Author Topic: Cobra motor disassembly and rebuild (Read 107652 times)

edwardmorris · « **Reply #50 on:** December 17, 2015, 10:59:12 AM »

Quote from: Bill/BentON Racing on December 17, 2015, 05:09:07 AM

Close. It's a piece of foreign material. We use them all the time......Let's see engine out,been in engine room for a couple months , plugs out....hmmmmm checked with boroscope and blew air in plug hole... should have opened a valve and blew through there. The air moved it that you could see. So what is it? Pic later, Bill

I'll take an unlikely guess: Temp oil leak stop putty or antisieze?

Jerry Rxman Griffin aka MuthaF'er · « **Reply #51 on:** December 17, 2015, 11:15:21 AM »

Is it the spark plug cap?

754 · « **Reply #52 on:** December 17, 2015, 11:20:56 AM »

Is it an electric cooled pony harness jack ?
...code words for cut off end of tie wrap...ftp://

madmtnmotors · « **Reply #53 on:** December 17, 2015, 11:28:12 AM »

Muffler bearing?

Bill/BentON Racing · « **Reply #54 on:** December 17, 2015, 01:37:46 PM »

Drum roll, don't ask me how. F me silly. It was the cut off head of a tie wrap...smh!

, Bill

gschuld · « **Reply #55 on:** December 17, 2015, 02:19:41 PM »

That was my very next guess

George

Restoration Fan · « **Reply #56 on:** December 17, 2015, 03:15:28 PM »

Quote from: Bill/BentON Racing on December 17, 2015, 01:37:46 PM

Drum roll, don't ask me how. F me silly. It was the cut off head of a tie wrap...smh! , Bill

So you're saying that "Baby Face's chew toy" might have been correct then?

Bill/BentON Racing · « **Reply #57 on:** December 17, 2015, 04:47:02 PM »

Well it was plastic! Looks like old number 2 gave up the ghost
somewhere along the line. 3's on 3, 1s on 4, 4's on 2, and 4's on 1. 1,3 and 4 were probably original to crank. Lost number 2, either moved others for clearance or ignorance!

Can't figure it out yet. Cases ground on 1&2. Bolts on rods which were ground on are 3&4. Well, I'll probably use the other 4 RC
steel H/D marked properly and installed correctly.Plastigage time. We will see, lots of options. Bill.

Bill/BentON Racing · « **Reply #58 on:** December 17, 2015, 04:51:33 PM »

The tapered pins are exactly like my old NOS set leftover from a Drag Specialties closeout sale. 39 grams.

Bill/BentON Racing · « **Reply #59 on:** December 17, 2015, 05:10:18 PM »

Maybe use these rods.

MRieck · « **Reply #60 on:** December 17, 2015, 05:19:40 PM »

Quote from: Bill/BentON Racing on December 17, 2015, 04:47:02 PM

Well it was plastic! Looks like old number 2 gave up the ghost
somewhere along the line. 3's on 3, 1s on 4, 4's on 2, and 4's on 1. 1,3 and 4 were probably original to crank. Lost number 2, either moved others for clearance or ignorance! Can't figure it out yet. Cases ground on 1&2. Bolts on rods which were ground on are 3&4. Well, I'll probably use the other 4 RC
steel H/D marked properly and installed correctly.Plastigage time. We will see, lots of options. Bill.

Looks to me like rod bolts are ground on 2 & 3 Bill. Looks like a lot of shenanigans with that crank set up Bill.

Bill/BentON Racing · « **Reply #61 on:** December 17, 2015, 05:28:29 PM »

They are ground on 2&3. But the rods now on 2&3 were on 4&3. 3 still has the rod that came on it. The rod on 2 was number 4 early on! Yes, lots of decisions. ...we can always throw this in the mix!! Bill

cbr954 · « **Reply #62 on:** December 17, 2015, 05:44:07 PM »

Are those shorter rods or do you have stroker pistons?

gschuld · « **Reply #63 on:** December 17, 2015, 06:16:22 PM »

Don't bring out the welded up stroker crank and shorty golden rods Billy, you know it will only agrivate Mike's health condition.

