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300/4.9L carburetion options for future project?

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1986F150Six

300/4.9L carburetion options for future project?

Administrator

Earlier this week in the WHYDTYTT forum [page #99], Gary posted photos of a CLIFFORD 2 X 4 intake manifold with adapters which work with Motorcraft 2100 or 2150 carburetors.

This manifold was an "impulse" purchase, as I have been driving for over 10 years with the stock log intake and a Carter YF. It is a NOS unit and I wanted an opportunity to preserve it.

As I approach retirement and will not depend on having the truck at the "ready", it is possible that the manifold might be experimented with. If so, since the engine is still quite healthy, the intake manifold and probably F.I. exhaust manifolds will be swapped for the stock system on the stock engine [Duraspark conversion already done, since 1986 was feedback].

What carburetors are suggested?

Gary Lewis

Re: 300/4.9L carburetion options for future project?

Administrator

I don't have a lot of experience with different carbs, so won't have a lot of "recommendations". However, I do have a lot of "thoughts" that I'm more than happy to share.

First, let's document here, as I did in the other thread, the difference in CFM ratings for 1 & 2bbl carbs vs 4bbl carbs. The 1 & 2bbl carbs are rated at 3" of vacuum, while the 4bbl's are rated at 1.5" of vacuum. So to convert a 2bbl rating to a 4bbl you divide by 1.414, and to convert a 4bbl rating to 2bbl you multiply by 1.414.

Let's take an example. The YF on your truck is supposedly rated at 196 CFM at 3" of vacuum. But if we want to compare to a 4bbl we'd divide by 1.414 and get 139 CFM. Or, to go the other way, one of the smallest 4bbls available is a 450 CFM, and multiplying by 1.414 I get 636 CFM.

But a 4bbl is usually progressive, meaning you run on the primaries and only open the secondaries when needed. Let's assume the primaries are 40% of the overall capability of the carb. That means the primaries on the hypothetical 4bbl would be rated at 180 CFM, which is ~1.3 times that of the YF 1bbl's rating of 139 @ 1.5". So the primaries of two of the little 4bbl's would be 360 CFM, and that's ~2.6 times the rating of the single YF currently on your engine.

But what if we just went with two of the 1.08" 2150's? They are rated at 287 CFM @ 3", so each one of them is ~1.5 times that YF, and therefore two of them are almost 3.0 times the rating of the YF. In other words, the "little" 2150's are even bigger than the primaries of a small 4bbl.

You want to keep the velocity through the venturi up in order to get crisp throttle action, so I worry a bit about two 2150's. But I've read that the 2100's were available in even smaller sizes.

However, that brings me to the big difference between most 4bbl carbs and most 2bbl carbs - the 4bbl's are usually progressive and the 2bbl's usually aren't. So, if you could find 2bbl carbs that are progressive then you could have your cake and eat it too. Or, two small 4bbl's actually give you a bit less CFM capability in the primaries than a pair of small 2150's.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

85lebaront2

Re: 300/4.9L carburetion options for future project?

Administrator

You would need another pair of adapters, but, the Pinto 2.0 and 2.3L engines came with Holley/Weber progressive two barrels as did the first round of Mustang II V6 engines. On the Ford versions, they are mechanical secondaries with no cold lockout provision. Chrysler used a vacuum secondary style on the 2.2L engines.

Pros and cons:
Ford pro, all jets are removable and easily changed for tuning.
Ford cons, water heated choke, mechanical secondaries.

Chrysler pros, electric choke, vacuum secondary
Chrysler con, idle (low speed) jets are not removable and plug easily.

Rochester built a progressive 2 barrel used on the last of their in-line sixes (250/292) and the 2.5L 4 cyl engines in the 80s, it is an odd bolt pattern and not as easily tuned as the Holley/Weber carbs. It has a Quadrajet style air valve on the secondary.

Two of the smaller 2100 carbs from the 2.8L and 3.8L V6 engines could be a good choice. One item for consideration, this manifold probably does not include a heat provision and may be very cold natured.

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

1986F150Six

Re: 300/4.9L carburetion options for future project?

Administrator

What about making an adapter plate and using a 2nd Carter YF? Perhaps a sheet metal shield(s) could be attached to the exhaust manifolds to direct heat towards the underside of the intake.

Gary Lewis

Re: 300/4.9L carburetion options for future project?

Administrator

In reply to this post by 85lebaront2

Bill - That's good info.

