Carbs or Ing Sys, Intermittent miss-fire Options

[Razorbobsr]

As you guys said, cleaned jets in carb, replaced plugs and wires, smooth at 900 rpms in drive, smooth at 2/3/4 K rpms in driveway, pulls hard W/O, sill I have a miss-fire that I can feel coming and going[surging, sound of engine when all 4 hit at proper times] Could I have a coil prob? Or where off to next?? 2L/carbs/5K sense rebuild/1500 miles driven to get this car home..... NKG plugs but do have Bosh plugs waiting...... Getting warmer outside, Help! Bob PS, British car friends are starting to make fun of the 914........... AND ME

[VaccaRabite]

Where in the rpm range is it missing? Is it missing when you are doing low load cruising? Or when you have your foot in and real power going down? Could be that your mIn jets are a tad big.

[Razorbobsr]

Where in the rpm range is it missing? Is it missing when you are doing low load cruising? Or when you have your foot in and real power going down? Could be that your mIn jets are a tad big.

Seems to start missing as soon as you put a load on the engine in any gear, but W/O goes like raped ape! Dial it back, miss comes back. No backfires, carbs syned, miss not steady but mostly missing. I had a new plug go bad, same kind of miss......... NKG........ Changed THAT plug and idle miss went away........ 2 bad plugs in a new set?????? Naw, odds too great for that. You think? Bob

[VaccaRabite]

Can you get it to miss sitting in your driveway? Without load maybe not. But if you can, you can isolate the bad cylinder with a timing light (find out which cylinder is not firing consistantly.)

Zach

[Razorbobsr]

Can you get it to miss sitting in your driveway? Without load maybe not. But if you can, you can isolate the bad cylinder with a timing light (find out which cylinder is not firing consistantly.) I have tried that, and why I changed the plug wires and that one NEW plug. Last thing on my list is the coil

Zach

[VaccaRabite]

Coils usually either work or don't work. I've not heard of coils being intermitent.

If you pull the plug and look at the tip, what does it look like? Is it a nice brown color, or wet and black?

What kind of dizzy do you have? If points, are you sure that your points are set and dwell is correct?

Zach

[indianmort]

if the misfire develops after the car has warmed up, it could be the coil. when cold it could run fine, as the coil heats up, it expands. if there is a failure in the windings as it expands the wires separate and the coil breaks down.

[Borderline]

How did you synch the carbs/linkage? I have found that spending additional time with the linkage can make all the difference. I synch the carbs twice. The first time is at idle with one of the links removed. The second time I synch the carbs with both links installed. I tighten the adjuster nut on the throttle cable to bring the engine speed up to 1500 - 2000 rpm. I then use the unisyn to check flow on both carbs and adjust the links to balance it again. When this is done properly the engine smooths out and runs great! You spend a lot of time at partial throttle when you're cruising on the street and hwy, having the carbs synched there really helps. FWIW (IMG:style_emoticons/default/biggrin.gif)

[Razorbobsr]

Coils usually either work or don't work. I've not heard of coils being intermitent.

If you pull the plug and look at the tip, what does it look like? Is it a nice brown color, or wet and black?

What kind of dizzy do you have? If points, are you sure that your points are set and dwell is correct?

Zach

Excep for the NEW plug, they all looked good and normal. 009 Dizzy. Bob

[Razorbobsr]

How did you synch the carbs/linkage? I have found that spending additional time with the linkage can make all the difference. I synch the carbs twice. The first time is at idle with one of the links removed. The second time I synch the carbs with both links installed. I tighten the adjuster nut on the throttle cable to bring the engine speed up to 1500 - 2000 rpm. I then use the unisyn to check flow on both carbs and adjust the links to balance it again. When this is done properly the engine smooths out and runs great! You spend a lot of time at partial throttle when you're cruising on the street and hwy, having the carbs synched there really helps. FWIW (IMG:style_emoticons/default/biggrin.gif)

I know how I do that.......... But how do u do it?? Where to u make the disconnect??? Bob

[Razorbobsr]

if the misfire develops after the car has warmed up, it could be the coil. when cold it could run fine, as the coil heats up, it expands. if there is a failure in the windings as it expands the wires separate and the coil breaks down.

