Author Topic: Backfiring, Ect (Read 1646 times)

tanman · « **on:** April 29, 2006, 10:52:11 AM »

hey, my 67 beetle is running a little rough. ive pretty much had to re-do everythign on this car except for the body, so the engine work is coming, i know it. i tried to set the valve gaps and found out that two of the intake valves will not open at all, at any point. when i tried to fix this, i started to strip the screws they were so tight... so i decided to leave it for now. if a mechanic cant fix this, i assume i will need a new head or rocker assembly or whatever its called (im a newbie). will this fix my problem? it seems to be running really wussy too, and it backfires quite a bit unless i keep the revs a bit higher than normal. im just wondering if this is the problem or if im going to need something else, a whole new engine, ect.
thanks!
ugh its so close to being done!
also... anyone know a body shop or some place that will put in seals for one piece windows? (car came with them, not my choice)

BUSDADDY · « **Reply #1 on:** April 29, 2006, 02:18:17 PM »

If by won't open at all you mean the valve adjuster jam nuts are too tight to loosen and are stripping then it's an easy fix, mr. vice grip is a willing helper and I'm sure you can get new nuts at airspeed. At the very worst you will need another used rocker assy., easy to find. You will want to deal with that soon as tight valves lead to burnt valves which leads to engine out and heads off.

If you mean the valves themselves are not moving better check your sump screen for the missing parts of your cam and lifters, rev up the checkbook.

The other cause for a crappy idle is the idle cutoff valve on the lower left side of the carb (the gizmo with the wire sticking out of it), check to see if it's loose and make sure it clicks when you turn on the ignition. Check that with the ignition on (engine not running) and pull the wire off and touch it to the terminal a few times. Or pull off the wire with the engine running and the engine should quit.

The other causes are vaccum leaks and timing.

Ask someone for john muirs idiot manual for your birthday, I'm not calling you an idiot but it covers everything you have run into and most of the things you will. A must read for any first time VW owner.

tanman · « **Reply #2 on:** April 29, 2006, 03:31:04 PM »

i appriciate it. i'll try the vice grips and see what i can get going. the carb is brand new.
tanner

BUSDADDY · « **Reply #3 on:** April 29, 2006, 03:58:09 PM »

New or not the cutoff valve could still be loose try wigglin it and listen for the click.

silas · « **Reply #4 on:** April 29, 2006, 10:24:55 PM »

Quote

when i tried to fix this, i started to strip the screws they were so tight...

ok, this is a stupid question but, you know that the jam nuts need to be loosened off a bit before you can turn the adjusting screw, correct? i only ask to clarify that you've tried this. no harm meant. is so, try the vise grip method busdaddy mentioned.

deal with the valves and then the set the gap to .006\"
then adjust your points to .016\"
then adjust your timing.
then adjust your carb.

it sounds like it may be a little lean.

tanman · « **Reply #5 on:** April 30, 2006, 12:41:27 PM »

yea its all so tight that i cant get anything loosened off to adjust to .006
i did all but 2 of them, they were just way too tight (like rediculously tight) so im going to try
the vice grips today i think. then i'll go back through with the points and the timing and the carb.
hopefully that will be it, it backfires a bunch unless i rev high, and runs really wussy, no power.
what do you mean by a little lean?
tanner

silas · « **Reply #6 on:** May 01, 2006, 05:26:51 PM »

Quote

what do you mean by a little lean?

in order to have a complete burn in the combustion chamber you need a spark to ignite the correct ratio of air and fuel.

if you dump too much fuel in there you'll get fouled plugs, black exhaust, washed cylinder walls...rich

if you dump too much air in there you can get backfires, loss of power, and a hot motor which can also lead to burnt valves...lean

i dont know what type of carb you have but there are adjusting screws on the side that you can turn clockwise/counterclockwise to perfect the mixture.

mind you, i'm still fairly new to this too, so if i'm off on a topic or if i missed something, someone please correct me or add to it.

tanman · « **Reply #7 on:** May 01, 2006, 05:29:36 PM »

ok i'll make sure to check that too. it is running hotter than normal

jason_hamilton · « **Reply #8 on:** May 01, 2006, 09:47:43 PM »

http://en.wikipedia.org/wiki/Stoichiometric_air_ratio

BUSDADDY · « **Reply #9 on:** May 02, 2006, 06:47:26 AM »

Did all this start after the alternator change? How do the rubber boots that join the intake manifold to the end castings look? (cracked, crooked, clamps tight?) What happened with the thermostat flaps? if you didn't take them out did you hook up cross the link bar properly put the spring back on and make sure they moved? Did you have the end castings off the heads? Exactly what carb do you have on your motor? Look at thr LH side of the float bowl, should say something like 34-PICT-3.

tanman · « **Reply #10 on:** May 02, 2006, 10:05:01 AM »

no this was happening before the alt change. im not sure what number is on the carb, i will check later today. the rubber boots look fine, and im not sure about the thermostat flaps... as far as i know they are still moving, but i will check that too. its hard now that ive started full time work again... being a student gave me so much free time to mess around with it whenever i wanted!