So I might be stupid but Weber help Please!

[Johnkowsky]

So here is my issue, I followed the how to thread for the weber conversion and I have everything together as the thread tells me to and I can start the car but it won't idle it just surges to 5000rpm and beyond. I checked to make sure everything was plugged the world over but obviously there is something I missed. I search barred and googled the shit out of this issue and I can't find any answers. Hopefully someone can tell me where I went wrong!

My engine is 100% stock and I have the weber 38/38.

I've gotta get this thing going for next week so I can pick up an exhaust from 87roach!!

[Vanilla Sky]

Have you adjusted anything? Do the throttle butterflies close as they should? Any throttle cable binding? Have you checked for vacuum leaks?

[Johnkowsky]

I've plugged everything, throttle butterflies are completely closed, cable doesn't bind at all, adjusting fast idle screw does nothing. Haven't touched the regular idle mixtures screws yet because it says to do that with a warm engine and I for obvious reasons can't let the engine run cold at those rpms. The only thing I'm a little iffy on is where I plug the vacuum advance, the thread says to plug it into the back of the manifold and the weber instructions say plug it into the carb and I can't find any pictures where I can see what other people have done in that area. I've tried both and I get no improvement.

[Vanilla Sky]

I think I'd start bombing it with some carb cleaner to check for vacuum leaks. Surging to 5,000 RPM is a bit fast for a properly tuned carb to allow an engine to surge, but it can happen if the idle mixture is rich and there's a vacuum leak. If you don't find any vacuum leaks, try backing down the idle mixture a bit. If that's what makes the change, keep backing it down until you are at a more reasonable engine speed and let the engine warm up and adjust again.

Are you having any dieseling problems when you turn the car off? Does it smell like the car is running rich?

[Johnkowsky]

The car is trying to redline I'm shutting the engine off at 5000, and I get a plume of blue smoke which i know is unhealthy, there is dieseling after shut off and it does smell a bit rich i'll try adjusting the idle screws out a bit.

[lostforawhile]

the car is dieseling because you are shutting it off at high RPM, if was idling normally it probably wouldn't do that. The instructions say to run the advance to the carb, is there a port on the carb? is it blocked off? it sounds like a leak or something is up with the idle screw

[Johnkowsky]

port on the carb is there and advance is plugged into it. Searched and searched for leaks the only spot I can think of where a leak could be is where the carb meets the side of the adapter that has the corners shaved down. I was looking at the choke and the fast idle screw is nowhere near the the linkage it's supposed to be touching, could this be my problem? The choke being stuck on fast idle?

And I feel like an idiot for saying it was dieseling haha my mind is not in the right place right now obviously...

Edit :

just checked the choke wire, no power coming to it.

[2oodoor]

You're not stupid are ya, come on now...

Are you using an extra throttle return spring? sometimes the throttle looks pulled close and it will actually not be, it doesn't take much to raise the rpm with a 38.
If you havn't adjusted idle " mix" screws that could be a lot of it. You should read the redline set up instructions a few times to thouroughly undrstand.
Did you run across the toyota, jeep, opel, datsun forums that have Weber set up threads? There is a LOT of good info available. I linked a really good one from the Datsun one in the Weber help thread here
Ive never installed a Weber that did'nt need an idle set up done several times right after starting it. You can't start off at zero base throttle and expect it to run perfect, you have to gradually work the idle sped up, with minimum opening, going back and forth between the base idle throttle stop screw and the two "mix" screws. T
The fast idle adjustment should come later, unless the spring from the fast idle cam is missing, and they do get missing, the fast idle shouldn't even be coming on with the choke open.

[Johnkowsky]

I went by the redline instructions to reset the idle mix screws to 2 turns out from lightly seating, no change

I was expecting it to have a rough idle when I first started it and there are many many many threads on this site and others to do with the jeeps, datsuns etc. about that but I have yet to find one that says anything about surging on startup and what the cause would be. I think I'm going to have to pull it all off and check all the gaskets and see where I get from there.

Edit :

I do have an extra throttle return spring.

