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Welding question and link to my new project car

Posted: Sat May 12, 2007 11:01 am
by scrabblegod
I am in the process of building a knock off of the old Lotus 7 car.
It is a locost and here is the build site. Just scroll down to the build log.

http://www.scrabblegod.com/locost

My question relates to the oil pan for this car. The pan on the SHO is cast. What is the actual material of cast pans and how does it take to welding?
I would like to remove 1.5 inches from the pan. The way the pan is made, I can slice out the section, and the pan will line right back up.
A friend tells me that once a cast pan has had oil in it fo some years, that it can not be welded due to contamination in the pores of the cast. Is this true, and if so, is it possible to bake out or otherwise clean it for welding?

Thanks,
Gene

Posted: Sat May 12, 2007 12:55 pm
by Boscolingus
there is truth in what he says. Once the structure of the aluminum has been impregnated with impurities, such as oil, you will have a difficult time welding it - but does not necessarily mean that it cannot be welded.

Once ready for welding the joint will have to be wire brushed ( stainless bristless only ) and heated up with a torch ( for better heat transfer when welding ). The method of choice here is going to be TIG w/ at least 1/8" filler rod.

Once welded, swish around some solvent ( smaller molecules than water ) to check for leaks. Essentially it is not any different from welding anything else, just get everything medical grade clean, and then clean it agian, followed by more cleaning - then weld it.

Posted: Sun May 13, 2007 2:38 pm
by Fastback86
Is it not worth it to jsut get a new oil pan and cut and weld that one, or are they no longer available/prohibitevly expensive?

Posted: Sun May 13, 2007 4:10 pm
by Boscolingus
Naw, the comparison between the two while welding would not make that much of a significant difference while welding to constitute spending a shit load, or even a crap-load on a new pan.

Just stick with the one you have and have it welded up, if the welder says he can't do it - move on, he lacks experience.

Posted: Sun May 13, 2007 6:16 pm
by p8ntman442
you should be able to clean the aluminum up enough by propane torching it. I wouldnt go near aluminum with oxy-actylne too fast melting.

After you burn out any oil in it a half decent welder should be able to weld it up on the inside, and make it work no problem.

Posted: Wed May 16, 2007 12:47 pm
by Boscolingus
p8ntman442 wrote:you should be able to clean the aluminum up enough by propane torching it. I wouldnt go near aluminum with oxy-actylne too fast melting.

After you burn out any oil in it a half decent welder should be able to weld it up on the inside, and make it work no problem.
exactly - just clean the hell out of it with acetone or brake parts cleaner ( same thing right? :) ) then a monkey could weld it together

I swear if anyone mentions JB Weld I'm gonna reach through the monitor and bitch-slap them, hahaha

Posted: Wed May 16, 2007 1:13 pm
by The Dark Side of Will
Boscolingus wrote: I swear if anyone mentions JB Weld I'm gonna reach through the monitor and bitch-slap them, hahaha
I used JB-Weld to fill in the EGR slots in a set of '93 Northstar cylinder heads...

Posted: Wed May 16, 2007 3:54 pm
by Boscolingus
...I can't seem to get my hand through the glass of the monitor... hang on a second, let me get a hammer.....

Posted: Wed May 16, 2007 4:44 pm
by The Dark Side of Will
Flat panel displays work better. The plastic is more compliant than glass CRT's.

Filling 1/8" x 3/16" slots with JB weld is a lot easier than welding them and and just as reliable as long as you pay attention to surface preparation.

Posted: Wed May 16, 2007 5:21 pm
by whipped
Filling in those "mouse holes" gained you 5hp.

True story.

Posted: Wed May 16, 2007 6:38 pm
by The Dark Side of Will
Just like porting the bay-bay breathing windows, getting the pistons coated, using gapless rings....

I'll be rivalling your HP before long...

Posted: Wed May 16, 2007 7:01 pm
by Boscolingus
just make sure you install the piston return springs!