distributor vacuum trouble
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distributor vacuum trouble
Greetings from Norway
Hi! I have refurbiched the heads on my 400. I have removed the EGR and smogg/air pump, and plugged all vacuum lines.
I have installed a new distributor.
Have a 2 barrel motorcraft id: D7TE CTA a7j12.
question: where do I install the vacuum line from the distr ??
The only vacuum i find now is on the intakemanifold, and on the base of the carb (choke pulloff ) these are constant vacuum!
Dont I need variable vacuum to the distributor ?
I have timed the ignition to 10 degreas advanse. But i eksperience some knocking noises after revving the engine at prox 2500-3000 rpm.
I would think this is due to poure vacuume on the distr ?!?
All answers are welcome :-)
Hi! I have refurbiched the heads on my 400. I have removed the EGR and smogg/air pump, and plugged all vacuum lines.
I have installed a new distributor.
Have a 2 barrel motorcraft id: D7TE CTA a7j12.
question: where do I install the vacuum line from the distr ??
The only vacuum i find now is on the intakemanifold, and on the base of the carb (choke pulloff ) these are constant vacuum!
Dont I need variable vacuum to the distributor ?
I have timed the ignition to 10 degreas advanse. But i eksperience some knocking noises after revving the engine at prox 2500-3000 rpm.
I would think this is due to poure vacuume on the distr ?!?
All answers are welcome :-)
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I have tryed that port. same as choke pulloff. But this port has konstant vacuum, not variable when revving ! Isn't the distr suposed to get variable vacuum with more throttle ?
MSEE
Joined: Apr 2004
Posts: 10,386
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From: Austin, TX
Choke pulloff should be conneted to manifold vacuum; the carburetor should have a port on the back for this. There should be a port on the passenger side of the carburetor on the bottom for ported vacuum to feed the distributor vacuum advance. If it's pulling vacuum at idle, your idle speed could be very high, or this could be some sort of uncommon carbruetor.
By the way, you should not have removed the EGR system; it's why you're having issues with spark knock. It's unlikely that adjusting the vacuum advance alone will alleviate the issue; you may also have to change the weights in the distributor and change the carbuetor jetting. At the end of the day it's easier just to leave the engine the way it was intended to be set up. An EGR motor is not simply a non-EGR motor with an EGR valve.
By the way, you should not have removed the EGR system; it's why you're having issues with spark knock. It's unlikely that adjusting the vacuum advance alone will alleviate the issue; you may also have to change the weights in the distributor and change the carbuetor jetting. At the end of the day it's easier just to leave the engine the way it was intended to be set up. An EGR motor is not simply a non-EGR motor with an EGR valve.
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I found the problem. there vas a port in front, under the choke. It was broken off. I replaced the outlett pinn, so now i have the right vacuum.
But i still have the knocking noices when i revv the engine ??
could i be a piston skirt breakoff ?
But i still have the knocking noices when i revv the engine ??
could i be a piston skirt breakoff ?
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I have removed the EGR valve from the adapterplate, and sealed the holes with a metall plate. Also plugged the innlett hole on the inntakemanifold. The engine should runn regardless of the EGR ? or is the carb depending on it ?
Wouldnt changing to alu inntake and 4barrel carb work on a EGR engine?
Wouldnt changing to alu inntake and 4barrel carb work on a EGR engine?
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MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Does the engine knock when you rev it out of gear, or when you're accelerating? If it's the latter, it's because you removed the EGR system, as I said before. EGR motors use leaner carburetion and a steeper timing curve to compensate for the altered combustion chemistry; if you simply remove the EGR valve and void the combustion mixture of inert exhaust gas, the combustion chamber temperatures increase, and you get spark knock.
You can change to a 4-barrel setup; but you still may have to rejet the new carburetor just as you'd need to with the existing one. It also doesn't change the timing curve.
You can change to a 4-barrel setup; but you still may have to rejet the new carburetor just as you'd need to with the existing one. It also doesn't change the timing curve.
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Hi again.
The knocking is harder under pressure in gear. but i kan also slightly hear it when revving in neutral at aprox 2500-3000 rpm, when the valves are "floating"
changed the dirtributor, but got a dual vacuum instead of a single as a had before. Kould this be a broblem?
I putt the secondary vacuum on the vacuum port on the intakemanifold! vil try to change the vacumm housing on the distr to the old one today.
I sett the timing to 6 degr instead of 10. Got better respons on the engine then.
Do you have a formula for tuning the carb non EGR ??
Or do you only recomend reconekting the EGR
My english is not all that good, hope yoy understand
The knocking is harder under pressure in gear. but i kan also slightly hear it when revving in neutral at aprox 2500-3000 rpm, when the valves are "floating"
changed the dirtributor, but got a dual vacuum instead of a single as a had before. Kould this be a broblem?
I putt the secondary vacuum on the vacuum port on the intakemanifold! vil try to change the vacumm housing on the distr to the old one today.
I sett the timing to 6 degr instead of 10. Got better respons on the engine then.
Do you have a formula for tuning the carb non EGR ??
Or do you only recomend reconekting the EGR
My english is not all that good, hope yoy understand
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Found the problem i think ! after fiddeling with the ignition today and tuning the carb notthing seemed to work. But then i disconekted the vacuum to the distribuator when revving, the knocking stopped 
does it get too much vacuum from the carb then ?
does it get too much vacuum from the carb then ?
More Turbo
Joined: Dec 2010
Posts: 619
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From: Liberty Hill, Tx
What you are talking about is spark knock, and what he was telling you is that with the EGR removed the distributor is advancing too much under a load to help with what gases it expects to be in there from the EGR, there is nothing bad about having EGR, if the engine had it you should use it
Last edited by ford_pickup; Mar 23, 2011 at 10:12 AM. Reason: MISPELLING
More Turbo
Joined: Dec 2010
Posts: 619
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From: Liberty Hill, Tx
just to add a little input, I just put a 1979 351M into a 1974 truck that someone had blocked off the EGR valve, it spark knocked like crazy, I replaced the EGR valve, added hoses, and hooked it all up, now no knock and it runs well