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Big six 2v conversion- halfway finished

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motzingg
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Big six 2v conversion- halfway finished

Post #1 by motzingg » Thu Aug 22, 2013 12:41 pm

Hey y'all, finally posted up my progress on the 2v conversion in my build thread on fordification.

I know lots of ya are on both sites, but i'm looking for some '6 specific' advice from anyone who has done this, or if you're just interested in what i'm doing, check it out.

http://www.fordification.com/forum/viewtopic.php?f=22&t=71650&start=15

The questions i have in the last post there on page two are basically this:

what should i do about turning the 2 venturii into one big dopey-shaped venturii?

Anyone that could post or direct me to pics of what they've done would be much appreciated... I spent a fair bit of time digging around the internet and forums and couldn't find much evidence from others doing this.

I'm going to machine the adapter plate tonight so i'm curious if you think i should be putting the two venturii all the way down to the hole or carrying the big hole up into another adapter/spacer hand ground for a good transition.

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Re: Big six 2v conversion- halfway finished

Post #2 by rpatt1 » Fri Aug 30, 2013 10:42 pm

If you look on the Classic Inlines store/tech page (associated with this forum) and take a look at the direct mount 2 barrel carb conversion heads for the small ford six - you will see they simply have an open adapter into an open 'hogged out' factory one barrel intake log - similar to what you have done.

I see no reason why the same approach would not work in your big six project. You can try the 'open adapter to open plenum' approach first and see if you like how it works. If after you test your first design and you think there is room for improvement - you can always buy or make the separate venturi two barrel spacer and try it later too!

Good luck,
Rusty.

motzingg
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Re: Big six 2v conversion- halfway finished

Post #3 by motzingg » Thu Sep 05, 2013 10:06 am

More questions and an update! Hopefully y'all read this and someone can help me out.

First the update: The adapter block is fab'd and mounted, everything fits and lines up and i'm pretty darn proud of myself. After screwing it up 3 times (not so proud of that) I finally was able to get the holes lined up.

You can see from the picture what i did to make it work. I tried bolting it right on to the casting by drilling/tapping holes in the cast iron, that didn't go so good. The only hole i drilled had about 1.5 threads worth of meat behind it... bummer. So I decided to use the 3 3/8" bolts holding the exhaust and intake manifold together, and run a bolt down to grab a couple threads from the one that is to the outside.

This was not a bad idea, but the plane that the carb sits on is angled at 6 degrees, so i had to drill the bolt holes at an angle, and the bolt holes are not symmetrical so the first screw up was making the plate upside down, the second screw up was making it backwards, and the third screw up was drilling the holes at the backwards angle... grrrr.... Finally at about 9 pm I came out of the shop with this:

Image

Aside from the minor problem that the throttle linkage doesn't clear (I'll get the spacer machined out tonight or tomorrow, aluminum this time!) Everything worked out pretty well. There is just barely enough gasket clearance to make it work.

On to the carb rebuild- The 2100 that i have was in kinda rough shape when i got it. Aside from standard crustiness, some of the screws were stripped, one of them was completely stripped out, and some things are different/weird from the diagram that came with the carb kit.

For one thing the cylindrical check ball weight that goes under the screw that retains the fuel discharge nozzles was missing. I'm not 100% certain, but i'm pretty sure there were 2 check balls stacked up on top of each other. Is that factory, or an acceptable kludge? If not, i'd love to buy or make one of those weights if anyone could provide me with the dimensions. There was a cylinder thingy in the rebuild kit but it is way way too big. The hole i'm working with looks like a 10-24 and the weight i have is much bigger.

The other thing i'm missing is the little metal tab that goes under the head of that screw, they refer to it as an air spreader i think.

Anyhow, the parts in question are 33 and 30, respectively, on the following diagram: (sorry i cant embed, stupid 600 pixels for people viewing this on a 13 inch CRT monitor.)
http://www.carburetorfactory.com/expvw07.html

If anyone could help me out, that would be awesome. I'm thinking I'll put it back together with out the air spreader and 2 check balls instead of a weight, but if it doesn't run right, then i'm really up a creek as i've added new kludgy variables to the equation.

