HIF carb problem

K

KiwiRover

Active Member
I am a bit mystified as to the problem i'm having with my '72 V8. It was having carby issues when i parked it up last year and now I have resurrected it. In the process of trying to get it to start I removed the carbs, cleaned them out, drained the tank and refilled with fresh premium. The filter is quite recent and the factory electric pump works well. Initially the car ran ok, a bit fluffy but it had been sitting for a year but after a couple of days it got worse. Spluttering and hesitating mostly.
So yesterday I decided to sort it out. Both carbs off and completely dismantled, everything visually inspected and blown through with compressed air. All looks good. Bearing in mind this is a low mileage car too. Reassembled everything, set the chokes and mixture screws evenly and started up. It's only running on one carb! The rhs carb works just fine but the lhs does absolutely nothing. Both pistons rise together, I can see fuel being pulled from the jet while it's running but if I clap my hand over the intake of the lh carb... nothing! Makes no difference to the running of the car at all. Playing with the mixture screw makes no difference, pulling the choke makes no difference. I pulled a couple of the plugs and they are sooty but not wet.
If I had a complete spare carb I would try that but I don't. I only have a dubious one off a 2200TC. I would happily ditch the HIFs in favour of HSs (sorry Harvey) but I don't have any spares of those either. I'm reluctant to spring for an overhaul kit at this point because I hope to have the car on injection before too long but I would like to drive it a bit and make sure everything else is tickety-boo before launching into the unknown.
Any thoughts? What have I missed?
 
If both pistons are rising evenly that implies that the carb balance is OK. Seems to me there are two main possibilities. Either there is inadequate fuel at the duff carb - stuck float needle or similar? - or you have the ignition leads back on in the wrong order / have another ignition issue - duff plugs / leads / capacitor? I suppose there could be too much air around for the duff carb - Harvey correctly identified a leaking O ring on a choke on another HIF6 on a current thread, or drawing air somewhere in the manifold (but wouldn't that affect the piston rising?).

I think I'd start with the float and needle valve on the duff carb and just prove fuel supply to it by cracking a pipe as well.

Chris
 
Thanks Chris. Ignition system is all good. A SimonBBC module and Bosch GT40 coil, new cap and rotor, NGK plugs and Bosch 8mm leads all less than 1000mls old and I haven't touched the firing order since it was running well.
There is definitely fuel getting to the carb as I can see it coming out of the jet when the engine is running. I'll have to have another check for air leaks but considering how bad it is, I would expect one doozy of a leak! You're probably right about the needle valve though. I'll try to borrow some bits from that 2.2 carb.
I never have these problems with HS carbs but the bl**dy HIFs always give me grief. :x
 
Have a look at the elbow on the bottom of the jet . and make sure it hasn't slipped down the main shaft of the jet . better still measure the length of the jet compared to the other side , or a known good one . I had this problem last year and it took a week of afternoons to diagnose . ( some one else on here had the same problem ) it means the elbow touches the lid ( base ) of the float chamber and won't adjust down :wink:
 
Not heard of that one Stina, i'll have a look next time I get in there although they look fine from the top.
Dave, I haven't adjusted the idle screws since it was balanced but I will check again when I look for air leaks.
 
My white car has the exact same habbit. Drops 4 cylinders for absolutely no reason. I could start it another day then and it'll run on 8 cylinders again for a few months. It is losing one carb completely. Whatever is causing it on mine can sometimes be cured with a few gentle taps of a hammer :? .
Regards,
Dave
 
Whatever is causing it on mine can sometimes be cured with a few gentle taps of a hammer
Click to expand...

That sounds like my kind of solution! Where did I put that 4lb mallet? :LOL:
Seriously though, I might give that a try.
 
Hi, as I think Harvey will attest it is not the size of the hammer, it is knowing where
to hit it!!

Colin
 
I`m going through similar fun and games with the Elegant Thirsty Dinosaur at the moment. I have done a quick clean and rebuild to both carbs (new jets , needle valves, seals and a good clean). One was fine, on the other I have noticed that the float seems to occasionally jam against one of the little ledges on one side of the chamber. I noticed when I had the carb inverted setting the float height. It seems to be caused by one of two things:

1) the float hinge tube has worn allowing it to move around, I guess it could be the brass pin itself but I`d be pretty surprised if the brass eroded before the plastic..
2) the arm between the float hinge tube and the main float has kind of softened - when I let the float drop shut to check the height I saw the arm bend and the float twist.

When it jams it can either cause no fuel to that carb which equals dire performance, hesitation and stalling when opening the throttle or flooding, with almost no power and fuel pi$$ing out the bottom.

I`m just waiting on a replacement float which will hopefully cure this issue. I did notice that the jet that was in there was not the same as the other side. Instead of the elbow at the bottom it had a trumpet shaped intake. I wonder if these are from the wrong variant of HIF carb. It seemed to fit the bi-metal assembly ok but god only known how it was affecting the fuel height.

Cheers

PS if a tap of the hammer cures it, Dave, it is most likely the float sticking in the full position, starving the carb occasionally. There are few tools more effective than a "Bristol Screwdriver" , I mean , hammer!
 
Some good ideas coming in here folks. I'll pull a spare carb to bits and have another crack at it tomorrow if I get a chance. I have to change a clutch on a Hiace first. :(
 
rottenlungs said:
PS if a tap of the hammer cures it, Dave, it is most likely the float sticking in the full position, starving the carb occasionally. There are few tools more effective than a "Bristol Screwdriver" , I mean , hammer!
Click to expand...

Thanks for that. I'll open up the float chamber for a look the next oppertunity I have.
Regards,
Dave
 
KiwiRover said:
I hope to have the car on injection before too long but I would like to drive it a bit and make sure everything else is tickety-boo before launching into the unknown.
Click to expand...

Almost got away with that one :LOL: Update required!!!


Graeme
 
Fair enough! I pulled the carb apart again today and swapped the float and needle valve from the carcass of another, blew through all the orifices ( :oops: ) and put it all back together. She started quickly and seemed to be running on more cylinders so once it was off the choke I did the old misfire test (pour a bit of water over the exhaust manifolds) and found that #1 and #7 weren't firing. So I pulled the plugs and gave them a bit of a clean and dry and voila! All 8 again! Had a bit of a fiddle with the idle speed and mixtures and got them about right (roughly) so took it for a drive. It runs well but starts to hesitate when pushed. Feels like fuel starvation to me so a bit of work still required. I will swap the NGK plugs for a set of Champions, (some cars are fussy about them) replace the fuel filter and probably change the dashpot oil back to atf, then recheck the timing and balance/mixtures. Also, I think the fuel pump may have a built in filter. I'll have to look into it.
As for the EI, not a lot to report but it has been playing on my mind for a while so I have been starting to gather bits and i'm taking another look at all the info. Phase one of the project was getting the V8 running. Unfortunately the Triumph PI fuel pump I picked up has a knackered commutator so that's not much good but the plan is to start by assembling the fuel delivery parts onto the car first. This means mounting the pump and filter, finding a period fuel damper and some kind of swirl pot and an inertia switch and working out the wiring while the car is still running on carbs. Then I can swap the manifold over and wire up the ecu in one go. Fun!
It sure is nice having the V8 back on the road though, smooth and silent. Just lovely! :D
 
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