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Chinese carburetors? Yet another 3Y thread

Posted: Mon Sep 25, 2017 11:54 am
by NZ_N57R
Hi. Just wondering if many people have had success with a Chinese carburetor? Specifically for a 3Y petrol engine. I'm also having difficulties with my vacuum lines on the carburetor on my 3Y. All my altitude compensation, and emissions control has been removed over the years, now all I have is two lines from the block side of the carburetor, and one on a small diaphragm type looking thing (I read somewhere on this forum it's for a hot start and I'm not sure what that is). :frustrated:

If anybody has a good running 3Y engine with only a few vacuum lines and could post a few pictures of the lines I'd appreciate that heaps... Thanks

Re: Chinese carburetors? Yet another 3Y thread

Posted: Mon Sep 25, 2017 1:32 pm
by dax021
Hi Jez, got these from this forum some time ago. Can't recall who posted them, but credit goes to him. Don't know if they will help.

Cheers,
Peter

Re: Chinese carburetors? Yet another 3Y thread

Posted: Mon Sep 25, 2017 3:22 pm
by Mud Dog
IIRC the 3Y used the same carb as the 4Y, just differently jetted. Same vacuum diagram should apply. The diagram above seems to be from a different spec vehicle than those we got here in RSA but not sure how yours compares.

Here is another one .....
4Y VACUUM HOSE iNFO.jpg

Re: Chinese carburetors? Yet another 3Y thread

Posted: Mon Sep 25, 2017 7:43 pm
by Family_Dog
Chinese jets tend to be very thirsty and require some modification (drilling and re-tapping) in order for the standard jets to be fitted. Any Carb specialist should be able to do this.


-F_D

Re: Chinese carburetors? Yet another 3Y thread

Posted: Tue Sep 26, 2017 12:41 am
by NZ_N57R
Thanks for the replies guys, very helpful!
That emissions control diagram is doing my head in! My truck's missing a lot of that stuff. It appears the the 4Y carb has a few more vacuum ports than the 3Y
Mud Dog wrote: Mon Sep 25, 2017 3:22 pm IIRC the 3Y used the same carb as the 4Y, just differently jetted. Same vacuum diagram should apply. The diagram above seems to be from a different spec vehicle than those we got here in RSA but not sure how yours compares.

Here is another one .....

4Y VACUUM HOSE iNFO.jpg
Mud dog, where the hoses appear to join up and form one line, do they actually do that? I think I might try and hook everything up in that fashion. My distributors an arse and has two vacuum ports. I read somewhere on here that you can block the rear line off and it acts the same as a normal vac advance.

Also, I've set my timing on the road (to detonate, then back a few degrees) When I put my timing light on it, it's showing up as 30 degrees BTDC, could this be because my harmonic balancer has shifted over the years? Surely it would detonate if it was 30 deg/BDTC.

Thanks all

Re: Chinese carburetors? Yet another 3Y thread

Posted: Tue Sep 26, 2017 2:57 am
by Mud Dog
The hoses don't form one line. There was a little branch manifold with three or four stacked tubes. IIRC my old 4Y dizzy had one port for the advance, but the 22R had two.

Re: Chinese carburetors? Yet another 3Y thread

Posted: Tue Oct 03, 2017 4:44 am
by NZ_N57R
Quick update; I got it running a lot better! I added an earth wire from the base of the carburetor to the head itself and she no longer dies when at idle under load (braking, with the lights on at night). I figured that the bolts through the manifold would be enough, but apparently not. May have something to do with my home made intake gasket!

Re: Chinese carburetors? Yet another 3Y thread

Posted: Tue Oct 03, 2017 3:10 pm
by Mud Dog
Yep, that earth is important - the idle solenoid valve and the choke both depend on it, but one doesn't always think of it when troubleshooting. One tends to think that the bolts are adequate but with a little corrosion in the aluminium thread of the manifold can lead to problems as you have been experiencing. Glad to hear that it's running better. :winkx:

Re: Chinese carburetors? Yet another 3Y thread

Posted: Thu Oct 05, 2017 8:33 am
by pietpetoors
Chinese jets tend to be very thirsty and require some modification (drilling and re-tapping) in order for the standard jets to be fitted. Any Carb specialist should be able to do this.
Insn't it easier to braze the jet and redrill to smaller size? ie same size as OEM jet?

