engine and drivetrain Carburetor and Acceleration Help...

[lach]

Hi All,

Need a little help, and I have searched but not coming up with good results.

I have had my new BMW factory engine for about 800 miles now, and am starting to stretch its legs a bit.

Unfortunately, the car still seems to run out of steam around 4500 rpm. I have checked the Weber 32/36 carburetor, and both the main and secondary valve are opening, but the secondary seems to be coming on at the very tail end of the pedal travel, is this normal?

I have a pertronix unit, with a 6A MSD ignition. The car otherwise is running great, nice and smooth...just a little disappointed with the acceleration.

Am I expecting too much, or should the car spin up the rpms with no problem?

Thanks in advance for any advice.

Bob

[jrhone]

Check your timing.

[02for2]

Check your timing.

+1 and your valve lash!

Cheers!

[c.d.iesel]

first - test your gas pedal/throttle linkage

bet it doesn't open fully

press the gas pedal to the floor while standing

outside the door so you can see the back of the carb,

the throttle linkage should be tapping against the

FULL OPEN stop on the back of the carb - adjust

the rod from the fire wall so it has straight alignment

to the carb - then on to the utter stuff:

......give these a try -

Float Level 40mm

PRIMARY

idle 60

main 140

air correction 145

SECONDARY

idle 55

main 170

air correction 175

AND -PLUG THE SECONDARY ENRICHMENT HOLE

AT THE TOP OF THE CARB AS MY DIAGRAM SHOWS.

SEE THE HUGE DIFFERANCE IN ACCURATE FUEL

METERING THROUGH OUT ALL RPM AND THROTTLE OPENINGS.

read and do this >>> http://www.bmw2002faq.com/content/view/62/32/

and this assumes you use a timing light

to set the timing?(BALL mark in the inspection

hole behind the starter- at 1500 rpm) and

yer valves are adjusted to about 0.006" cold -

otherwise forgitaboutitt

...and it's not so much just the 'main" jets,

it's the matching of the 'air correction' to 'main' jet

for smooth power delivery accross 1/4 throttle

opening , low rpm, transitioning up to 3/4 - FULL

throttle and high rpm - they both effect each other

make sure your compression is healthy

(above 140 psi), valves adjusted (0.006"),

dwell(if you have points (59 degrees or 0.016")

and timing using a light setting the ball in the

inspection hole next to the starter motor

at 1500 rpm and no vacuum hoses connected

to the distributor if you have any while performing the

timing check. Reattach the vac advance hose after setting.

another often missed fine detail - while holding your

gas pedal to the floor, stand outside the door so you

can see if the carb linkage it tapping the FULL OPEN

STOP on the carb. Adjust your fire wall rod as needed,

or possible your pedal box throttle lever is positioned

incorrectly on it's splines???

but adjust so with moderate pressure on the gas

pedal to the floor - the carb is indeed opening

fully against it's stop.

happy spring time

[lach]

Awesome advice, thank you!

I will update the thread on my progress...

[TobyB]

The second barrel should be opening about half- way through the

pedal travel. If your motor mounts are soft, they tend to pull the

linkage out of adjustment so that you only get a little bit of secondary-

I'd start there.

Then I'd make darned sure I had good fuel supply- that'll

make the car go 'soft' like you've described.

I get to around 6k on the street car with the 32/36 before it

says 'eh, why not shift?'

There's more there, I think.

t