Bill/BentON Racing · « **Reply #64 on:** December 17, 2015, 06:24:37 PM »

, stock length Mike luvs old #$%*.....on the shelf!! Lol.

gschuld · « **Reply #65 on:** December 17, 2015, 06:53:02 PM »

Yea, save that stroker setup for the "go for broke" motor that you won't cry if it let's go on you.

George

dragracer · « **Reply #66 on:** December 17, 2015, 08:12:27 PM »

In the real world, it doesn't matter what rod is where as long as they're all the same weight. Unless the builder was using old bearings to clarify. With the appropriate new bearings, clearance would be fine for any rod placed in any position. Explain to me in simple terms how those numbers stamped on the rods affect function in that scenario. . I'm not an SOHC guru like you fellas but I have built a lot of engines. Now if we're talking pistons, I'd be concerned that they were mixed from one hole to the next due to wear characteristics. From my point of view, I have to acknowledge that this is a dragbike engine, its seen a lot of hard passes over its life, there will be failures from time to time so if we're looking for perfection, don't buy used motors.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #67 on:** December 17, 2015, 09:44:31 PM »

Bolt heads appear different. maybe not ground. Mix and match

calj737 · « **Reply #68 on:** December 17, 2015, 09:55:27 PM »

Quote from: Bill/BentON Racing on December 16, 2015, 08:28:04 PM

LMAO, He got a bath last week. ...me too!! Hehe.

FFS, I hope you didn't share the tub at the same time, Bill-

Bill/BentON Racing · « **Reply #69 on:** December 17, 2015, 10:29:20 PM »

They only numbered for convenience and proper placement. As in 1 would go on 1, 2 on 2. Then if disassembled easy to put back where they were. Kinda like marking a piston to reinstall. Same weight don't matter about no stamped dots, numbers etc. But if removed, no bearings changed you sure want them back on the journal they came off of. Carry on,

....I'm an assembler! Round holes and square pegs, that be me!!! Lol., Bill

Retro Rocket · « **Reply #70 on:** December 18, 2015, 12:30:23 AM »

Stop avoiding the big question Bill, Did you have a tub with the dog or not !!!....

johno · « **Reply #71 on:** December 18, 2015, 01:06:04 AM »

Centre popping the rod numbers on two halves is bad practice, if you decide to do it the rods must be resized after, if you find a set of rods done like that carefully check the big end for roundness with the rods torqued up to spec to make sure the person resized round again.

MRieck · « **Reply #72 on:** December 18, 2015, 04:31:13 AM »

Quote from: Bill/BentON Racing on December 17, 2015, 10:29:20 PM

They only numbered for convenience and proper placement. As in 1 would go on 1, 2 on 2. Then if disassembled easy to put back where they were. Kinda like marking a piston to reinstall. Same weight don't matter about no stamped dots, numbers etc. But if removed, no bearings changed you sure want them back on the journal they came off of. Carry on, ....I'm an assembler! Round holes and square pegs, that be me!!! Lol., Bill

Bill.....I am absolutely sure they are not numbered for placement...... the dimples are to make sure the rod big end goes with the correct rod. It doesn't matter where you put the rod.

Bill/BentON Racing · « **Reply #73 on:** December 18, 2015, 05:13:55 AM »

I agree, don't matter. You do it so big ends don't get mixed up. Nothing to do with measurements, just convenience. But still when new, I always put 1 on 1 , etc. But yall right, rod and crank don't know, like Frank first said if you're reusing them and the bearings then they need to go back where they came. That's why we always put 1 on 1 etc. Just made sense, Honda didn't number 1-4 for sure. So any rod can go on any of the rod journals I agree, now the $64,000.00 question, no not with BabyFace, but the real question is what pieces aim going to use. Thinking of the stroker crank on bottom pic with the RC steel rods off of the middle crank in pics, Bill

dragracer · « **Reply #74 on:** December 18, 2015, 08:10:58 AM »

Go big or stay at home!!! Screw a 10 second ticket, put the striker crank in there and run some 9's.

Just do it!! Oh, but put new bearings on the rods first. You'll be pulling the bottom end apart a lot for maintenance so at least start with a fresh set to begin with.

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Author Topic: Cobra motor disassembly and rebuild (Read 107652 times)