Author Topic: Cobra motor disassembly and rebuild (Read 107676 times)

Bill/BentON Racing · « **Reply #275 on:** April 19, 2016, 03:04:48 PM »

Yep, it's outta there, some sort of steel, it's magnetic! Waiting for liquid steel to dry. Then drill 1mm hole and put it together and test it and 24v system. Lots of good things besides carbide tip bits came today! More in the works, Purple Rain was an embarrassment, yeh it ran ok, but needed quite a bit to be right! Fixing it now, we will be ready for the Rock! Bill

gschuld · « **Reply #276 on:** April 22, 2016, 06:07:52 PM »

Billy's cobra motor is back up and running...

George

edwardmorris · « **Reply #277 on:** April 22, 2016, 07:15:51 PM »

Retro Rocket · « **Reply #278 on:** April 22, 2016, 07:30:10 PM »

Sounds sweet Bill...

Jerry Rxman Griffin aka MuthaF'er · « **Reply #279 on:** April 22, 2016, 08:36:05 PM »

Hollywood Bill, you crackin my ass up son :-)

Badass and angry Cobra. Sounds great.

Bill/BentON Racing · « **Reply #280 on:** April 22, 2016, 08:51:30 PM »

Thanks guys, living the dream!

, Bill

dragracer · « **Reply #281 on:** April 22, 2016, 09:26:47 PM »

Good job Bill. Its sounds ready to put up some low numbers. Will you be dyno'ing it next or going straight to the dragstrip?? Or did you get the WEGO set up to data log the numbers yourself?? I think that would be more practical if you're looking for real world AFR numbers to get your jetting right. Ahhh, but i know your focus is on how much power its making and the majority of the forum members watching this thread are too.

I think you mentioned the 24volts system is now 12 volts?? What happened?? Starts pretty easy now. No more kick backs on the old leg.

Have fun!! You worked hard for that moment.

Bill/BentON Racing · « **Reply #282 on:** April 23, 2016, 01:08:41 AM »

Thanks all. The 24 volts took its toll on the eBay 1100F starter motor! After working some 10-15 times, it all of sudden went click. Turned out motor was still getting power, just wouldn't spin. So I thought why beat the hell out of a starter system if not nessecary. So I went 12v. Seems to work just fine, my leg loves it! Dyno next! Calling in the am for next week appointment! Yippee Kai Yeah, Bill

Bill/BentON Racing · « **Reply #283 on:** April 23, 2016, 01:10:48 AM »

Pic of finished crank repair.

Medyo Bastos · « **Reply #284 on:** April 23, 2016, 06:16:36 AM »

sounds great, vrooom, vroooom!

dragracer · « **Reply #285 on:** April 23, 2016, 06:52:35 AM »

Thought you would have received the cut down rotor by now. Might be wise not to race it without getting that heavy thing off th end of the crank. Just my 2 cents from personal experience.

MRieck · « **Reply #286 on:** April 23, 2016, 07:45:43 AM »

Quote from: dragracer on April 23, 2016, 06:52:35 AM

Thought you would have received the cut down rotor by now. Might be wise not to race it without getting that heavy thing off th end of the crank. Just my 2 cents from personal experience.

He has it Frank

754 · « **Reply #287 on:** April 23, 2016, 08:38:23 AM »

it would be interesting comparing the with and without.
the only reason I think RC did not recommend them for estart, is lowere output with the chopped rotor.. They sure pick up revs quick tho..

Jerry Rxman Griffin aka MuthaF'er · « **Reply #288 on:** April 23, 2016, 10:52:50 AM »

Quote from: MRieck on April 23, 2016, 07:45:43 AM

Quote from: dragracer on April 23, 2016, 06:52:35 AM
Thought you would have received the cut down rotor by now. Might be wise not to race it without getting that heavy thing off th end of the crank. Just my 2 cents from personal experience.
He has it Frank

Bill hold a normal rotor up beside that one

MRieck · « **Reply #289 on:** April 23, 2016, 02:22:44 PM »

It is still heavy as it is an early style rotor. Frank has a very light piece

754 · « **Reply #290 on:** April 23, 2016, 02:44:32 PM »

I dont know how you can tell its early ? once flange is cut off how could you tell ?

dragracer · « **Reply #291 on:** April 23, 2016, 02:58:37 PM »

The expert on rotors hasn't stepped forward yet but i can say even when cut down, there is a weight difference. I've got two on hand in a few variations.

754 · « **Reply #292 on:** April 23, 2016, 03:05:51 PM »

The early one has the extra weight flange, everyone cut them (for lightening) a bit different , or rather there are difference between the way even say one person cuts them. I can get more weight off them now than I used to.
I know the one I was running on my 836 was under 4 lbs vs 6 plus for an early stocker...

gschuld · « **Reply #293 on:** April 23, 2016, 03:06:10 PM »

754,

I think Mike was referring to the cut down starter rotors. There were two different schools of thought (with no charging in mind, but requiring an electric starter). One was a maximum flywheel effect version theoretically helping launch with a slick, with the charging rotor removed. Starting with the heavier K0/K1 style rotor, most of the mass is in the main flange, close to the engine and crank bearing. So it should reduce the load on the crank. 4.5 lbs with starter gear clutch housing. (Factory K0 is 6.9 lbs)

The other school of though was a much lighter weight version. Basically little more than what is structurally needed to serve as a starter hub. 2.7lbs with the starter gear clutch housing. They are independently balanced (thanks Mike)

Both versions could be reduced in weight further. But it's a starting point.

Oh Frankie please....I am far from the expert on this subject. Just playing around with a lathe.

George

kmb69 · « **Reply #294 on:** April 23, 2016, 03:07:09 PM »

It can be cut down considerably more if all you need is the starter clutch and charging is not an issue. I think Billy is running total loss.
Yep, just like that George. You could take more off of those too if flywheel effect is not needed.

754 · « **Reply #295 on:** April 23, 2016, 03:13:45 PM »

Bill showed a pic of a still functioning rotor like we run on the street..it charges..
How can you call it a rotor if it does not charge? What you have shown is just a flange rotor part is cut off, if you want it easier on the crank just make one that fits beside the engine case like the starter gear did, easy to cut a taper...

Jerry Rxman Griffin aka MuthaF'er · « **Reply #296 on:** April 23, 2016, 03:28:40 PM »

Oh Frank, don't be soooo technical..... ;-)

Retro Rocket · « **Reply #297 on:** April 23, 2016, 03:59:39 PM »

Quote from: 754 on April 23, 2016, 03:13:45 PM

How can you call it a rotor if it does not charge?

Because it rotates....

gschuld · « **Reply #298 on:** April 23, 2016, 04:02:16 PM »

Yeah, the one on the left is as far as I went with the Later model rotor. It could be cut and drilled further if needed, but you'll spend more and more time taking less and less weight off.

Interestingly enough, the flywheel effect K0 based "starter hub" is nearly the same weight as the RC lightened later model rotor at 4.6lbs.

For drag racing purposes, this is not an issue. Billy is not using the RC rotor for charging, it's just along for the ride in this case.

George

754 · « **Reply #299 on:** April 23, 2016, 04:10:22 PM »

Yes but the rotor has been cut off, leaving the hub....not a lightened rotor, a cut right off rotor. Whick meand you can now run a narrower cover...

News:

Author Topic: Cobra motor disassembly and rebuild (Read 107676 times)