Is the Holley the 5200? There's a lot of info out there on it, including this thread on the Classic Opel Community. In it is this info:

Most models primary venturi diameter is 26mm and the secondary is 27mm. Throttle bore diameters are 32mm and 36mm with a 43mm center spacing on a metric flange. The stud spacing measures 47mm x 93mm.

When introduced, this carburetor only came in one size, 270CFM at three inches of mercury. In 1978, a 235CFM model was introduced on Ford and Mercury 4-cyl. engine with a 23mm primary venturi and 27mm secondary. Since 1979, Chevettes have been equipped with a 245CFM model with primary and secondary venturis of 23mm and 29mm.

Assuming using the standard 26/27mm venturi and 270 CFM @ 3", the primaries would be rated at probably something like 125 CFM. So two of them would give you a total of 250 CFM, and that's a reasonable bump up from the 196 of the YF. Then, when you are "on it" you'd have a total of 540 CFM available, which is more than adequate.

So, to your cons, the mechanical secondaries would just be something the driver would learn to live with. But the chokes could have the heater hose, or a branch thereof, looped through them. Yes?

Gary, AKA "Gary fellow": Profile

85lebaront2

Re: 300/4.9L carburetion options for future project?

Administrator

Yes, that was what Ford did on the Pintos and they are, as I mentioned very tuneable as even the emulsion tubes can be switched. Suggestion would be prowl junkyards for some, pick up several, just try to get at least two that are the same. Others will be for spare jets etc.

Bill AKA "LOBO" Profile

FuzzFace2

Re: 300/4.9L carburetion options for future project?

Holley makes a 390 CFM v4 vacuum secondary carb that the Jeep / AMC 258 six guys use.

Holley also makes a model 2300 v2 carb in a 350 CFM & 500 CFM. This is the bolt on for the MC 2100 / 2150 carbs.
The 500 CFM is a little much for the 258 six but when you have one on the shelf that's what you use.

My son did have 2 of the Webber / Holley carbs you talk of on his Jeep before the 500 CFM but we could not get them to run right and why the 500 went on. This is also the carb Clifford sells with his kit.

I think if I could get the Webber / Holley carb to work run right would be the way to go but I have tuning parts for the Holley 5200 and would try the 350 CFM carb.

Then again with all the stock "logs" out there maybe try my hand at 2 or 3 stock YF carbs :)
You would not need to weld them together just the 2 end ones to close them off and use hose & clamps to join them together, don't they do this on some of the bike carbs?
You could even make water heat plates under each carb to plumb hot water to the intake.

Then again I like KISS and why a kept the stock carb and only went with EFI exh. manifolds.
Dave ----

Dave G.
81 F100 flare side 300 six / AA OD / NP435 / 2.75 gear
http://cars.grantskingdom1.com/index.php/1980-Ford-F100?page=1
81 F100 style side 300 six/SROD parts truck -RIP
http://cars.grantskingdom1.com/index.php/1981-Ford-F100

Ford F834

Re: 300/4.9L carburetion options for future project?

Administrator

In reply to this post by 1986F150Six

I am following this with keen interest but not a lot to add in terms of knowledge. David, do you have any information on the Webber carbs that Clifford usually sells with this manifold when ordered as a kit? Not that you necessarily want to go that route but it would be something to compare with besides the stock YF. I started a Facebook thread with the inline six group and learned a thing or two about the HD manifold. It’s a bit off topic here, but I will summarize and start another thread for it this evening. One other carb option that I have seen run as multiples are reproductions of the old Stromberg 97. There are progressive linkages made, and they are often sold in pairs or threes. I know very little beyond that... but I thought I’d throw it out there as another option. The have a 3 bolt base, so you would need to adapt them a little...

https://www.speedwaymotors.com/Primary-9-Super-7-3-Bolt-2-Barrel-Carburetor-Plain-Finish,24691.html?sku=91511655&utm_medium=CSEGoogle&utm_source=CSE&utm_campaign=CSEGOOGLE&gclid=EAIaIQobChMIuITM89yZ5AIVEttkCh3HDQzvEAQYByABEgI5CfD_BwE

https://www.summitracing.com/parts/sbc-9241s-chr?seid=srese1&gclid=EAIaIQobChMIuITM89yZ5AIVEttkCh3HDQzvEAQYASABEgJFFPD_BwE

SHORT BED 4-DOOR DIESEL: 1986 F350 4x4 under construction-- 7.3 IDIT ZF5+GVOD

STRAIGHT SIX 4X4: 1981 F150 2wd to 4x4-- 300 I6 close ratio diesel T19, hydroboost brakes, Saginaw steering

BIG F: 1995 F-Superduty under construction— converting to 6.9L IDI diesel ZF5+DNE2

FuzzFace2

Re: 300/4.9L carburetion options for future project?

