Hey ppl
My 7 has a 12a Bridgeport in it. I know there supposed to be hard to drive and all but recently its become stupid. When driving between 2800 and 3800rpm the gearstick shakes like a bitch, the whole car shakes and the car coughs and splutters, lurches and receeds and is just an uncomfortable ride.. epecially as thats my usual cruising revs. If it starts shaking and i floor, it just lurches more, and wont rev any higher. I have to completely back off the gas and then floor it to get it past this evil flat spot.

In neutral it does the smae thing, i lifted the bonnet and the whole engine/tranny shakes vigourisly at these revs and it doesnt look or sound healthy.

Now.. i found an old video clip that i downloaded of this forum which had a car with exactly the same problem, its a 16mb file so i cant host it, but if that person is still here please let me know what you did.

What i have done so far:
Played with mixtures
changed spark plug leads
swapped coils (with a spare i had)
played with timing
cleaned plugs
tightened all mounts
checked for vacuum leaks (none)
cursed and swore many times

ive been trying for over a week to fix it but it wont change. Its wierd coz if i floor it from idle, i can accelerate no worries, just a little burp as i pass that rev area, but if i then try to cruise she does mad.

PLEASE if anyone has any ideas let me know because this is killing me

thanks in advance

-James

P.S. its a 12a BP
48IDA webber
lightened flywheel/hd clutch
etc etc

 

Possibly fuel related. Check you fuel filter. It probably needs replacing anyway if it has been very long since it was changed. Next, I would look at the fuel pump and make sure that it is working properly. I would also check the air filter as well. The air filter by itself is most likely not the cause but it wouldn't hurt to make sure that it is still clean.

 

I just noticed that you said that you cleaned the plugs. If they have more than 10,000 Miles/ 15,000 km then replace them.

 

new plugs is next on the list, but as there $14.95 each i have to work to a budget...
oh and i forgot to say that i replaced the fuel filter, fuel pressure is still at 4.5psi

and it stil does the same thing without the airfilter on it.


any other suggestions??? its just wierd because its only at this rev range... i think its ignition related. but it could be the carby (which i have stripped and cleaned twice)



thanks for the quick replys
-James

 

check somewhere else for plugs, the local Napa has the stock plugs for around $7 each, little better then the $15

 

check your float levels

 

ive dropped the float level just a little and it seems to of softened the problem.. its stillthere but less fierce... the reason i had the flat level high was i was starving of fuel, i might put the 3mm needle back in and give it a whirl

thanks for the help guys, ill keep you posted
-James

 

any luck fixing your prob. i have the same. PM me.

carl.

 

I would say change the saprk plugs as well. Engine shaking and a generally bad temperment can be helped with new plugs.

 

what about an out of balance drive shaft or maybe an out of balance rotating assembly

 

If it was something out of balance it would get worse as revs increase, but this is only happening at a certain RPM range.

 

It could also be motor mounts.

 

...or it could be an incorrect flywheel counterweight.

 

No it couldn't. See my last post.

 

Well It wierd to say and I might not be right on this cause I'm no expert ^_^. But when I first got my 13B back from my uncle It vibrated like a bitch I really bad bitch looking for a wooping. So we did give her one...needless to say problem soved. I guess if your engine is new I might just need a little break-in time and it also depends on how agressive your street/bridge port is.
Well just my two cents. It might not be alot but I do what I can ^_^;
Good luck
Nector

 

i had the same exact problem with my motor . it was a wire coming off of the leading ignitor that goes to the coil . It was broken open and was arcing off of my radiator support. It actually happened to me twice, it was all green from antifreeze and corrosion. So check your wires going to your ignitors. My motor is bridge ported and shakes a little bit also but thats normal for a bp motor .

 

ok... well it was still there but it was just a small problem... and two days ago i put in new goild Bosch GT40, and a full set of B9EGV plugs, gapped to 1mm.

She was fine in the morning but since then its been as bad as it was ages ago... Tonight im going to check all ignition wiring. The idle mixture is good, and i know the main mix is a little lean but i dont push it too hard up top.

Im pretty sure its not the rotating assembly coz when i first built it the thing was fine.

If this doesnt fix it, ill get a new cap and rotor button for the dizzy, then i attack th3e webber and see if its something in there.


OH HAPPY DAYS!!!!!!!!

-James

P.S. Cheers for the helpful suggestions guys.. keep em coming

 

It is possible that an out-of-balance flywheel counter weight could actually find a harmonic balance at certain revs; not necessarily being worse at a higher rpm.

 

Have you tried lowering the fuel pressure and jetting accordingly. It just seems that most people are running much less than 4.5psi on webers. I dunno if thats your problem because all my info just comes from reading, but maybe thats it.
Grant

 

i was told that 4.5 was best pressure for webbers... ill give it a whirl tonight and see what happens.

-James

 

oh and also... if it was an unbalanced flywheel.. why would the shakes almost disappear for a few months and then suddenly come back hard??

James

 

MAYDAY MAYDAY!!!!!!!!

I just did the worst thing ever, i tried to work on my car during my lunch break.. Now it wont start

What i did was have a look at the ignition wiring,... and it was all backwards, so i corrected it all, set it to what i think is right (see pic) and now it wont start, and if i turn the dizzy all the way clockwise, it can start but doesnt sound healthy and wont hold an idle


WHAT HAVE I DONE!!!!!!!!

i cant remember how it was before... so now i need you guys to help me out if you can

Please help

James

 

anyone??

I need to fix this before i can go home tonight



James

 

Sorry I cant help you with your latest problem but the overall problem - I have the same one. It just popped up out of nowhere too... Has been running smooth for quite some time but just started vibrating a lot! I'll report any findings back here... and try a few of the things suggested.

Cheers,

 

well, if those ignitors are in the spot that you drew them , then you wired them backwards.


the ignitor to the leading is on the left, and the ignitor under the alt. is the trailing.

last time i worked on my 7 during lunch, it wouldn't start either, i found a dead connection in the connector to the msd box.

carl.