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Re: Big six 2v conversion- halfway finished

Post #4 by Harte3 » Thu Sep 05, 2013 10:24 am

DIY development of an idea can sometimes be frustrating but perseverance rewards in the end. That looks like a nice piece of work :thumbup:
'83 F150 300, 0.030 over, Offy DP, Holley 4160/1848-1 465 cfm, Comp Cam 260H. P/P head, EFI exhaust manifolds, Walker Y Pipe, Super Cat, Turbo muffler, Recurved DSII, Mallory HyFire 6a, ACCEL Super Stock Coil, Taylor 8mm Wires, EFI plugs.

motzingg
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Re: Big six 2v conversion- halfway finished

Post #5 by motzingg » Thu Sep 05, 2013 10:44 am

yep, thanks! if there is a way to do it myself that requires 3 times the effort and twice the expense of paying/purchasing it from someone else, i almost always choose to DIY.

this actually would have been a pretty tidy 3 hour job if i had gotten it right the first time.

I actually drew prints for all this stuff and could produce these things, but it would be well over 100 bucks plus shipping the manifold back and forth, not exactly a bargain compared to the cost of a Offenhauser which is nice aluminum and bolt-and-go.

I'm hoping that the stock manifold maintains better fuel economy and torque than a big cavernous Offy, but we shall see. I also like the idea of feeding 3 cylinders from each bore. In my head that 'feels' like it would result in a more torque/economy friendly powerband... kindof like the difference between 4-into-1 headers vs. try-y headers.

I've done some analysis on intake manifold designs from the hemhholz resonator perspective and the thermodynamic 'filling-emptying-volume' perspective and this manifold is so far off the map with either of those that its not even comparable. Based on the fact that it pitches down from both sides to the middle where the heat is, I'm thinking they were trying to maximize fuel atomization/suspension with this design and not so much looking at air flow- which makes sense for a low low RPM engine.

To me, the offenhauser design doesn't give you the even runner lenghts, mounts the carb in the wrong orientation, and doesn't have good volume properties. Plus you loose the features that make the stock manifold good, which is the heat and fuel suspension provisions.

After spending a lot of time with my hands on this casting, i'm thinking that the double 1v carbs, with some kind of balance tube, might be the best way to go. You'd have 4 equal length runners and 2 slightly shorter, you would have to put water heat in the manifold but that is no biggie, and you would optimize that 'tri-y' thinking. Either that or a 'split plane' with two runners to each port, one long and one short, the long ones feeding off of a small 4 barrel spreadbore (q-jet) primaries and the short ones feeding off the secondaries.

It would be a helluva casting, but perhaps someday....

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Re: Big six 2v conversion- halfway finished

Post #6 by motzingg » Fri Sep 06, 2013 11:00 am

well, just happened to see that other thread there talking about the two different kids of offenhauser intakes, i guess i didn't realize that the DP offenhauser was a true dual plane... thats cool, maybe try one of those next. Four barrels just seems like mega overkill to me. Even my 2 barrel seems kinda silly.


Anybody got any thoughts on the missing spreader/check weight thing? I'm going to put the carb on tonight (if i get home from work before dark) and see if it will run with the 2 check ball rig-up.

otherwise if any kind souls have those parts laying around and wouldn't mind selling them...

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Re: Big six 2v conversion- halfway finished

Post #7 by Harte3 » Fri Sep 06, 2013 11:36 am

The DP is designed for the exclusive use of a 4v carb. Some have questioned as to how to use a 2v with a DP but I don't know of anyone that has actually done it. The Offy C is certainly adaptable to 2v carbs with readily available adapters.
'83 F150 300, 0.030 over, Offy DP, Holley 4160/1848-1 465 cfm, Comp Cam 260H. P/P head, EFI exhaust manifolds, Walker Y Pipe, Super Cat, Turbo muffler, Recurved DSII, Mallory HyFire 6a, ACCEL Super Stock Coil, Taylor 8mm Wires, EFI plugs.

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Re: Big six 2v conversion- halfway finished

Post #8 by MechRick » Fri Sep 06, 2013 1:36 pm

It's possible to turn a 4bbl into a 2bbl by reworking the linkage and blocking off the secondary metering...

https://www.dropbox.com/s/obyeo3cnunhwkqx/modified4180.jpg

I put that one on a reworked 2.3.

