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Rocker Arm question
- Thread starter Nunyas
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Dr.Entropy: alright, sorry I over slept. Thanks for the info. It looks like I may be in the same situation I was in before with the rocker arms and adjusters, but with an assy that is in better overall condition. I'm thinking that I'll be saving the adjsters off of my old assy. for use at a later time.
So, maybe the PO's did have the head rebuilt on this car at some point in time, because the parts on the rocker assy. are so mismatched. I'm beginning to think that I may have or will have problems the cam/tappet/rods area that are probably as bad as the old rocker assy. because the clatter didn't go down as much as I thought it would with the rocker assy. Ah well, looks like another project to add to the list... /ubbthreads/images/graemlins/smile.gif
On a side thought for future reference, does anyone make or know of roller rockers with ballbearings instead of metal bushings for the part that rides on the shaft? Seems like you could have a lot quieter longer lasting rocker assy. that way... I can only seem to find roller rockers with bronze bushings for the part that meets the shaft...
So, maybe the PO's did have the head rebuilt on this car at some point in time, because the parts on the rocker assy. are so mismatched. I'm beginning to think that I may have or will have problems the cam/tappet/rods area that are probably as bad as the old rocker assy. because the clatter didn't go down as much as I thought it would with the rocker assy. Ah well, looks like another project to add to the list... /ubbthreads/images/graemlins/smile.gif
On a side thought for future reference, does anyone make or know of roller rockers with ballbearings instead of metal bushings for the part that rides on the shaft? Seems like you could have a lot quieter longer lasting rocker assy. that way... I can only seem to find roller rockers with bronze bushings for the part that meets the shaft...
D
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From a performance stand point, I have heard that the standard rockers have less reciprocating weight than the roller rockers and are therefore more desirable ( reference Fab-Teck www.fast-mg.com )
Also the original design does not increase what could already be a carefully calculated amount of lift. What are anyone else's thoughts on the subject?
Also the original design does not increase what could already be a carefully calculated amount of lift. What are anyone else's thoughts on the subject?
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Nunyas! N.P.!! I got tangled up in the hard top refinish. Comin' "down to th' wire" and had time to spend on that this AM. We'll discuss the tappett/pushrod/rocker issue soon.
The rockers Jeff is pointing to are (IIRC) lighter than originals, but there's STILL the oiling issue. For economy's sake the "kits" from Moss and VickieBrit are FINE for a street application. AFAIC "rocker rollers" in an otherwise streetable engine is a "braggin' rights" issue: The money would be better spent on machine work, "cc'n" the head, port matching or a good cam/lifter combo. Reciprocating mass of those rockers is a concern when you're looking to eek out the last tenths on a mill in a racing application but not much 'in the equation' with a daily driver. Reliability IS. Regarding lift, there are a few variants (higher or lower rocker centre, length from rocker centre to rod socket), but again: the original design is practical for a street engine needing to meet State and Federal emissions standards. Better to look to induction/exhaust (volumetric efficiency) for the most effective return on money and effort spent. 12 to 12.5 to 1 A/F ratio across the acceleration "spectrum" is a more practical goal in this instance. It'd require seat inserts, valves, machining, carb/carb bit$ and some test equipment, certes. But again: This is JUST the opinion of some shmuck sittin' at a keyboard!
Talk among yerselves /ubbthreads/images/graemlins/cheers.gif
The rockers Jeff is pointing to are (IIRC) lighter than originals, but there's STILL the oiling issue. For economy's sake the "kits" from Moss and VickieBrit are FINE for a street application. AFAIC "rocker rollers" in an otherwise streetable engine is a "braggin' rights" issue: The money would be better spent on machine work, "cc'n" the head, port matching or a good cam/lifter combo. Reciprocating mass of those rockers is a concern when you're looking to eek out the last tenths on a mill in a racing application but not much 'in the equation' with a daily driver. Reliability IS. Regarding lift, there are a few variants (higher or lower rocker centre, length from rocker centre to rod socket), but again: the original design is practical for a street engine needing to meet State and Federal emissions standards. Better to look to induction/exhaust (volumetric efficiency) for the most effective return on money and effort spent. 12 to 12.5 to 1 A/F ratio across the acceleration "spectrum" is a more practical goal in this instance. It'd require seat inserts, valves, machining, carb/carb bit$ and some test equipment, certes. But again: This is JUST the opinion of some shmuck sittin' at a keyboard!
Talk among yerselves /ubbthreads/images/graemlins/cheers.gif
I was merely passing on some info regarding the availability of the rockers.
However, one advantage to the rollers is more consistency in the ratios, as they are CNC'd from billet stock. They are available in stock ratios, as well as higher lifts. For my A series engines I can get them in the stock 1.3:1, 1.5:1, and 1.7:1.
Another major advantage to the rollers is decreased side loading of the valve stems, prolonging valve and guide life.
I heartily agree that they aren't really necessary for an otherwise stock street engine, and if the higher ratios are selected, there has to be a commensurate cam change involved to accomodate them. For instance, on one of my street 1098 engines, that is pretty well built to the hilt, I cammed it for the stock 1.3:1 ratio. Just for grins, I tossed on a set of 1.5 rollers, and had them on for a day and a half. I picked up about 700 RPM on top, but lost the same amount down low, rendering the thing nearly undriveable below about 2100. Not the best choice in traffic, and proving the fact that any engine build should be viewed as a total system, not a hodge podge of go fast parts tossed on piecemeal.
