count down to driving, nothing is working HELP Options

[jmill]

just tried all that and blew out the idle jets and circuit,removed the linkage, set the idle @900, no change. allow me to put forth a theory

when i had the problem with the valve adjustment screw stripping off on the passenger side, the balance on the drivers side was fine , since i replaced the screw and readjusted the valves on the pass side, the driver side carbs are off. could it be that i need to readjust the driver side valves, they were done before the engine went into the car. the engine hasn't been run for more than 2 hours since.

Having your valves out of adjustment will affect your flow. If the gap is set bigger than the rest your intake will open late and shut early = lower flow. Check the valves. If thats not it pull out the mixture screw and the idle jet. Blow out the idle port with them removed. Blow out and inspect your idle jet. Check the holes in the butterfly. Make sure they're clear and that they look the same as the others. Some backyard tuners drill out the holes to lean up the progression ports. If that doesn't work I'm out of ideas. Maybe Joe can come up with something. He usually catches what I miss.

[IronHillRestorations]

A copy of my carb tuning method post for Trekkor, a few years ago.

Assumptions: the carbs have the optimum jet and venturi package (good luck on this one), the float level in the carbs is correct, the cams are correctly timed, the valves are properly adjusted, the ignition timing is dead on, you have the proper spark plugs for your engine, the linkage is good, the fuel is good, the engine is good.

Remember that the mixture and air bypass adjustment screws are precision needle valves, not head gaskets. Use your fingers to tighten them, not your fist.
Start and warm up the engine.
Make sure the two drop links for the throttle linkage are exactly the same length, and disconnected. You can use a 8mm thin igntion wrench to snap them off.
Turn the mixture screws all the way in and then 5 half turns out.
Turn the air bypass screws all the way in.
Turn the idle speed screws out til it just touches, and then in 5 half turns.
Put on your hearing protection and start the car.
Use your STE and find the barrel that pulls the most. We'll call this one baseline.
Balance the barrel in the other carb that pulls the most with the idle speed screw. (if you have a Uni-syn, give it to someone you don't like and purchase a STE airflow meter)
Go back to the other carb, with the baseline barrel. You will have one all the way in, then use the air bypass screws and balance the other two barrels.
Go to the other carb and do the same thing.
Snug the jamb nuts on the air bypass screws.
All six (or four)barrels should pull the same amount of air at this point, if not repeat air adjustment proceedure.
Snap the throttle linkage drop links back on the carbs. If the idle changes then you need to barely adjust the linkage mounts so snapping the drop links on, doesn't change the side to side idle balance.
Use the hand throttle or a vice grip and rag to lock the linkage between 1400 and 1800 rpm.
Start back at the baseline barrel and adjust the mixture screw in or out, to get the smoothest running and highest rpm, then turn it in 1/4 turn.
Do the same with the five other mixture screws.
If you have to turn the mixture screws more than two turns either way, you've got the wrong jets.
Recheck side to side and individual air balance, adjust as needed.
Road test the car.
If you get snapping and poping out the intake, it's generally a lean condition.
If you get heavy exhaust fumes, or pboofing out the exhaust it's probably too rich.
If you get a flat spot or popping out the intake at between 2800 and 3200 rpm, you probably need larger idle jets.

That's a rough, five minute draft of my carb tuning proceedure, hope it helps!

If it goes good it should take about 45 minutes, if not about three years.

PK

Another good tip: If you think you have a lean cylinder (idle jet plugged) you can back out the jet carrier a half to one full turn and the engine should stumble, if it doesn't change theres a good chance the jet is clogged. This primarily applies to the 3 barrel carbs, as the 2 barrel IDF's have a different type idle jet set up.

Don't diminish the value of correct ignition timing, and valve adjustment, it makes a difference. Also make sure your linkage is dead nuts the same length.

[ME733]

(IMG:style_emoticons/default/popcorn[1].gif) (IMG:style_emoticons/default/popcorn[1].gif) 1) welll yea!!!Please do get ALL the valves adjusted FIRST.2) may I suggest that the ...butterflys are not aligned , equally, with the IDLE ports(fuel ports,) .....I think you originally said ...everything was balanced and running well ..EXCEPT...one cylinder was off....that (cylinder may have a bent or distorted butterfly, which needs to be realigned....equally opening with it,s partner on the other bore,side.(both butterflys open equally.)....3) you have gotten some really good advise from those who made comments....you just should remove the carbs and overhaul them properly......and use a hose clamp on the fuel lines.....checking ALL the jet sizes ,and correction jet sizes is real good advise......postpone driving until the carbs are repaired,fixed..torching a valve,or burning a piston WILL really (IMG:style_emoticons/default/icon8.gif) P.Y.OFF. (IMG:style_emoticons/default/popcorn[1].gif)

[turboman808]

Man I really hope you get to drive this weekend. Good luck Rich

[Joe Ricard]

He is really just an RCH from perfect.