Any progressive 2bbl will work on the Offy DP. It would take a custom adapter. A Weber 32/36 might not be big enough for the 300 but would be an interesting experiment...

One of the things I've wanted to do is whack the throttle shafts in the middle on a vacuum secondary Holley 4bbl to turn it into a progressive two barrel. Another option would be one of the progressive throttle body setups on some of the imports (Mazda rotary, Nissan pickup). That would require aftermarket EFI of course...
1994 F150, 4.9L/ZF 5 speed, C-Vic police driveshaft
EFI head w/mild port work, 3 angle valve job
1996 long block, stock pistons, ARP rod bolts
Stock cam, aluminum cam gear
Hedman header, full mandrel bent duals, crossover, super turbos
http://fordsix.com/forum/viewtopic.php?f=2&t=73244
Bronco II with a 2.3L swap http://fordsix.com/forum/viewtopic.php?f=13&t=72863
1988 F250 2x4, 460 ZF 5 speed.

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Re: Big six 2v conversion- halfway finished

Post #9 by bubba22349 » Fri Sep 06, 2013 3:12 pm

For one thing the cylindrical check ball weight that goes under the screw that retains the fuel discharge nozzles was missing. I'm not 100% certain, but i'm pretty sure there were 2 check balls stacked up on top of each other. Is that factory, or an acceptable kludge? If not, i'd love to buy or make one of those weights if anyone could provide me with the dimensions. There was a cylinder thingy in the rebuild kit but it is way way too big. The hole i'm working with looks like a 10-24 and the weight i have is much bigger.

The other thing i'm missing is the little metal tab that goes under the head of that screw, they refer to it as an air spreader i think.


For the missing check ball weight I think they were about 3/4 to maybe 1 an inch long about an 1/8 rod (Alum. or steel) you should be able to make one fairly easy. The tolerance is quite loose it needs to be able to slide easy into the hollow screw #29 when installed in the screw length will be about as long as the holes depth. You could probably make the #30 part too out of some sheet metal. For reference both the 2V 2100 or 4V 4100 will used those same parts. Good luck!
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

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Re: Big six 2v conversion- halfway finished

Post #10 by motzingg » Sat Sep 07, 2013 1:51 pm

BUBBA! thanks a bunch thats exactly what i needed to hear.

the two check balls stacked up were too tall to clear the screw.

someone had this thing assembled and (allegedly) running with both the spreader and weight missing... so who knows. Its easy enough to get at once i have it installed. This weekend i'll work on my riser and mounting, if it doesn't work i'll make those pieces later this week and give it a shot.

I tried to pull the studs out of the exhaust-intake connection and they both broke off in the holes. Go figure. That puts me down a day having to extract them, bummer.

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Re: Big six 2v conversion- halfway finished

Post #11 by bubba22349 » Sat Sep 07, 2013 2:11 pm

I think it could work ok without the spreader part early Autolite carbs didn't even have them, the weight could probably be made easy by cutting a finish nail
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

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Re: Big six 2v conversion- halfway finished

Post #12 by guhfluh » Sun Sep 08, 2013 3:03 pm

I would think that the mass of the check weight needs to be accurate for it to work correctly?

Also, Offy intakes retain the stock exhaust heater flange and holes, so that isn't lost unless you change exhaust manifolds.

So far everything looks nice. Keep up the work!
1967 F-250 Crew Cab 2wd, 300 6cyl, T-170/RTS/TOD 4-speed overdrive
240 head, Offy C, EFI exhaust manifolds, Comp 268H, mandrel 2.5-3" exhaust, Edelbrock 500, Pertronix ignitor and coil, recurved dizzy. 200whp/300wtq

motzingg
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Re: Big six 2v conversion- halfway finished

Post #13 by motzingg » Mon Sep 16, 2013 2:58 pm

Made some good progress this weekend, almost back to where i started....

Got at the CNC machine on saturday and made the spacer/riser block, got the studs torched out of the old manifold and heli-coiled (at this point i was about 3 hrs in and the $25 helicoil set is $10 more than i would have paid for a junkyard manifold... doh)

Sandblasted and painted the exhaust and intake manifolds and got everything installed.

