Weber winter project

[Pmccooey]

I have a Cobra with 427 S/O, medium riser heads and single 4 barrel carb currently inning and driving. I acquired a set of Italian Weber 48 IDA’s, intake, heads and parts. The Weber’s were done over by Jim Inglese at some time. Other than that I know nothing else about them.

I am looking to swap over to the Webers this winter and looking for guidance on what needs to be done. Assuming the intake is for medium risers (I forget right now what intake they are on) can I just swap out the intake manifolds, plumb in the Webers, and reduce fuel pressure (mechanical fuel pump) to 2.5?

Looking for guidance on if it would be that simple? Obviously would need to tune from there if it starts. Unknown the cam specs in my engine by not too radically, idles nicely. I bought the Weber book to learn about tuning these babies, but other than that this is a whole new world for me.

Car is mostly used for shows and cruising.

Thanks for any help or pointing me to somewhere for me to gain some knowledge.

[twobjshelbys]

Old: Car is mostly used for shows and cruising.

New: Car is mostly used for shows and cruising and adjusting and tuning webers

[talos]

The best place to start is with your camshaft. Basically the LSA should be between 112-114. Compare that with your cam. I'm sure there are many people on this forum to give you the correct grind. To get optimum results you most likely will have to change it. There is plenty of info on this forum, the web, and you tube. Do your research thoroughly. This will be a project but fun if done with patience.

[PDUB]

Originally Posted by twobjshelbys

Car is mostly used for shows and cruising and adjusting and tuning webers

Perfect!

[Gaz64]

Originally Posted by talos

You will have to start with the cam. The LSA should be between 112-114. Compare that with your cam. Most likely you will have to change it. There is plenty of info on this forum, the web, and you tube. Do your research thoroughly. This will be a project but fun if done with patience.

That is a myth. The reason and pure coincidence of the camshaft timing is the opening and closing points of the intake valves.
For example, ending up with an ICL of 112, and generally with a LSA of 112, I can still have crazy intake valve timing of say 54/90? ICL of 112, LSA of 112.

I have run Webers on IR manifolds, one choke per cylinder, with cams right down to 105, and still have near EFI drivability. That was a 40/70 intake timing.

Since the OP says his engine idles nicely now, the cam mustn't be too wild.

[1795]

One of the more important issues that you need to be on top of is the linkage for the Webers. Most people spend undue time tinkering with jetting, chokes, etc., when the real issue was that their linkage was not correctly setup and the carbs were operating at slightly different throttle responses. After you have it installed move the throttle lever and watch for any inconsistencies or torquing of the assembly. You may have to add additional support to the bell crank depending on the style. If anything even moves a 1/16" out of sync with the other carbs, it will not run right and changing jetting will not fix it.

Good luck,

Jim

[Pmccooey]

Originally Posted by 1795

One of the more important issues that you need to be on top of is the linkage for the Webers. Most people spend undue time tinkering with jetting, chokes, etc., when the red issue was that their linkage was not correctly setup and the carbs were operating at slightly different throttle responses. After you have it installed move the throttle lever and watch for any inconsistencies or torquing of the assembly. You may have to add additional support to the bell crank depending on the style. If anything even moves a 1/16" out of sync with the other carbs, it will not run right and changing jetting will not fix it.

Good luck,

Jim

Thanks for the help. I noticed the linkage has some ‘slop’ to it. Is there a good recommendation for a more precise or tighter throttle linkage that I can go to?

As to the other posts about the cam, I have read that Webers like a milder cam. Like I said I don’t know what cam is in it but it’s not radical. Very easy idle so I would assume it should be no problem with the Webers.

[1795]

Post a picture of the throttle linkage so we know what you are working with. There different linkage setups available.

[Pmccooey]

Here’s the linkage that I got with it. Needs to be tighten up, bolt on one side is hitting and only allowing throttle to move roughly 1/4”. Unfortunately I can’t seem to post the pics??

[Pmccooey]

Here’s the linkage that I got with it. Needs to be tighten up, bolt on one side is hitting and only allowing throttle to move roughly 1/4”. Unfortunately I can’t seem to post the pics??

[talos]

Technically you are correct, but I was just trying to simplify his process and give him an important starting point (the camshaft). It's not fun especially on a fe putting everything together and then finding out you need a different camshaft for the application.

[1795]

Originally Posted by Pmccooey

Here’s the linkage that I got with it. Needs to be tighten up, bolt on one side is hitting and only allowing throttle to move roughly 1/4”. Unfortunately I can’t seem to post the pics??

Say hi to a few people in other threads. You have to post a minimum number of posts/replies on the site before you are allowed to post pictures.

[bobcowan]

Any IR intake system runs best with a cam that has a wide LSA and minimal overlap. Because there isn't a common plenum, the runners are subject to some pulsations as the valves open and close. If there is too much overlap, you'll develop the dreaded Weber fuel cloud at lower rpm's (like, <3,500)

As said above, the balance is critical. If it's not exactly right, it will never run well no matter how you tune it.

The linkage is the first step. There should be very little slop anywhere. And it should be infinitely adjustable. I messed with mine for a long time, until I finally trashed what I had gotten with the system and started over.

Second, you'll need a balancing tool. This synchronometer worked well for me: https://classiccarbs.co.uk/product/w...rsynchronizer/

And, finally, you'll want some kind of vacuum source. Preferably a small plenum. Some Weber type manifolds have them, and some don't. If yours doesn't, consider something like this:

[Pmccooey]

Pictures of linkage

[Pmccooey]

Pictures of linkage #2

[bobcowan]

Duplicate post.

[1795]

What is going from the throttle pedal to the center crank in the linkage? A rod or a cable?

[Pmccooey]

Pictures of linkage #2

[Pmccooey]

Nothing right now. The intake and Webers are sitting on my bench.