBC? Can anyone confirm or deny this?
Last edited by enkeivette; 10-17-2007 at 07:32 AM.
#2
Drifting
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why would you want to do this? all you are doing is asking for all kinds of trouble. like: spring bind or broken springs, bent or broken pushrods, piston to valve clearance.
put a bigger cam in it!
vc
put a bigger cam in it!
vc
#4
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St. Jude Donor '11, '17
You need to know your current lift, cam specs, spring rates, piston to valve clearance, etc. before you even contemplate this. Once you know all the specs you will then be able to calculate whether or not you can move to 1.7's. BeeJay knows what he has & that's why he can run 1.65's. As far as running BB or Ford rockers you'll need to know the physical specs of each (shaft size, overall length, trunnion to end lengths). I don't know the answers & I'd check for myself before outright believing someones opinion, especially concerning my own engine.
#5
Pretty much all in the title. I want to upgrade to some 1.7 full roller rockers. Will the 1.7 rockers cause any kind of pushrod clearance issues? If so, how about the 1.65 rockers? I am using guideplates if that matters.
Also, 1.7 rockers for a SB are hard to come by, and the ones that are out there are pricey. So stupid question, would it be possible to use BBC rockers on a SBC? If so what needs to be done?
*I just read on another forum that SBF and BBF rockers will work without modification on a SBC? Can anyone confirm or deny this?
Also, 1.7 rockers for a SB are hard to come by, and the ones that are out there are pricey. So stupid question, would it be possible to use BBC rockers on a SBC? If so what needs to be done?
*I just read on another forum that SBF and BBF rockers will work without modification on a SBC? Can anyone confirm or deny this?
tip is longer then a small block rocker they will not work.
Last edited by Little Mouse; 10-17-2007 at 01:07 PM.
#6
Team Owner
Bigger cam is not always an option. Bigger ratio rocker arms is. I use CC 1.7 steel roller rocker with 7/16th rocker studs
When I looked through the lobe profiles of racing solid lifter lobes you have to use 1.7 or higher to exceed .700 lift.
IMO - ratios above 1.6 are not recommended for any kind of H cam. The higher ratio multiplies the pressure on the h-push rod plunger. also the lower pound springs rates are not made for very high lifts. Valve float becomes an issue
Solid cams I would say go for it!
When I looked through the lobe profiles of racing solid lifter lobes you have to use 1.7 or higher to exceed .700 lift.
IMO - ratios above 1.6 are not recommended for any kind of H cam. The higher ratio multiplies the pressure on the h-push rod plunger. also the lower pound springs rates are not made for very high lifts. Valve float becomes an issue
Solid cams I would say go for it!
#7
Burning Brakes
We run 1.7's on a solid lift cam to get to 0.740 lift and don't have any problems but again; lots of expensive parts and an engine that was built that way.. You need to do a lot of math before you make the jump to a bigger ratio.
#8
Melting Slicks
Thread Starter
Wow, thanks moms for worrying about me. Don't worry about whether or not my springs will handle the lift or whether I'll have piston to valve clearance issues. Obviously I will measure that when I pull of the heads before I buy the rockers.
My question was:
Will the 1.7 rockers cause any kind of pushrod clearance issues? And will SBF or BBF rockers will work without modification on a SBC?
gkull, thanks for the warning. What do you mean pushrod plunger? Are you talking about the lifter or the pushrod? My pushrods are one piece chromeoly, do you think that they would be able to handle the added stress?
My question was:
Will the 1.7 rockers cause any kind of pushrod clearance issues? And will SBF or BBF rockers will work without modification on a SBC?
gkull, thanks for the warning. What do you mean pushrod plunger? Are you talking about the lifter or the pushrod? My pushrods are one piece chromeoly, do you think that they would be able to handle the added stress?
Last edited by enkeivette; 10-17-2007 at 04:48 PM.
