HW 5200 Bogs at Midrange

[MercuryMarc]

The HW 5200 seems to be fine now that I have the vacuum leak fixed at the carb adapter, and the linkage is now set up nicely. Idles great. But when I accelerate from 30 mph to a faster speed, the car hesitates then picks up briskly. I seem to be abe to "feel" the secondary throttle plates open since the car really accelerates at a certain point, but just before that the car stumbles.
I am going to rebuild it - but anything else I should check for?
Thanks!

 

[powerband]

Merc Marc,

I have been participating in the discussion on the use of the H/W 5200/DFAV carb for some time and have had discussions with vendors and race carb builders concerning this mid range bog problem with no resolution. It's been bugging me for the past few weeks and I've been chasing my tail with jetting and ignition changes with no significant changes, (I can make it worse but not better). I found and puchased a NOS H/W 5200 setup for a 2.8 (170CID)V6 Capri because I want to see what the "stock" jetting was established for this application. I'll be posting the observations on the stock "economaster" for the 2.8 (170CID) V6 when I receive it..

Powerband

 

[gtm1086]

Try increasing the size of you accelerator pump nozzle a couple of thousandths

 

[mustang6]

Someone needs to use an Air/Fuel mixture gauge to get this figured out.

 

[MercuryMarc]

Thanks for all the comments.
Scott- do you bog, too?

 

[mustang6]

Yes, if I open the throttle fast I can feel it, slower rates of opening and it's less obvious. I've always wondered what the A/F ratios are through the range. I've been looking at those wideband O2 sensor gauges but they still aren't cheap.

 

[Redfalken]

Although my Falcon is exempt here in Washington state, I've considered paying the $14 to the testing station to have my emissions read someday. Just out of curiosity. I'll have to look in my files to see what kind of info I get on the printout when they test our `96 Ranger but I'm pretty sure they do A/F ratio.

Or maybe I don't want to know!!!

 

[powerband]

Bog problem data acquisition:

I posted previously that I obtained a brand new - old stock 5200 spec'ed for use by a 170CID (Capri 2.8 V6). I received it today and opened it up to see what what size jets it has.

Primary / Secondary
Idle Jets - 65 / 50

Air Bleeds - 190 / 180

Mains - 171 / 477 (Yes that's right 477) I guaged the 477 to @ .071" .

The '477' jet appears to be the on the largest end of the scale available and physically is much larger than any I've seen. There is some confusion (on my part) because there was a change from 'flow rate' to diameter in mm. and can be mixed. Can anyone convert .071" to mm?.

I don't have any time to install and try this jet setup for a while so I'm throwing this out for comment.


The NOS carb is actually disappointing because although 'brand new', is in poor shape from shelf storage and has significant Aluminum corrosion. It will need complete disassembly and carb kit before use. I will probably use the jets in my existing carb which is a fresh rebuild from Langdon's Stovebolt.

Powerband 8)

 

[Redfalken]

If 1 inches = 25.4 millimeters, then .071" should be 1.8034 mm.

 

[TheDude]

I also have been experiencing mid range bog with my Holley 5200. I suspected a vacuum leak at the carb so I redid the carb adapter and intake log gaskets but that did not help. As far as I know, my vacuum lines were hooked up correctly. I also suspect the choke but the Mustang has been put away for the winter so there will be no more test drives for a while. It might be time to rebuild the carb although it was bought from Stovebolt as a rebuilt unit.

 

[JackFish]

OK, I'll throw out some conjecture:
The secondary is designed to open at close to or WOT on little engines. I think that these things may run out of fuel before the transition phase gets to where the secondary becomes effective. You're getting as much performance as the tiny one barrel can put out and applying it to engines that are in some cases modified for better flow. I don't think they can put out enough gas.
Is anyone running one successfully? Maybe a larger power valve?
I have a 5200 to put on, but unless someone comes up with something here, I'm reconsidering a 2100, or the like.
Have to say, the 1946 I rebuilt works great on this engine but I want more power at the top end.

 

[MercuryMarc]

Looks like I am not the only one with these issues. My Holley 1940 carb with the larger diameter base opening (to fit my E0 head) works far better than my HW5200. After driving for a week with the HW5200, I am not very impressed. It is possible that I need to tune it better. I am tempted to put my old 1940 back on, but I want to wait and calculate my MPG afer a tank or two on the HW5200.

 

[Anonymous]

Looking at old 5200 on the bench today.Noticed that accelerator pump discharge nozzle for secondary was not drilled. NO pump shot to secondary. Max pump shot with linkage pin in bottom hole.Found clearance between pump actuating lever and cam on throttle shaft. bent lever to reduce clearance. Got more pump shot.

 

[powerband]

I won't be able to work on my car for a while but I'm follwing the discussion closely. Here's some more "conjecture" :

Discussion with Earl Parker of Nascar/Circle track carb notoriety leads me to a few conclusions:
I believe the accel pump does not sustain enough to solve the bogging problem. It isn't designed to do so - only to eliminate a quick stumble when hitting the throttle. Setting the pump cam to max (#3 position) is advised but didn't have any effect on my bog problem. ( the pump doesn't do anything at static positions = WOT) Also the idle port opening in relation to the throttle plate is critical on these carbs. You should see "a half moon" of it with the secondary closed. If some carbs bogged and some didn't this could be a symptom but since they all do = it probably isn't the cause. He advised a fuel pressure regulator as there supposedly is a problem with the needle valve being pushed open at high RPM's and mechanical pumps.

Mr Langdon of Stovebolt ..., cautioned me that his application of these carbs are for large displacement sixes but are used for multi-carb intakes. I would presume you could have synchronous linkage and depend on the individual 5200's progressive design for driveability. He did not claim any "knowledge base" in our use of single 5200 carbs.

I think the 2100-350 or XX??-500 CFM Holley's use a much different bolt pattern (bigger) but there are adapters . If you check these out on E-Pay or the web you will find the carbs are the standard for circle track use and widely available. I know some of the FSP members have them, I'd like to hear their results.

As a last resort, I wonder if I should drill out a spare jet for the secondary to say 2,5 mm and see if it has any effect . I have been toying with the idea of an Offy adapter with 3 5200's but the adapter I have won't fit the runners after @ 1973 (D7XX).

Powerband

 

[t-west]

Just out of curiosity, is everyone who has bogging troubles using similar jetting? Stock, or something that follows the suggestions here:

http://fordsix.com/forum/viewtopic.php? ... =weber+jet

I'm just curious if there's something obvious that we're all missing.

--tom