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pushrod rubbing heads grind for clearance???

Posted By: n20mstr

pushrod rubbing heads grind for clearance??? - 01/04/09 05:29 PM

Upon disassembly, im finding that even thought the pushrods have .050 or so clearance, in some spots they are slightly rubbing. I see a very slight polishing on the pushrods and the same on the heads. The pushrods are rotating because its all the way around in one spot and very slight(Indy 440-1's and Smith bro pushrods) Now im tempted to grind the heads just a little in the polished spots, but im reconsidering that the pushrods need that little "support" They dont touch when the engine is on the stand...they have clearance (I already ground the heads and block for the clearance) Should i touch them up or leave it?? No problems so far roughly 200 passes like this
Posted By: blownzoom440

Re: pushrod rubbing heads grind for clearance??? - 01/04/09 05:34 PM

we would realy have to see how much it is rubbing but i say leave it.
Posted By: MR_P_BODY

Re: pushrod rubbing heads grind for clearance??? - 01/04/09 05:38 PM

How thick of wall and diameter are your P/Rs
Posted By: Ari440

Re: pushrod rubbing heads grind for clearance??? - 01/04/09 05:41 PM

are thet 3/8ths or 7 1/6ths pushrods


they should not be touching or rubbing
Posted By: n20mstr

Re: pushrod rubbing heads grind for clearance??? - 01/04/09 05:44 PM

Quote:

How thick of wall and diameter are your P/Rs




3/8 im not sure of the wall, maybe .080?? All they put in the bag is a business car with the dimensions written on it
Posted By: Cab_Burge

Re: pushrod rubbing heads grind for clearance??? - 01/04/09 06:04 PM

Did you check the clearances in the motor cold and all the way through the lift cycle opening and closing? If not do that first, if the ones rubbibg clear then the pushrods are probaly flexinf enough in the problem spots to rub. Manton syas there is nothing wrong with aving extra pushrod support as long as the motor isn't making metal or killing the pushrod cups due to the pushrod not allowing oil into the cup and adjuster seat I have found ut the hard way that you don't want a Hemi pushrod rubbing becuase it can kill the rocker end of the pushrods do to lack of oil in the pushrod cup. I had to replace three exhaust single tapered pushrods in one of my customers motors, at $24.00 a piece, back in the mid 1990 due to my allowing thme to rub to much there are a lot of pushrods running in motors all across the country that are living well without causing problems, they shine where they rub
Posted By: n20mstr

Re: pushrod rubbing heads grind for clearance??? - 01/04/09 06:08 PM

Quote:

Did you check the clearances in the motor cold and all the way through the lift cycle opening and closing? If not do that first, if the ones rubbibg clear then the pushrods are probaly flexinf enough in the problem spots to rub. Manton syas there is nothing wrong with aving extra pushrod support as long as the motor isn't making metal or killing the pushrod cups due to the pushrod not allowing oil into the cup and adjuster seat I have found ut the hard way that you don't want a Hemi pushrod rubbing becuase it can kill the rocker end of the pushrods do to lack of oil in the pushrod cup. I had to replace three exhaust single tapered pushrods in one of my customers motors, at $24.00 a piece, back in the mid 1990 due to my allowing thme to rub to much there are a lot of pushrods running in motors all across the country that are living well without causing problems, they shine where they rub



I have checked and they are not rubbing on the engine stand going through the lift cycle...
They are "slightly" rubbing because yes they just have that Polished look where they are tocuhing, not much at all im sure
Posted By: MR_P_BODY

Re: pushrod rubbing heads grind for clearance??? - 01/04/09 06:15 PM

I have checked and they are not rubbing on the engine stand going through the lift cycle...
They are "slightly" rubbing because yes they just have that Polished look where they are tocuhing, not much at all im sure



Sounds like they just arent strong enough and are
deflecting to much, normally .050 thru the whole
range is plenty
Posted By: n20mstr

Re: pushrod rubbing heads grind for clearance??? - 01/04/09 06:17 PM

Quote:

I have checked and they are not rubbing on the engine stand going through the lift cycle...
They are "slightly" rubbing because yes they just have that Polished look where they are tocuhing, not much at all im sure



Sounds like they just arent strong enough and are
deflecting to much, normally .050 thru the whole
range is plenty




Maybe i really DONT have .050??? I guess im grindind and checking LOL LOL
Posted By: 69Cuda340S

Re: pushrod rubbing heads grind for clearance??? - 01/04/09 09:27 PM

If its a hydraulic cam you may need to install check springs because the lifter may not be pumped up when the engine is on the stand.
Posted By: CompWedgeEngines

Re: pushrod rubbing heads grind for clearance??? - 01/04/09 10:25 PM

Normally "slight" rubbing ( as you seem to be explaining ) isnt a huge issue. I am a Manton WD dealer and they recommend only .010 clearance and many times the slight rubbing is fine. I used to over-clearance these areas but have since changed my ways and found it to be better.Its not a problem to have that support, but I would also guess that a thicker walled pushrod could be a good thought in your case knowing somethings about your combo and ET as you have posted before.
Posted By: Al_Alguire

Re: pushrod rubbing heads grind for clearance??? - 01/04/09 10:29 PM

I agree slight rubbing is not an issue. .050" is plenty of clearance for a pushrod, maybe even a bit more than necessary IMO. If it spins over fine on the stand and has that much clearance dont worry about it. Many would argue that the slight rubbing is acting like a "guide plate" of sorts to help stabilize the pushrod. I tend to agree. If it is only slight rubbing dont sweat it.
Posted By: jpm1916

Re: pushrod rubbing heads grind for clearance??? - 01/05/09 12:27 AM

how much spring pressure may need .120 or 135
wall thick pushrods
Posted By: Sport440

Re: pushrod rubbing heads grind for clearance??? - 01/05/09 12:43 AM

If its only "slightly" rubbing as desccribed, and not producing chips, consider it a guide plate. mike
Posted By: n20mstr

Re: pushrod rubbing heads grind for clearance??? - 01/05/09 02:39 AM

i read the info on Mantons site, i will double check my clearance while assembling the engine this time, but yea its rubbing VERY little, and even at that, its only on the intakes and all its doing is putting a slight polish on the pushrods. I remmeber having smallblocks that had the large cork gastkets rubbing the pushrods and that left more of a mark on there than this...Thanks for all the replies
Posted By: Monte_Smith

Re: pushrod rubbing heads grind for clearance??? - 01/05/09 02:44 AM

It's pretty simple. If you have plenty of clearance and they don't rub when you roll it over, your pushrods are not good enough. Now as mentioned, it will probably not hurt a thing, other than cost you power. Valvetrain deflection is one of the biggest power robbers there are. There is a reason that really high HP engines have pushrods that look like tree trunks and use large cam cores.

Monte
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