Went to put the carb on and realized my throttle linkage was still hitting. Brought the riser block into work today to cut a clearance notch for the throttle linkage and i'm going to be making a bracket so i can hook up the throttle cable somehow. Not exactly sure how that will be accomplished just yet so stay tuned.

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Re: Big six 2v conversion- halfway finished

Post #14 by Firepower354 » Mon Sep 16, 2013 7:31 pm

Aboot the 2v on a Dual-Port, why couldn't one make a plate to set the carb over either the smaller or larger set of runners for a high-velocity setup? The rare 2v-staged big-body Holley could use both planes with a barrel each, eh?
It gets 10MPG, but goes up to 14 if I lie.

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Re: Big six 2v conversion- halfway finished

Post #15 by Harte3 » Mon Sep 16, 2013 7:45 pm

Well do it and while you are at it post pics, updates on the progress and of course, the results.
'83 F150 300, 0.030 over, Offy DP, Holley 4160/1848-1 465 cfm, Comp Cam 260H. P/P head, EFI exhaust manifolds, Walker Y Pipe, Super Cat, Turbo muffler, Recurved DSII, Mallory HyFire 6a, ACCEL Super Stock Coil, Taylor 8mm Wires, EFI plugs.

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Re: Big six 2v conversion- halfway finished

Post #16 by motzingg » Tue Sep 17, 2013 10:24 am

Swing and another miss... damn. I clearanced the plate for the throttle but not for the little lever that holds throttle open when the choke is on. Also missed the power valve cover clearance by a hair.

I might try to get that done over my lunch break real quick, i gotta pick up my son from day care today after work so I cant stay after. Throttle bracket will have to wait for tomorrow but i think I got it figured out how to make it.

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Re: Big six 2v conversion- halfway finished

Post #17 by motzingg » Tue Sep 17, 2013 10:27 am

also found this for my turbo 'hat'

http://www.portcityracing.com/site/?d=1369&dt=94&brand=FLBB

Not the best information available from the Mfg, but it looks plenty thick to keep from blowing off, I can weld a spigot on the side and add reinforcement to the top if it needs it.

way cheaper than building my own at that price. might even pay my metal supplier to cut the spigot with their 6-axis tube laser.

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Re: Big six 2v conversion- halfway finished

Post #18 by nightwatchman59 » Thu Sep 19, 2013 9:23 pm

I've got this 3310 750 vac. sec. Holley sittin' here... and if I don't come across a 2150 Motorcraft soon, I'm thinking of making the Holley a 3bbl by blocking off one of the primaries- theory being I'd have a 1bbl 'till I (you know).. then the vac. secondaries would spoon feed the mighty 6 and peg the smile meter.....

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Re: Big six 2v conversion- halfway finished

Post #19 by nightwatchman59 » Sat Sep 21, 2013 10:09 am

Thank you for the pics. Looks like a great job. Please share your results, as I am working on a similar project.

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Re: Big six 2v conversion- halfway finished

Post #20 by motzingg » Mon Sep 23, 2013 1:22 pm

^ that's a pretty cool idea. No idea how the jetting would cope, is there some kind of balancing arrangement or co-jetting on those? I guess being a holley each side is totally independant of the other, isn't it?

I got everything rigged up pretty well so far. I'm a bit concerned about one of the intake manifold mounting ears being broke off. I'm also thinking i might be missing one bolt but it is down in a really bad place right behind the big knob where the manifolds bolt together. I cant tell by feel if there is a bolt hole there or not. ]

Here is the updated post with nice pictures on Fordification. I'd post them here but they are all big. I hate to take traffic away from this site, which has more good 'six' info than fordification, but I want to keep all the lush writeups on my project thread here, and keep this to more specific questions.

http://www.fordification.com/forum/viewtopic.php?f=22&t=71650&p=658052#p658045

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Re: Big six 2v conversion- halfway finished

Post #21 by motzingg » Mon Sep 30, 2013 12:46 pm

THE TRUCK IS RUNNING

woohoo!

got to drive it down the road a ways yesterday, there is a big PCV hole in the manifold i haven't dealt with yet and the dizzy isn't hooked up to manifold vac, i've got to put a port in for all that mumbo-jumbo, but the carb runs great. the jetting is really darn close to being right, even the randomly-chosen accelerator pump position seems good.