When you say, breaks down........ Just how would that sound/feel. The spark at idle is blue and strong, jumps 3/4 of an inch. Bob

[McMark]

009 Dizzy is garbage. As Dave Darling loves to say, "Give it the float test. Throw it in a lake and if it floats, it's good." The problem your having sounds like typical 009 problems. With the 009 it either idles great, but sucks a WOT, or runs great at WOT and has crap idle.

I also agree about synching the carbs. If you've got some extra cash, just toss out the cross bar linkage and get a CSP Bellcrank. Otherwise, it's takes a lot of trial and error and a lot of fidgeting to get the cross bar linkages to work right.

[Razorbobsr]

009 Dizzy is garbage. As Dave Darling loves to say, "Give it the float test. Throw it in a lake and if it floats, it's good." The problem your having sounds like typical 009 problems. With the 009 it either idles great, but sucks a WOT, or runs great at WOT and has crap idle.

I also agree about synching the carbs. If you've got some extra cash, just toss out the cross bar linkage and get a CSP Bellcrank. Otherwise, it's takes a lot of trial and error and a lot of fidgeting to get the cross bar linkages to work right.

Why is the 009 junk? CPS Bellcrank?? Why are cross bars a pain? Would rather not change parts till I find the right combo, kinda costly and I am CHEAP!! LOL On the face of it this prob sounds simple, miss fires.............. Changed plugs and wires, cleaned cap...... Bob

[McMark]

Normally I retype all this info. But there is so many posts about 009s and recently the CSP vs. Crossbar info. Check out the search function at the top of the page.

Really simplified:
1. The 009 doesn't have enough total advance. It's like a bed sheet that's too short. It covers your feet, or it covers your body, but not both at the same time.
2. The crossbar linkage has too many moving parts that can introduce slop, the parts are never manufactured to any sort of tight tolerance, and so even when it's set up as well as possible it's still easy to open one carb and not the other. The ideally perfect linkage would never, ever, ever allow that to happen. The CSP is much closer to that ideal than any of the cross bar linkages.

[Razorbobsr]

Normally I retype all this info. But there is so many posts about 009s and recently the CSP vs. Crossbar info. Check out the search function at the top of the page.

Really simplified:
1. The 009 doesn't have enough total advance. It's like a bed sheet that's too short. It covers your feet, or it covers your body, but not both at the same time.
2. The crossbar linkage has too many moving parts that can introduce slop, the parts are never manufactured to any sort of tight tolerance, and so even when it's set up as well as possible it's still easy to open one carb and not the other. The ideally perfect linkage would never, ever, ever allow that to happen. The CSP is much closer to that ideal than any of the cross bar linkages.

CPS link? How much advance is correct? Bob

[Razorbobsr]

Coils usually either work or don't work. I've not heard of coils being intermitent.

If you pull the plug and look at the tip, what does it look like? Is it a nice brown color, or wet and black?

What kind of dizzy do you have? If points, are you sure that your points are set and dwell is correct?

Zach

Car started easy this am, fuel mix screw in+ rich?..... Screw out= lean? Still dont see where to disconnect cross bar to syn carbs better. Ran both idles out till eng slowed, both in.... till eng just did pick up rpms a hair, then back a 1/2 hair. One was pretty far off the other, I think? At start I reved it a little can could hear spitting ever so slightly back threw A carb.... poss both, stopped when engine warmed. Normal?

[VaccaRabite]

Always adjust carbs when they are fully warmed up. Adjusting them while cold will make them run fast when warm.

