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worn fuel rod again!!

Started by 4404spdcharger, July 09, 2014, 05:42:01 PM

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4404spdcharger

I swapped out the fuel pump rod in my 440 after some sputtering at 3000+ rpms after recalling a thread about worn rods.  Great!!  Fixed the problem.  Now it's sputtering again.  I pull out the rod and it's worn down almost 0.2" in less than 1500 miles.  WTF?  No fuel filter problems and I had a rebuild done last year which has been perfect.  This was a Comp Cams 4626 rod.  Anyone know of a proper rod that has the correct heat treat?
Previous Planning Prevents Piss-Poor Performance

ws23rt

The rod of course should last much longer than yours did.  The cause or reason it failed is lack of lubrication. (parts that have lube don't touch so they don't wear).
If you were to find a higher grade of material for a new rod than the next thing to fail from the same reason would be the cam lobe that moves it.
The cam lobe condition may be the reason your replacement rod failed.  The new rod didn't break in it broke out :Twocents:


4404spdcharger

I agree that lubrication should prevent premature wear.  The oil pump was rebuilt within the past year during a rebuild and the block was degreased and fully cleaned prior to the machine work so the galleries had to have been clear. The rod lobe on the cam is just in front of the distributor gear which is exposed to all the splashing going on in the valley. I'm using BP 10W30 oil.  I put a gob of grease on the rod tip when I inserted it in the engine.  The oil pressure looks normal and runs about 55 psi at cruise and maybe 40 at idle.  I'm at a loss for an answer.     
Previous Planning Prevents Piss-Poor Performance

ws23rt

My thoughts about this are like yours.  The lube comes from splashing and not something that can be changed.
I suspect that the lobe has scoring from the first rod wearing out and was the cause for the replacement not lasting long.

If I was dealing with this I would try another rod and hope it breaks in ok.  If that fails the same way than the cam has to come out. :eek2:

I would weigh that against an electric fuel pump :shruggy:

Back N Black

What brand fuel pump are you using? the fuel pump could be the issue. I had a new holley pump and the spring pressure was way to stiff and wore down the push rods at 700 miles. Changed it out for a stock pump and 8000 miles later no problems.

Cooter

Are you running the GOOD oil? Or off the shelf auto parts store?
" I have spent thousands of dollars and countless hours researching what works and what doesn't and I'm willing to share"

ws23rt

Quote from: Back N Black on July 09, 2014, 08:56:29 PM
What brand fuel pump are you using? the fuel pump could be the issue. I had a new holley pump and the spring pressure was way to stiff and wore down the push rods at 700 miles. Changed it out for a stock pump and 8000 miles later no problems.

That is interesting. I have only used carter pumps and thought the springs in them were stiffer than needed.

4404spdcharger

I'm using Brad Penn 10W30 oil.  The fuel pump is a remanufactured pump from Year One identical to the stock fuel pump. This is the same pump that was in use for the past 13 years.    The wear is all on the cam lobe end of the rod as it's shiny and the fuel pump end is barely scuffed.  I plan to goop the end of the new rod going in and put some grease on it from above (thru the distributor hole) once a month.  I shouldn't have to do this but whatever it takes.  Lack of oil lubrication seems hard to believe as it's right next to the dist gear.  Beats me.
Previous Planning Prevents Piss-Poor Performance

ws23rt

Quote from: 4404spdcharger on July 09, 2014, 09:56:15 PM
I'm using Brad Penn 10W30 oil.  The fuel pump is a remanufactured pump from Year One identical to the stock fuel pump. This is the same pump that was in use for the past 13 years.    The wear is all on the cam lobe end of the rod as it's shiny and the fuel pump end is barely scuffed.  I plan to goop the end of the new rod going in and put some grease on it from above (thru the distributor hole) once a month.  I shouldn't have to do this but whatever it takes.  Lack of oil lubrication seems hard to believe as it's right next to the dist gear.  Beats me.

Lack of lubrication as a cause of failure is just a term.  Better to add-- proper lubrication--

This lobe on the cam is no different than the lifter lobes in that they need the right lube at startup to allow the contact points to "seat". The original surface is like new sand paper--lots of sharp high points.  Sorta like sand paper, as it is used the high points go away. A break in lube helps to prevent the particles from turning into snowballs. After that a normal oil film will prevent metal to metal contact unless conditions become extreme. --high temp--high pressure--low viscosity--dirt--etc

Think of it like breaking off the high points vs pushing the high points into globs like snow balls.

If the cam lobe is in bad condition it will not heal well but could work for the fuel pump for some time. :Twocents:




fy469rtse

Don't take a chance on quality , get the one from milodon , proper hardened end , moly lube and break it in