Possible Holley Carburetor troubles

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garyf
Posts: 187
Joined: Tue Jan 16, 2018 2:14 pm

Possible Holley Carburetor troubles

Post by garyf » Fri Jun 26, 2020 12:02 pm

Hi All

I have recently had rough running trouble with my standard Tiger Engine fitted with a replacement 350 CFM Holley carburetor which was fitted in around 2001.

The car was very reluctant to start (Not normal), ran very rough, wouldn't tick over and eventually broke down on me and wouldn't re-start :x

After investigation and finding nothing wrong apart from a strong smell of fuel in the Engine bay I assumed I had somehow flooded it.

After leaving the car for 20 minutes or so whilst I fetched a Gallon of fresh fuel it eventually started but again was running very rough and wouldn't tick over, I managed to limp the car the half a mile or so home and investigated further.

I still had a strong smell of fuel in the engine bay but couldn't see any leakage from the carb or fuel hoses/filter which I had recently changed.

Upon checking the oil level I was alarmed to find the dipstick showing the oil level way above the high mark!

I had somehow got about a Pint or so of Petrol in my engine oil. The only thing I could think that may have happened is I had got some muck or a sliver of rubber in the fuel system causing the Needle Valve to jam partially open?

When I broke down I mistakenly left the ignition on and fuel pump running for 5 or 10 minutes :? .

So I decide to remove the Needle valve to check it (Photo attached) I couldn't see anything jamming it and after a good spray of Carburetor cleaner it seemed to be shutting off correctly, the only thing that looked a bit iffy was the sealing 'O' Ring looked a bit shrunken?

After draining and changing the Engine oil and on replacement of the Needle valve the car started up 2nd turn of the key, ran on all 8 and was ticking over as smooth as ever once warmed up.

So, can anyone offer any advice what the problem may have been?

I've read that Ethanol can play havoc with old cars fuel systems and in particular any rubber components in the Fuel Pump or Carburetor, I've also read this modern fuel goes off a lot quicker than it used too, could it be with the Fuel being around 6 months old it had started to deteriorate?

I'm tempted to buy a rebuild kit for the Holley carb, which includes a new Needle valve and all the other components which may be affected by Ethanol in fuel, I have queried with the Holley carb technical department if all the rebuild components are Ethanol resistant and have been told they are.

Also Is it a straight forward job to rebuild a 2 Barrel Holley carb?

Any advice or comments welcomed.

Cheers

Gary
Attachments
Needle Valve.jpg
Needle Valve.jpg (175.96 KiB) Viewed 4232 times

garyf
Posts: 187
Joined: Tue Jan 16, 2018 2:14 pm

Re: Possible Holley Carburetor troubles

Post by garyf » Thu Sep 10, 2020 1:28 pm

Can anyone advise the best place to get a rebuild kit in the UK?

I've been told Mustang Maniacs and Realsteel

Had a reply off Mustang Maniacs for a Kit but it's not a genuine Holley Kit and I can't get an answer if the kit is Ethanol resistant or not?

Had a look on E-Bay and someone does list one but its £165 which seems excessive to me.

Any advice welcome please

tgr747
Posts: 54
Joined: Mon Apr 21, 2008 6:29 pm

Re: Possible Holley Carburetor troubles

Post by tgr747 » Sat Sep 12, 2020 10:51 am

Have you tried John Woolfe racing.

garyf
Posts: 187
Joined: Tue Jan 16, 2018 2:14 pm

Re: Possible Holley Carburetor troubles

Post by garyf » Mon Sep 14, 2020 10:04 am

tgr747 wrote:
Sat Sep 12, 2020 10:51 am
Have you tried John Woolfe racing.
I haven't, but I will now?

Thanks

garyf
Posts: 187
Joined: Tue Jan 16, 2018 2:14 pm

Re: Possible Holley Carburetor troubles

Post by garyf » Tue Sep 22, 2020 1:29 pm

Just ordered a kit from Mustang Maniacs, not a Genuine Holley Kit but supplied via Rock Automotive I'm led to believe, so hopefully reasonable quality and Ethanol resistant, I've given the Carburetor Model and Part Number so I just hope it fits.

A genuine Holley Kit was over 3 times the price of the Mustang Maniac Kit, 3 weeks delivery off John Woolfe Racing although kits are listed and available on E-bay.

Anyone rebuilt a Holley Carburetor recently and can they offer any words of advice?

Gary

garyf
Posts: 187
Joined: Tue Jan 16, 2018 2:14 pm

Re: Possible Holley Carburetor troubles

Post by garyf » Tue Feb 09, 2021 4:28 pm

Hi All

I finally Managed to pluck up the Courage to have a look at my Over fuelling problem recently, removing the 2 Barrel Holley Carburettor was straight forward, Air cleaner off then disconnected the Throttle and Choke connections, removed the Vacuum advance and Fuel pipes and blanked off the Fuel pipe.

Then 4 bolts to undo connecting the Carb to the Inlet Manifold and off it comes.

I had purchased a rebuild kit via Mustang Maniacs to suit this carburettor, however on strip down I found a problem with the Accelerator Pump parts.

In the Kit I had purchased you get a small ball bearing and retaining clip that fits under the Accelerator Pump Diaphragm, however my car is fitted with a Top hat rubber type blank, I've subsequently found out this is called check valve?

A quick E-Mail to Mustang Maniacs and they tell me this part isn't always in the kit!

Anyone I managed to source a couple of new ones for a few Pounds off a company called Customville American, a quick call and I got them via the post the next day, thanks Russ :D

So that's a job for the weekend to fit the Check Valve and then reassemble the Carburettor and refit it, I've already stripped it down and fitted new Power Valve, Needle Valve and cleaned up all Fuel ways and all mating surfaces, new Gaskets are in the kit.