Ford F834 wrote

I am following this with keen interest but not a lot to add in terms of knowledge. David, do you have any information on the Webber carbs that Clifford usually sells with this manifold when ordered as a kit? Not that you necessarily want to go that route but it would be something to compare with besides the stock YF. I started a Facebook thread with the inline six group and learned a thing or two about the HD manifold. It’s a bit off topic here, but I will summarize and start another thread for it this evening. One other carb option that I have seen run as multiples are reproductions of the old Stromberg 97. There are progressive linkages made, and they are often sold in pairs or threes. I know very little beyond that... but I thought I’d throw it out there as another option. The have a 3 bolt base, so you would need to adapt them a little...

https://www.speedwaymotors.com/Primary-9-Super-7-3-Bolt-2-Barrel-Carburetor-Plain-Finish,24691.html?sku=91511655&utm_medium=CSEGoogle&utm_source=CSE&utm_campaign=CSEGOOGLE&gclid=EAIaIQobChMIuITM89yZ5AIVEttkCh3HDQzvEAQYByABEgI5CfD_BwE

https://www.summitracing.com/parts/sbc-9241s-chr?seid=srese1&gclid=EAIaIQobChMIuITM89yZ5AIVEttkCh3HDQzvEAQYASABEgJFFPD_BwE

No I don't have any information on the Webber carbs.

I don't know where my son got them (2) from but what I remember they were newish looking.
He might have bought a kit to replace the old carb on his Jeep, there are places that sell this to the Jeep crowd.
Think we rebuilt 1 of them but with both I could not get them to idle right for some reason?

I do think if we could have gotten it to work that was the way to go.
As Gary pointed out with the small primary would be like the stock YF till you kicked it in the azz.

The other thing that has to be kept in mind is the intake manifold.
If the passages are to large the flow will be slower and the fuel will drop out of the air and pool on the floor of the intake manifold causing issues.

As they say it is the whole package that has to work together.
Dave ----

Ford F834

Re: 300/4.9L carburetion options for future project?

Administrator

So from what I am gathering, the Clifford dual intake is sold with a pair of Weber 38’s. It is rated at 390 cfm with 2.5 inches of depression, which calculates to 302 cfm at 1.5 inches. They are a progressive 2 barrel. I don’t know what the cfm of just the primaries would be, but there are some specifications here:

http://www.lcengineering.com/LCTechPages/pdf/38DGAS.pdf

85lebaront2

Re: 300/4.9L carburetion options for future project?

Administrator

They may be progressive, but the external gear system would concern me getting crud in the teeth and sticking. The Pinto and Vega ones use a link to open the secondary throttle shaft. The Chrysler ones use a vacuum diaphragm to open the secondary. These can be synchronized with a small vacuum hose linking the vacuum diaphragm housings (like Ford did on the 427 setups).

Bill AKA "LOBO" Profile

Ray Cecil

Re: 300/4.9L carburetion options for future project?

Going to follow this thread. Ive had the idea of doing a 300 3 Pack. 3 singles. Each feeding 2 cylinders. But I am unsure about velocity, and sizing. If I ever find two more stock 300 intakes, maybe Gary or Dave or anyone else with more carb knowledge could recommend the proper carb.

1988 F250 Supercab Longbed 7.3 IDI, C6, 1356, GEARVENDORS, 4.10 Sterling with autolocker

1986 F150 302, C6, 9" 2.75, Wood Flatbed

Gary Lewis

Re: 300/4.9L carburetion options for future project?

Administrator

The "proper carb" for a 3-carb setup is very similar to those for a 2-carb setup, only maybe smaller if that is possible.

Carb sizing can be summarized by two limiting factors: the carb must be small enough that at off-idle conditions the throttle response is still good. Too big of a carb will cause a bog or a soft feeling just off idle. But, too small of a carb will limit performance at high RPM.

That would seem to be a hard problem to solve, but fortunately we have progressive carbs, meaning ones that run on a smaller primary and then open up the secondaries when needed. Some Webers are that way. The Holley/Weber that Bill mentioned is. And most 4bbl carbs are, although it is very unlikely that you can find a small enough 4bbl to work properly with a 100 cubic inch engine, which is what you'll have with 3 carbs on a 300.

And, speaking of that, if you cut up three manifolds as I think you are suggesting, you will have three separate engines connected by a crankshaft. And that's a slightly different problem to solve than the Clifford manifold that serves all six cylinders from two carbs. In the two cylinder case the carb will see only those two cylinders and the pulses will be strong and widely spaced. But with the Clifford manifold there will always be six pulses to the carbs, although each carb will see three moderate pulses and three weaker pulses.

