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Bike Carbs On Pinto

Barksavon - 4/9/10 at 04:35 PM

Ive just bought a set of bike carbs with a manifold for my Pinto, tried to fit them today and the left hand carb is fouling on the distributor cap and wont fit, has anyone had this problem before, will one of the angled distributor caps get me out of this fix or any other suggestions welcome.......

ashg - 4/9/10 at 04:39 PM

you shouldn't be using a distributor with bike carbs as you wont have any vacuum advance which will make the car slower than it was before you changed the carbs.

ideally you need a ford edis ignition unit with a megajolt and a rr session to see any benefit

interestedparty - 4/9/10 at 04:47 PM

quote:
Originally posted by ashg
you shouldn't be using a distributor with bike carbs as you wont have any vacuum advance which will make the car slower than it was before you changed the carbs.

ideally you need a ford edis ignition unit with a megajolt and a rr session to see any benefit

I agree about the rr, but not to sure about the rest, I'm surprised there is no vacuum with bike carbs (are you sure about that) but vacuum only significant at low throttle (when the most vacuum) so under full acceleration shouldn't really make any difference IMO

DRC INDY 7 - 4/9/10 at 05:15 PM

quote:
Originally posted by ashg
you shouldn't be using a distributor with bike carbs as you wont have any vacuum advance which will make the car slower than it was before you changed the carbs.

ideally you need a ford edis ignition unit with a megajolt and a rr session to see any benefit

Rubbish i have bike carbs on my pinto with stock bosch distributor no vac connected and running 15 degrees btdc at 800rpm no problems and goes like a rocket

bigpig - 4/9/10 at 05:26 PM

I've got a set of GBS bike carbs with a big sausage filter. No clearance issues at all. I'm using a normal dizzy with no vac connected and its all fine. Was just told to set at 30 adv @ 3500 rpm (or was it 3000, I can't remember now).

RichardK - 4/9/10 at 05:49 PM

quote:
Originally posted by ashg
you shouldn't be using a distributor with bike carbs as you wont have any vacuum advance which will make the car slower than it was before you changed the carbs.

ideally you need a ford edis ignition unit with a megajolt and a rr session to see any benefit

Nah, you'll be ok if you can squeeze them in mate, just block off the vacuum tube to the dizzy and leave it as static it'll be fine!

Megajolt/edis is better though, more controllerable, you may find on static its maybe lumpy at tick over or may have a slight flat spot but should still be driveable.

Cheers

Rich

jacko - 4/9/10 at 05:53 PM

Or buy a modified dizzy from H&H ignition solutions

mcerd1 - 4/9/10 at 06:10 PM

there are a few different kinds of dizzy and caps around, and it depends on the style of manifold and so on.......

so first off have you got any pics ??

(you don't need megajolt, but its probably the cheapest 3D mapable setup which would help your fuel econnomy and drivability)

[Edited on 4/9/2010 by mcerd1]

interestedparty - 4/9/10 at 06:14 PM

So why no vacuum with bike carbs then? Do they work on a different principle? What happens in the inlets when the throttles close?

snapper - 4/9/10 at 06:19 PM

If the carbs are spaced and the manifold is straight then the No.1 inlet will just cut through the top of the distributor cap regardless of what cap you fit.
Megajolt or new manifold, given the cost of either I would go megajolt

jacko - 4/9/10 at 06:21 PM

carbs on manifold

engine

snapper - 4/9/10 at 06:21 PM

There is vacuum with bike carbs, some have a vac take off on the carb others need a take off from each inlet runner others use TPS instead of vac

RichardK - 4/9/10 at 06:22 PM

There is vacuum when using bike carbs but it would mean taking a "take off" off each inlet and connecting them to a sealed box and then another tube to the dizzy, the box is there to utilise all four vacuums and equalise all of the pulses.

I think, that's how it works in my head any how and people just cant be arsed as they tend to be ok just blocked off.

Cheers

Rich

[Edited on 4/9/10 by RichardK]

mcerd1 - 4/9/10 at 06:24 PM

quote:
Originally posted by interestedparty
So why no vacuum with bike carbs then? Do they work on a different principle? What happens in the inlets when the throttles close?

there is a vacuum, in fact there are 4 seperate ones that come and go as the valves open and close and thats what causes the problem
(its not just bike carbs, its any setup with 1 carb per cylnder)

on a single carb there are connected together in a big plenum and it averages out the vacuum so the carb gets a nice constant load signal and adjusts the advance curve accordingly

you can join the 4 different ones into a seperate chamber and then take a feed off that to the carb, but its much simpler to either get a carb with the vacuum advance removed (a 2D system) or use TPS sensor with an electonic system like megajolt which is a fully programable 3D system (and can/should be cheaper than an uprated dizzy)

[edit]too slow again....

[Edited on 4/9/2010 by mcerd1]

mcerd1 - 4/9/10 at 06:29 PM

btw - you can get these caps for bosch dizzys
(some twin webber setups have caused the same problem for years)

but I'm not sure exactly which dizzy it fits...

Barksavon - 5/9/10 at 11:32 AM

thanks for the responses and particularly the photo's, i'm considering megajolt but dont know whether i'm up to fitting it...is it difficult. I may try one of the dizzy caps shown in the photo cos its definately not going to fit with the manifold ive got as its not offset to allow the 1st carb to miss the dizzy......Theyre not problems theyre 'challenges' i keep telling myself.

mcerd1 - 5/9/10 at 08:20 PM

dizzy caps linky

[Edited on 5/9/2010 by mcerd1]