1rx7owner

I have a weber 48 dco which has adifferent float then the dcoe. I need to know what the float level is to my carb. The carb is also making my engine miss at high rpms. Anybody have any ideas? Clues?

bill Shurvinton

Can't remember offhand the float level, but know who has my weber bible so can get it looked up if no-one has answered by tommorrow.

As for the miss, at what RPM does this occur. If you can give an idea of what causes it I might be able to advise something.

Better is to buy or borrow a wideband and see what the AFRs are around the miss point.

Bill

1rx7owner

It starts missing usually around 5000 rpms. I know its not a fuel problem cause I have checked that. I happened rather quickly too. I drove it from work and the car ran fine, by the time I got home about 15mins later it ran like crap.

bill Shurvinton

Is this each time it gets hot, or does it now happen every time you drive?

If it runs fine each day for 15 mins then misbehaves, you most likely have a heat soak issue to deal with. If not, then I have to think

Bill

1rx7owner

It never used to happen until the other day. It ran fine one minute then just started running like crap the next.

bill Shurvinton

More information would be useful.

Without that, you need to look at
1. Crud in filter
2. Crud in carb
3. Heat soak
4. Loose venturi

1rx7owner

What information are you looking for? Some more I can tell you is if you barely push on the throttle it will make the engine miss. It works good through mid range but at soon as it gets to 5000rpms the engine starts missing again. I will take the carb apart in a few days and clean everything. I am thinking something is clogged somewhere. Hurricane about to hit here so I wont be tearing it apart yet.

bill Shurvinton

That's more useful. I'll have think and get back to you.

Bill

1rx7owner

thanks.

bill Shurvinton

Had a think. The miss at low throttle openings is either related to the progression (which is the usual problem with carbs) or your accelerator pump.

At high RPMs the accelerator pump comes in to provide extra fuel, so this is a possibility. Easy way to check is to look down the trumpets and crack the throttle. You should get some gobbets of fuel out the accel jets.

If you back off and then reapply the throttle will it rev cleanly to the red line? I have had a carb with an awful miss at 5k, but this was over-richness rather than anything else.

Bill

mwatson184

The accelerator just sends a stream of raw fuel when you mash on the throttle, not really to do anything with high/low rpm. The progression circuit for low throttle, right as you crack it open. The main circuit for that +5000 rpm driving. If there is a problem in both of them I would guess something is clogged, like you suspect.

-Marques

bill Shurvinton

I'm sorry Marques , but you are wrong. If you read the Weber manuals you will see that the acceleration jets come into play at high RPM and WOT. Not many people go back to the original source material so this fact is often forgotten

1rx7owner

No it will not make it to redline. Well maybe it could but it misses so bad I cant stand to do it. I will take the whole thing apart in a few days and try to clean it. I did have the top off the other day and was messing with the accel pump and it seems hard to move with my fingers, I am thinking that could be the problem.

680RWHP12A

if the car was running fine, then all of a sudden it isnt, the float level is not your problem! remove the jets and blow them out , if the problem presists, try changing your spark plugs , those might be fouled up. do you have msd's ? im betting you dont, get 2 6 A units ,you will love them!!!

1rx7owner

I have removed the jets and cleaned everything out I can reach in from the top. The spark plugs are only a few months old and the wires are only like a month old. I dont have msd's, but would like them. One day I will do that mod.

680RWHP12A

what size fuel jets are you running?
what emulsion tubes are you running?
pull the spark plugs and check the color , if they are black then you fouled the plugs

1rx7owner

Alright I will do that when it stops raining.