Carburetor and Fuel System
Title: Mismatched
intake/manifold ports
AT ANY RATE...THIS IS WHERE THE PROBLEM LIES....I could not get the stock size O-RING in between the manifold and lip of the intakes!!!! So I opted to go to the rubber band set-up!! It seemed to work real nice
...It slipped, now I have a step where the intake moved out.....I need smaller thickness O-RINGS to get them to slip in to what lip is left then use the wrap around intake clamps to tighten them up......and hopefully this will solve the alignment issue
Well someone please advise me as to what, if anything I should do? Am I on the right tract in attempting to solve this problem!!??
The bike is breaking up at around half throttle and I believe this is the problem.
Post by Cotten on Apr 30, 2006, 5:57pm
Bibs!
The geometry of the chubble manifold and ports is much more difficult to install than the Pan. In spite of having assembled dozens over the decades, I still must resort to pressuretesting while installing in order to find the exact 'sweet spot' where the clamps will form the o-ring into a seal.
(Then a support must be massaged to hold the carb mated upon it without stress or bind.)
A trimmed assembly can only be more difficult.
Next time, whittle only on the easily replaced manifold!
It is a simple lathe operation to carve its o-ring spigots back to spec. (Unless it has been ruined with chrome.)
Some folks are successful with trimming the entire spigots off and using only the late bands, with a late manifold. I would consider that a last resort, and can only once again stress pressuretesting to avoid motor damage.
....Cotten
Post by bibs on May 1, 2006, 3:47am
uuum....I think I got 'er squared away.( I THINK)at any rate,I took the manifold off,took a good long look at it and checked into my stash....lo and behold....what do I find!!!? O-rings half the thickness of the original!!! SO..... I put 'em on the intake along with some hi temp silicone and the 2 pc. clamps....tighten things up,put the carb(S&S) back on and haul ass down the pike.....ran 'bout 20 miles and she starts breakin up again....although not quite as bad.I got 'er home and break out the C.V.carb that I sent out to RON TROCK for him to modify and put it on.....She runs MUCH smoother....havent got down the road with 'er yet but monday is the trial day.I'll see how she runs....if she aint up ta snuff she's goin out the door for whatever Ican get close to 8-9 grand.....I'm gettin REAL tired.
Post by billy on May 1, 2006, 7:04am
bibs-
When aligning an intake, during a build, Best to leave the base nuts loose, & twist Cly's as needed for best Fit. Then tighten things down & (of-course) pressure test intake everywhere..
Using Cotten's Tried & True method.. (then ya know for sure)...Other-wise no carb will fix a leak..
Hope things work out, adding silicone.. :-/ (time will tell)
Sounds like you're almost there. Don't give up!! You'll regret it., down the road..
Post by bibs on May 1, 2006, 12:03pm
yeah,it was an act of frustration at the time....but not entirely unheard of as I know peaple that have done it before and had excellent results.When I put the heads on,I left them just loose enough to get the alignment with the intake.....the problem was in the size of the intake(it was probobly for taller cylinders)....oh well,ya live and learn.
Before I put the C.V. on last nite the manifold felt really solid and the alignment was spot on!!
I'm curious to see just how well she runs....the S&S I had on there was problematic on another motor......we shall see :
Post by fourthgear on May 1, 2006, 2:59pm
Bibs
Are you trying to put the o- rings between the protruding lips of the manifold ? They actually go on top of them and your clamps smash the o-rings some what to flatten them over top of the small lip. As has been said , aliening of the intake is done when cyl. & heads installed . There should be very little gap between head spigot and manifold and of course aliened as close as possible . It sounds to me like you are trying to fit the o-rings between the two. I roll the o-rings over top of the head spigot and hold the manifold in place and roll the o-rings on top of the two and then install the clamps.Of course you have to pressure test as per Cotten instructions which can be found here before carb. is in stalled. I usually mount my carb in position before I tighten the clamps all the way for alignment and then pull carb off and pressure test manifold.
Post by bibs on May 1, 2006, 7:48pm
Thats exactly what I did.....but the lips on the heads and intake(shovel type....cause I got STD heads) arenty as long as they once were(duh!!!) so in my INFINITE wisdom LOL.,I trimmed down the standard black o-rings and used them....I did what we all do,rolled them up on the manifold then positioned the manifold between the heads and used split clamps(I hate them damm things) cause they were all I had.I ordered the good type aircraft type along with another intake manifold just in case I needed one.
