300/4.9L carburetion options for future project?

[1986F150Six]

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]

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.

[85lebaront2]

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.

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.

[1986F150Six]

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.

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]

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 - 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?

[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?

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.

[FuzzFace2]

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.

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 ----

[Ford F834]

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

 

[FuzzFace2]

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]

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 ----

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