Change to 1.8 rocker arms, what’s the increase in lift?
06-20-2006 | 03:06 PM
#1
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From: Omaha, Nebraska. Boat on the Mighty Mo! Longest river in the USA!
Change to 1.8 rocker arms, what’s the increase in lift?
This is a carry over question from my previous thread http://www.offshoreonly.com/forums/s...d.php?t=132833
If I change the intake rocker arms to a 1.8 ratio how much will the lift increase?
I want to make sure I do not have any coil bind. When I measured the valve to piston clearance there was plenty of room.
The cam is Comp XM 270
Intake 226 and .544
Exhaust 236 and .547
If I change the intake rocker arms to a 1.8 ratio how much will the lift increase?
I want to make sure I do not have any coil bind. When I measured the valve to piston clearance there was plenty of room.
The cam is Comp XM 270
Intake 226 and .544
Exhaust 236 and .547
Last edited by 1BIGJIM; 06-20-2006 at 03:09 PM.
06-20-2006 | 03:23 PM
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From: Omaha, Nebraska. Boat on the Mighty Mo! Longest river in the USA!
Re: Change to 1.8 rocker arms, what’s the increase in lift?
Chris,
I assume I should be safe with binding the springs?
I will try to check when I install the first one. I just dont need any problems at the start of the summer
I assume I should be safe with binding the springs?
I will try to check when I install the first one. I just dont need any problems at the start of the summer
06-20-2006 | 03:47 PM
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From: On A Dirt Floor
Re: Change to 1.8 rocker arms, what’s the increase in lift?
When changing ratios on even the BBC, make sure to also check for pushrod intereference on the cylinder heads. It sometimes happens. If not checked and there is interference, the pushrod will be at wrong angle since rubbing on head, and have intereference at the guide plate and put rocker at slightly incorrect angle. Guidplate and/or pushrod will break.
Never bolt something on without checking for all or any issue.
Never bolt something on without checking for all or any issue.
06-21-2006 | 01:11 AM
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Rob
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From: Ms
Re: Change to 1.8 rocker arms, what’s the increase in lift?
I put some 1.8's on a semi stock 365 mag.Guides went bad, I think thats what wore out the guides ??? The extra side load on stock guides? not 100% sure, was turning it 5400 though 
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06-21-2006 | 05:20 AM
#7
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From: Kissimmee, Florida
Re: Change to 1.8 rocker arms, what’s the increase in lift?
When increasing lift with higher ratio rockers you not only have to worry about coil bind, but whether the retainer will clear the top of the valve guide. Some heads, like the SBC Vortec, are capable of a limited amount of lift with out further machining.
You also need to check the rocker geometry to be sure they aren't putting excessive side loads on the valve stem which will accelerate guide wear and check pushrod clearance through the head.
You also need to check the rocker geometry to be sure they aren't putting excessive side loads on the valve stem which will accelerate guide wear and check pushrod clearance through the head.
06-21-2006 | 07:56 AM
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Rob
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From: Ms
Re: Change to 1.8 rocker arms, what’s the increase in lift?
I agree iggy 
I also saw were I needed a longer rocker arm stud when I did it .
Also ck the guild plates in the u shaped part see if the push rod is bottoming out in them.I had bought some cheap ones and the exhaust on # 1 and 8 was sidelaoding and broke ,I went back with the GM ones and clearance a few .
Ive see one person put to long of a intake bolt and hit the push rod before
There's a pick on this thread on the rocker arm geometry contact patch on the top of a vale for an idear
http://www.offshoreonly.com/forums/s...t=500efi+build
I also saw were I needed a longer rocker arm stud when I did it .
Also ck the guild plates in the u shaped part see if the push rod is bottoming out in them.I had bought some cheap ones and the exhaust on # 1 and 8 was sidelaoding and broke ,I went back with the GM ones and clearance a few .
Ive see one person put to long of a intake bolt and hit the push rod before
There's a pick on this thread on the rocker arm geometry contact patch on the top of a vale for an idear
http://www.offshoreonly.com/forums/s...t=500efi+build
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The Only Time You Have To Much Ammo Is When Your Swimming Or On Fire.
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The Only Time You Have To Much Ammo Is When Your Swimming Or On Fire.
06-21-2006 | 09:44 AM
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From: Omaha, Nebraska. Boat on the Mighty Mo! Longest river in the USA!
Re: Change to 1.8 rocker arms, what’s the increase in lift?
These are Edelbrock heads. I would check to make sure the retainer is not hitting the guide. Thats simple.
Also checking guide plates simple.
Coil bind. I cant believe increasing the lift .025 would bind the spring? I had the machine shop setup the heads with matching comp springs and to there recommend hieght and pressure. I hope the tollerances are not that tight
Also checking guide plates simple.
Coil bind. I cant believe increasing the lift .025 would bind the spring? I had the machine shop setup the heads with matching comp springs and to there recommend hieght and pressure. I hope the tollerances are not that tight
