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Lurching on Acceleration. Help?


jackrabbit

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Alright so Trinker's 32/36 just recently started giving me trouble on acceleration where it starts to lurch real bad. I checked both idle jets for clogging, cleaned out the secondary and replaced the primary (running #55 on the primary and #50 on the secondary). No luck. Where to look next? The lurching is normally worst from ~1500-3000 RPMs and once it gets up to freeway speed in 4th they become much less noticeable (perhaps just because of the speed...).

74 BMW 2002 Atlantik "Trinker"

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Give it a throttle-tune. Give it full throttle and just as it reaches full RPM, close the choke. This will clean out any rocks, mice or other things stuck in the carb.

Caution; don't do this while driving unless you have a manual choke.

Seriously, throttle-tunes sometimes work.

No amount of skill or education will ever replace dumb luck
1971 2002 (much modified rocket),  1987 635CSI (beauty),  

2000 323i,  1996 Silverado Pickup (very useful)

Too many cars.

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down the primary barrel throat (the one closest to the pax side) and work the accelerator linkage. You should see a squirt of fuel emerging from a little orifice on the forward (towards the front of the car) edge of the primary throat. That's the accelerator pump nozzle, that gives you an extra squirt of fuel when you suddenly accelerate. No squirt=malfunctioning accelerator pump, which can cause lurching under acceleration as the engine is momentarily starved for gas. Easy to replace the pump diaphragm.

But do check your ignition timing, point gap, plugs etc too. That quote, incidentally was what my late and sorely missed father-in-law told me back when he was teaching me how to work on cars (so mine wouldn't break down when his daughter was out with me). And he was usually right!

cheers

mike

'69 Nevada sunroof-Wolfgang-bought new
'73 Sahara sunroof-Ludwig-since '78
'91 Brillantrot 318is sunroof-Georg Friederich 
Fiat Topolini (Benito & Luigi), Renault 4CVs (Anatole, Lucky Pierre, Brigette) & Kermit, the Bugeye Sprite

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Guest Anonymous

Mike, Its an honor to see your reply, have enjoyed your writing for years. My goal is a 69 2002 and you have owned one from birth, look forward to building one just the way I want, stock looks with ti inards, not a race car but a custom classic, bought my first 76 from picnpull for $375, complete car and such an easy build, got spoiled by the ease of it, second was an ebay buy, a sweet 70 roundie that had bad rust worms, loved the car but too much to handle, now I lucked into an original paint 76 for $500 bones, I look to the stars and thank the creator for blessing me, I look forward to driving said car to SF and parking her at pier 39 and loading the trunk with sour dough, clam chowder and trinkets for the grand kids, mama told me to be a simple man and thats my plan, I hope you understand.

Dave Miller

DBMW2002

76 Golfie Screamin Yellow Zonker

97 BMW 328is For when you absolutly positivley have to get there fast.......

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.....you've got one seriously f'd up distributor

look at the point plate mechanical advance function

non-functioning

....that is if you really have no problem with the carb as you state

'86 R65 650cc #6128390 22,000m
'64 R27 250cc #383851 18,000m
'11 FORD Transit #T058971 28,000m "Truckette"
'13 500 ABARTH #DT600282 6,666m "TAZIO"

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Just replaced all mounts a month ago :/ The engine definitely feels like it's missing where it will start to accelerate and then it will temporarily lose power, lurch, then pick back up. Then it will pretty much continue doing that until you shift or let off the throttle.

74 BMW 2002 Atlantik "Trinker"

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Just replaced all mounts a month ago :/ The engine definitely feels like it's missing where it will start to accelerate and then it will temporarily lose power, lurch, then pick back up. Then it will pretty much continue doing that until you shift or let off the throttle.

Yea Toby that was stupid!!! LOL checked your fuel pump? and filter?

Scott B.

1969 2002, 1972 2002, 1967 1600, 2001 540It

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yeah, that WAS stoopid... heh... If your float bowl's not fulla junk,

then maybe you're not getting fuel flow.

Easy to check- put a gauge on it. If it drops to (near) zero, there you are.

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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yeah, that WAS stoopid... heh... If your float bowl's not fulla junk,

then maybe you're not getting fuel flow.

Easy to check- put a gauge on it. If it drops to (near) zero, there you are.

t

Ill take the backlash as well as you did ( I promiss)...

Scott B.

1969 2002, 1972 2002, 1967 1600, 2001 540It

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