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Clearancing push rod holes #2669574
06/24/19 10:11 PM
06/24/19 10:11 PM
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USA
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440mopar Offline OP
mopar
440mopar  Offline OP
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I need to clearance the push rod holes on my Eddy heads and have to buy a bit for my hand grinder to do so. Would like to know what type of bit works best. Should I get a single cut cylinder bit or a double cut or perhaps something else?

Re: Clearancing push rod holes [Re: 440mopar] #2669581
06/24/19 10:21 PM
06/24/19 10:21 PM
Joined: Feb 2005
Posts: 14,579
PA.
pittsburghracer Offline
"Little"John
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PA.
A double cut is easier to control and takes smaller bites. I usually recommend either turning down the air pressure or better yet getting a router control at Harbor Freight for you electric grinder. Keep your burr clean buy dipping it in transmission fluid or wd40. Lots of ways to go about it but that will get you started. If you need burrs quickly Summit sells them.


1970 Duster
Edelbrock headed 408
6.143@110.85 mph
9.73@135.05 mph shifting at 6700 RPM
422 Indy headed small block
5.982@112.56 mph
9.42@138.27

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Re: Clearancing push rod holes [Re: 440mopar] #2669585
06/24/19 10:39 PM
06/24/19 10:39 PM
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Posts: 33,149
Bend,OR USA
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Cab_Burge Offline
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Bend,OR USA
Buy the burr for cutting aluminum, not steel tsk
Candle wax works well on the burrs cutting aluminum to keep them clean, manually spin the burr in the wax before starting and again regularly enough to keep them clean up scope


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Clearancing push rod holes [Re: 440mopar] #2669697
06/25/19 09:01 AM
06/25/19 09:01 AM
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Posts: 15,995
S.E. Michigan
ZIPPY Offline
I Live Here
ZIPPY  Offline
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S.E. Michigan
This cutting fluid has always worked well for me:
http://www.tapmagic.com/


This space intentionally left blank
Re: Clearancing push rod holes [Re: ZIPPY] #2669706
06/25/19 09:26 AM
06/25/19 09:26 AM
Joined: Oct 2005
Posts: 7,043
Ontario, Canada
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Stanton Offline
Don't question me!
Stanton  Offline
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Ontario, Canada
Quote
Buy the burr for cutting aluminum, not steel


This is the best advice !! Aluminum cutters are much coarser so they don't clog as easily.

I have used the cutters that all those chinese tools vendors sell at the swap meets with no problems.

You'll also need cutters with a long stem to reach where you need to cut so get ones with 6" stems.

Re: Clearancing push rod holes [Re: Stanton] #2669725
06/25/19 10:15 AM
06/25/19 10:15 AM
Joined: Sep 2003
Posts: 11,356
north of coder
moparx Offline
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also, bar soap works for a lube. best stuff, [in my opinion, your mileage may vary] is machinist's wax. works super on aluminum using course cutters at a somewhat slow speed.
most guys crank the speed to max, but slow and steady does the best job.
make sure to use eye and face protection ! if not, "You'll take yer eye out, kid !" [to paraphrase a popular movie saying. biggrin]

beer

Re: Clearancing push rod holes [Re: 440mopar] #2669728
06/25/19 10:24 AM
06/25/19 10:24 AM
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Posts: 3,616
northern,Ohio,USA
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Clanton Offline
master
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northern,Ohio,USA
Did you think about opening the oil drain holes?I used a 1/4 double cut bit 4" long on both

20151011_130820.jpg
Last edited by Clanton; 06/25/19 10:28 AM.

GOTBOOST!New improved with Victor heads.
http://www.enginelabs.com/mopar-big-bloc...t-of-necessity/
Re: Clearancing push rod holes [Re: Clanton] #2669875
06/25/19 06:28 PM
06/25/19 06:28 PM
Joined: Oct 2005
Posts: 7,043
Ontario, Canada
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Stanton Offline
Don't question me!
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Ontario, Canada
Quote
make sure to use eye and face protection


Another piece of VERY good advice !! Whenever I do ANY grinding with burrs I always wear long sleeves and welding gloves with the sleeves tucked in. Those little pieces of metal are sharp as hell and fly everywhere. Welding gloves are thick enough the shards won't penetrate.