#9
Drifting
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Wow, thanks moms for worrying about me. Don't worry about whether or not my springs will handle the lift or whether I'll have piston to valve clearance issues. Obviously I will measure that when I pull of the heads before I buy the rockers.
how do you measure piston to valve clearance after you pull the heads off? THIS IS WHY WE ARE TALKING TO YOU LIKE YOUR MOM!
hey wtf just throw them on and fire it up and see what happens!
vc
how do you measure piston to valve clearance after you pull the heads off? THIS IS WHY WE ARE TALKING TO YOU LIKE YOUR MOM!
hey wtf just throw them on and fire it up and see what happens!
vc
#10
Team Owner
My question was:
Will the 1.7 rockers cause any kind of pushrod clearance issues? And will SBF or BBF rockers will work without modification on a SBC?
gkull, thanks for the warning. What do you mean pushrod plunger? Are you talking about the lifter or the pushrod? My pushrods are one piece chromeoly, do you think that they would be able to handle the added stress?
Plungeron the h-roller or h-flat lifter. Oil pressure brings them up to being nearly solid in function. But they do have a max valve spring limitation. All H-lifters have a max valve spring weight of @ 145 pounds. About that limit you start to depress the "Plunger" and it will result in loss of lift.
In effect, higher ratio rockers multiply the felt spring pressure on the pushrod and lifter. If you look at the comp Cams graph on a spring it might be made to 440 inch pounds. You only have .500 inches of lift cam. you start with 120# seat pressure and add 220pounds for an open pressure of 340# open. Now add 1.7 ratio rockers and the the lift goes to .600. That adds 44 pounds to 384 pounds of open pressure. At some point it will exceed the lifters internal construction and you get loss of lift or damage to the lifters and push rods.
most
#11
Melting Slicks
Thread Starter
Okay, thank gkull. So I need to find some info about my lifters then...
Well, first you pull the heads off, then you put a piece of clay on top of the piston. Then you torque the head on, rotate the engine, pull the head off again, cut the clay, and measure the thickness of it. That would be your piston to valve clearance.
A better question would be: How do you measure piston to valve clearance before you pull the heads off?
A better question would be: How do you measure piston to valve clearance before you pull the heads off?
#12
Team Owner
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Bigjim54 (10-24-2022)
#13
Melting Slicks
Thread Starter
Regardless I will be pulling the heads off, to give you guys some background from my other thread: I need to mill my heads a bunch to up the compression.
Last edited by enkeivette; 10-18-2007 at 04:10 PM.
#14
Drifting
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#15
Team Owner
I borrowed one from a shop years ago (fiber bore scope)when i was doing a port match job on my single plane intake to the head port.
#16
Burning Brakes
I had interest in this years ago & was told that sbc geometry wouldn't be good w/ 1.7 rockers. Any thoughts?
#17
Team Owner
For 10 years and 100,000 miles I used 1.6 roller tips with near .600 lift on 186 and 292 casting heads
#18
Safety Car
tORQVETTE, if your engine is a mild build under 10 to 1 comp, less than 460 lift ,overlap is civil,ect... 1.6 would be OK, 1.7 sometimes run into problems with the pushrod guides wearing,studs pulling out, spring and valve damage. Also keep in mind if your heads aren't ported your gains will be small. On stock engines I've played around with 1.6 rockers on the exhaust side only. The engine revved-up pretty good.
#19
Le Mans Master
NO! BBC or Ford rockers wont work on a SB Chevy head without modifications. Valetrain Geometry is all screwed up by going to high ratio rocker arms. Years ago a guy in New Jersey mounted BBC rockers onto a small block head, you may have heard of him: Dan Jessel as in Jessel rocker systems, to put the BBC rockers on he had to plug exisitng rocker holes and move them back towards the intake manifold, then the valve covers wouldn't fit then something else screwed up then after years of working on a system, he made a set of shaft rockers for a SB Chevy. Thing have been good for Dan Jessel ever since although I am putting on some Larry Torres shaft rockers on my new motor (T&D rockers.) You can run a 1.65 ratio rocker with the stock stud location but, if you ever watch the geometry of a stud mounted high ratio system you would be very afraid for the long term reliability of any system. Get the right cam profile and run 1.5 or 1.6:1 rocker arms on your Vette.