Replacing a Mikuni Carburetor with a Weber Carburetor

[85Ram50]

A cheap hand held dwell/tach meter will do the job. The dwell isn't much help on an ECM distributor system other than to tell you it's out of spec.

Here's my beef - new school shops can't (or don't understand how to) tune old school engines. There is a subtle art to digging up hidden performance in an old school and every shop I dealt with used the 'factory spec' tune. That's when I started doing my own tune ups and learning how to find that little extra. I had one bunch or muppets undo a good tune I performed on a friends Mazda 808 (40 minutes of dialling in the ignition and resetting the breaker points for optimisation) - when he picked it up from getting something else done to it, it was a slug compared to how it went in.

I usually walk away if they say "we make it like the factory built it" or some version of that. It is a red light warning that they do not know about your rig and may not know about motors in general. Almost every vehicle gets improved and fixed after it has gone into production. Design flaws and other items not built properly show up and need changes. Frequently owners improve them too. If your shop doesn't know this or know to look up Technical Service Bulletins for what has changed on your vehicle they are probably not reliable.

[SubGothius]

I usually walk away if they say "we make it like the factory built it" or some version of that.

Which could also just be tail-covering; they're less liable if they tune everything "by the book". The factory tune may have been nerfed for emissions rather than performance, and doesn't account for upgrades like a better carb, replacing points with electronic ignition, etc.

[BJH324JH]

Should I block this hose? I put my finger on it and its creating vaccum. I intend to put the original air cleaner on when I have the time.


The hose on the valve cover is the one I mean.

[geezer101]

You have 2 options - there is either an elbow under the base of the air filter mount you can install that connects to the breather hose (most likely will make it compliant for emissions) or put a smaller breather element on it. But don't plug it up or delete it as it helps crankcase ventilation and recirculates gas build up back into the engine to be burnt.

[geezer101]

Which could also just be tail-covering; they're less liable if they tune everything "by the book". The factory tune may have been nerfed for emissions rather than performance, and doesn't account for upgrades like a better carb, replacing points with electronic ignition, etc.

Book goes bye bye with a carb swap. The factory tune is a compromise between emissions and worst case scenario cold engine starts. If the tune is in the ball park it 'should' start. I'd encourage anyone who wants to learn sumpin' to buy feeler gauges, a hand held tach/dwell meter and a timing light (you're only going to need the timing light as a diagnostic tool to know what the base timing looks like. There's free performance up for grabs with some patience and trial and error.

[BJH324JH]

You have 2 options - there is either an elbow under the base of the air filter mount you can install that connects to the breather hose (most likely will make it compliant for emissions) or put a smaller breather element on it. But don't plug it up or delete it as it helps crankcase ventilation and recirculates gas build up back into the engine to be burnt.

Got it. Thank you very much.