Engine running problems

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Higgins56

Well-known member
Joined
Jan 2, 2012
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Location
Finland
My Car
1971 Mach 1 Fastback now with 503 CID 4 bolt block with AFR Bullit heads , Edelbrock Performer RPM AirGap intake and ProSystems carburettor 1050.
4 sp Toploader with 9" Wavetrac rear.
Caltracs and shocks at the rear.
Hi,

I am about to get my 429 mach 1 back on the road after 14 years of rebuilding ( not me but the owners before ...:))

I have owned the car now two years and this spring we rewamped the electronics to MSD street fire + Blaster coil and the MSD distributor.

The carburettor was changed to a brand new Holley Street avenger 870.

The engine has been run only for short bursts - max 5 min so far as the rebuilding is on its way still.

Now the electronics ( lights etc) were checked and the tacho was get running via the MSD adaptor box... BUT after again a short burst of running with now problems ( 10 gal fuel in the tank) the engine started chaking when pushing the gas pedal - I mean that the revs went to zero like the engine was getting too much fuel / could not breathe....

The fuel levels at the carb were checked and adjusted but no cure.

Always when starting from cold the engine starts running nicely and accepts more gas but within a minute it happens again - reves sunk to zero if trying to giver more gas / holding the foot on the pedal.

It is ompossible to get the revs up from the idle level now...

Interesting is that there is no black smoke or smell of fuel during this and the exhaust pipes are nice and clean.

All this happened the other day during a normal test run. No adjustments made to the carb....

Any clue from anybody where to check next / does anyone had similar symptoms during the rebuilding project... ?

The spark plugs were dry and a bit sooty and the gap ab 1 mm...

 
Have you changed the fuel filter to make sure it isn't picking up some junk after running for a few minutes?
No - have not checked the fuel filter which is brand new 2013 ( run max 20 min all together)....The fuel tank was changed by the previous owner and there is a date stamp of 2005 in the sensor plate...

The copper tube fuel line is made ab. 2005 .

 
Test with a known good ignition system. I suspect the electronics in yours are heating up and causing a weak spark
The system is a brand new MSD - all: distributor, coil and street fire box...should be alright - and has been so far...The MSD adaptor was just added to get the original tacho working...

 
The components you listed can be bad, even when new. MSD units fail all of the time. . . You may also want to troubleshoot your electronics installation, just because they sort of work doesn't mean they are installed properly

 
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Well, like a good friend of mine (who was a parts store guy for 25 years) always says, "'New' doesn't necessarily mean 'Good.' It just means 'New.'"

Check connections, shoot a laser thermostat against all electrical components (noting rapid temperature changes), and check to make sure you have the correct timing vacuum port on the carb hooked up to the distributor. If you're not getting the right amount of vacuum advance once the engine has 'warmed up,' it'll run like crap with the wrong timing (that's what it sounds like to me).

 
Well, like a good friend of mine (who was a parts store guy for 25 years) always says, "'New' doesn't necessarily mean 'Good.' It just means 'New.'"

Check connections, shoot a laser thermostat against all electrical components (noting rapid temperature changes), and check to make sure you have the correct timing vacuum port on the carb hooked up to the distributor. If you're not getting the right amount of vacuum advance once the engine has 'warmed up,' it'll run like crap with the wrong timing (that's what it sounds like to me).
Yes I agree - new is not necessarily a good thing - anyway... what would be the right port in the carb for the distributor vacuum connection.

Now it is taken from the front part of the carb....

 
Well, like a good friend of mine (who was a parts store guy for 25 years) always says, "'New' doesn't necessarily mean 'Good.' It just means 'New.'"

Check connections, shoot a laser thermostat against all electrical components (noting rapid temperature changes), and check to make sure you have the correct timing vacuum port on the carb hooked up to the distributor. If you're not getting the right amount of vacuum advance once the engine has 'warmed up,' it'll run like crap with the wrong timing (that's what it sounds like to me).
Yes I agree - new is not necessarily a good thing - anyway... what would be the right port in the carb for the distributor vacuum connection.

Now it is taken from the front part of the carb....
I'm sorry, but "I got nothin'" when it comes to Holleys - I'm a staunch "Edelbrock" guy, myself. I'll take a stab at it and say, "if the Holley has both 'timed' and 'constant' vacuum ports, I would try the 'constant' vacuum port." Check the Holley book for more information. Beyond that, I couldn't say.

One other thing, make sure all unused vacuum ports are capped (I had left one of the manifold ports open when I was hooking up my brake booster, and it ran great at idle... but ran like crap when I ran up the RPMs).

Someone should be along soon with the right answer, though - there are lots of guys running Holleys here.

 
Well, like a good friend of mine (who was a parts store guy for 25 years) always says, "'New' doesn't necessarily mean 'Good.' It just means 'New.'"