The issue is the start/stop that strong pulses try to invoke. Fuel has a significant mass to it when compared to air, and because of that it is harder to tune a carb that sees really strong pulses than it is a more even set of pulses.

Gary, AKA "Gary fellow": Profile

Ray Cecil

Re: 300/4.9L carburetion options for future project?

Gary, the plan was to use three center sections, and tie them together with steel pipe so that it is one manifold.

So, are the dual webers that clifford uses progressive?

Maybe I cant find the right carb for a 300 3 pack. But Id like to keep trying before just throwing clifford money.

1988 F250 Supercab Longbed 7.3 IDI, C6, 1356, GEARVENDORS, 4.10 Sterling with autolocker

1986 F150 302, C6, 9" 2.75, Wood Flatbed

Gary Lewis

Re: 300/4.9L carburetion options for future project?

Administrator

The Webers I see in Clifford's kit are the 38/38 DGAS, and this Redline writeup says they are synchronous, which means both throttle plates open at the same time. It would be the 32/36 DGEV carb for progressive linkage.

I don't know why Clifford is using those carbs, but they've probably done a lot of research and I haven't, so I'll bet it works.

As for yours, I think joining the sections with pipe is a good idea as it will smooth out the pulses. Sorry, I missed that.

I'm still thinking the progressive Holley/Weber 5200's have merit. Bill suggested them and the info I've found looks promising.

Gary, AKA "Gary fellow": Profile

85lebaront2

Re: 300/4.9L carburetion options for future project?

Administrator

Ok, further thoughts, partially for Ray Cecil. Ray, being a brand C type you are probably aware that the original potra-potty's (Corvettes) were 235 ci 6 cyl engines, called "Blue Flame" and were a slightly higher compression hotter cam version of the standard Chevrolet 235 engine. These had 3 one barrel carburetors, but due to the height of the engine and the low hoodline of the Corvette, they used a Marine carburetor, modified to a hand choke. The choice was the Carter YH, which is essentially a Carter YF on it's side.

These were probably the size of the Rochester B one barrel, just three of them. The intake did have equalizer passages between the three intake ports (235 had a design with square and rectangular exhaust ports and round intake ports, all were paired except the end exhaust ports which were single. On the Blue Flame, there were split exhaust manifolds and dual exhausts.

On a truck where there is plenty of clearance over the engine, I would expect that 3 singles could be fitted with out a problem and if three EGR spacers were used a maybe 1/2" ID balance tube between them would work unless you wanted them progressive in which case you would be better off simply adding the flanges like the performance kits for the small Ford sixes with the integral manifold used.

On the Clifford intake, two 32/36 DGEV carbs would be my choice for new, the Holley Webers from Pintos, Vegas or Mopars would be a good alternate.

Bill AKA "LOBO" Profile

Ray Cecil

Re: 300/4.9L carburetion options for future project?

Bill for the WIN!!

I hadnt thought about the 53 vette blue flame! Dad had a 59 vette 283.

Anyway, i like where this is going.....

1988 F250 Supercab Longbed 7.3 IDI, C6, 1356, GEARVENDORS, 4.10 Sterling with autolocker

1986 F150 302, C6, 9" 2.75, Wood Flatbed

Gary Lewis

Re: 300/4.9L carburetion options for future project?

Administrator

In reply to this post by 85lebaront2

85lebaront2 wrote

On the Clifford intake, two 32/36 DGEV carbs would be my choice for new, the Holley Webers from Pintos, Vegas or Mopars would be a good alternate.

Yes, Bill for the win!

I like the idea of the 32/36 DGEV's, but they are pricey. So the Holley/Webers would be a good option as they should be available from a salvage. But, as Bill said previously, get several of them to have parts.

Gary, AKA "Gary fellow": Profile

1986F150Six

Re: 300/4.9L carburetion options for future project?

Administrator

In reply to this post by Ray Cecil

The 2 X 4 Clifford intake and adapters will be at the Garagemahal Truck Show so it can be looked at, by anyone interested.

grumpin

Re: 300/4.9L carburetion options for future project?

“the original potra-potty's (Corvettes)“

Wow, Bill! Never heard that term before!

Dane
1986 F250HD SC XLT Lariat 4x4 460 C6-Sold
1992 Bronco XLT 4x4 351W E4OD
1998 GMC Sierra SLE K1500 350 4L60E
Arizona