Something else to do that has not been mentioned yet. you have been setting the balance of the carbs at idle. so this means you should have one side of the linkage disconnected. and setting things with idle stop screws.

Once you get that sorted. you have to connect the linkage and artificially pull tension on the throtle cable till you reach about 2500 RPM now you need to synch the carbs using the hiem jointed reach rod on one side.

That is the final step when the carbs are pulling the same at "x" rpm everything will seem right with the universe.

[nycchef]

[
o.k running better. took a nice 20 min drive. still high pitch popping on acceleration out of the carbs hesitation on acceleration. dobn't think this is pedal cluster related. redid all the valves, balanced the linkage, set the air bypass screws all in, mixture screws a .2.5 turns out, idle about 1000 rpm's, 3 barrels @5 on the syncrometer 1 @ 3.5., cannot find the trick to this one, if i raise the idle or tweak the mixture, both sides go up exponentially on that carb, if i back out the idle jet screw on the low barrel nothing seems to happens, if i back it out on the good barrel it stutters, i.m gonna buy new jets, venturi's and so forth but i have 2 questions
could this be a timing issue. i timed it @ 27btdc, this is a stock cam converted to carbs by the po.
given that. what size venturis , jets etc should i get.
i am posting this on 2 sites for maximum info

[neil30076]

[
o.k running better. took a nice 20 min drive. still high pitch popping on acceleration out of the carbs hesitation on acceleration. dobn't think this is pedal cluster related. redid all the valves, balanced the linkage, set the air bypass screws all in, mixture screws a .2.5 turns out, idle about 1000 rpm's, 3 barrels @5 on the syncrometer 1 @ 3.5., cannot find the trick to this one, if i raise the idle or tweak the mixture, both sides go up exponentially on that carb, if i back out the idle jet screw on the low barrel nothing seems to happens, if i back it out on the good barrel it stutters, i.m gonna buy new jets, venturi's and so forth but i have 2 questions
could this be a timing issue. i timed it @ 27btdc, this is a stock cam converted to carbs by the po.
given that. what size venturis , jets etc should i get.
i am posting this on 2 sites for maximum info

For kicks you could swap the carbs over and see if the probelm moves wth them - you have to move the linkages from one end to the other on teh throttle shafts, but it's not difficult - I did this on mine to try and isolate a bad barrel on one carb ( #2 cylinder) and it had no effect, the same cylinder was screwed up - found a nick in gasket to manifold on that barrel that i did not see before.
Just a thought - you are expert at removing them anyway, by now they should jump right off into your hands when you snap your fingers (IMG:style_emoticons/default/lol-2.gif)

[nycchef]

[[/quote]
For kicks you could swap the carbs over and see if the probelm moves wth them - you have to move the linkages from one end to the other on teh throttle shafts, but it's not difficult - I did this on mine to try and isolate a bad barrel on one carb ( #2 cylinder) and it had no effect, the same cylinder was screwed up - found a nick in gasket to manifold on that barrel that i did not see before.
Just a thought - you are expert at removing them anyway, by now they should jump right off into your hands when you snap your fingers (IMG:style_emoticons/default/lol-2.gif)
[/quote]
are you suggesting switching just the carbs or carbs and manifolds?. would'nt that put my linkage in the back? neil while i have your attention. i see on your linkage a large spacer on the pass side. i didn't get one in my kit. i put an extra nut on to keep the angle symetric.

[r_towle]

its a bit of a project but he is suggesting switching the carbs...that means you take off the linkage plates, swap carbs, then put the linkage back on and re-sync.

It is a valid test, but all it will do is show you one of two things.
You have one cylinder that has the valves adjusted wrong...or its got a leak...
OR
You have not adjusted the carbs correctly.

Each cylinder will perform differently, especially on an old motor.
Each venturi will behave differently also.