The only problem i'm left with is that my butterflies are hanging up a tiny bit just off idle. If i stab it and let them snap they'll close, but if i gently ease off idle and gently let off they will hang up. I'm going to take it all off tonight and try to get them to seat better, loosen the screws and wiggle them around a bit, but i'm concerned that i'm doing it wrong...

any suggestions for getting those throttle blades seated? the way i did it during the rebuild i just let everything close tight with the throttle blade screws loose, then tightened them down, but it didn't work. they appear to be in correctly, just hanging up ever so slightly.

oh yeah and my dumb air cleaner hits that weird nugged on the top of the float bowl... looks like an un-drilled vent or inlet or something... grrrr.

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Re: Big six 2v conversion- halfway finished

Post #22 by Harte3 » Mon Sep 30, 2013 3:47 pm

Maybe a stronger throttle return spring...
'83 F150 300, 0.030 over, Offy DP, Holley 4160/1848-1 465 cfm, Comp Cam 260H. P/P head, EFI exhaust manifolds, Walker Y Pipe, Super Cat, Turbo muffler, Recurved DSII, Mallory HyFire 6a, ACCEL Super Stock Coil, Taylor 8mm Wires, EFI plugs.

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Re: Big six 2v conversion- halfway finished

Post #23 by motzingg » Tue Oct 01, 2013 2:40 pm

ehh yeah i don't want to get the pedal too stiff, right now its almost perfect. I put a very nice modern moped brake cable, braided steel with a plastic liner, in for a throttle cable so there is almost no resistance on that part of the setup, i'd rather just get my throttle blades working perfecto. I guess i'll just take the carb back off tonight and screw with it unless there is some kind of 'old timer' trick to doing this that i don't know of.

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Re: Big six 2v conversion- halfway finished

Post #24 by motzingg » Tue Oct 22, 2013 9:00 am

just reminded me to update this with my results...

i've been driving the truck to work the last few days, just about put a tank of gas through it, so what like 20 miles? ha not really, just a big difference from my 35 mpg escort!

the carb runs great, still a bit rich, but i'm playing with the air filter setup and working out the bugs in the brakes/suspension/drivetrain. as for the carb, the binding issue turned out to be a sloppy shaft. when i hooked up the return spring, it pulled the throttle blade to the side and jammed it into the wall of the carb. When i unhooked the return spring, it moved smooth as butter.

so i took the carb off, held the shaft to the side, and adjusted the blades so they were off set and in the neutral position with the shaft all the way to the side.

it was still hanging a bit so i added a second small spring to help it a bit more. definitely not a perfect solution but it will work until i do something more permanent. I'll probably bush the shaft eventually.

The other problem is that my spring is over-center at the closed throttle position, making a 120 degree angle to the linkage. I need to modify the linkage to put the spring on center at idle, and make it go over center so the pedal force decreases at high idle for comfy cruising.

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Re: Big six 2v conversion- halfway finished

Post #25 by motzingg » Tue Oct 22, 2013 9:00 am

just reminded me to update this with my results...

i've been driving the truck to work the last few days, just about put a tank of gas through it, so what like 20 miles? ha not really, just a big difference from my 35 mpg escort!

the carb runs great, still a bit rich, but i'm playing with the air filter setup and working out the bugs in the brakes/suspension/drivetrain. as for the carb, the binding issue turned out to be a sloppy shaft. when i hooked up the return spring, it pulled the throttle blade to the side and jammed it into the wall of the carb. When i unhooked the return spring, it moved smooth as butter.

so i took the carb off, held the shaft to the side, and adjusted the blades so they were off set and in the neutral position with the shaft all the way to the side.

it was still hanging a bit so i added a second small spring to help it a bit more. definitely not a perfect solution but it will work until i do something more permanent. I'll probably bush the shaft eventually.

The other problem is that my spring is over-center at the closed throttle position, making a 120 degree angle to the linkage. I need to modify the linkage to put the spring on center at idle, and make it go over center so the pedal force decreases at high idle for comfy cruising.

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