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Got my Fentons on now need Carb tuning advice
#1081232 Sat Jan 24 2015 11:33 PM
Joined: Feb 2001
Posts: 1,130
D
Dusty Offline OP
Shop Shark
I have added Fenton exhaust with intake manifold heat pipes, I have kept the standard intake manifold and single carb (Zenith).

The Fentons are definately doing something , as now I have the horrible bog off idle. It was running great with the original exhaust manifold.

Is there something tuneable in the Zenith to cure this, or do I need dual carbs also.

Last edited by Dusty; Sat Jan 24 2015 11:33 PM.
Re: Got my Fentons on now need Carb tuning advice
Dusty #1081235 Sat Jan 24 2015 11:40 PM
Joined: Sep 2001
Posts: 30,337
ace skiver

Did you adjust the carb's air/fuel mixture?

If not, do you have a vacuum gauge?
Set the idle speed and then adjust the mixture to maximum vacuum.
Then, if necessary, reset the idle speed, and then the mixture.

Did you set the timing (to maximum vacuum at idle)?


Tim
1954Advance-Design.com [1954advance-design.com]
1954 3106 Carryall Suburban [stovebolt.com] - part of the family for 49 years
1954 3104 5-window pickup w/Hydra-Matic [1954advance-design.com] - part of the family for 15 years
- If you have to stomp on your foot-pedal starter, either you, or your starter, or your engine, has a problem.
- The 216 and early 235 engines are not "splash oilers" - this is a splash oiler. [chevy.oldcarmanualproject.com]
Re: Got my Fentons on now need Carb tuning advice
Dusty #1081236 Sat Jan 24 2015 11:43 PM
Joined: Feb 2004
Posts: 20,885
H
Boltergeist
That's the price you pay for eye candy. The dual manifolds can't provide enough heat to the intake to keep the mixture atomized, even with the "heat" tubes. Unless you're planning to run wide open throttle and high RPM most of the time, the dual exhausts are a big mistake. You could jet the carb way over-rich and hope you keep enough fuel atomized to cure the bog, but gas mileage will suck and you'll carbon-foul spark plugs regularly. Dual carbs will make the problem worse, not better.
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: Got my Fentons on now need Carb tuning advice
Dusty #1081239 Sun Jan 25 2015 12:02 AM
Joined: Sep 2001
Posts: 30,337
ace skiver

The heat tubes and plate work fine on the three engines that I have used Fenton dual headers on. My carbs (duals or single) seem to be well matched to the engines and my gas mileage is better, unless I step down on the accelerator.

Before you give up, Dusty, how did you adjust your carb and timing?

What size engine do you have?
What size engine did the Zenith come from?


Tim
1954Advance-Design.com [1954advance-design.com]
1954 3106 Carryall Suburban [stovebolt.com] - part of the family for 49 years
1954 3104 5-window pickup w/Hydra-Matic [1954advance-design.com] - part of the family for 15 years
- If you have to stomp on your foot-pedal starter, either you, or your starter, or your engine, has a problem.
- The 216 and early 235 engines are not "splash oilers" - this is a splash oiler. [chevy.oldcarmanualproject.com]
Re: Got my Fentons on now need Carb tuning advice
Dusty #1081271 Sun Jan 25 2015 02:09 AM
Joined: Nov 2010
Posts: 1,189
W
Shop Shark
My truck runs just fine with the heat tubes installed,too. If you need more heat,Patrick's,(in the "Bolt" "Links" section), sells a kit for water heat,that's plumbed to the water pump. Their kit instructs how to plumb the intake.You may have over-looked a vacuum line,or maybe didn't get it tight enough?? Sounds more like a vacuum leak than a carburetor problem,if it ran good before the "Fenton's" were installed. I agree with Jerry 99% of the time,but I LIKE the sound of the "Fenton's",PLUS I gained better gas mileage,(1 Rochester B),and better performance! Hope this helps.

Last edited by wetwilly5757; Sun Jan 25 2015 02:14 AM.