I rode the bike a little earlier and she seemed okay....just sneezing a little cause I aint familiar with the C.V. she now has on 'er.
By the way...heres a link for O-RINGS in case anybody is interested http://www.applerubber.com/library/tips.cfm
I'll let yas know if I get the problem resolved ,or if I might half to go back to the drawing board.
Post by panster on May 2, 2006, 12:04am
Wouldn't it be good if we could get O rings that were a combination of the bands and the round section rings ?
I'm thinkng they should look like a T section, thin enough band, to use "aircraft"
type clamps, and maybe a square instead of round protusion, to better suit the step.
Any rubber moulding manufacturers out there ?
(I'll accept a modest sum for the idea).
Post by Cotten on May 2, 2006, 1:19pm
Bibs!
Modern gas eats sillycone, and often it just greases the clamps up for easy slippage later. Goo' luck.
and Panster!
Your hybrid seal idea would only be assemble-able on the chubble manifold, as you would have to remove a head to service a Pan.
Factory design works very well when assembled clean and dry, and tested.
....Cotten
Post by bibs on May 4, 2006, 1:44am
Just what exactly is a chubble manifold?
Post by billy on May 4, 2006, 5:31am
bibs-
a chubble manifold came stock on chubblehead motors. '66-'84
HD made them after the Panhead ended production. ;D
I do believe the term originated as a "Cottenism"
Post by Cotten on May 4, 2006, 1:43pm
I've never had an original thought;
My buddies from Chicago say it that way naturally.
There used to be a Chubblehead site, but I imagine it is extinct.
....Cotten
Post by bibs on May 5, 2006, 2:33am
BWAAAAAAHAHAHAHAHAHA!!! GOOD ONE,MY DUMB!!!Now then...back to the situation.I got the O-RINGS today they are .139 thick and look like they may do the trick.
The manifold I was operating on was a stroker manifold(chubbel)...I also scored a new stock manifold so um thinking....mebe I could use the new stock chubbel with the original .220 thick O-RINGS...I,m thinking that even if the manifold is a little loose in between the ports(heads) the aircraft style clamps will draw every thing together snug like then make up a little support bracket to hold that C.V. nice and horizontal like!!!....waya think?
Post by Cotten on May 5, 2006, 1:07pm
Bibs!
You cannot trust to blind instinct on this one; A tight and firm assembly means nothing. In fact, it is designed to have some flexibility!
Avoid tailchasing, chinscratching, and further knucklebusting by watching the bubbles.
They will tell you when the alignment is perfect, and they will also tell you if you overtorque the bandclamps, as bubbles don't lie!
Again, return to OEM design, clean and dry: no goobers, tapes, or gimmicks. Save those 2-piece 'stupor-clamps' for truck mufflers.
....Cotten
Post by bibs on May 6, 2006, 3:01am
Cotten....what bubbles doth thou speaketh of!!!!!! I'm dumber than a doorknob about these matters...please explain!
Post by billy on May 6, 2006, 7:28am
bibs-
Here's Cotten's Test proceedure...(although it can also be found in many, many posts in the archivers here).......
Manifold leaktest
Post by bibs on May 7, 2006, 2:28am
Thank you!! much....lots of great info there!!
Post by billy on May 7, 2006, 5:06am
Cotten IS the one to thank...
anyone can cut-n-paste a link..(even me) ;D ;D
Post by Cotten on May 7, 2006, 2:07pm
I did not invent pressuretesting.....perhaps it was Heron of Alexandria? (I'm sure he had soap.)
It's just my mission to bring motorcycle wrenching up into the First Century B.C.
....Cotten
Post by kell on May 7, 2006, 5:20pm
"Heron or Hero of Alexandria was an important geometer and worker in mechanics who invented many machines..."
Post by Cotten on May 8, 2006, 2:35am
And he was a showman of the likes to put P.T. Barnum to shame!
...Cotten
Post by txpan49 on May 8, 2006, 4:15am
While we are on this subject I am hoping someone can set me straight on the clamps...I am running 1963 outside oiler heads on my 49FL. In regards to the intake clamp do you use both the o-rings between the cylinders and the intake and the rubber bands over the o-rings followed by the clamps over that? Sorry if this sounds like a dumb question.
Post by billy on May 8, 2006, 5:27am
txpan49-
"Band style" seals were not used until '78 chubble.
As long as you have a good alignment, & no damage to the nipples, oem/style "0" rings should be fine..
(personally) I prefer the 1 piece clamps..like oem..(my 2 cents)
Plus - psi-test as previously mentioned !!
