Twin HIF6 Setup Guide

Thanks for the pic's Pat - these are helpul :) . I think I will go with Harvey's advice (generally a good idea anyway) and what you have found and remove the spring washers. I noticed the big tensioner spring on yours looks as though it doesn't have very much tension (the locking nut is only partially screwed along the thread). When I went to take mine off, it was screwed all the way home and when I refitted, I set it about halfway.

I had sent off for a set of carb to manifold o-rings. Unfortunately, I was set a set of inlet manifold gaskets - despite describing what I needed on the phone :( . So, I am stuffed this weekend in terms of taking the my carb's off to fit o-rings and gaskets. I'll have to sort out the mix up next week.

One other thing I noticed is that your carbs have gaskets between car and manifold adapter plate. I'm not sure if mine do - didn't notice any. So. I think I'll put some on.

I clocked up about 300 miles in the last couple of days and although my idle isn't quite as smooth as it was earlier in the week when I had set things up, it's still perfectly acceptable. So, I am pretty sure my problem was poor carb-manifold fit causing an air leak on the front carb.

I hope your work goes well over the weekend. Have you got your camshaft off yet?
 
I am now starting to pull my hair out with my carb's.

Last weekend I got the carb to inlet manifold o-rings and fitted them. The old ones were definitely knacked and fitting the new ones have stopped the air leak on my front carb. Feeling happy, I thought that all I needed to do was make sure mixture was set correctly and that they were balanced.

:twisted:
Now, the rear carb is running fine. However, the front carb is running very rich and I cannot weaken it using the adjuster screw. Even when I turn the adjuster screw as far as it will go counter=clockwise, the mixture is way to rich. When I took the piston out, I could see that the base of the jet was sticking out maybe 2mm above the bridge which I think is far too high (with the good rear carb the jet sits below the bridge as suggested by manuals & HIF6 setup guides).

So, the mixture adjustment seems to be working OK and I don't think it's a problem with the needle. It's just that something has happened to this carb that means it delivring way too much fuel?? When I rev the engine, the problem is still there. So, it doesn't seem to be just an idle problem.

I tried swapping the needles between front & rear but this made no difference. I have double checked that the choke isn't on on this carb (even disconnected the choke cable to make sure). Also, double-double checked that both needles are fitted correctly in their pistons and appear to be biased by same amount in same direction. The only thing that seemed to improve the mixture was pushing the lifting pin on the offending carb up (this makes the mixture at idle almost normal).

Although I am tempted to get a refurb kit, I am reluctatnt to do this without having an idea what is wrong with the carb. I am also thinking that it wasn't like this before I removed the carbs to inspect them, clean them up and fit the new o-rings. Could I have disturbed something on the choke setup? Perhaps some obvious DOH! moment when refitting? Any help please :?:
 
JVY said:
Could I have disturbed something on the choke setup? Perhaps some obvious DOH! moment when refitting? Any help please :?:
Click to expand...

It could be the "O" rings on the choke barrel have failed so you're drawing petrol through there all the time just as though the choke is on. Another thing I never do when just removing/refitting carbs, is tip them upsidedown, so if you've done that, it could have disturbed some debris that's now floating about loose inside.
 
harveyp6 said:
JVY said:
Could I have disturbed something on the choke setup? Perhaps some obvious DOH! moment when refitting? Any help please :?:
Click to expand...

It could be the "O" rings on the choke barrel have failed so you're drawing petrol through there all the time just as though the choke is on. Another thing I never do when just removing/refitting carbs, is tip them upsidedown, so if you've done that, it could have disturbed some debris that's now floating about loose inside.
Click to expand...
Harvey, you could just be right about the choke barrel o-ring??

I took off the front carb again and found the o-ring looked worn and dried out. When I tried to carefully (honest!) remove it, the thing snapped. I assume these o-rings should have a round cross-section? Mine looks very square and worn on the outside and it is easy to imagine fuel was being drawn past it when the choke was off.

Tried finding the part on the Burlen site with no luck. So, took a punt on this being the correct type and size:
nitrile o-ring, 10.5mm bore, 14.4mm OD and 2mm cross-section
from this site:
http://simplybearings.co.uk/shop/Seals-O+Ring+Seals-NITRILE+O-Rings/c19_4501_4705/index.html

While I am waiting on the parts, I might try to bung up the "choke" hole in the float chamber and refit the carb to see if this clears the problem?
 
I know it may be a bit inconvenient, but I think I'd wait until I got the bits and then do the job, rather than trying to keep it going in the meantime.
 
Harvey, thank you so much for suggesting the choke o-ring again.
I got impatient today and bought a selection box of o-rings from Halfords (it's a PH in Scotland today, so most other places were shut). Lo and behold, there was one size in the box that seemd to fit perfectly, So, I replaced the rings on both carb choke barrels, :D :D :D Both carbs are now running perfectly.
So, thanks once again!

I can now continue with some P6 summer driving and might even get better MPG?
 
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