Check connections, shoot a laser thermostat against all electrical components (noting rapid temperature changes), and check to make sure you have the correct timing vacuum port on the carb hooked up to the distributor. If you're not getting the right amount of vacuum advance once the engine has 'warmed up,' it'll run like crap with the wrong timing (that's what it sounds like to me).
Yes I agree - new is not necessarily a good thing - anyway... what would be the right port in the carb for the distributor vacuum connection.

Now it is taken from the front part of the carb....
I'm sorry, but "I got nothin'" when it comes to Holleys - I'm a staunch "Edelbrock" guy, myself. I'll take a stab at it and say, "if the Holley has both 'timed' and 'constant' vacuum ports, I would try the 'constant' vacuum port." Check the Holley book for more information. Beyond that, I couldn't say.

One other thing, make sure all unused vacuum ports are capped (I had left one of the manifold ports open when I was hooking up my brake booster, and it ran great at idle... but ran like crap when I ran up the RPMs).

Someone should be along soon with the right answer, though - there are lots of guys running Holleys here.
HI again,

thanks for your support - I really appreciate that - and all the others too - of course.Lets see if the "Holley man" appears to make the statement what would be preferred to be done now.

Of course I can change the fuel filter or as my friend said - please check the carb inside -by taking the "heads off" and seeing if there is "any extra".... :)

I checked your "Rustang" project photos - WOW... you have done it the proper and longer way - but I am sure it rewards you now !

 
I checked your "Rustang" project photos - WOW... you have done it the proper and longer way - but I am sure it rewards you now !
Thanks! I still have a long way to go... even though it all mechanically works, it still needs lots of work to be driveable.

Good luck getting this issue taken care of!

 
Perhaps you could upload a picture of your engine with enough detail for us to see the vacuum line routing.

Ported vacuum comes from above the idle plates. At idle there is none because the plates are closed.

Manifold vacuum comes from below the plates, it will advance the timing when connected with a running engine even at idle.

a third way is to run manifold vacuum through a vacuum modulator that is usually plumbed into the thermostat housing. What this does is open up at a preset temperature and allow the vacuum advance to be engaged on a warm engine, but not a cold one.

These are the 3 simplest ways to run a vacuum advance line. With the engine running at idle, remove the vacuum advance line from the carburetor and if nothing happens it was hooked to ported.

Here is why I suggested a known good ignition system be used. Breaking in an engine with a poorly functioning ignition or carburetor can drastically shorten the engine's life, by interfering with rings seating and allowing cam lobes to be damaged before they have mated to the lifter surfaces. A points distributor with a coil is a fine ignition system and perhaps the simplest to verify that the basic functions are working

 
IMAG0178[1].jpg

Perhaps you could upload a picture of your engine with enough detail for us to see the vacuum line routing.

Ported vacuum comes from above the idle plates. At idle there is none because the plates are closed.

Manifold vacuum comes from below the plates, it will advance the timing when connected with a running engine even at idle.

a third way is to run manifold vacuum through a vacuum modulator that is usually plumbed into the thermostat housing. What this does is open up at a preset temperature and allow the vacuum advance to be engaged on a warm engine, but not a cold one.

These are the 3 simplest ways to run a vacuum advance line. With the engine running at idle, remove the vacuum advance line from the carburetor and if nothing happens it was hooked to ported.

Here is why I suggested a known good ignition system be used. Breaking in an engine with a poorly functioning ignition or carburetor can drastically shorten the engine's life, by interfering with rings seating and allowing cam lobes to be damaged before they have mated to the lifter surfaces. A points distributor with a coil is a fine ignition system and perhaps the simplest to verify that the basic functions are working

Here are a couple of photos of the installation

IMAG0176[1].jpg

IMAG0175[1].jpg
 
First off, clean set up you have there, very slick. I was going to comment and second the thought of having a vacuum leak. I just ran into this with my car, everything looked like it was hooked up right but as soon as I tried to give it any kind of gas the engine would just die. Check to make sure you don't have any open ports that are leaking vacuum.

Do you get a heavy smell of unburnt fuel when the engine dies? This would make me think spark issue if you do, if you don't I would think more of a vacuum issue

 
Thoughts:

Confirm your timing isn't 180 degrees off. This is easy to do and a lot of engines will 'run' this way.

When it is at idle, what manifold vacuum do you have cold/warm.

Looks like a manual choke. Are you using it?

I know a little about holleys. Not an expert by any means but my thoughts. When you give a holley gas it transfers from the idle system. Gas literally flows a different path. With the engine off, take a look down the carb and pull the throttle open. Did you see a squirt of gas? You should. That's the accel pump shooting a little fuel in as the carb transitions from the idle circuit.

