Question About Roller Rockers
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New User
Joined: Jan 2005
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From: Springfield, NJ
Question About Roller Rockers
I noticed some of the manufacturers offer pedestal mount roller rockers in a set of 8 1.6 ratio and 8 1.7 ratio. I was thinking of buying these for my '96 F250 with a 351W and using the 1.7s on the exhaust side to help the exhaust side flow a little better - in essence - turn the factory cam into a dual pattern in terms of lift using rocker ratios. Is this going to help at all? Will it cause any problems with the electronics/emissions and make the motor run crappy? I plan on installing shorty headers and a cat back system as well.
Thanks for any help. I really have no experience with modifying a fuel injected car. I've always dealth with carburetors in the past!
Ted
Thanks for any help. I really have no experience with modifying a fuel injected car. I've always dealth with carburetors in the past!
Ted
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This should cause no problems whatsoever. The rocker ratio does not change cam duration or timing, only valve lift, opening, and closing rates. The computer will not know anything has been changed. Your E7(factory) heads have valve springs which are fine for up to .500 lift at the valve, if kept under 6000 RPM. The stock cam with 1.7's will not surpass this. If you go with an aftermarket cam in the future you may need different springs. The change in ratio alone would not make a noticable difference. However, if you go with headers and a free flowing exhaust, you should enjoy slightly more power and gas mileage as well. Let us know the results. Cheers.
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Joined: Jun 2005
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From: Manitoba Canada
I did that swap, but I installed the 1.7:1 on both intake and exhaust. WORD OF NOTE** the push rods ARE longer when using the Crane (made for ford) aluminum roller rockers. They are longer by ALMOST 1/8 of an inch. I found this out after fighting with mine for quite some time. As for the camshaft, as was said earlier, you should have no clearance problems. Myself, I did a cam swap and did the springs too. If your going to go that far and do the springs also, there ARE some made that do not require any machine work (beehive style) but if your gonna buzz this on a regular basis... don't cheep out. Take the heads of, get the necessary machine work done and know that things will stay together. As far as how MUCH cam you can have... well, there is a limit. I went with a Crane cam (pt#444211) that had an advertised lift of.530" @ the valve with the factory 1.6:1 ratio rockers and had no interfearance problems while running the 1.7:1 rollers putting it at a respective .563".
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New User
Joined: Jan 2005
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From: Springfield, NJ
Rocker Ratios and Cam
Tinscrew,
Thanks for the reply. Do you happen to know the lift or any other specs on the stock '96 roller cam in a 351W? I know the headers and cat back will not increase my emissions, but would the tiny bit of lift increase on the exh. side with 1.7 rockers cause any issues when I have to go get my emissions checked for NJ State inspection? Thanks again. Your response is appreciated.
-Ted
Thanks for the reply. Do you happen to know the lift or any other specs on the stock '96 roller cam in a 351W? I know the headers and cat back will not increase my emissions, but would the tiny bit of lift increase on the exh. side with 1.7 rockers cause any issues when I have to go get my emissions checked for NJ State inspection? Thanks again. Your response is appreciated.
-Ted
Originally Posted by Twinscrew
This should cause no problems whatsoever. The rocker ratio does not change cam duration or timing, only valve lift, opening, and closing rates. The computer will not know anything has been changed. Your E7(factory) heads have valve springs which are fine for up to .500 lift at the valve, if kept under 6000 RPM. The stock cam with 1.7's will not surpass this. If you go with an aftermarket cam in the future you may need different springs. The change in ratio alone would not make a noticable difference. However, if you go with headers and a free flowing exhaust, you should enjoy slightly more power and gas mileage as well. Let us know the results. Cheers.
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New User
Joined: Jan 2005
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From: Springfield, NJ
Crane Made-for-Ford Rockers
F150 Hybrid,
So the stock roller rockers on '93 Cobras made by crane for Ford require a longer pushrod? Did not know that. Thanks for the heads up! Is this the case with all crane pedestal mount roller rockers? Also, are you running the factory Speed Density injection as well? Thanks again for the info.
Ted
So the stock roller rockers on '93 Cobras made by crane for Ford require a longer pushrod? Did not know that. Thanks for the heads up! Is this the case with all crane pedestal mount roller rockers? Also, are you running the factory Speed Density injection as well? Thanks again for the info.
Ted
Originally Posted by F150 hybred
I did that swap, but I installed the 1.7:1 on both intake and exhaust. WORD OF NOTE** the push rods ARE longer when using the Crane (made for ford) aluminum roller rockers. They are longer by ALMOST 1/8 of an inch. I found this out after fighting with mine for quite some time. As for the camshaft, as was said earlier, you should have no clearance problems. Myself, I did a cam swap and did the springs too. If your going to go that far and do the springs also, there ARE some made that do not require any machine work (beehive style) but if your gonna buzz this on a regular basis... don't cheep out. Take the heads of, get the necessary machine work done and know that things will stay together. As far as how MUCH cam you can have... well, there is a limit. I went with a Crane cam (pt#444211) that had an advertised lift of.530" @ the valve with the factory 1.6:1 ratio rockers and had no interfearance problems while running the 1.7:1 rollers putting it at a respective .563".
Hotshot
Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
if you go thru the trouble of those exhaust mods also consider a bassani Y pipe as well otherwise you wont see much of a gain. the stock Y pipe on our rigs is a major bottleneck
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Joined: Jan 2004
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From: Troy,NY
Originally Posted by TeddyY
F150 Hybrid,
So the stock roller rockers on '93 Cobras made by crane for Ford require a longer pushrod? Did not know that. Thanks for the heads up! Is this the case with all crane pedestal mount roller rockers? Also, are you running the factory Speed Density injection as well? Thanks again for the info.