That is why there are individual adjustments for the air/fuel mixture on each venturi right from the factory...cause they all are different...just a fact of life.

I would suggest that you check the valve adjustment again on that one low cylinder, then, and only then, if everything else is ok...adjust the lower screw, not the one with the spring, not the idle just...
The lower one with the lock nut on it.
Adjust it while you have the sync tool in place.

Rich

[neil30076]

[quote name='nycchef' date='Aug 6 2009, 04:35 PM' post='1200215']
[[/quote]
For kicks you could swap the carbs over and see if the probelm moves wth them - you have to move the linkages from one end to the other on teh throttle shafts, but it's not difficult - I did this on mine to try and isolate a bad barrel on one carb ( #2 cylinder) and it had no effect, the same cylinder was screwed up - found a nick in gasket to manifold on that barrel that i did not see before.
Just a thought - you are expert at removing them anyway, by now they should jump right off into your hands when you snap your fingers (IMG:style_emoticons/default/lol-2.gif)
[/quote]
are you suggesting switching just the carbs or carbs and manifolds?. would'nt that put my linkage in the back? neil while i have your attention. i see on your linkage a large spacer on the pass side. i didn't get one in my kit. i put an extra nut on to keep the angle symetric.
[/quote]
Switch the carbs only - leave the top plate of the linkage where it is and the manifold to head. Do not adjust anything, see what the sync says.

The CB kit for a 914 should come with that spacer, its black about 1.5 inches long - with the ball end for the drop link. Without it the two linkages cannot be parallel, they need to be in both in the front to back and side to side planes, or the carbs will be out of sync at full throttle - the drivers side carb will lead the other - not good, at full throttle the drives is wide open, the passengers still has a way to go.

[neil30076]

and only then, if everything else is ok...adjust the lower screw, not the one with the spring, not the idle just...
The lower one with the lock nut on it.
Adjust it while you have the sync tool in place.

Rich

Rich makes a good point also if the lower screw is not perfectly seated, or the O ring is messed up, you will see a difference on just one cylinder. Did you remove these at any time, maybe accidently swapped them over. Remove the one on that cylinder only and examine it, if the point is not perfect and not seating that could be your probelm.

[nycchef]

and only then, if everything else is ok...adjust the lower screw, not the one with the spring, not the idle just...
The lower one with the lock nut on it.
Adjust it while you have the sync tool in place.

Rich

Rich makes a good point also if the lower screw is not perfectly seated, or the O ring is messed up, you will see a difference on just one cylinder. Did you remove these at any time, maybe accidently swapped them over. Remove the one on that cylinder only and examine it, if the point is not perfect and not seating that could be your probelm.

you guys are taling about the idle jet correct, i backed the offending barrel just about all the way out and had no effect. the other side started to shudder wheb i did that. i removed the idle jets and blew out the circuit , i did not see an o ring. does it stay in the carb?

[r_towle]

Idle jet is at the top.
It has a rubber o-ring.
It might stay in the carb...get a mirror and CHECK all four of them...make sure you have an o-ring on each one.

Idle air bypass is the screw with the spring...that is the one that gets screwed in tight, then backed off 1.5 turns.

Idle mixture screw is typically something that is set at the factory and should not be messed with..
Its setup on a flow bench to match each port to the other port...that is a simple function..

so, if that screw has been moved (it has a lock nut on it) then you may have setup that port wrong...it wont match the other port (thermo dynamics thing...air flow etc)

So, we are talking about three screws here.

What have you changed?
Did you adjust the screw with the nut on it? Its at the base of the carb, it does not have a spring.

Top screw, Idle Jet
Bottom middle screws, Idle mixture screws
Bottom screws with Jam nuts...Air bypass screws (used to balance carb on flow bench)

So...which ones are set where?

Rich

[neil30076]

Idle jet is at the top.
It has a rubber o-ring.
It might stay in the carb...get a mirror and CHECK all four of them...make sure you have an o-ring on each one.

Idle air bypass is the screw with the spring...that is the one that gets screwed in tight, then backed off 1.5 turns.

Idle mixture screw is typically something that is set at the factory and should not be messed with..
Its setup on a flow bench to match each port to the other port...that is a simple function..

so, if that screw has been moved (it has a lock nut on it) then you may have setup that port wrong...it wont match the other port (thermo dynamics thing...air flow etc)

So, we are talking about three screws here.

