Tubing head bolt holes

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cgarb
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Tubing head bolt holes

Post by cgarb » Thu Nov 02, 2017 10:24 pm

Have an old set of 340292 heads I'm going to revisit porting. I'm getting them flowed first as they are already ported probably 10 years ago...by myself. I copied some Ladd ported double humps my uncle had. I want to establish a baseline first by flowing them, then my plan was to add material to the pinch on the outside by brazing, ( I have the vintage BRC shaft rockers to go with them .25" offset intake rocker. Brand new, with the 1970's paperwork that's falling apart too) then open up the inside and tube the head bolt holes and straighten out the common wall, also go from a 2.02 to a 2.055 valve. There is not much info I could find on this other than Thomas on headbytes youtube and I figured that probably wasn't the best place to start. Mostly what I gather people use a very slight press fit with JB weld. My question is, with a slight press fit wouldn't it just push out the epoxy and none be under the tube? Has anyone used Loctite 638 on them? I would think a few thou slip fit with that on there and pretty much nothing short of a cutting torch is getting them out. Also I thought of a dry reamed hole and a thou or two press fit, put the tubes in nitrogen and slip them in. Whats the SOP for installing them correctly? I know I could just buy a set of AFR heads but that's not how I roll...lol. Any help would be appreciated.

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Re: Tubing head bolt holes

Post by fastvette » Thu Nov 02, 2017 10:41 pm

I make it so they just slide in, maybe a light tap with hammer. Epoxy in place.
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Re: Tubing head bolt holes

Post by cgarb » Thu Nov 02, 2017 10:46 pm

Hi Randy, Been racing any lately? I haven't seen or heard anything local for a while. I race at Hagerstown and I work with Tony in Taneytown. I helped him work on his Allis Chalmers tractor some when he was fooling with that.

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Re: Tubing head bolt holes

Post by fastvette » Thu Nov 02, 2017 11:04 pm

No I haven't raced anything for a while. Helping the boys with their kart racing keeps me busy.
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Re: Tubing head bolt holes

Post by Scotty » Thu Nov 02, 2017 11:04 pm

I shoot for .0005" crush with a shoulder left on the deck side and fit with loctite 680 to seal any discrepancies or porosity.

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Re: Tubing head bolt holes

Post by cgarb » Thu Nov 02, 2017 11:11 pm

Keeping the kids happy, that's important. Sounds like there is no SOP...lol. One a slight press with Loctite, one a light press with epoxy. Use the brass thin wall hobby tube? I think ace hardware sells it in town near me. I do like the shoulder idea, but where would it go anyway? The deck surface is right there.

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