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Weber 38 Won't Run Right :(


e28rusty

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I finally got my car back together after overheating it.  I ran it up and down the street on my old 32/36 to make sure it ran right and then swapped on a 38 I got from ebay a while back.

 

The car is a 76 california car with petronix ignition, no emissions crap, tube header, 292 regrind from IE and it runs pretty good on the 32/36, but feels like it runs out of air at high rpms.  

 

The 38 will start and I got it to idle, but driving it is terrible. It has power off idle and then immediately falls flat and struggles to rev.

I currently have 142 mains, 185 air correction, and 45 idle jets.  It is idling ok at about 1 3/4 turns out.

I set the float height to 41 and 51mm which made no change.

 

I ordered some jets, but I feel like it should be running better on the jets that are in there as they seem to be in the right range.

 

Do I need to get a different fuel pressure regulator? I'm using the mechanical fuel pump and the regulator that was hanging off the 32/36.

 

I checked for vacuum leaks and couldn't find any.  I tried retarding the timing and that made it run a bit better..

 

Any ideas?  I'm getting pissed and I might just put the 32/36 back on for now but I've spent 2 days working on this and I'd love to get it working right.

Thanks,

Luke

 

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if anyone was curious I figured out what it was after much faffing around.

one of my spark plug leads was loose in it's boot, so it was sparking barely at low rpms and as soon as it revved up it wouldn't fire.

Now to put the 38/38 back on :)

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142 main jet seems really small you should jump up to 155-160 and a 195 air correction also try a 4.0 aux venturri you should be able get all that stuff cheep on ebay


142 main jet seems really small you should jump up to 155-160 and a 195 air correction also try a 4.0 aux venturri you should be able get all that stuff cheep on ebay

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With every solution comes more problems.  The engine is running well, but I blew out my third guibo since getting the car a year ago.  I replaced it again and this time I shimmed the transmission up a bit to try to eliminate the slight angle I had in the drivetrain.  Now my shifter tower rubs on the driveshaft occasionally making a terrible noise.  I lowered the trans halfway back to where it was and I'm still getting a bit of rubbing usually when I shift.  Is this a common problem?  Anyone know what can be done aside from lowering my transmission back down?

 

Second problem, more worrying, is that at high rpms (over 5000) I'm getting a steady plume of blue smoke.  I rebuilt the head 6 months ago and had no oil burning problems until i overheated it not long ago.  This seems like oil getting past the rings?  I had the head surfaced and used a new head gasket, did I screw something up?

 

If it is the rings, I probably will just burn oil until the spring when I can commute on the motorcycle and afford to have the car taken apart for a while.  Is it worth the extra $400 for IEs 9.5:1 pistons or should I just re-ring it?  Is there significant performance gains to be had or should I save my money for more guibos  :P

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142 main jet seems really small

I was switching between a 135 and a 140 when I had one on... and that was 'a little lean, a little rich'

 

Before you tear the motor down, unhook the crankcase vent tube.

If that cures the smoke, then you just need a different way to vent the crankcase.

It needs quite a bit of 'breathing' room- I've made small changes that have lead to puking 

huge quantities of oil from a solid engine...

 

Try checking the side- to- side on your trans, too.

It makes a big difference in how things flop around.

And a 320i trans mount helps, too.

 

Finally, guibo quality's been really variable lately, with

some brands being a lot more fragile than they once were.

 

hth

 

t

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