What have you changed?
Did you adjust the screw with the nut on it? Its at the base of the carb, it does not have a spring.

Rich

Agree, i'm also talking idle mixture screw, which on my carbs is seated firmly and has not been adjusted after i did carb rebuild - most sources seem to say close it completely and don't touch it as it is very sensitive - which i did.

[r_towle]

Idle jet is at the top.
It has a rubber o-ring.
It might stay in the carb...get a mirror and CHECK all four of them...make sure you have an o-ring on each one.

Idle air bypass is the screw with the spring...that is the one that gets screwed in tight, then backed off 1.5 turns.

Idle mixture screw is typically something that is set at the factory and should not be messed with..
Its setup on a flow bench to match each port to the other port...that is a simple function..

so, if that screw has been moved (it has a lock nut on it) then you may have setup that port wrong...it wont match the other port (thermo dynamics thing...air flow etc)

So, we are talking about three screws here.

What have you changed?
Did you adjust the screw with the nut on it? Its at the base of the carb, it does not have a spring.

Rich

Agree, i'm also talking idle mixture screw, which on my carbs is seated firmly and has not been adjusted after i did carb rebuild - most sources seem to say close it completely and don't touch it as it is very sensitive - which i did.

No, sorry...that is why I posted the picture.
Idle mixture screw is the one with a spring. Its typically seated, then backed out about 1.5 turns...then you adjust each one in until the car starts to die...then back it out about a 1.4 of a turn. Done.

I posted the pic so we would use the same terms.

The screw with the jam nut...that is not so easy to mess with...
That screw.....the "AIR bypass screw" is exactly what its called.
Its set at the factory.
If you remove it when rebuilding or cleaning...that could easily be his issue at idle.
It could explain why they do not sync up at idle from one side of the carb to the other.

Rich

[neil30076]

Idle jet is at the top.
It has a rubber o-ring.
It might stay in the carb...get a mirror and CHECK all four of them...make sure you have an o-ring on each one.

Idle air bypass is the screw with the spring...that is the one that gets screwed in tight, then backed off 1.5 turns.

Idle mixture screw is typically something that is set at the factory and should not be messed with..
Its setup on a flow bench to match each port to the other port...that is a simple function..

so, if that screw has been moved (it has a lock nut on it) then you may have setup that port wrong...it wont match the other port (thermo dynamics thing...air flow etc)

So, we are talking about three screws here.

What have you changed?
Did you adjust the screw with the nut on it? Its at the base of the carb, it does not have a spring.

Rich

Agree, i'm also talking idle mixture screw, which on my carbs is seated firmly and has not been adjusted after i did carb rebuild - most sources seem to say close it completely and don't touch it as it is very sensitive - which i did.

No, sorry...that is why I posted the picture.
Idle mixture screw is the one with a spring. Its typically seated, then backed out about 1.5 turns...then you adjust each one in until the car starts to die...then back it out about a 1.4 of a turn. Done.

I posted the pic so we would use the same terms.

The screw with the jam nut...that is not so easy to mess with...
That screw.....the "AIR bypass screw" is exactly what its called.
Its set at the factory.
If you remove it when rebuilding or cleaning...that could easily be his issue at idle.
It could explain why they do not sync up at idle from one side of the carb to the other.

Rich

Rich is correct, I replied without seeing his diagram first- we are both talking about the same screw - the one with the jamb nut - the AIR bypass screw - now - Richy - did you adjust it or not ?
I'm going back to my 928 and getting the a/c reinstalled and working - r_towle has the floor (IMG:style_emoticons/default/lol-2.gif)

[nycchef]

air by pass screw yes i have been screwing with it all day. have never touched the idle jet, am goin back to the car to make sure they are all the way in and then try to adjust it using the right screw.

[jmill]

With your mixture screws all the way in I have no doubt you had some popping going on.

The air bypass is for equalizing air flow between barrels at idle. You only open it to adjust air flow. It will be set closed from the factory. Sometimes you open one, none or 3. You use it to bring the flow up to the highest flowing barrel.

I set the idle mixture at 2.5 to start with. At 1.5 you might not be out far enough to adjust in to best mixture. If your best mix is at 2 you'll miss it.

[r_towle]

Um....
First...remove each idle jet and check with a mirror that each one has an o-ring...
You need to know.

then screw them in all the way...they are not adjustable.

rich

[turboman808]

I am watching this with high hopes. For some reason I really want your car running this weekend.