Re: Chinese carburetors? Yet another 3Y thread

Posted: Thu Oct 05, 2017 8:59 am
by NZ_N57R
Thanks Muddog, it's been quite a mission. New plugs, leads, rotor and cap. Reconditioned carb, intake gasket gooed up with RTV, new voltage regulator and battery. She should be good for another 100,000 clicks. Has a bit of a tap to her in the top end but I'm pretty confident the 3Ys are bulletproof. Now to do some saving up so I can buy myself a beach/bush hack. An old 3y surf, or even a 2.4 turbo is on the cards.. Never enough money around ! :-)

Re: Chinese carburetors? Yet another 3Y thread

Posted: Thu Oct 05, 2017 9:37 pm
by Family_Dog
pietpetoors wrote: Thu Oct 05, 2017 8:33 am
Chinese jets tend to be very thirsty and require some modification (drilling and re-tapping) in order for the standard jets to be fitted. Any Carb specialist should be able to do this.
Insn't it easier to braze the jet and redrill to smaller size? ie same size as OEM jet?
The carb boys do something like this, drill out or braze the old thread and tap a new thread. The Chinese threads do not match the threads on the locally available jets.


-F_D

Re: Chinese carburetors? Yet another 3Y thread

Posted: Sun Oct 08, 2017 8:37 am
by NZ_N57R
Looks like I might be trying that Chinese carburetor business out after all. I thought I'd located the idle issue by regrounding the carb for the (idle?) solenoid. It seemed to make a difference, now it's back to its same old tricks. Maybe the idle solenoids burnt out? I'll pop the solenoid out tomorrow & test the bastard thing.

Other than that I don't know where else to start/keep looking.

Re: Chinese carburetors? Yet another 3Y thread

Posted: Sun Oct 08, 2017 9:37 am
by Mud Dog
I vaguely recall a thread from a good few years back where someone was having idle solenoid issues but the solenoid valve was working. Now if I recall correctly he traced it back to a relay behind the dash but I'm under the impression that the switching is triggered by a vacuum switch. Long time since I had my 4y, so it's all a bit fuzzy. :scratch:

Re: Chinese carburetors? Yet another 3Y thread

Posted: Mon Oct 09, 2017 5:10 am
by NZ_N57R
I've found via my multimeter that the solenoid with the pin has power all the time. seems to be working okay on a bench test. A weber carburetor or an EFI setup is looking more & more tempting. I can get a 3Y-E motor complete running from a surf with the EFI computer. I'm not sure how the fuel pump's set up on those, would one have to change the lift pump inside the tank too? Just throwing ideas around at this stage..

Re: Chinese carburetors? Yet another 3Y thread

Posted: Mon Oct 09, 2017 8:41 am
by Mars
It is very unlikely that you would need to replace the lift pump too. Just make sure that you have a fuel pump that delivers sufficient pressure for the injection rail.

Re: Chinese carburetors? Yet another 3Y thread

Posted: Sat Oct 14, 2017 6:35 am
by NZ_N57R
*Quick update*

After reading Muddogs comment about the solenoid relay playing up I decided to do more digging.. Turns out that little box was only sending out voltage when it was cold .. Or something..... :crazy: :crazy:

Anyway, I hardwired the anti-dieseling solenoid (the one on the rear of the carburetor, half way down, closest to the firewall) straight to ACC on the ignition, and to my ground I made up from the carburetor to the block.

Initial testing showing a drastic improvement of engine performance at idle. I have yet to take it for a long drive and tune her idle speed while warm (manual choke keeps the revs up when she's cold).

I hope this new information can help someone else, I assume this is a pretty common issue, not the first Y series motor that's done this to me... But it is the first one I've fixed! (maybe, sort of.. :D:) :dance1: :dance1: :dance1: