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fuel pump eccentric failure

2212 Views 13 Replies 8 Participants Last post by  hotbo, 
jetjunky
Hey guys, it's me again! I pulled my motor down last weekend in an attempt to understand what caused my exhaust valve to stick. No definitive answer on the valve stick issue however I did find the fuel pump eccentric worn down about .090" or so. I ran a quick fuel mech. pump on my bbc for 10mos. while B.G. warrantied my out of warranty mighty enduro elec. fuel pump:)devil and it seems the push rod killed the hyd. roller bump stick. How common is this? Do those pumps put extreeme pressures on the cam eccentric? Are you supposed to run a particular type of push rod with a hyd. cam deal? If I recall correctly the push rod was a moroso deal, tube type with I assume hardened contact end caps. The push rod looks perfect, cam not so much. Is there an oil galley passage in a Dart Big M block that could have been blocked off or something? I've got my safety glasses and dust mask on so, commence the flingin. lol
Thanks,
Warren
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Jetaholic
jetjunky said:
Hey guys, it's me again! I pulled my motor down last weekend in an attempt to understand what caused my exhaust valve to stick. No definitive answer on the valve stick issue however I did find the fuel pump eccentric worn down about .090" or so. I ran a quick fuel mech. pump on my bbc for 10mos. while B.G. warrantied my out of warranty mighty enduro elec. fuel pump:)devil and it seems the push rod killed the hyd. roller bump stick. How common is this? Do those pumps put extreeme pressures on the cam eccentric? Are you supposed to run a particular type of push rod with a hyd. cam deal? If I recall correctly the push rod was a moroso deal, tube type with I assume hardened contact end caps. The push rod looks perfect, cam not so much. Is there an oil galley passage in a Dart Big M block that could have been blocked off or something? I've got my safety glasses and dust mask on so, commence the flingin. lol
Thanks,
Warren
Click to expand...
Yeah I believe when you go roller cam you're supposed to run an electric fuel pump. :D

Just kidding...actually (and I'm no expert) I believe they make a fuel pump pushrod that has a bronze tip on the cam lobe/eccentric end specifically for roller cam dealios. I know with a roller cam you're supposed to run a bronze distributor gear, and I've seen fuel pump push rods with a bronze tip on them, so I'm putting 2 and 2 together on this.
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obnoxious001
That's correct,, roller cam needs either bronze tip, or now composite fuel pump pushrod, same as the distributor gear unless the cam maker specifies otherwise, or if you have a two piece cam with the cast iron gear.
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jetjunky
Thanks guys for cluing me in and helping me to be a little less ignorant. I guess from now on before I do anything I'll call the part mfg's. involved so I don't f shit up some more. It seems reasonable that maybe metal from this problem or from the contact between the cam gear and oil galley plugs may have caused/contributed to the valve stick issue. So bronze being a softer and "self lubricating" or "sacrificial" material is o.k. to have floating around the motor? If there is so much pressure on the push rod and cam as to wear a somewhat hardened cam surface that much, wouldn't bronze wear out even faster? I guess I'll have to call my metalurgist client to gain more knowledge here, and comp cams of course.

Thanks,
que no sabe
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Jetaholic
jetjunky said:
Thanks guys for cluing me in and helping me to be a little less ignorant. I guess from now on before I do anything I'll call the part mfg's. involved so I don't f shit up some more. It seems reasonable that maybe metal from this problem or from the contact between the cam gear and oil galley plugs may have caused/contributed to the valve stick issue. So bronze being a softer and "self lubricating" or "sacrificial" material is o.k. to have floating around the motor? If there is so much pressure on the push rod and cam as to wear a somewhat hardened cam surface that much, wouldn't bronze wear out even faster? I guess I'll have to call my metalurgist client to gain more knowledge here, and comp cams of course.

Thanks,
que no sabe
Click to expand...
From what I've been taught, using bronze on a roller cam is more sacrificial than anything. You want the dizzy gear and the fuel pump pushrod tip to be the softer metal so that if anything wears it will be one of these two parts and not the cam itself.