I'm going to remove the Brass Float and check its not holed, I've not seen anything obviously wrong with all the old parts I've removed, no perishing of any rubber components on the Accelerator Pump Diaphragm or anything a-miss with the Power Valve. The only thing that looks a bit iffy is the Needle Valve sealing rubber seems to have shrunk, could this have been letting fuel by and over filling the Fuel Bowl maybe?

I'm going to reset the fuel level in line with the Holley instructions and hopefully when re-fitted the over-fuelling problem will be solved?

I hope so, or else I'm baffled what it can be, the only other possible problem is to high a fuel pressure, Holley recommend 6 PSI with a max of 7.5 PSI so I will have to check this if I still have issues with over-fuelling
7. Rebuild Kit.jpg
7. Rebuild Kit.jpg (112.78 KiB) Viewed 2149 times
when it's all refitted.

A few Photo's
Attachments
2. Old & New Power Valves.jpg
2. Old & New Power Valves.jpg (80.97 KiB) Viewed 2149 times
1. Old Check Valve.jpg
1. Old Check Valve.jpg (98.57 KiB) Viewed 2149 times
Last edited by garyf on Tue Feb 09, 2021 4:40 pm, edited 1 time in total.

garyf
Posts: 187
Joined: Tue Jan 16, 2018 2:14 pm

Re: Possible Holley Carburetor troubles

Post by garyf » Tue Feb 09, 2021 4:29 pm

Some more photo's
Attachments
6. Needle Valves.jpg
6. Needle Valves.jpg (135.76 KiB) Viewed 2149 times
5. Acel Pump Components.jpg
5. Acel Pump Components.jpg (124.08 KiB) Viewed 2149 times
4. Acel Pump Diapraghm.jpg
4. Acel Pump Diapraghm.jpg (204.84 KiB) Viewed 2149 times

garyf
Posts: 187
Joined: Tue Jan 16, 2018 2:14 pm

Re: Possible Holley Carburetor troubles

Post by garyf » Tue Feb 09, 2021 4:32 pm

Final few, If any one can advise any possible reasons why I've been getting the over fuelling trouble, and Fuel in my Oil I'm all ears? :roll:
Last edited by garyf on Sun Mar 07, 2021 5:22 pm, edited 3 times in total.

garyf
Posts: 187
Joined: Tue Jan 16, 2018 2:14 pm

Re: Possible Holley Carburetor troubles

Post by garyf » Tue Feb 09, 2021 4:34 pm

Valve block and Power Valve
Attachments
3. Valve Block.jpg
3. Valve Block.jpg (160.28 KiB) Viewed 2149 times

garyf
Posts: 187
Joined: Tue Jan 16, 2018 2:14 pm

Re: Possible Holley Carburetor troubles

Post by garyf » Mon Feb 22, 2021 2:37 pm

Final Instalment (Hopefully) on the Holley Carb troubles

I managed to re-assemble and refit my Holley Carb on Saturday, all pretty straight forward and I've replaced all the Major items, checked the Brass float is not holed, given everything a good clean and replaced all the relevant gaskets.

A bit of a scare initially when I switched on the fuel pump, with flooding yet again via the Float Chamber to the overflow at the top of the Carb, removal and resetting the Level and re-centring of the Needle Valve tip seems to have sorted it and the car started first turn of the key and ticked over smoothly with no Fuel leaks :D

I then re-checked the Float Bowl Fuel level again inline with the Holley Instructions and a slight adjustment needed to lower the float height to get the slight trickle of fuel out of the Site Hole when the car is rocked.

I let the car warm up thoroughly for 10 minutes or so and everything seemed fine, so hopefully my Flooding problems are now resolved.

As stated previously, I didn't find anything obviously wrong with any of the components I've changed apart from the shrunken 'O' ring seal on the old Needle Valve, this could possibly have been the problem all along, with it letting fuel by-pass the valve causing over-filling of the Fuel Bowl, with the overflow dumped into the inlet manifold via the overflow.

I will see how the car performs and if I do have flooding trouble again I will check the Fuel Pressure is no more than 7 PSI as recommended by Holley, if it is a Fuel regulator will be fitted, around £40 for a Holley regulator?

Cheers for now

Gary

garyf
Posts: 187
Joined: Tue Jan 16, 2018 2:14 pm

Re: Possible Holley Carburetor troubles

Post by garyf » Tue May 04, 2021 4:54 pm

Just a Quick update for anyone interested?

I took the Car for its M.O.T. Test recently and everything seems fine with the Carburettor :D , the Tick over was smooth with no Over-fuelling issues, a bit of a reluctance to start initially (I'd not started the car for a couple of months?) but once warmed up the car ran and pulled well.

I need to get out for a longish run when the weather warms up to be sure but it seems all the effort was worth while.

Regards

Gary
Attachments
M.O.T. Pass.jpg
M.O.T. Pass.jpg (99.29 KiB) Viewed 565 times

garyf
Posts: 187
Joined: Tue Jan 16, 2018 2:14 pm

Re: Possible Holley Carburetor troubles

Post by garyf » Wed Jun 09, 2021 9:47 am

A further update for anyone interested

I've been out in the Tiger a couple of times now and the flooding problem seems to be resolved (Fingers crossed), however I have noticed a slight Hesitancy/Hunting of the Engine on very light throttle, this occurs between 30-40 MPH on light throttle only, acceleration through the gears and cruising at 60-70MPH are both fine.

I don't know if this is something to do with the rebuild of the carburettor or possibly the Float Height, I'm going to have a look at the colour of the Plugs and also double check the Float height is correct.

Does Anyone have any ideas what might be causing this Light Throttle Hunting/Hesitancy?

Gary

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