I'm currently running the Non-adjustable Rocker arms and want to change over to Adjustable Rocker Arm. My question is the Non adjustable has a ratio of 1.73 and the Adjustable is 1.76. will I run into problems with the valves hitting the pistons or push rods rubbing passages in heads. I'm running 9.5 to1 pistons with .530 lift cam 230 duration. I'm also using the C4AE tall port heads. Thanks for any and all help
If you have non adjustable rocker arms you have hydraulic lifters and therefore you have 0 valve lash. No adjustments can be made. Installing adjustable rocker arms will not do you any good, you would have to change to solid lifters so adjustments could be made. That would also involve something to do with removing or adding a plug to the oil gallery for the lifters. Hope someone else can elaborate on that.
The adjustables will give you a tic more lift. Any cam over .550 lift you'll need em. Your almost on the edge. The plus with adjustables is not having to mess with different pushrod sizes. And sure you can use them on what you have now. You'll need new pushrods (ball/cup style) and rocker arms. You can use you current stands, springs, and hardware if in good shape. Lots of guys run them with hyd cams to avoid the pushrod issues. There is no real performance gain unless your planning a future rebuild. If the engine runs good now I'd think twice. You'll spend close to $200 on stock adj rockers alone. Another $100 for GOOD pushrods. Used sets can have worn out adjusters. The oem adjuster has a 7 ft lb breakaway torque value. Meaning it takes 7 ft lbs to turn them. Worn adjusters can be replaced but there is only a .030 replacement. And if the worn rocker arm is only a .020 fit they are a bitch to replace. They have a pitched diameter thread. Crane sells a set of adjusters with a lock nut. But the rocker arms will need to be tapped to size and slight shaving for clearnace needed for the lock nuts. Or Crane sells the whole rockers arm with adjuster and lock nut. Price is very close to a new set of oems. Isky sells the same rockers only packaged as Iskys. LOL. So plan before you spend. Been there...dun dat!!
Don't believe all that about needing adj. rockers over .550 lift. I've been running the Comp 292H for the last 5 years and it has .565 lift. I am using stock NON adj. rockers & stock length pushrods. This engine sees 6500 - 7000 rpm regularly and have had zero problems. The FE lifters have more travel than most others and are very forgiving as far as pushrod length. I do agree with FFR428 that the added expense for the little gain in ratio is not worth it. Posford.
Thanks for all the wonderful thoughts of adjustables and non adjustable rocker arms. After reading about a comp cam 292 running stock non adjustables and stock push rods, I may just have to revaluate my project.
Thanks again all
bryanscott, I really like the comp 292H I have in the truck now. With your build it would work well with either a Performer RPM , Edelbrock Streetmaster, or a Holley Street Dominator intake. I prefer the Holley Street Dominator for 2 reasons. #1 - I have one #2 - with slight modifications it will out perform the RPM even in the lower rpm ranges.( look up Jay's intake shootout on the fordfe.com forum ) the same goes for the Streetmaster. Back to the cam, the 292H also has a very rough idle & pulls good down to around 2500 rpm. This is installed straight up, I had it advanced an additional 4* when I ran it in my 360 and it would pull good down to around 1500 rpm and that's with the 360s low compression. I'm going for a Comp. 306S in the 396 for this coming season because I need a little more top end power and I already have the pushrods and the Crane roller rockers (they were a gift from my son). He also gave me a set of Edelbrock 6006 Performer RPM heads which I had 2.15 intakes installed, the bowls blended,the short turn radius done, & milled .040. Not sure if I'm gonna run the heads yet as I still have cast pistons in the 396. I'm in the process of gathering parts to put together a 428+. Hopefully that will be done by next season (2008). Tyqmonn.
Piston to valve clearance problems have little to do with total valve lift. When the valves are fully open, the pistons are nowhere near them. Valve clearance problems come into play on the overlap cycle of the engine, at the end of the exhaust stoke when the exhaust valve is closing and the intake valve is starting to open. Lobe center plays a significant role here. A cam ground on 106 to 108 degree lobe centers put the valves more in the way of the pistons while 110 to 112 tend to keep the valves away. The use of 1.76 Rockers will not have any adverse effect on piston to valve clearance issues, but it is always a good idea to check.
Old Age and Treachery Will Overcome Youth and Skill Any Time
1965 AC Cobra
1967 410 HP 427 Fairlane
1994 Taurus SHO
1964 Ford SS/N NHRA National Record Holder 12.03 Absolutely HATED by the Chevrolet and Mopar crowd.
1964 SS/X Custom 500 Absolutely HATED by the Chevrolet crowd.
Bill H, that's a pretty impressive list of cars you've had. And the one you have now is no slouch either!! LOL Tell me more about your Cobra....427 or 428? Street or comp? or S/C? Did you buy the car new? I'd love to hear more about your cars.
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