Re: Clearancing push rod holes [Re: 440mopar] #2669972
06/25/19 09:48 PM
06/25/19 09:48 PM
Joined: Oct 2007
Posts: 3,256
New York
polyspheric Offline
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New York
Remember that (although it's frequently the easiest way) a larger round hole does not track the actual path of the pushrod tube as it cycles.
The relief hole's actual shape has a length (on the crank axis) of the tube OD + safety margin, but the cross (left-right) axis is 2 holes this size joined by a relief that allows the full in-out swing of the rocker arm (not an ellipse, the sides are parallel). This will depend in part on your rocker ratio - high ratio rockers are commonly made by shortening the tappet (short) lever, which increases the sweep of the adjuster. If you're copying a known-to-be-safe similar engine, beware of cam & rocker differences.


Boffin Emeritus
Re: Clearancing push rod holes [Re: polyspheric] #2670101
06/26/19 09:34 AM
06/26/19 09:34 AM
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Posts: 3,616
northern,Ohio,USA
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Clanton Offline
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Clanton  Offline
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northern,Ohio,USA
Originally Posted by polyspheric
Remember that (although it's frequently the easiest way) a larger round hole does not track the actual path of the pushrod tube as it cycles.
The relief hole's actual shape has a length (on the crank axis) of the tube OD + safety margin, but the cross (left-right) axis is 2 holes this size joined by a relief that allows the full in-out swing of the rocker arm (not an ellipse, the sides are parallel). This will depend in part on your rocker ratio - high ratio rockers are commonly made by shortening the tappet (short) lever, which increases the sweep of the adjuster. If you're copying a known-to-be-safe similar engine, beware of cam & rocker differences.
Well said.I have center located push rods in the roller lifter 1.5 rockers.I opened the oil drain holes to help from the head gasket and after market block covering a lot of the holes open area but I think it would help in any case.


GOTBOOST!New improved with Victor heads.
http://www.enginelabs.com/mopar-big-bloc...t-of-necessity/
Re: Clearancing push rod holes [Re: Clanton] #2670343
06/26/19 06:48 PM
06/26/19 06:48 PM
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Posts: 2,904
back in Georgia
dthemi Offline
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back in Georgia
Someone needs to invent rat tail file pushrods. Put'm in, crank it, clean the oil filter, and go cat go lol.

Re: Clearancing push rod holes [Re: dthemi] #2671065
06/28/19 11:09 AM
06/28/19 11:09 AM
Joined: Dec 2007
Posts: 11,895
Great Neck,LI,new york
hemi-itis Offline
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Great Neck,LI,new york
Originally Posted by dthemi
Someone needs to invent rat tail file pushrods. Put'm in, crank it, clean the oil filter, and go cat go lol.


haha haha haha That WOULD work! Terry Manton told me years ago I only need 10 thou of clearance as the flexing could use the help!


HEMI-ITIS has no cure. My condition is fully BLOWN!!!

New best 60ft,, 1.42,1/8, 6.0 @117,, 9.38 @146.75 with 6 lbs boost @3700 lbs
Re: Clearancing push rod holes [Re: Cab_Burge] #2675783
07/08/19 11:07 PM
07/08/19 11:07 PM
Joined: Aug 2007
Posts: 687
USA
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440mopar Offline OP
mopar
440mopar  Offline OP
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USA
Been away on vacation so I haven't worked on clearancing the pushrod holes yet but I plan on picking up a bit this week. I will get a bit for aluminum but have one more question. Should I get a 1/2" diameter bit (the size of the pushrod hole), insert it in the hole and just work it upward till I have the needed clearance (basically ovaling the hole vertically) or would it be better to do the same but use a smaller diameter bit like 3/8" (the diameter of my pushrods) and just notch the hole at the top where the pushrod is making contact? I hope my question makes sense.

