Dimension of GC inlet manifold

[parrish]

Im in the process of having a manifold made to fit a 2.0 twin cam cylinder head for a pair of Jenvey TB's (Throttle bodies).
The TB's are currently on a Guy Croft offset manifold, and are a direct replacement for twin Webers.
I need to get the TB's closer to the cylinder head, i also need to get rid of the offset which is causing me clearence problems between the last TB and the bulkhead, i have an Omex ignition system fitted so ive done away with the distributor.
I have someone who is willing to manufacture a manifold for me, however detailed dimensions of the set up are required.
I have the mounting hole dimensions of the TB's they are 110mm top 70mm bottom holes.
Im currently away from my car and wont be able to get back until August.
Apparently, and i was'nt aware of this, their is a difference in distance between the pair of carbs on a twin manifold, see question from manufacturer: Question: the problem is the spacing is different for the early series Webers and the later carbs. The 13/15 series are 3/4" closer together than the later 70 series carbs. We make either flange, so that's not a problem. I just need the dimension between the mounting holes for the two tbs.
So i can place the order and have the manifold at home ready for fitting in August im in need of the afformentioned dimension.
If any one can help it would be appreciated.
Regards
Steve
Ive attached 2 photo's of the current set up:

[Guy Croft]

Steve, I have to say this doesn't make any sense to me.

The notion that DCOE bolting points (as per my manifold see att) have ever changed is new to me, to say the least and I've seen more DCOE than most.

I think the people you're talking to a getting a bit muddled. There is a difference in the distance_between_the carb_pairs according to engine, the Ford setups have more room, the TC are closer together. That can be an issue for throttle linkage but it does not affect the throttle body (or carb mounting points).

G

[parrish]

Guy,

I have probably not made my self very clear,
its the distance between two pairs of carbs when side by side, so the gap between one pair and the other!
The middle ground between two pairs on a manifold?
I was not aware of any difference.
It's "Allinson Automotive" that will be doing the manifold I believe you may be aware of them, they certainly know of you, but then again who wouldn't in the world of Fiat Twin cams.

I hope the above explains what it is I'm trying to find out.
Regards
Steve

[Guy Croft]

Sure I know Mark, and he is a member here too!

You can make the distance between the pairs anything you like! The only thing is affects is the shape of the runners because they have to marry up to the ports at the other end. What is fixed is the mounting bolt array I published a moment ago. If Mark is asking what distance you want between the throttle bodies you could do worse than specify 91mm between centers of the two middle barrels - ports 2-3. The space betw port 1-2 and 3-4 is 87mm FWIW.

If you are still in the dark get Mark to drop me a line.


G

[mark allison]

Guy
thanks for the response. I was under the impression he was using IDFs currently. Since the spacing between the early and late IDFs is different, I'm offering either top flange. I'm trying to supply Steve with a setup that will allow him to bolt his tb's directly on without having to modify his linkage. It's rare to see a DCOE setup here in the states, I don't know the dimension between the 1-2 and 3-4 mountings

[Guy Croft]

If I understand correctly Mark you are making something with exactly the same mounting points as a DCOE, for which I have uploaded a dwg of the stud posns for the flange. The throttle bodies for sidedraft ones are the same as DCOE on every type I know, simply because they are so often used as replacements for carbs on the same_manifold. So you have there the ordinate dims for each throttle - 110, 70mm etc.
At the head end you will already have the manifold-head fixing positions I imagine.

As for the spacing from one throttle body to the other you can sketch this out and make it pretty well what you want, given that the two center ports are 91mm apart not 87 like the other two. So you're going to have bends in the runners. The only other criteria really being that the rear body doesn't foul the bulkhead and the throttle balance quadrant fits between them.

I've sketched here what it would be like if you placed the TBs symetrically with a manifold 2" long, think I got it right.

Hope that clarifies a bit, I know you want to get it right.

G

[mark allison]

Guy
thanks so very much! That's exactly what I need

[parrish]

Thank you Guy seems Mark is happy with the info.
For those others who have read this thread and may be interested in the manifold, ill make some additional posts in future.
Ill also include some data/info on the complete ECU/EFI system ive fitted to my 131 Fiat Twin Cam engine.
As the manifold is coming from overseas and as im not back to work on my car until August so it will be about then i post.
Regards
Steve

[mark allison]

Guy
can I get the drawing of the carburetor mounting flange for your manifold?

[Guy Croft]

That is surely the one published above - DCOE centers?

G

[mark allison]

Guy
sorry to be such a pita, but do you have a drawing of the DCOEs side by side? I'm assuming you have the top flange port spacing the same as the cylinder head port spacing, but I'd like to be sure. I want to send Steve an intake manifold that won't require him to fabricate new synchronization linkage.
Thanks for all of your help so far.

Mark

[robert kenney]

Hi Mark,
I made a drawing for an application of my own so I adjusted it to match Guy's 88MM bore to bore spec. Should work for you. If not I have the cad file you are welcome to.
I believe I have enough dim. points to allow you to add any dim you need. Simply gets to cluttered when all are added.

Robert

[mark allison]

thanks Robert

[robert kenney]

Mark,

You're welcome, just want to point out that the main bores will need to be sized to suit your throttle body. These were sized for a 40mm unit.

[mark allison]

I was under the impression that the throttle bodies have the same mounting footprint as the DCOEs.