But, as said, unless you are chasing that last tiny percentage of power, the money spent could probably be better utilized elsewhere.
Jeff
However, one advantage to the rollers is more consistency in the ratios, as they are CNC'd from billet stock. They are available in stock ratios, as well as higher lifts. For my A series engines I can get them in the stock 1.3:1, 1.5:1, and 1.7:1.
Another major advantage to the rollers is decreased side loading of the valve stems, prolonging valve and guide life.
I heartily agree that they aren't really necessary for an otherwise stock street engine, and if the higher ratios are selected, there has to be a commensurate cam change involved to accomodate them. For instance, on one of my street 1098 engines, that is pretty well built to the hilt, I cammed it for the stock 1.3:1 ratio. Just for grins, I tossed on a set of 1.5 rollers, and had them on for a day and a half. I picked up about 700 RPM on top, but lost the same amount down low, rendering the thing nearly undriveable below about 2100. Not the best choice in traffic, and proving the fact that any engine build should be viewed as a total system, not a hodge podge of go fast parts tossed on piecemeal.
But, as said, unless you are chasing that last tiny percentage of power, the money spent could probably be better utilized elsewhere.
Jeff
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Well, update on my weekend project. Got the suspension all back together (swapped the kinping assys. and installed 550# 2" springs up front and 1" blocks out back). Then took her out for a spin prolly drove around 15 miles over various roads that I new to be the opposite of glass. My observations: The front end definitely feels "tighter". Under hard braking there is hardly any nose dive, and over moose sized speed bumps I noticed a lot less dip and rebound of the front. There's even less body roll in turns than there was before. I initially had concerns about dragging over those SUV sized speed bumps I regularly go over on my daily commute, but the test drive showed them to be a non-problem. Then again, these particular speed bumps are the massive 15MPH bumps that the rear tires are on the bump before the fronts leave it. However, I think I may need to play with tire preasures again. I noticed that the car still has understeer under hard cornering. If tire preasures doesn't correct it I'll put some serious consideration into a set of those negative camber wishbones.
On the valve clatter: Last night's noisiness might have been because the oil hadn't reached all the bits. I didn't drive it last night I only idled it til it was in the normal operating range. Today, there was noticeably less valve clatter than lastnight and before the swap. No abnormal heat in the floor pan has me confident that the rockers are adjusted properly too. /ubbthreads/images/graemlins/smile.gif
here's some before and after pics... I need to wash her now.. /ubbthreads/images/graemlins/tongue.gif
front before:
Front after:
side:
There is a small amount of rake the rear is a little higher than the front, but not a whole lot.
On the valve clatter: Last night's noisiness might have been because the oil hadn't reached all the bits. I didn't drive it last night I only idled it til it was in the normal operating range. Today, there was noticeably less valve clatter than lastnight and before the swap. No abnormal heat in the floor pan has me confident that the rockers are adjusted properly too. /ubbthreads/images/graemlins/smile.gif
here's some before and after pics... I need to wash her now.. /ubbthreads/images/graemlins/tongue.gif
front before:
Front after:
side:
There is a small amount of rake the rear is a little higher than the front, but not a whole lot.
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Glad to see there was a desired outcome! Lots'a work involved with the suspension, most of it dirty-nasty until reassembly.
With regards to the understeer: juggling tire pressures can have a fair influence and if you can "strike a balance" that way you'll be better off than goin' with longer lower arms. Bearing loads will change (increase) dramatically, tire wear as well. And as pointed out with engines as 'Systems', same thing with geometry: can't just change one bit without some "penalty" up or downstream of it. Lowering sway bar stiffness may be a better first 'compromise' for a streetable car, if TP juggling isn't enough. *Some* body roll is not necessarily a BAD THING.
Jeff? Your input here would be better than mine: More experience/track time with these issues.
With regards to the understeer: juggling tire pressures can have a fair influence and if you can "strike a balance" that way you'll be better off than goin' with longer lower arms. Bearing loads will change (increase) dramatically, tire wear as well. And as pointed out with engines as 'Systems', same thing with geometry: can't just change one bit without some "penalty" up or downstream of it. Lowering sway bar stiffness may be a better first 'compromise' for a streetable car, if TP juggling isn't enough. *Some* body roll is not necessarily a BAD THING.
Jeff? Your input here would be better than mine: More experience/track time with these issues.
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yeah, there was quite a bit of cleaning involved. The swivel axels were caked with years and years of grease dirt and what ever else car parts can find. I ended up scraping the crude off with a flat head screw driver and then dosing with mineral spirits and scraping again... for about an hour.
Nunyas, I would expect that the rake will settle out in a couple of months...mine settled about half an inch. /ubbthreads/images/graemlins/eek.gif
And for cleaning of gunked up parts, I prefer to use kerosene (parafin in UKese) instead of mineral spirits as it is cheaper and non-explosive, but should still be used outside. Grease filled keorsene is also a good accelerator to dump on that unwanted stump in your yard, let soak for few minutes and light /ubbthreads/images/graemlins/grin.gif
Bruce /ubbthreads/images/graemlins/cheers.gif
And for cleaning of gunked up parts, I prefer to use kerosene (parafin in UKese) instead of mineral spirits as it is cheaper and non-explosive, but should still be used outside. Grease filled keorsene is also a good accelerator to dump on that unwanted stump in your yard, let soak for few minutes and light /ubbthreads/images/graemlins/grin.gif
Bruce /ubbthreads/images/graemlins/cheers.gif