Straightening Cam Cover After Welding

Technical advice Q&A

Topic author
Geoff Green
Posts: 141
Joined: Tue Apr 22, 2014 3:13 am
United States of America

#1 Straightening Cam Cover After Welding

Post by Geoff Green » Mon Mar 18, 2019 12:26 am

XK cam cover with 6 of the stud holes needing repairs from cracks and pull outs. This was a very poor piece and if it was ruined it would not matter. I knew welding would cause the cam cover to distort. I was not prepared for the amount of warpage.

Holding one end of the cam cover to the steel the other end lifted a little more than 1/4 inch, 0.250 thousands, 6.35 mm up off the steel surface. I believe I can heat the cam cover and clamp it to a flat stiff metal and let it cool returning the cam cover to the shape of the flat surface. I had a piece of c channel 4 inches wide and 30 inches long. The length was perfect however the width is too narrow. I tried it anyway. Garage overhead door opened about 1 foot for fresh air.

Setting the steel channel on two vertical 1/8 inch thick aluminum panels would allow me to heat the underside of the steel and the cam cover without burning the tables holding my experiment and eliminate heat transfer out of the c channel and cam cover. I heated the steel and placed the cam cover on the steel and heated it also. Lots of heat from the Oxygen / Acetylene rosebud torch heating tip.

After getting both pieces hot I clamped one end of the cam cover to the channel. Continuing to heat the cam cover. Gradually I clamped the other end of the cam cover and tightened it towards the steel as I heated the metal. After many passes up and down the length of the cover I had clamped it tight. Well past "smoking hot" Articles I have read allude to 400 degrees Fahrenheit.

I added two additional clamps near the middle and left things to cool. After 8 hours in a garage that started at 60 degrees F, about 15 C, it was now 50 degrees F, about 12C. Outside temperature was much colder. I could now handle the metal without gloves.

To my surprise when I removed the clamps the cam cover was straight. Well there is about 1/64 inch, 0.019 thousand, 0.46 mm warpage in an area about 10 inches long. I have a couple of ideas to try towards getting this last bit of irregularity out. Better than I expected! Possibly removing .010 thousands will be enough for a gasket to seal, or 0.015, or 0.020. How much can be removed from the base of the cam cover? This one still has the factory machine marks.

I need to make some changes for the next adjustments to this cam cover and I have another to try that is not as bad. I need a wider c channel, heat treat it and machine it flat. I am thinking of bolting the front of the cover to the steel because I may be bending things with the clamp slightly off center on the dome over the timing chain area. I will need to paint the steel channel as heating it will speed up rusting. I want to make some spacers to go over the top of the cam cover where the clamps go in the narrower valve area which will help keep from adding a twist due to off center clamping. I also intend to measure the temperature of the metal as I heat things. If a twist occurs placing a shim in appropriate areas will remove the twist on the second go.

News alert! Just picked up a piece of 8 inch wide c channel and will begin getting it ready for the next try at straightening. Send your warped, twisted, cracked, and other cam covers so I can be sure this gives consistent straightening and that I did not just get lucky.

The second cam cover with one hole welded was just under 1/4 inch warped. I heated it more than the one in the photos, mostly on the top surface, and it straightened by itself as I heated it to a higher temperature than the first one. I clamped it while it cooled and all is well.
Image

Image

Image

Image

Image

Image

Image

Image

Image

Image

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

JerryL770
Posts: 331
Joined: Sat Dec 09, 2017 2:58 pm
Location: Northants
Great Britain

#2 Re: Straightening Cam Cover After Welding

Post by JerryL770 » Mon Mar 18, 2019 12:24 pm

Question:

Were the cam covers adequately pre-heated before welding?

There's nothing like - suck-it-n-see :salute:
Jerome Lunt
1970 S2 FHC - Dark Blue, Red Interior, MX5 Seats

Link:
BBcode:
HTML:
Hide post links
Show post links


Gfhug
Posts: 2035
Joined: Thu Jun 19, 2014 3:08 pm
Location: Near Andover, Hampshire,in D.O. Blighty
Great Britain

#3 Re: Straightening Cam Cover After Welding

Post by Gfhug » Mon Mar 18, 2019 4:00 pm

Geoff

That sounds very impressive work. Wellseal smeared on the gasket to help get a good seal, plus I've used "Dowty washers" on the bolts to hold the covers down. They may not be copper for the purists, but they certainly stopped any weeping from there.

Geoff
S2 FHC Light Blue
S2 OTS LHD - RHD full restoration

Link:
BBcode:
HTML:
Hide post links
Show post links

Post Reply Previous topicNext topic