As far as whether or not you want bronze flakes running around in your motor, the builders and machinists can answer this question much better than I can.
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Outlaw
jetjunky said:
Thanks guys for cluing me in and helping me to be a little less ignorant. I guess from now on before I do anything I'll call the part mfg's. involved so I don't f shit up some more. It seems reasonable that maybe metal from this problem or from the contact between the cam gear and oil galley plugs may have caused/contributed to the valve stick issue. So bronze being a softer and "self lubricating" or "sacrificial" material is o.k. to have floating around the motor? If there is so much pressure on the push rod and cam as to wear a somewhat hardened cam surface that much, wouldn't bronze wear out even faster? I guess I'll have to call my metalurgist client to gain more knowledge here, and comp cams of course.

Thanks,
que no sabe
Click to expand...
if your cam is toast, you can get a roller cam made with a steel gear
so don't have to run a bronze gear, I'm not a fan of metal particles
floating around in an engine either.
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jetjunky
I guess it's just absolutely unreasonable for the cam mfg to harden the eccentric so you can safely run a standard push rod. I guess the extra costs involved would absorb to much profit not to mention the additional sales from the errors of people like me. Don't we pay MORE for roller cams, shouldn't we get MORE for that additional expense than just a better profile with ramps that set the valve down a little softer yet still bounce the valves off the seats? Would we not pay $360.00 for a roller cam that is completely hardened if we're already paying say $340.00 and then have to go spend another $30.00+ on some special push rod and then hope that the softer material in that part doesn't wear or fail and junk yet another motor? How is it the cam mfgs. can forge, grind, harden and sell at a profit a flat tappet cam that can handle those wear loads at $80.00-$180.00 yet not build rollers with at least that same hardened surface at approximately twice the price? I guess that's just the NEW american way.:|err:)violent This is rediculous!
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jetjunky
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photos

Cam wear photos for cstraub.

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R
My understanding is the roller cams are made of a different steel than flat tappet cams. Something to do with incompatibility between the two metals when it comes to roller cams. Maybe some one that knows for sure will chime in.

Tim
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Jetaholic
River Rat 005 said:
My understanding is the roller cams are made of a different steel than flat tappet cams. Something to do with incompatibility between the two metals when it comes to roller cams. Maybe some one that knows for sure will chime in.

Tim
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Flat tappet cams are made from ductile iron, whereas roller cams are typically made from billet steel. On a roller cam, you run a bronze tipped fuel pump pushrod and a bronze dizzy gear...plain and simple. I just don't see what the issue is other than someone not posessing the knowledge required to properly install and set up a roller cam. Every component is designed to be compatible with certain parts while not being compatible with others. I understand how difficult it is to not have knowledge and not even know to ask for it. But unfortunately some things have to be learned the hard way. This is known as experience.
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S
Jetaholic said:
Flat tappet cams are made from ductile iron, whereas roller cams are typically made from billet steel. On a roller cam, you run a bronze tipped fuel pump pushrod and a bronze dizzy gear...plain and simple. I just don't see what the issue is other than someone not posessing the knowledge required to properly install and set up a roller cam. Every component is designed to be compatible with certain parts while not being compatible with others. I understand how difficult it is to not have knowledge and not even know to ask for it. But unfortunately some things have to be learned the hard way. This is known as experience.
Click to expand...
Not all rollers are billet (as in the above photos) and there are different steel alloys as well. I believe there are steel roller cores that you can run a stock (or steel) fuel pump rod on, and you can run a melonite gear on a steel core. You can also get a steel roller core with an iron gear. In some cases there are even steel flat tappet cores for certain class rules.
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Jetaholic
steelcomp said:
Not all rollers are billet (as in the above photos) and there are different steel alloys as well. I believe there are steel roller cores that you can run a stock (or steel) fuel pump rod on, and you can run a melonite gear on a steel core. You can also get a steel roller core with an iron gear. In some cases there are even steel flat tappet cores for certain class rules.
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And this shows MY lack of experience :D Thanks Steel!
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C
Warren,
that is a a cast core from Comp Cams. It should be compatable with a std fuel pump pushrod but you may want to confirm that with Comp. If it was a billet core it would not have the casting look between the lobes as yours does. A billet would have to take a bronze tip fuel pump pushrod...
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hotbo
cstraub said:
Warren,
that is a a cast core from Comp Cams. It should be compatable with a std fuel pump pushrod but you may want to confirm that with Comp. If it was a billet core it would not have the casting look between the lobes as yours does. A billet would have to take a bronze tip fuel pump pushrod...
Click to expand...
i had the same problem with my uncles cam,same cam grind# and all.
was cast core the damn stock pushrod ate the lobe,had to put a electric on it to make it run.:|errwtf gives???anyway thought i would share that:)hand
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