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Old 11-04-2014, 01:23 PM   #1
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Default Carbureted b6

Yes, this thread is about carbs. Sorry. This question is in regards to swapping a b6 into a car that is not setup for fuel injection at all. I don't want to swap a harness, ecu, etc. The car is not a miata, but a 88 festiva, that is factory carb'd.

I've been looking into the few carb'd BP's that exist out there but I noticed that they all still run on the ECU for the distributor, ignition advance, etc.

So, the car is my buddies 88 festiva, we'd like to swap it in and run it off a carb without messing with the wiring. 100HP > 55hp of the stock car, so it's not like im looking for big power.

MY QUESTION: Is there a distributor/coil setup that could be used on the B6, converting it to a vacuum advance system, like the old carb'd vehicles, so that I could just run a carburetor and a distributor, and that's it? No ecu, no wiring harness, no sensors, no nothing? The stock "b3" in the festiva is run this way, so I'd like to keep that simplicity with the extra displacement if at all possible.

If this won't work, it won't work, so be straight with me. I only ask here because you guys are pretty well versed in all things b6/bp related, and i know for a fact theres a guy on the forum running carb(s), miata2fast maybe? Black miata with a weber setup, i couldn't find his thread while searching though.
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Old 11-04-2014, 01:26 PM   #2
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I came across this from a factory b6 sohc car:



Clearly a vac advanced dissy. The question is, would this work on my dohc b6, and would it work without any ecu wiring controlling it? I just want it to run off the base timing at idle, and advance timing mechanically through vac.

Edit:

This one only has 3 wires, is for a b6 sohc, and i think it might work.. Only 3 wires, same as the stock distributor on the b3 in the festiva.
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Old 11-04-2014, 01:36 PM   #3
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Erm....MegaSquirt.
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Old 11-04-2014, 01:40 PM   #4
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having zero wiring in the engine bay already would make it easier to do this swap with fuel injection rather than harder.

I wonder if the b3 distributor would bold directly in place of the CAS.
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Old 11-04-2014, 01:45 PM   #5
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Are you swapping a dohc B6 or a sohc? If it's a sohc 8v all the b3 stuff bolts right up.
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Old 11-04-2014, 01:47 PM   #6
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Yes I understand, but building an ECU, wiring the car, etc. is more than we want to do. If we're doing that, we would want to turbo it, and if we're turboing it we'd need a better transmission, etc.

This car is simply a shitbox, that is already surprisingly peppy with 50hp, and we want to double that and keep carb'dsimplicity if at all possible. If it's not possible, we're keeping the stock B3.

I too was wondering about using the stock b3 dissy, but was thinking the firing would be off due to the difference in stroke of the motors. But maybe I'm way off here, this old carb/dissy stuff really goes past my head sometimes being a 90's kid.
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Old 11-04-2014, 01:48 PM   #7
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Quote:
Originally Posted by B6Tfastiva View Post
Are you swapping a dohc B6 or a sohc? If it's a sohc 8v all the b3 stuff bolts right up.
it's a 88 festiva with a sohc b3. I have a dohc b6 from my 1990 miata sitting in the garage. The goal is to make these work together as simply as possible on a carb setup.

I know i'll have to fab a manifold for the carb, and understand how to get that working. What i don't understand is the timing side of things. It looks like the dissy above would bolt in place of the CAS on the b6, but i'm not sure of that either.
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Old 11-04-2014, 01:54 PM   #8
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Quote:
Originally Posted by Fireindc View Post
I too was wondering about using the stock b3 dissy, but was thinking the firing would be off due to the difference in stroke of the motors. But maybe I'm way off here, this old carb/dissy stuff really goes past my head sometimes being a 90's kid.
They have the same stroke, the bore is different.
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Old 11-04-2014, 01:58 PM   #9
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The carb b3 disty will slide right in you might have to get creative to bolt it down the bolt holes won't line up. It should work without a problem all the distributor does is trigger the coil and the ignition curve is controlled by a centrifugal and vaccuum advances.
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Old 11-04-2014, 02:17 PM   #10
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Quote:
Originally Posted by Leafy View Post
They have the same stroke, the bore is different.
Quote:
Originally Posted by B6Tfastiva View Post
The carb b3 disty will slide right in you might have to get creative to bolt it down the bolt holes won't line up. It should work without a problem all the distributor does is trigger the coil and the ignition curve is controlled by a centrifugal and vaccuum advances.
Wow, thanks guys. Well then, that simplifies things quite a bit.. the only things i have to come up with are a carb solution (thinking log manifold build off the stock IM flange), not sure on the merits of side vs downdraft so I'll look into that. Spark/timing is controlled by the oem b3 vac advanced dissy, and fuel controlled by a good ole fashioned carb,
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Old 11-04-2014, 02:37 PM   #11
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why not one of the many cheap 1.6 itb manifolds with a webber flange?
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Old 11-04-2014, 03:40 PM   #12
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You should consider running an electromotive system. You can get a very simple system that has coils and crank trigger. The coil pack board has ***** that control the timing curve. There is an idle control, a 3500 rpm or so control, and a 7000 rpm or so control.

