Anybody need a "quick cam change" front cover?

[KendallF]

http://photos.yahoo.com/bc/frederik32212/lst?.dir=/hybrid+front+cover

No, it's not the first prototype 2 piece 3.8 front cover. I have started working on my hybrid front cover, however. I cut the lower half of a 3800 cover and the top half of a 3.8 cover, and I'm going to mate the two.

Now I see why Ruggles got big bucks for these things, too...they don't match up very well. The bolt pattern and oil pickups are the same, but the 3.8 cover is "taller" viewed lying down so a sheet aluminum patch piece is necessary to fill the gap. I chose to trim the 3.8 cover farther up so that the patch piece will slope downward and not leave a "shelf".

This is just the first rough cut on the bandsaw. The next step is to bolt the halves to a spare block, start making cardboard templates for the patch piece, and get the die grinder out!

 

[TurboTR]

That rules! How does the geroter pump get driven, specifically? Any pics of the front of your crankshaft or whatever part drives it? And how does the oil route in and out of the pump?

TurboTR

 

[KendallF]

OK...I added some more pics. The pump is normally driven by the lower timing gear; it has flats machined on the sides of it which engage flats in the inner rotor. See the 5th and 6th photos. The pickup and feed passages match the 3.8 locations; see photo 8. The last picture shows the cover from the side where the filter housing bolts up; the large center hole is for the relief/bypass valve and spring.

I am going to machine flats on the hub of the balancer to drive it, but the gear is perfect for centering the cover for welding. It fits on a 3.8 crank; I'm going to install a crank into my spare block, put the gear on it, bolt the cover halves down, and weld it. That should locate it adequately.

 

[geno]

That will be a real bitch to keep flat even bolted to the block. I guess the piece,s better fit nice and tight to keep the warp down to a minimum..Maybe a small strongback or gusset on the outside might help keep it flat that wont get in the way of anything.Those front covers are a pretty dirty casting and might not weld to nice but im sure it can be done I still want one when your done

 

[Scott231]

Very cool Kendall. At this rate with the custom pieces you are doing, your motor should be ready for the 2006 season

 

[KendallF]

Originally posted by Scott231
Very cool Kendall. At this rate with the custom pieces you are doing, your motor should be ready for the 2006 season

Ouch! Hey, sometimes I think I enjoy the fab work more than working on the finished product.

Geno, that's a good idea...I wonder if I can't put a gusset or two inside, specifically.

 

[n20junkie]

there are a few secrets to welding with minimal warping, one is a good heat sink, especially with alum, the block if it is cool will work very nicley, so bolting the part to it will help to align and cool, another one is to do the minimal amount of welding, i think that putting gussets will only put more heat into the piece and warp it more, any weld will warp, so the fewer welds the better, and i think that the casting should weld good, a good cleaning and a square wave machine will do the trick, i think that your project is really cool, the georotor design is a very efficient one, used in the newer ls1 and the titan brand oil pumps, good luck, and have fun
Grant J Farmer

 

[geno]

Im sure you already thought of this but.
I would fit and weld all the pieces on one half complete gussets and all.
Then fit that half up to the other with minimun gaps to reduce stress and heat. The gussets i would skip weld on to reduce the heat like n20junkie said. You could almost fit and weld all the pieces on and let the ends run wild and then cut then off the right length and angle to match the other half with the ban saw again. The other thing you might want to think about is how to control the thrusting of the cam sensor since the pump shaft wont ge there to thrust against anymore.The back cut gears are going to be pulling down and the only stop is a single screw on the end of the shaft holding the bell on. Just trying to help you brain storm your project..

 

[KendallF]

Geno,

Thanks for some good ideas. I wondered too about the cam sensor but since it doesn't bottom out normally on the pump drive, I think it'll be OK. I do think I may need to make sure and shim it so it can't chatter up and down, at least. The dry sump front covers don't have any pump drive shaft either, and people seem to be running them with distributors and cam sensors OK. Maybe I need to beef up the gear roll pin?

I mocked it up on the stage block tonight...hindsight being what it is, I think it would've been better to cut it lower on the driver's side. Maybe on the next one...

 

[ijames]

Grant, would it be better to start with the aluminum at room temperature or to preheat it to maybe 200 degrees? Our welder once showed me some aluminum brackets that were basically unweldable (pits, spatter, gobs, no sticking ) until he preheated everything to 150-200 degrees then it was perfect. I'm wondering if the preheating wouldn't cut down the warpage. You would probably have to preheat it on the block with a torch or burner or maybe a big heatlamp. Anyway, just wondering out loud.

 

[geno]

I know my buddy Dennis had problems with his cam sensor. He has a external pump and eat up cam sensors until he controlled the thrust.

 

[S10xGN]

Hey Kendall,

Glad to see you're making progress! After getting a good look at the 3800 oil pump, I can't help but wonder - will the stock GN balancer snout fit in there? It looks like the seal / pump drive area is smaller ID than our balancer snouts OD... And what exactly drives the oil pump - is something keyed to the crank snout?

Later,

 

[S2V6RACER]

Would be nice if you could "bolt up" the lower and upper half. I see what you mean by quick change.

 

[n20junkie]

to anwsner you question,
you could preheat the part, but yo would have to put a consitertible amount of heat in the part to make a difference, the molten pool of metal is well over 1,000 degres f , so if you only get the part to 200, it won't make a diference, and you sand a chance of warping the whole piece, you will be ok welding the part at room temp, it will warp a little, that is unavoidible, a little maching might be needed, but that is part of welding, good luck, i would like to see the finished prouduct
Grant J Farmer

 

[KendallF]

I've heard of people preheating things like aluminum blocks...I actually preheated my Stage block in the block oven when I welded a crack above the pan rail. We carried it to the welding booth with a steel bar down the cam bores. It came out beautifully but I don't know if the preheat was necessary.

Cleaned up cast aluminum that's moderate thickness like these front covers are actually fairly decent to weld, at least for the welding instructor at the school. For things like this, I bribe him to weld them; he makes it look a heck of a lot easier than I do!