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G16A conversion in Sierra, carby air filter clearance issue
https://auszookers.com/forum/viewtopic.php?f=5&t=37567		 Page 1 of 1
Author:  barnoon [ Wed Dec 05, 2012 7:51 pm ]
Post subject:  G16A conversion in Sierra, carby air filter clearance issue
Hi everyone, I have a G16A in my Sierra (bought the vehicle with the conversion already complete) the car hasn't been running too well (horrible idle, poor fuel consumption, coughing and spluttering on acceleration) so I put it in today to have a full carby rebuild. It now idles and starts PERFECT but the carby guy noticed it is starving for air as the Vitara carb is using the much smaller Sierra hat on the top of the carb, when you run the car without the hat on the carby it drives like a little rocket, no hesitation at all, as soon as the top hat is put back on it struggles and hesitates on acceleration.

The solution was to put a Vitara hat on it as its much larger, put one on tonight but the problem is with the Vitara hat on the bonnet won't close :(

Just wondering if anyone who has done the G16A conversion what solution you use for the air intake? Is there a way to make the Vit hat fit or do I need to somehow make the Sierra intake flow more air?

Thanks :D

Have attached a pic of the Vit hat installed on my car and the stock Sierra one sitting on top of it
Author:  joeblow [ Wed Dec 05, 2012 8:22 pm ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
You will find what is happening with the Sierra hat is that now the head is sitting higher the hose to the filter may be stretched. When you give it a boot full it may be sucking the hose in on itself. What carby are you running?
Author:  barnoon [ Wed Dec 05, 2012 8:26 pm ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
Thanks for the reply, I checked the hose and it doesn't seem stretched but sucking itself closed could very well be a possibility, not sure how to check it under load might have to go for a quick run around the block with the bonnet off lol. I'ts running the stock G16A carby, it has a plastic bottom on it not sure on many other details I can go get a pic of it if you like.
Author:  joeblow [ Wed Dec 05, 2012 8:39 pm ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
Are you running a spacer between the hat and carby? The Sierra hat will not seat correctly on top of the Vit carby.
Author:  barnoon [ Wed Dec 05, 2012 8:43 pm ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
yep its got a 10mm spacer which allows it to sit nice and snug, also the carb guy dynoed the car today 26kw of fury with the Sierra hat on and 33kw with no hat. So without the hat the power is around 20% more which will make a lot of difference on a car with such little power output.
Author:  christover1 [ Wed Dec 05, 2012 8:56 pm ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
There is adjustment in the bonnet hinges, may help.

Or power bulge in bonnet.

Sometimes it is only the cross bracing under bonnet that is catching.
You may be able to notch or similar.

Body lift?
Author:  JrZook [ Wed Dec 05, 2012 10:08 pm ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
Elongate/open up/re-drill the engine mounts will help sit it lower
Author:  barnoon [ Thu Dec 06, 2012 8:54 am ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
Will look into bonnet lift adjustment when I get home from work, from what I could tell yesterday I need about an extra 1.5 inches clearance to be able to close the bonnet, 2" body lift would be perfect but not cashed up enough for that route at the moment. Will also look into what I can do with the engine mounts to lower the engine slightly.

Does anyone know if there is a filter like on this Weber carby pictured below for the Vitara carb? just a small one that sits right on top of the carby.
Author:  JrZook [ Thu Dec 06, 2012 9:34 am ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
When you dyno'd was that just with the 1.3 hat ie not connected to the airbox? What did the AFR's look like when the power dropped? Rich or lean?
Author:  barnoon [ Thu Dec 06, 2012 9:37 am ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
I wasn't there when he dynoed it but from what he told me one run was with the 1.3 hat connected to the airbox and the other run was without the hat altogether, he said with the hat on there is a big restriction and it causes it to run really rich.
Author:  barnoon [ Thu Dec 06, 2012 9:39 am ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
When I run the car now with the 1.3 hat on it has so many flat spots and hesitation during acceleration, take the hat off and run no filter and it runs perfect.
Author:  JrZook [ Thu Dec 06, 2012 9:43 am ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
So your saying its not just the 1.3 hat it's the 1.3 hat/airbox/airfilter that's causing the issue?
Author:  barnoon [ Thu Dec 06, 2012 9:48 am ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
He seems to think that the 1.3 hat itself being so small compared to the Vit hat is causing all the problems, I spoke to him on the phone just then and he said if I can space the 1.3 hat up a further 5cm with a bit of PVC pipe or something it should fix my problem and allow more air to flow in the top of the carb, I'll have a good play around this weekend looking at all different options.
Author:  barnoon [ Fri Dec 07, 2012 8:58 am ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
Hmm well I tried spacing the 1.3 hat up a further 5cm with some pvc pipe and it didn't help at all, I guess the only solution will be lowering the motor / body lift with the Vitara top hat, or find a exposed performance filter that will sit directly on top of the carb, tried a unversal SAAS one this morning but the bottom hole on it was way too big.
Author:  JrZook [ Fri Dec 07, 2012 10:06 am ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
When you spaced the 1.3 hat up did you run it with only the hat connected ie no airbox/airfilter etc?
Author:  barnoon [ Fri Dec 07, 2012 10:21 am ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
Yep I tried it both connected to the airbox and just the hat itself not connected to the airbox. When connected to the airbox it won't rev over 4000rpm at all, when it gets there it just splutters and coughs and backfires constantly, without the airbox connected and just the top hat on it goes much better but it still splutters like crazy and coughs and farts, take the hat off altogether and she revs smoothly all throughout the rev range.
Author:  Zook_Fan [ Fri Dec 07, 2012 11:34 am ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
I had a 40mm spacer with a 2" body lift with the sierra top hat and airbox. I swapped over to the vit setup just because it swung the other way and in retrospect the engine did run better with the vitara airbox
Author:  barnoon [ Sun Dec 09, 2012 5:04 pm ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
Managed to get it to clear, took an angle grinder to the inner bracing on the bonnet and all is good now, car runs much better, thanks again for everyones advice
Author:  christover1 [ Sun Dec 09, 2012 5:14 pm ]
Post subject:  Re: G16A conversion in Sierra, carby air filter clearance is
I love a happy ending :)
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