On the mix screw
Turning in closes the the jet (less fuel and air)
Turning out opens the jet (more fuel and air)
the mix screw does not change the ratio of air to fuel, just the volume of it. The object of adjusting this screw is to get the cylinder to run smoothly on as little fuel and air as possible.

Turning the idle screw changes the idle speed for that bank of carbs.

You disconnect the bar by unbolting the drop links that go from the cross bar to the carb body. They are usually held on with small bolts (m4 or m5). Depending on the make of the bar, some have snap joints instead of bolts. Take a picture of your connection and we can help you out.

Also, try to be a little more clear when you post. It may just be me, but I have a hard time understanding what you are trying due to your posting style.

Zach

[McMark]

On the mix screw
Turning in closes the the jet (less fuel and air)
Turning out opens the jet (more fuel and air)
the mix screw does not change the ratio of air to fuel, just the volume of it. The object of adjusting this screw is to get the cylinder to run smoothly on as little fuel and air as possible.

Zach, you're confusing two screws here. The idle mixture screws cange only the volume of fuel at idle. Screwing them in will make it run leaner, out is richer. This screw does not change airflow at idle. Right next to the idle mixture screw is an air bypass screw. This one has a lock nut on it and it changes that amount of air bypassing the throttle plate at idle. Screwing it out allows more air to pass, and in allows less. The air bypass screws need to be adjusted while the linkage is disconnected and with a UniSyn or Synchometer (better). The function of the air bypass screws is not to change mixture, but to equalize the air flow of the two throats.

You disconnect the bar by unbolting the drop links that go from the cross bar to the carb body. They are usually held on with small bolts (m4 or m5). Depending on the make of the bar, some have snap joints instead of bolts. Take a picture of your connection and we can help you out.

(IMG:style_emoticons/default/agree.gif)

[Razorbobsr]

Always adjust carbs when they are fully warmed up. Adjusting them while cold will make them run fast when warm.

On the mix screw
Turning in closes the the jet (less fuel and air)
Turning out opens the jet (more fuel and air)
the mix screw does not change the ratio of air to fuel, just the volume of it. The object of adjusting this screw is to get the cylinder to run smoothly on as little fuel and air as possible.

Turning the idle screw changes the idle speed for that bank of carbs.

You disconnect the bar by unbolting the drop links that go from the cross bar to the carb body. They are usually held on with small bolts (m4 or m5). Depending on the make of the bar, some have snap joints instead of bolts. Take a picture of your connection and we can help you out.

Also, try to be a little more clear when you post. It may just be me, but I have a hard time understanding what you are trying due to your posting style.

Zach Could be my lack of formal education?? Or the British sports car guys dumbed me down?? Or just natural? Will try to do better! Cleaned D/cap with carb cleaner, buffed rotor and cleaned, backed idle on carbs all the off, in till I picked up a hair of RPMs then backed off 1/2 hair. Backfires much more muffeled now, poom V BANG Better............ AA guys tell me I have TOO open exhaust sys and need more back pressure, cherry bomb muffler just about stright through...... Correct?? Bob

[VaccaRabite]

Zach, you're confusing two screws here. The idle mixture screws cange only the volume of fuel at idle. Screwing them in will make it run leaner, out is richer. This screw does not change airflow at idle. Right next to the idle mixture screw is an air bypass screw. This one has a lock nut on it and it changes that amount of air bypassing the throttle plate at idle. Screwing it out allows more air to pass, and in allows less. The air bypass screws need to be adjusted while the linkage is disconnected and with a UniSyn or Synchometer (better). The function of the air bypass screws is not to change mixture, but to equalize the air flow of the two throats.

(IMG:http://www.914world.com/bbs2/uploads_offsite/th192.photobucket.com-1435-1300325684.1.jpg)
WTF was I thinking? I seriously need to get out and play with my car, I am way out of practice here.

Razor,
From your other post, I think you are using a Eurorace header. If it has the turbo muffler, there is not much going on inside it. Part of the reason its so loud.

Zach