XXO/BVGC '38 Chevy Coupe Build

[zenndog]

38- If you ever feel like trying it....call your tooling supplier and ask for ceramic cutting inserts for "hard turning", they cut hardened material just like it is regular steel. It is crazy to watch, like a welder throwing sparks, no cutting fluid is used, just dry. These A2-5 spindle noses were cut by hard turning, hardened first, then machined. Can't remember the hardness off the top of my head, good thing I have it written down, 86L20 Steel, heat treated 60 rockwell.





Sorry for the poor pictures.

That motor looks great, good luck with the break in and beyond.....

[Jack Gifford]

... the cam pattern was designed for a 1.260 lifter diameter, so I had to turn the bases of all of them down ...

If the lobes care whether the foot diameter is "too large", then the lobe design is fubar. I could understand, if you needed to cut them down for clearance to block or whatever?

[BoredAndStroked]

... the cam pattern was designed for a 1.260 lifter diameter, so I had to turn the bases of all of them down ...

If the lobes care whether the foot diameter is "too large", then the lobe design is fubar. I could understand, if you needed to cut them down for clearance to block or whatever?

The cam would not have hit the foot profile out there (otherwise it would have been off the edge of the lifter), but I also wanted a smoother edge than they came with (as they were not turned/ground on the OD).   I'm sure I could have ran them "as-is" . . .

[desotoman]

  Great looking engine and work,can't wait to see and hear it at Bville.
  Is part of the breakin for the cam and solid lifters? there should be little or no boost at a steady rpm untill
you put a load on egine or blip the throttle.

              JL222

Yes, I want to get the cam and lifters broke in good, before we add too much load.

Buddy,

They will run without the blower belt for break in. Although it does look funny when the blower is turning and there is no belt attached. LOL.

Tom G.

[Seldom Seen Slim]

Wait a minnit-- hunh?  "...it does look funny when the blower is turning and there is no belt attached."  So forgive me -- I'm not a car guy -- but if there's no belt, what's making the blower turn?  Is the air moving through it that forceful that it overcomes internal losses in the blower?  I could see that in a turbo, maybe, but in a screw type blower -- hunh?

[desotoman]

SSS,

You bring up a good point and I should have clarified my post. Back in 1972 I built a boat motor with a 6-71 GMC supercharger but it had no teflon strips in it, and it ran fine with out the blower belt hooked up, and that is how I broke my cam in on that motor.  A screw blower should work also as there is no friction on the case the way they are made.

I don't have any experience with a GMC blower set up with teflon, so they may not turn as free because of the friction of the teflon against the case, so someone else will have to chime in on that type of set up.

I guess you could say the rule of thumb would be if you can spin the blower with you hand, the motor should run without the blower belt. This would be for a blower mounted on top of the motor. Others types that have 10 feet of intake tract might not work.

Tom G.  

[BoredAndStroked]

SSS,

You bring up a good point and I should have clarified my post. Back in 1972 I built a boat motor with a 6-71 GMC supercharger but it had no teflon strips in it, and it ran fine with out the blower belt hooked up, and that is how I broke my cam in on that motor.  A screw blower should work also as there is no friction on the case the way they are made.

I don't have any experience with a GMC blower set up with teflon, so they may not turn as free because of the friction of the teflon against the case, so someone else will have to chime in on that type of set up.

I guess you could say the rule of thumb would be if you can spin the blower with you hand, the motor should run without the blower belt. This would be for a blower mounted on top of the motor. Others types that have 10 feet of intake tract might not work.

Tom G.  

You can't really spin a newly stripped teflon blower by hand - they are very tight.  And, if you can easily turn a stripped blower - it probably needs new strips!

There really isn't an issue breaking it in with a blower - we just run a much lower pulley ratio (under-driven) and we're running at a fairly constant RPM once it gets started --> somewhere around 2,000.   As long as we're getting a lot of oil splash on to the lifters and cam and bore, it should break in properly.   Obviously we'll have the right break-in oil in it as well - with a lot of anti-wear additives.  (Like Brad Penn stuff).

[BoredAndStroked]

38- If you ever feel like trying it....call your tooling supplier and ask for ceramic cutting inserts for "hard turning", they cut hardened material just like it is regular steel. It is crazy to watch, like a welder throwing sparks, no cutting fluid is used, just dry. These A2-5 spindle noses were cut by hard turning, hardened first, then machined. Can't remember the hardness off the top of my head, good thing I have it written down, 86L20 Steel, heat treated 60 rockwell.

Thanks for the info - I've never used ceramic inserts, will have to give them a try!   I do know there is no way in hell I'd attempt to turn a chunk of 8620 at a hardness of 60 with carbide!

[38flattie]

Zenndog, thanks for the info!

Dale, great story about Navarro and the lifters- the engine is looking great!

Actually, Brian proposed this idea a couple of years ago, when Kevin and I were trying to figure out solid lifters:
http://www.jalopyjournal.com/forum/showthread.php?t=332457&page=13

Pete1 has came up with a square bodied roller lifter design, that shows promise-we may try them on the roller cam

I've been busy trying to get the changes done on the car, and looking for good aero mods. I want them to work, and at the same time, I want them to have the 'vintage' look.

I've settled on a modified version of fairings like the Lockhart car had.
,

[38flattie]

Garry is making great progress on his Flatcad porting work, achieving 200 CFM on the #5 and ##6 intake ports. Now, he just has to match the other 6 intakes with them!

Garry added a second intake gasket, .050" thick, and flowed our design again. The flow went from 166 CFM to 173 CFM- looks like it may be a transfer area issue. Garry is making some mods to the design, and will flow it again next Thursday.

[dw230]

Pleas refresh my memory - what class are you proposing to run with the wheel fairings?

DW

[38flattie]

Dan, XXO/BVGCC

Did I miss something?

[38flattie]

I can't find any 8mm belts longer than 70.55". I can't go smaller than a 53 tooth on the crank pully, due to the crank support.

Soooo, does anyone know where I can find a belt in the 72"-73" range?

[RichFox]

Might try     http://www.ebmmill.com/EBM_Mill_Elevator_Supply.htm  They have belts up to 175 inches or so.

[desotoman]

Buddy,

RCD makes a belt you might be able to use.

Tom G.

1312-2000-075 is their part number.   

2000-8M-75 POWER GRIP RUBBER (250T, 78.7 X 3) BLOWER BELT    $259.00