Just sold: 1955 2nd Series 6500 2-Ton Flatbed Truck
Mo' Tater
In the Stovebolt Gallery
More pics and videos on Photobucket

It takes an awful big dog to weigh a ton.
Re: Got my Fentons on now need Carb tuning advice
Dusty #1081275 Sun Jan 25 2015 02:18 AM
Joined: May 2006
Posts: 8,490
L
Master Gabster
Are you sure you're thinking of Patrick's? I'm pretty sure that Patrick's kit is for exhaust heat, and that Langdon's is the one that has the water heat kit.
For the record, I'm using exhaust heat for mine. Made my own plate and tube kit using a stainless plate and 3/8" brake line. Plus, the headers and tubes are wrapped with Kevlar header wrap to keep the heat in. I don't have any issue with a bog on acceleration.


Bill Burmeister
Re: Got my Fentons on now need Carb tuning advice
Dusty #1081281 Sun Jan 25 2015 02:29 AM
Joined: Feb 2001
Posts: 1,130
D
Dusty Offline OP
Shop Shark
Thanks for your thoughts guys.

tc , I adjusted the idle mixture and the timing a tiny bit on my 216 and have 20" vac the engine starts perfect and the hot tubes get REALLY hot , maybe I could try lagging the tubes. I have no idea what the Zenith is off. I just threw it on the engine (4 yrs ago) 'cause the original W-1 was weeping bad .

A pic of it is here http://www.jalopyjournal.com/forum/threads/dustys-truck-stuff.908428/page-3

Jerry , I do so hope you are wrong about this issue.


Last edited by Dusty; Sun Jan 25 2015 02:32 AM.
Re: Got my Fentons on now need Carb tuning advice
Dusty #1081308 Sun Jan 25 2015 03:32 AM
Joined: Feb 2004
Posts: 20,885
H
Boltergeist
OK- - - -I see part of the problem- - - - -the tubes between the manifolds and the heater plate are far too small, unable to flow enough volume of exhaust gas to keep the intake plenum hot. Try to increase the tubing size to 1/2" (12 MM maybe?) so enough gas can flow under the carb to keep the mixture atomized. If the Zenith carb was performing OK with the stock exhaust there's no reason to believe it can't function as well with duals. Unless you can find some VERY small carbs for a dual setup, the bog will get much worse. Most people seriously over-carburete a twin carb engine.
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: Got my Fentons on now need Carb tuning advice
Dusty #1081332 Sun Jan 25 2015 05:12 AM
Joined: Sep 2001
Posts: 30,337
ace skiver
Dusty,

Your tubes look like the 1/2" malleable metal tubes on one of my engines. I use same sized 1/2" copper tubing on another engine.

Did you adjust your timing and carb mixture to maximum vacuum, using a vacuum gauge?

What size engine are you working with?

A Zenith carb from a 228 would be significantly different from a 270 or a 302 (and maybe even a carb from a 248 would be too much carb).


Tim
1954Advance-Design.com [1954advance-design.com]
1954 3106 Carryall Suburban [stovebolt.com] - part of the family for 49 years
1954 3104 5-window pickup w/Hydra-Matic [1954advance-design.com] - part of the family for 15 years
- If you have to stomp on your foot-pedal starter, either you, or your starter, or your engine, has a problem.
- The 216 and early 235 engines are not "splash oilers" - this is a splash oiler. [chevy.oldcarmanualproject.com]
Re: Got my Fentons on now need Carb tuning advice
Dusty #1081346 Sun Jan 25 2015 05:55 AM
Joined: Feb 2001
Posts: 1,130
D
Dusty Offline OP
Shop Shark
Thanks for your thoughts Jerry , TC.

The engine is 216 standard.

The heat tubes are 3/8" dia, the manifolds came threaded for the brass fittings I have used.

I will see if I can increase the size to 1/2"

Yes TC, I used a vac gauge to get max vacuum.

The only ID on the Zenith is 20 on the throttle housing.

I have always run the timing on the ball , but today I advanced it 2 deg on the octane selector (91 octane fuel) got another 1" on the vac gauge , it has improved a bit , but I think the heat makes more difference. I will try to find some 1/2" fittings and tube.

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