[2oodoor]

we all have different ways of describing things so what exactly do you mean by surging? can you explain it another way so I can cross compare what you are saying to what I am reading
To me, surging would be "hunting" which on a carb, would be a float issue or fuel pressure.
The 38 can idle baby butt smooth at 600 rpm, not that you should do that but that is just a sample of it's excellent idle circuit.
If you are reving over 3k then the idle circuit isn't even in the picture. It stops at around 2300, varying among set ups.
Is this a new out of the box carb or was it set up for another car before>? A picture speaks a thousand words if you can get some of your set up, it could help somebody spot something that may need attention.

[2oodoor]

There is a spring on the carb itself, in this pic you see it just above where the throttle cable connects to the linkage. There is a dowel sticking out of the carb and like a 3 inch spring, those get missing and can cause the issue you describe.

[Johnkowsky]

Ok guys I've got it all figured out, first off I'm an idiot haha, but what do you get when you have never worked on cars before and you try to do a carb swap, I had my throttle cable too tight therefore it was holding the butterfly plates open and making the car rev like a banshee or in my lingo "surge" haha I was looking at my idle speed screw and it wasn't making contact with the throttle linkage at all therefore I realized duh butterfly plates are open and there is no load on the engine so of course it's going to shoot up to 5000 rpm and beyond.

In short thanks for the help and the 38 purrs like a kitty now Pics will be in my other thread soon!

[2oodoor]

I woulnn't use the vacuum advance yet, it throws a wild card in the idle mixture set up. I would get it set up without it and run it a while, then try to use it and re do the set up.
I have always been able to advance the base ign timing a good bit when using a weber, particually a 38. It comes in like a lion and leaves like a lamb though so don't be too disappointed in the top end of the rpm range using the butt dyno.

[Johnkowsky]

Thanks for the info roo, I need all the help I can get with carbs haha

[Vanilla Sky]

We all started somewhere. Kudos to jumping in head first and doing something many here consider to be difficult.

[lostforawhile]

I think you need to run the advance off of manifold vaccume, I'm not sure if the port on the carb is a timed port or anything, the advance on the dizzy was designed for manifold vaccume

[Johnkowsky]

It was pretty simple actually all things considered now that I've done it, if you have any basic mechanical skill and troubleshooting ability it's a snap! I just over complicated things when I was trying to figure out what my issue was haha. I'm definitely going to need to change the jetting though, I'll have to double check but I'm pretty sure the ones in there are too rich, but I'm going to wait till after I get the exhaust system on Thursday to see what effect that has so I can figure out what sizes to buy.

[DBMaster]

Johnkowsky, every mechanic, especially those of the "shade tree" variety, had some point in life before which they never worked on a car. You are getting a good trial by fire and successfully completing this install will give you confidence for the next project. Kudos to you for trying something of this level as an introductory project.

[2oodoor]

^^^^ definatley for sure

Don't go re jetting until you have tried advancing the base timing about 3 degrees btc from where ever it is right now. The idle rpm will come up some so you will have to back off the throttle base setting and do the best lean idle procedure according to Redline. If it pings and rattles like that , then take it back down. These cars are so de tuned from the factory it is amazing.

You are right about waiting until you do the exhaust mods before doing any more tuniing, so it may even be better to wait to bump up the advance for that as well though.
If you have a five speed, I bet you are enjoying the entirely different demeanor of your car now, even without exhaust work it has a totally different sound to it.

[cygnus x-1]

Viva le Weber 38!

You might check the FAQ/HOWTO section and look for the Weber thread. There are jetting sizes listed in there that should work pretty well for you. If you really want to squeak out the most performance/mileage get yourself a wideband O2 sensor/gauge and go to town. Be forewarned, it's addicting and you'll find yourself changing jets every time the temperature changes more than 20 degrees.

C|

[Johnkowsky]

Yea wideband O2 sensor is definitely next on the list so I can get the tuning perfect! Exhaust is now on big ups to Andrew aka 87roach for all the help with the install and by help I mean basically doing it all himself with me bugging him asking what I can do haha and the wicked price! Sounds super mean!