Re: Clearancing push rod holes [Re: 440mopar] #2675798
07/08/19 11:58 PM
07/08/19 11:58 PM
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Posts: 14,788
Valhalla... eventually
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BradH Offline
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How good are your grinding skills? Stick with the smaller bit, if there's any doubt. Or, depending upon how much material needs to be removed, use cartridge rolls to slow down the process enough to avoid removing too much too fast.


8^P
Re: Clearancing push rod holes [Re: 440mopar] #2675836
07/09/19 03:57 AM
07/09/19 03:57 AM
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Posts: 1,875
Milwaukee WI
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TRENDZ Offline
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Originally Posted by 440mopar
Been away on vacation so I haven't worked on clearancing the pushrod holes yet but I plan on picking up a bit this week. I will get a bit for aluminum but have one more question. Should I get a 1/2" diameter bit (the size of the pushrod hole), insert it in the hole and just work it upward till I have the needed clearance (basically ovaling the hole vertically) or would it be better to do the same but use a smaller diameter bit like 3/8" (the size on sizediameter of my pushrods) and just notch the hole at the top where the pushrod is making contact? I hope my question makesze sense.


You can’t be size on size with a burr bit. The bit always needs to be smaller than the radius, or you will get impossible to control chatter.


"use it 'till it breaks, replace as needed"
Re: Clearancing push rod holes [Re: TRENDZ] #2675884
07/09/19 09:17 AM
07/09/19 09:17 AM
Joined: Dec 2007
Posts: 11,895
Great Neck,LI,new york
hemi-itis Offline
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Great Neck,LI,new york
Terry Manton told me that 10 thou is all that's needed at it's closest point.It will act as a guide work


HEMI-ITIS has no cure. My condition is fully BLOWN!!!

New best 60ft,, 1.42,1/8, 6.0 @117,, 9.38 @146.75 with 6 lbs boost @3700 lbs
Re: Clearancing push rod holes [Re: 440mopar] #2676094
07/09/19 08:51 PM
07/09/19 08:51 PM
Joined: Dec 2011
Posts: 257
Eden, UT
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1KoolBee Offline
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Eden, UT
Originally Posted by 440mopar
I need to clearance the push rod holes on my Eddy heads and have to buy a bit for my hand grinder to do so. Would like to know what type of bit works best. Should I get a single cut cylinder bit or a double cut or perhaps something else?


What rockers are you using? I found that when I went to Harland Sharps for Edelbrock Heads on my Stealths, the material removal needed to clearance the pushrods was dramatically reduced. Fixed the scrub pattern too.


'68 Bee 383/TF/Factory Air...high school sweetheart
'67 GTX Clone project,500 six pack,Hemi4-speed,Dana
Re: Clearancing push rod holes [Re: 440mopar] #2676146
07/10/19 01:58 AM
07/10/19 01:58 AM
Joined: May 2008
Posts: 5,165
Aurora, Colorado
451Mopar Offline
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Depending on how much you are removing, a larger drill bit in the drill press gets the job done quickly.
Done that on small blocks a few times.

Re: Clearancing push rod holes [Re: 1KoolBee] #2676177
07/10/19 09:28 AM
07/10/19 09:28 AM
Joined: Aug 2007
Posts: 687
USA
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440mopar Offline OP
mopar
440mopar  Offline OP
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USA
Originally Posted by 1KoolBee
What rockers are you using? I found that when I went to Harland Sharps for Edelbrock Heads on my Stealths, the material removal needed to clearance the pushrods was dramatically reduced. Fixed the scrub pattern too.


Comp Pro Magnums.

Re: Clearancing push rod holes [Re: 440mopar] #2676184
07/10/19 10:07 AM
07/10/19 10:07 AM
Joined: Jun 2003
Posts: 51,314
Romeo MI
MR_P_BODY Offline
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I've learnt over the years to use tootsie rolls to do this.. on my B1 I
could use the mill and a end mill but I had a lot to take out.. seldom
do I ever use a alum cutter in a air grinder.. its to easy for it to wobble
around the hole and it takes too much material off to quickly(I would
rather use a steel cutting bit which is much easier to control
wave

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