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350 Holley dillemah


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#1 _Keithy's_UC_

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Posted 16 March 2006 - 11:41 AM

Hey guys,

I'm sure you've all heard my little problem before, but just thought i'd gather some opinions on the matter!!

I have a rebuilt 350 Holley on my 179HP and to be quite honest - it's running worse than when i took it in to get rebuilt in November.... I had all my choke gear on it (but disconnected and set up so she was running sweet), and after rebuild of the carby, noticed that my choke gear was no longer existant.

The car runs fine at idle, whilst driving at steady speed, or going flat out, but if i want to drive at 'average joe's' rate of acceleration, i have to either go granny or flat stick! It has a huge flat spot and i know for a fact that its not ignition or timing related. It is the carby as it was running sweet when i took the car in, but since has not had a day of great running. My coke gear has been removed, and i'm blaming it on that, but without adjustment of such, how can i get rid of the flat spot? I have booked the car in for a dyno tune and if i can find out what the problem is by myself, i'd be happier!

So its like this.... Granny drive - ok; Average throttle - flat spot (big one); 1/2 to full throttle - Beautiful! Even has the turbo whistle anything above the flat spot! I simply cannot diagnose this problem!!
HELP ME!!

Keith

#2 boomfunk

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Posted 16 March 2006 - 11:48 AM

no good to hear that !!

My 10 cents is that is sounds like it has an air leak somewhere, something may not have been blocked up when you removed the choke..

#3 _[BOTTLEDUP]_

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Posted 16 March 2006 - 02:05 PM

Sounds like an airleak of some sort... check the throttle shafts as well, and also the baseplate. How tight did you bolt it back down? They can crack very easily.

Holley's can be made to work successfully, tho they will always run 'richer' than an equivalent Weber, Varijet or the like, as they are not as efficient at atomising the fuel.

Stick at it, and I'd recommend buying a tech book on Holleys and learning how they work.

#4 tinkers

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Posted 16 March 2006 - 02:19 PM

Have a read of this thread on Performance Forums Click here
We used to have the pleasure of JMac's experience on here until the "wannabas & know-it-alls" got a bit much.

Might help or might be a good read :)

Oh and JMac doesnt know the meaning of "short answer" hehehe ;)

#5 Racehatch

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Posted 16 March 2006 - 02:45 PM

Nice links Tinks, I was wondering where he'd got to..... :spoton:

#6 _Keithy's_UC_

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Posted 16 March 2006 - 08:06 PM

Cheers for the advice fellas!

I actually had it done professionally, and fitted by the same 'carby specialist'! It was a performance carby shop, thats all they do, and this bloke for the life of him couldnt get it to run fine. Before it was rebuilt i tuned it myself and had no dramas whatsoever, i'm pretty spot on with the old holley, but this has me buggered!

I'm checking the 'click here' link now, thanks for that tinkers!!
I'll keep you posted if i find out what the prob is!!

Keith

#7 _draglc_

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Posted 16 March 2006 - 08:42 PM

Oh and JMac doesnt know the meaning of "short answer" hehehe ;)

U reckon!! im gonna send him an email, seems to be the guy to ask!

A1

#8 _Pete_

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Posted 16 March 2006 - 09:45 PM

I'm assuming the guy you've taken it to has checked stuff like the diaphram on the accelerator pump and made sure your running the correct power valve to suit your motor not just the one that came in the kit?

I tend to agree with the other guys concerning a vaccum leak somewhere, what type of dizzy and what kind of advance arrangement are you running? standard vaccum advance, full mechanical etc?

Sometimes theres silly things that can go wrong when in theory they shouldn't.

#9 _HB1200_

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Posted 16 March 2006 - 10:03 PM

I had a similar problem with a 350 holley on my 186. I stuck a vacuume gauge to the window while I was driving. I noted the vacuume when the flat spot started and when it stopped. I understood the readings as saying my power valve value was too low, I put one with a higher value and it fixed the flat spot. It may not be your problem but its easy and cheap to check.

#10 _Keithy's_UC_

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Posted 17 March 2006 - 11:25 AM

Cheers, might i ask where you get vacuum gauges from?? You simply plug it in at the base of the carby right??

Keith

#11 _HB1200_

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Posted 17 March 2006 - 05:06 PM

I screwed a tee conector into the inlet manifold intsead of the normal one the booster conects to so I could have both the booster and the vacuum gauge on at once.

#12 _Keithy's_UC_

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Posted 17 March 2006 - 05:30 PM

Ahh, a good idea! Can you run a vacuum gauge like a normal oil pressure gauge (i.e. all the time, set up like a fixed gauge)??

Keith

#13 _HB1200_

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Posted 17 March 2006 - 06:59 PM

You could but its only really necessary for tuning, I removed mine as soon as I had got the readings I was after.

#14 _Keithy's_UC_

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Posted 17 March 2006 - 07:59 PM

Oh ok, i've never used one before, thats all!! I have used a remote mounted tacho for tuning before, but not a vacuum gauge! Something new to learn i suppose!!

#15 barny_lx

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Posted 18 March 2006 - 01:33 PM

i have a vac gauge for sale keith, its Splitfire though.....

#16 _Keithy's_UC_

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Posted 18 March 2006 - 05:20 PM

Does brand really matter when it comes to vac gauges? They all say the same thing dont they??

Where do you live barny? I live in Townsville QLD. How much?

Keith

#17 _Bomber Watson_

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Posted 18 March 2006 - 07:50 PM

i have a vdo vac guage in the dash. it's cool, moves around a lot and gives my mates somethign to look at besides tits. also handy during tuning laps.

vdo vac guage: $44
2m of nylon hose for it (more than enough) $2

thats all you need, and somewhere to mount it.

i believe you will find that during your flat spot the vac will go to 0....

#18 _Keithy's_UC_

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Posted 19 March 2006 - 09:34 AM

That sounds alright! And by the vac reading going to 0, that means there is a manifold leak or something right??

Keith

#19 _UCV80_

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Posted 19 March 2006 - 11:04 AM

there is a box here filled with gauges, pretty sure there is a vac gauge, although im not sure its 100% going to work. dont see why it wouldnt.

or supercheap sells them for 25 new?

,nathan

#20 _Keithy's_UC_

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Posted 19 March 2006 - 03:11 PM

Cool, i'll have to get myself one when i get home... I will post up the problem when i have sorted it out....




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