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Comp Roller Lifters Problem |
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SKeown
AMC Addicted Joined: Jul/30/2009 Location: Texas Status: Offline Points: 3085 |
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I just went and confirmed what my measurements told me. What I did was using a dial indicator I brought my #1 EX lobe to full lift, removed the front galley plug, inserted the lifters and using a pin light I could see that the very upper tips of the cutouts are barely exposed. Now keep in mine that's at the very max lift only and this engine crosses the line at 7600 rpm.
4015spdjavAMX is running much more lift than either of us and maintains good oil pressure. Even though his lifters have to be bleeding more oil than mine, you'rs shouldn't have any problem.
SKeown
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73XBGT
AMC Apprentice Joined: Jan/28/2010 Location: Huntsville, AL Status: Offline Points: 123 |
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Skeown, what is your base circle diameter??
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73XBGT
AMC Apprentice Joined: Jan/28/2010 Location: Huntsville, AL Status: Offline Points: 123 |
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[/QUOTE]
For what it is worth, my block was a '72 401 block, but I'm not aware of any differences between that and the '70 390 block. [/QUOTE]
Do you know what your base circle measured?
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SKeown
AMC Addicted Joined: Jul/30/2009 Location: Texas Status: Offline Points: 3085 |
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I had to get the cam out, anyway, the base circle is 1.175". I'm going to have it re-ground, but there's no way it will ever raise the lifters higher than now.
SKeown
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amx39068
Supporter of TheAMCForum Joined: Feb/21/2008 Location: Arizona Status: Offline Points: 11576 |
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When I was using the faulty Comp solid rollers I had plenty of oil pressure at the upper rev range but dangerously low at the lower RPM ranges, particularly at idle when it would drop down to 5 and flicker the pressure dash light when the oil got hot even with Castrol 20-50. It ran fine and with no problems on the dyno right up to 6800 RPM when it was fresh and new and had multiple pulls using different intake and carb combos to find the max output that was streetable.
In that I was planning to run on bothe the street and strip, it didn't matter what the high speed oil pressure was. The low speed oil pressure was a starved bearing waiting to happen.
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Dan Curtis-Owner and CEO AZ AMC Restorations; Facebook: https://www.facebook.com/amcmusclecars/ & Curtis Real Estate Development
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4015spdJavAMX
Supporter of TheAMCForum Joined: Nov/18/2008 Location: Northern CA Status: Offline Points: 250 |
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Dan:
Your low idle oil pressure sounds like a separate problem, such as the lifters didn't fit the bores well, or they were undersize (which could be Comps fault). You are talking about the older lifters anyway, the new ones are clearly different. Did your problem cure itself immediately when you went to a different lifter? Did you check the lifter size relative to the lifter bore? The fit is critical. It seems like I can't be the only one that is running the new Comp lifters. Has anyone else seen any issues? I know Barry Allen thought they were fine, and would suspect he continues to use them, but he may bush the lifter bores..
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1972 Jav-AMX 401 4-speed....T56 next?
1970 AMX 390 auto, now 5-speed 1970 AMX 390 4-speed, stock |
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73XBGT
AMC Apprentice Joined: Jan/28/2010 Location: Huntsville, AL Status: Offline Points: 123 |
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I took measurements and had these results:
From the bottom of the oil galley that runs through the lifter bores (soonest to be uncovered from the bottom) to the (spot faced) top of the lifter bores is 1.180". The Comp lifters measure 1.580" from the highest point in the wheel cutout (soonest to intersect the oil galley) to the top of the lifter body. My cam's exhaust lobe lift is .385", and that puts the top of the lifter body .430" above the top of the lifter boss spotface. Based on those measurements the highest part of the wheel cutout is exposed to the oil galley by .030 at the moment of full lift on the new Comp lifters. That means that .355" lobe lift is max to not be uncovered at all (at least in my block), or a max valve lift of .568" using 1.6 rocker ratio plus lash.
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SKeown
AMC Addicted Joined: Jul/30/2009 Location: Texas Status: Offline Points: 3085 |
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Based on that, the 70 390 either had a larger diameter galley or it was placed lower in the block? There appears to be .035 difference there, but with a .025 lesser lift you should be seeing only .015 exposure, that's provided my measurements were correct. I was carefull, but it's difficult to be exact in that area with callipers. I can't double check mine, it's all appart now. Do the view test through the front lifter galley plug hole, make sure everything is oil free so you can see clearly. In any event, javAMX is exposing more than either of us.
If after real carefull re-examination, you're mule is still scared, you might want to have the cam re-ground to produce less lift. .030 less lift with the same duration is something you probably wouldn't notice performance wise. You could allways get it back to over .6" lift with 1.7 rockers anyway. I ran 11.30s in a 3200# stick AMX with a .57" lift flat tapit cam.
I'm sure you've noticed by now that creating performance AMC engines is a real challenge, you have all these little stumbling blocks along the way. Once they are together and setup right they work pretty darn good though.
You might want to put it together and run the oil pump with a 1/2" drive drill while monitering the oil pressure and turning the engine. That can be done on the stand, if you don't like you're findings, have the cam ground then. I run .0025 rods and .003 mains in my street/strip AMX. You definately need to find a good crank grinder though, those guys are supposed to work in the .0001". I get exact rod & main bearing measurements and specify exactly what I want in the finished crank.
SKeown
Edited by SKeown - Jun/16/2010 at 10:20pm |
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amx39068
Supporter of TheAMCForum Joined: Feb/21/2008 Location: Arizona Status: Offline Points: 11576 |
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The issue with Comp that I see is that they are pretty much GM, Ford and Mopar knowledgable but are not at all up to speed with AMC so I finally concluded that I would not use them again for a roller. I will still use them for hydro cams until I use up all the NOS Comp cams I have on hand but once they are gone or if I need a another custom grind, Crower is who I will use from now on. Additionally, Crower made a set of one of 1.7s 7/16ths stud roller rockers for the hipo book engine and gave them to us basically at their cost so why on earth would I even consider anyone else?
Crower wants our AMC business, will make any cam grind, lifter or rocker we want and even volunteered to make a billet 401 crankshaft if we wanted one. They want our business, are willing to work with us and give us very competitive pricing so I encourage anyone who wants a kick as custom grind cam to take a look at them and see what they can do for you. I have heard periodic complaints about their being unreachable but Forest never has trouble hooking up with them and he has the best pricing they offer so when all else fails, contact Forest and let him work with them to get what you want.
Heck, I'll bet he'd even work with Skeown if he stopped being a grumpy old fart! Edited by amx39068 - Jun/16/2010 at 10:49pm |
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Dan Curtis-Owner and CEO AZ AMC Restorations; Facebook: https://www.facebook.com/amcmusclecars/ & Curtis Real Estate Development
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73XBGT
AMC Apprentice Joined: Jan/28/2010 Location: Huntsville, AL Status: Offline Points: 123 |
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Forest,
Can you tell us about the lifters (features, price) that you discussed with Crower today? I guess they would use a smaller diameter wheel if they are going to either shroud it or lower the eyebrow further.
My opinion - the ideal roller lifter would work with a street roller, as well as a big cam (maybe up to .500" lobe lift), and would not require bushing the lifter bores. A true .904" diameter, pressurized oiling for the shaft/bearing. Not sure about the direction of the pushrod oil feed hole (perpendicular vs. parallel to the oil passage). |
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