You set the timing via timing light at each setting, and the controller automatically creates a curve to each programed setting. Very simple, and very easy to work with.

The coils are hot enough to handle as much compression or boost you are willing to throw at it. It even has a simple vacuum port available that will adjust timing in boosted applications.

This was the ignition controller of choice during the early days of Miata E Prod racing history.

This is the system that I run, and I have had it for many years.
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Old 11-04-2014, 03:50 PM   #13
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Quote:
Originally Posted by miata2fast View Post
You should consider running an electromotive system. You can get a very simple system that has coils and crank trigger. The coil pack board has ***** that control the timing curve. There is an idle control, a 3500 rpm or so control, and a 7000 rpm or so control.

You set the timing via timing light at each setting, and the controller automatically creates a curve to each programed setting. Very simple, and very easy to work with.

The coils are hot enough to handle as much compression or boost you are willing to throw at it. It even has a simple vacuum port available that will adjust timing in boosted applications.

This was the ignition controller of choice during the early days of Miata E Prod racing history.

This is the system that I run, and I have had it for many years.
Except their cheapest system costs more than a megasquirt. We've now figured out that spark is the easiest part of this swap for him and making the carby manifold is going to take the most work.
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Old 11-04-2014, 04:10 PM   #14
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That's fine and dandy Leafy. You are just so helpful.

He asked for my input. I gave it from the experience I have.

Also, MS does not include really good coils or accurate crank trigger. It is not a fair comparison.
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Old 11-04-2014, 04:19 PM   #15
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But he already has a CAS and the stock B6 coils and hes trying to put the engine into the car on the she stringiest of shoe string budgets with no aim at anything even related to performance. You're basically suggesting to someone that they need a built motor because they want to run a turbo kit on their 1.6 to make 170hp.
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Old 11-04-2014, 05:05 PM   #16
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Miata2fast, thanks so much for your input. That is very interesting, and it's good to have options. It's appreciated.

Leafy is pretty much right though, this thing is going to be bottom of the barrel budget wise. If it makes anywhere near 100hp (flywheel) it will be WELL worth the effort.

When the time comes to put real money into the festiva, it will have a b6t swap with all the ECU goodness that comes with it. This is mainly due to the need for a stronger trans.

The stock festiva trans -should- hold the ~100hp that the b6 will make, so that's a big plus. This thing is mainly a gas sipper for my buddy, but we'd like to give it a little more pep. The 1.6 will never go into a miata that I own, so may as well sell it to my buddy for cheap and get some fun out of it.
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Old 11-04-2014, 05:06 PM   #17
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Quote:
Originally Posted by Leafy View Post
why not one of the many cheap 1.6 itb manifolds with a webber flange?
Where can i find this? are we talking ebay cheap? or.. clubroadster JDM "cheap" (aka way overpriced) ?
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Old 11-04-2014, 05:08 PM   #18
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Quote:
Originally Posted by Fireindc View Post
Where can i find this? are we talking ebay cheap? or.. clubroadster JDM "cheap" (aka way overpriced) ?
I know there are webber flange itb manifolds, and I know there are cheap *** itb manifolds. I am not certain if these two properties intersect or not. Check ebay.
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Old 11-04-2014, 05:15 PM   #19
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The next thing on my mind would be the exhaust manifold. There are plenty of FWD n/a bp's (escort gt, etc) to get a exh manifold from, but I'm not sure how many DOHC fwd non-turbo B6 cars there are. Doing more research on that now.
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Old 11-04-2014, 05:25 PM   #20
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Something kia maybe an option?
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