Ted
So the stock roller rockers on '93 Cobras made by crane for Ford require a longer pushrod? Did not know that. Thanks for the heads up! Is this the case with all crane pedestal mount roller rockers? Also, are you running the factory Speed Density injection as well? Thanks again for the info.
Ted
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Senior User
Joined: Jun 2005
Posts: 103
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From: Manitoba Canada
I don't know the lift and duration for that cam, but the push rods are different length between roller lifter and conventional (flat tappet) lifters. As was noted later on, you CAN run the roller 1.7:1 roller rockers without changing pushrods... but there is then no pre load on your lifter. Using the correct length pushrods will make a difference. As far as being CARB approved, the "crane" 1.7:1 roller rocker arms do come with an EO number! So they are emissions compliant! if you do things rite, there will be a difference in both your total output and the quality. You gotta remember...rollers produce less friction...so even if you keep the same ratio, you will gain SOME power...however small the increase.
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New User
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From: Springfield, NJ
Lifter Preload
F150 Hybred,
I was reading in a book that covered through '94 that there must be a certain clearance between the rocker arm and valve head to get the right preload on the hydraulic lifter. According to the manual, there should be a clearance between .096 -.146 inches. Otherwise, different length pushrods are to be used to get the correct clearance with the lifter collapsed and the piston of the cylinder being checked at TDC. The manual shows in a picture to use some tool to ensure that the lifter is totally collapsed, I believe. It looks like a lever to pull the rocker arm back to collapse the lifter. Since I am doing a valve job, the valves will sit slightly higher up in the head. This, however, will probably yield a tiny change in where the valve sits in the head.
If I run 1.6 roller rockers, will I have to check all of this? Please note that my engine is a roller motor, so I don't know if these specs from this book apply.
Thanks,
Ted
I was reading in a book that covered through '94 that there must be a certain clearance between the rocker arm and valve head to get the right preload on the hydraulic lifter. According to the manual, there should be a clearance between .096 -.146 inches. Otherwise, different length pushrods are to be used to get the correct clearance with the lifter collapsed and the piston of the cylinder being checked at TDC. The manual shows in a picture to use some tool to ensure that the lifter is totally collapsed, I believe. It looks like a lever to pull the rocker arm back to collapse the lifter. Since I am doing a valve job, the valves will sit slightly higher up in the head. This, however, will probably yield a tiny change in where the valve sits in the head.
If I run 1.6 roller rockers, will I have to check all of this? Please note that my engine is a roller motor, so I don't know if these specs from this book apply.
Thanks,
Ted
Originally Posted by F150 hybred
I don't know the lift and duration for that cam, but the push rods are different length between roller lifter and conventional (flat tappet) lifters. As was noted later on, you CAN run the roller 1.7:1 roller rockers without changing pushrods... but there is then no pre load on your lifter. Using the correct length pushrods will make a difference. As far as being CARB approved, the "crane" 1.7:1 roller rocker arms do come with an EO number! So they are emissions compliant! if you do things rite, there will be a difference in both your total output and the quality. You gotta remember...rollers produce less friction...so even if you keep the same ratio, you will gain SOME power...however small the increase.
Elder User
Joined: Jan 2004
Posts: 819
Likes: 0
From: Troy,NY
Originally Posted by F150 hybred
As was noted later on, you CAN run the roller 1.7:1 roller rockers without changing pushrods... but there is then no pre load on your lifter. Using the correct length pushrods will make a difference. As far as being CARB approved, the "crane" 1.7:1 roller rocker arms do come with an EO number! So they are emissions compliant! if you do things rite, there will be a difference in both your total output and the quality. You gotta remember...rollers produce less friction...so even if you keep the same ratio, you will gain SOME power...however small the increase.
Maybe you are running guide plates and raised seated height of the rockers?
Elder User
Joined: Jan 2004
Posts: 819
Likes: 0
From: Troy,NY
Originally Posted by TeddyY
F150 Hybred,
I was reading in a book that covered through '94 that there must be a certain clearance between the rocker arm and valve head to get the right preload on the hydraulic lifter. According to the manual, there should be a clearance between .096 -.146 inches. Otherwise, different length pushrods are to be used to get the correct clearance with the lifter collapsed and the piston of the cylinder being checked at TDC. The manual shows in a picture to use some tool to ensure that the lifter is totally collapsed, I believe. It looks like a lever to pull the rocker arm back to collapse the lifter. Since I am doing a valve job, the valves will sit slightly higher up in the head. This, however, will probably yield a tiny change in where the valve sits in the head.
If I run 1.6 roller rockers, will I have to check all of this? Please note that my engine is a roller motor, so I don't know if these specs from this book apply.
Thanks,
Ted
I was reading in a book that covered through '94 that there must be a certain clearance between the rocker arm and valve head to get the right preload on the hydraulic lifter. According to the manual, there should be a clearance between .096 -.146 inches. Otherwise, different length pushrods are to be used to get the correct clearance with the lifter collapsed and the piston of the cylinder being checked at TDC. The manual shows in a picture to use some tool to ensure that the lifter is totally collapsed, I believe. It looks like a lever to pull the rocker arm back to collapse the lifter. Since I am doing a valve job, the valves will sit slightly higher up in the head. This, however, will probably yield a tiny change in where the valve sits in the head.
If I run 1.6 roller rockers, will I have to check all of this? Please note that my engine is a roller motor, so I don't know if these specs from this book apply.
Thanks,
Ted