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Hemi pushrod clearance #795047 09/06/10 11:06 PM 09/06/10 11:06 PM
Joined: Jun 2010 Posts: 798 Houston TX G GregCon OP super stock
GregCon OP super stock G Joined: Jun 2010 Posts: 798 Houston TX	How do you achieve pushrod clearance? I needed to get some clearance on 3 of the 8 exhaust pushrods. These are Stage V heads. In the past I have always used die grinder with a long carbide burr. But it's time consuming, messy, and never that exact. This time I tipped the head of my mill about 18 degrees on the Y axis and 3 degrees on the X axis and used a slightly undersized 5/8 end mill to egg shape the holes by about .055". I went ahead and did them all. Time was 1 hour for the first head (including setup time) and 15 minutes for the second. No more grinder for me! 6181773-IMG_2852.JPG (147 downloads)

Re: Hemi pushrod clearance [Re: GregCon] #795048 09/06/10 11:13 PM 09/06/10 11:13 PM
Joined: May 2004 Posts: 12,387 Taxes & Virus's R-US, NY Dragula I Live Here
Dragula I Live Here Joined: May 2004 Posts: 12,387 Taxes & Virus's R-US, NY	I am surpirsed they weren't clearanced enough already. The problem I have seen is usualy the gaskets hit the push rods. I am not sure if its the Barton T&D rocker set-up or the gaskets, but I have now seen it twice with those rockers. Never seen the issue with the heads, but they were close. '70 Cuda,...605 EFI Hemi Street Car (6.20 best pass, 1.33 60ft) https://www.youtube.com/watch?v=WYw6RA-k5Bk (6.25 at 108.75mph from inside car) https://www.youtube.com/watch?v=3zQEb9uxFng (6.25 at 108mph from outside car) https://www.youtube.com/watch?v=JCvfzsC4NgM (9.9) '66 Barracuda AWB Stretched nose Blown 440 Car in build stage '71 Duster Drag Car 400 Low Deck 512 best 6.002 at 115.44mph https://www.youtube.com/watch?v=Znuo3jMUXTk

Re: Hemi pushrod clearance [Re: GregCon] #795049 09/06/10 11:22 PM 09/06/10 11:22 PM
Joined: Jul 2010 Posts: 2,091 Delray beach, Florida P Performance Only top fuel
Performance Only top fuel P Joined: Jul 2010 Posts: 2,091 Delray beach, Florida	Quote: How do you achieve pushrod clearance? we have several different mini boring bars that we use with the block and heads mocked up for 3/8 7/16 or 1/2" pushrods. we use a corresponding puck in the lifter bore that we can change the height on to match the lifter height that will be used in the build. these are all tools we made in house. after many years of doing it with the mill or die grinder we decided there was indeed a better way. machine shop owner and engine builder

Re: Hemi pushrod clearance [Re: Performance Only] #795050 09/06/10 11:57 PM 09/06/10 11:57 PM
Joined: Jun 2010 Posts: 798 Houston TX G GregCon OP super stock
GregCon OP super stock G Joined: Jun 2010 Posts: 798 Houston TX	That's good Dan, 'cause these are going on the block that you will soon be seeing! I haven't assembled a Hemi yet that didn't need some sort of clearancing on the pushrods. I was actually pretty happy to see this engine needed only work on the three exhausts and no intakes. Last edited by GregCon; 09/07/10 12:00 AM.

Re: Hemi pushrod clearance [Re: GregCon] #795051 09/07/10 08:31 AM 09/07/10 08:31 AM
Joined: Nov 2003 Posts: 2,715 closer to Canadian beer! torkrules I'm neurotic
torkrules I'm neurotic Joined: Nov 2003 Posts: 2,715 closer to Canadian beer!	Quote: How do you achieve pushrod clearance? I needed to get some clearance on 3 of the 8 exhaust pushrods. These are Stage V heads. In the past I have always used die grinder with a long carbide burr. But it's time consuming, messy, and never that exact. This time I tipped the head of my mill about 18 degrees on the Y axis and 3 degrees on the X axis and used a slightly undersized 5/8 end mill to egg shape the holes by about .055". I went ahead and did them all. Time was 1 hour for the first head (including setup time) and 15 minutes for the second. No more grinder for me! Mine had tubes put in them since the ports break into the push rod area when ported, but they do have an added benefit of extra clearance. I got some Cometic gaskets through FHO that have the push rod area either removed or pre-clearanced.

Re: Hemi pushrod clearance [Re: GregCon] #795052 09/07/10 09:02 AM 09/07/10 09:02 AM
Joined: Jan 2003 Posts: 13,363 Marion, South Carolina [><] an8sec70cuda I Live Here
an8sec70cuda I Live Here Joined: Jan 2003 Posts: 13,363 Marion, South Carolina [><]	I used a long shank bur bit on my die grinder. My block (KB) needed a bunch of clearancing. The heads and gaskets (MP and Cometic) fit fine. CHIP '70 hemicuda, 575" Hemi, 727, Dana 60 '69 road runner, 440-6, 18 spline 4 speed, Dana 60 '71 Demon, 340, low gear 904, 8.75 '73 Chrysler New Yorker, 440, 727, 8.75 '90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt '06 GMC 2500HD LBZ Duramax

Re: Hemi pushrod clearance [Re: an8sec70cuda] #795053 09/07/10 11:34 AM 09/07/10 11:34 AM
Joined: Apr 2010 Posts: 24 Modesto, CA Chris_Holton member
Chris_Holton member Joined: Apr 2010 Posts: 24 Modesto, CA	I have a remer and add tubes, looks very clean...

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