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BJ8 restoring carburetors

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NIB

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Have been having problems for a month with the engine not being able to idle when hot, low engine power and not taking revs like it should.

Looked over the ignition, didn't find anything. I knew the carburetors were a bit worn in the throttle body shafts, so I decided to repair them. It's too cold to drive now anyways.

Maybe I found the real problem after just taking off the rear airfilter, it was full of oil. Must be worn rocker shaft assembly. Better replace that with a renovated I guess.
Is that enough to cause these problems?
DSCF1426.JPG


Rest of the pictures are here, dont think the carburetors look that bad. Feel free to comment if you see anything I have overlooked.
https://healey.850r.dk/albums/Picture%20Album/album/Restoring%20Carburetors/index.html#
 
The rockershaft is very easy to diagnose, yes!

If you can feel lateral movement in the throttle shafts where they pass through the bodies, then they are worn; often times, it's only the shaft, and the bushes in the body are okay. In this case, it is simple to replace only the shaft, not requiring any specialized reamers to align the bushes (as you haven't altered them).

Note the "clock angle" of any linkages pinned to the shafts before removing them.

When fitting new shafts, insert the butterfly plate, paying close attention to the direction of the beveled edges and fiddle with the alignment before snugging down the screws__pulling the shaft in/out as the plate aligns itself with the bore helps here.

If you want to really clean up the hardware to like-new appearance, get yourself a "tumbler" (THANKS to COTTON TOP...) and the hardware comes out like new.

IMG_1334.jpg


IMG_1335.jpg



With a clear spot on the bench to inspect and clean the parts, they're not too difficult to overhaul. Plenty of time to work on them while waiting for the rockershaft assembly to be reconditioned.

Here's a link to pictures recently restoring some H4 carbs (BN4 2-port): https://www.spcarsplus.com/gallery3/index.php/LS_BN4_engine_build/Final-push?page=18

And another link to a set of HD8s (BJ8): https://www.spcarsplus.com/gallery3/index.php/reMKIII?page=5
 
If your BJ8 has the original HD8s, I believe they have the Teflon shaft bushings - pretty easy to replace. The oil in the filter might be due to rocker shaft wear and oil spray but I would tend to suspect excessive blow-by.

Marv J
 
Take the valve cover off and run the engine. It will only dribble oil if it is okay and gush if you need a rocker job (about 200 bucks). That excess oil is being drawn into the rear air cleaner. Oil can be drawn into the rear carb and effect the balance with the front carb. Easy to check.
 
You are in luck. The problems you mention can be tied to one or more of three things:

1) Worn throttle shafts - they can cause sloppy or poor idle.
2) Throttle linkage adjustment - almost always off. Follow the manual and get this right. Your throttle linkages may only be opening the throttle part way. this can cause weak performance at full throttle.
3) Fuel Delivery - If your tank has rust in it, or your fuel pump is not working very well, you may only be getting slow fuel delivery to your carbs. This means you will get poor throttle response, especially on the highway. Take the fuel line off of the carb and see how fast the fuel comes out. It should have a nice steady flow. If it's just coming out very slow just above a dribble, then you have a problem.

Good Luck,

Alan
 
Thanx for all the ideas, now i have something to work on.
And one again great pics. Randy, i knew you had worked on carbs too, just couldn't find the pics anymore, but I see you have moved them.
Just need to find someone to help install the new bushes for the throttle shaft, dont have the proper tools for that.
 
Just need to find someone to help install the new bushes for the throttle shaft, dont have the proper


Does not require any special tools for the HD 8 carbs.Very simple to install them.
 
I need a 9.5 mm reamer to get the bushes in. I have found a workshop that can do the work. Randy´s pictures shows the process.
In the manual it says not to break the venturi, I think Randy did that, but I have instructed the workshop not to do that.
 
NIB said:
I need a 9.5 mm reamer to get the bushes in. I have found a workshop that can do the work. Randy´s pictures shows the process.
<span style="font-weight: bold">In the manual it says not to break the venturi, I think Randy did that</span>, but I have instructed the workshop not to do that.
Click to expand...
I'm not sure I follow you; is this what you mean?

IMG_1528.jpg


That's the way it came out, no rough-handling required. In any case, new ones are supplied in the kits, and it's the rubber diaphragm that's always the first component in an HD-Series carb to fail__they dry out and crack.
 
Hi Randy

I was thinking about this picture, it looks to me like you run the reamer all way through. In the manual, that came with the repair set, it says not to destroy the venturi. I understand that as going in from each side and not removing aluminum close to the venturi.
IMG_1730.jpg
 
NIB said:
Hi Randy

I was thinking about this picture, it looks to me like you run the reamer all way through. In the manual, that came with the repair set, it says not to destroy the venturi. I understand that as going in from each side and not removing aluminum close to the venturi.
IMG_1730.jpg
Click to expand...
I see. The replacement bushes go down into a recess, so that when seated, they take up (at least most of...) the metal removed.

Given that this, and most other Healeys on the road nowadays aren't exploiting anywhere near their maximum potential, it's a small price to pay to insure that the throttle shaft bores are perfectly aligned. An appropriately-piloted reamer would be the only alternative, and I didn't have one readily available. I've since gotten the Moss Motors supplied piloted reamer, but it only does +.010" oversize throttle shafts (by cutting into the original bushes).
 
A simple way to get the bushes aligned is turn down the shank of a 3/8 machine reamer to the same diameter as the throttle shaft and then put the reamer shank into the throttle shaft hole and ream the bushing bore with the back of the reamer flutes. Worked a treat for fitting the teflon/steel bushes into my H4s.

DSC07231.JPG


Andy.
 
You really need to verify what kind of bushings you have. Every HD8 I've worked on (Healeys and Jags) have had the Teflon bushings. Those come out and the new ones install with no special tools. No reaming involved.
 
I believe I have the teflon bushes, but the repair set you get from SU uses a different system with metal bushes. It´s not that big a problem anymore, a workshop will install them, when they get the right size reamer.

DSCF1461.JPG
 
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