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Weld or putty

General engine tech -- Drag Racing to Circle Track

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moparian
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Weld or putty

Post by moparian » Sat Nov 30, 2019 7:59 am

i have this pin hole in my exhaust port.What would be the best way to repair it i can get to both sides?putty or weld?
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travis
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Re: Weld or putty

Post by travis » Sat Nov 30, 2019 12:30 pm

I would weld it. I’ve had several aluminum heads welded up over the years and never had any issues with them over long term use. Epoxy *may* be fine, but I wouldn’t trust it to last long term in that environment

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Re: Weld or putty

Post by modok » Sat Nov 30, 2019 6:49 pm

May be able to put a threaded taper pin in it.
lock&stitch makes aluminum pins.

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Re: Weld or putty

Post by ProPower engines » Sat Nov 30, 2019 7:12 pm

In an exhaust port you have carbon contamination in the substrate that needs to be removed before welding.
If the head is thin there it will require the guide to be removed before welding prep is done but if you can get
to the water jacket side there is several epoxies that will do the job as long as any rust can be removed
prior to the epoxy application otherwise it will just come off and leak water again.
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moparian
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Re: Weld or putty

Post by moparian » Sat Nov 30, 2019 9:46 pm

Thanks guys if i could help it i did not wan't to play with the inserts,i had some heads welder before and the re cracked again so i am a little shy on welding them ,what is the best putty/resin to use ,eg jb weld or epoxy

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Re: Weld or putty

Post by 4sfed » Sun Dec 01, 2019 1:17 am

This is an excellent candidate for a weld repair. Clean the surface all the way to the bottom of the flaw with a cabide burr, weld (100% penetration), finish the weld within 0.010 then peen the weld with a round nose punch.

Unless it's peened, a weld will have a residual tensile stess ... which could be the cause of your previous results.

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Re: Weld or putty

Post by Geoff2 » Sun Dec 01, 2019 3:21 am

If the pin hole is into the coolant jacket, just use one of the myriad of coolant 'leak fixers'. Why risk welding, or epoxy burning up.

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Re: Weld or putty

Post by mag2555 » Sun Dec 01, 2019 7:06 am

Coltronics makes a ciramic epoxy that holds up to well over 2000 degrees f which is more then enough to last in a Exh port of a NA motor.

I would polish the area clean and then load it up good with the epoxy to the point of filling that channel some.
Who ever ground out that channel that deep was making a mistake as anytime I have ever done such while doing flow research I lost flow somewhere in the lift range of the Cam that was being concidered!

After the epoxy fix I would have a machine shop that can pressure test heads pour in one of the special sealers that are made for such a job and then pressurize the head.

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Re: Weld or putty

Post by 4sfed » Sun Dec 01, 2019 3:29 pm

The problem with epoxy is its coefficient of expansion. If that's your choice of repair method, I'd recommend looking for for one that is aluminum filled to match expansion rates as closely as possible.

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Re: Weld or putty

Post by SchmidtMotorWorks » Sun Dec 01, 2019 3:46 pm

Drill with the smallest tap drill that will clean-up the hole.

Drill through the water jacket and out the other side.

Tap from the outside through both holes at once with a long tap.

Insert a single threaded rod through both holes the same material as the head coated with some kind of sealant, maybe sodium silicate.
Grind about 0.020 proud
Peen both ends.
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Re: Weld or putty

Post by shoedoos » Sun Dec 01, 2019 4:51 pm

my experience is when you go to sell a set of heads with epoxy used in them, potential buyer's have lots of questions.....if they have been welded those sideways glances seem to be non existent...

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Re: Weld or putty

Post by moparian » Mon Dec 02, 2019 5:46 am

A lot of different ideas here,i will let you guys know how it turns out next week. cheers

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Re: Weld or putty

Post by cgarb » Mon Dec 02, 2019 6:07 pm

Another vote for pin* no risk there from the heat of a seat falling out or guide repair needed. Just a good mechanical repair that shouldn't give anymore trouble. Welding would be the best fix, but sometimes what's best and what's the most practical aren't the same.

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