 
First off, clean set up you have there, very slick. I was going to comment and second the thought of having a vacuum leak. I just ran into this with my car, everything looked like it was hooked up right but as soon as I tried to give it any kind of gas the engine would just die. Check to make sure you don't have any open ports that are leaking vacuum.

Do you get a heavy smell of unburnt fuel when the engine dies? This would make me think spark issue if you do, if you don't I would think more of a vacuum issue
Hi,

thanks of your comment - the engine bay is not yet detailed - anyway...

no smell of burnt fuel and during the last three months when the system was done the engine has run without problems ( test running only) - not yet on the road...

The exhaust pipes are really clean not even a hint of black color.

One of my friends said that it MIGHT be a drop of water that could be in the carburetor and prevent the gas flow.... ??



Thoughts:

Confirm your timing isn't 180 degrees off. This is easy to do and a lot of engines will 'run' this way.

When it is at idle, what manifold vacuum do you have cold/warm.

Looks like a manual choke. Are you using it?

I know a little about holleys. Not an expert by any means but my thoughts. When you give a holley gas it transfers from the idle system. Gas literally flows a different path. With the engine off, take a look down the carb and pull the throttle open. Did you see a squirt of gas? You should. That's the accel pump shooting a little fuel in as the carb transitions from the idle circuit.
Hi,

How could it change suddenly 180 degr ?

This running problem came from the clear blue sky while starting a test run after making the electronics connections: Engine started beautifully and idled nice - I could even give it some gas as normal - and then when pressening the pedal again the engine started coughing and was about to die and then I took my foot off from the pedal and the running continued when the engine first got a hold of the idle run again....

One of my friends said that it could be gas problem... too little and to find it out , just pour some gas in the throats when giving a foot to the engine. If it responds with more revs - then it is gas problem and there is a blockage somewhere in the gas line....



First off, clean set up you have there, very slick. I was going to comment and second the thought of having a vacuum leak. I just ran into this with my car, everything looked like it was hooked up right but as soon as I tried to give it any kind of gas the engine would just die. Check to make sure you don't have any open ports that are leaking vacuum.

Do you get a heavy smell of unburnt fuel when the engine dies? This would make me think spark issue if you do, if you don't I would think more of a vacuum issue
one more photo... and the performance system is:

comp cams Extreme energy 274

Edelbrock RPM performer

Hooker headers following 2 x 3 " exhaust line with single dampers at the rear

MSD street fire 5520 with rpm adjustment

MSD Tach adapter to run the original tach

MSD coil Blaster 3

MSD distributor 8477 with vacuum adjustment

Hurst 4 speed Toploader

Detroit locker

I cant wait to get it on the road :)



First off, clean set up you have there, very slick. I was going to comment and second the thought of having a vacuum leak. I just ran into this with my car, everything looked like it was hooked up right but as soon as I tried to give it any kind of gas the engine would just die. Check to make sure you don't have any open ports that are leaking vacuum.

Do you get a heavy smell of unburnt fuel when the engine dies? This would make me think spark issue if you do, if you don't I would think more of a vacuum issue
Hi,

thanks of your comment - the engine bay is not yet detailed - anyway...

no smell of burnt fuel and during the last three months when the system was done the engine has run without problems ( test running only) - not yet on the road...

The exhaust pipes are really clean not even a hint of black color.

One of my friends said that it MIGHT be a drop of water that could be in the carburetor and prevent the gas flow.... ??



Thoughts:

Confirm your timing isn't 180 degrees off. This is easy to do and a lot of engines will 'run' this way.

When it is at idle, what manifold vacuum do you have cold/warm.

Looks like a manual choke. Are you using it?

I know a little about holleys. Not an expert by any means but my thoughts. When you give a holley gas it transfers from the idle system. Gas literally flows a different path. With the engine off, take a look down the carb and pull the throttle open. Did you see a squirt of gas? You should. That's the accel pump shooting a little fuel in as the carb transitions from the idle circuit.
Hi,

How could it change suddenly 180 degr ?

This running problem came from the clear blue sky while starting a test run after making the electronics connections: Engine started beautifully and idled nice - I could even give it some gas as normal - and then when pressening the pedal again the engine started coughing and was about to die and then I took my foot off from the pedal and the running continued when the engine first got a hold of the idle run again....

One of my friends said that it could be gas problem... too little and to find it out , just pour some gas in the throats when giving a foot to the engine. If it responds with more revs - then it is gas problem and there is a blockage somewhere in the gas line....



First off, clean set up you have there, very slick. I was going to comment and second the thought of having a vacuum leak. I just ran into this with my car, everything looked like it was hooked up right but as soon as I tried to give it any kind of gas the engine would just die. Check to make sure you don't have any open ports that are leaking vacuum.

Do you get a heavy smell of unburnt fuel when the engine dies? This would make me think spark issue if you do, if you don't I would think more of a vacuum issue
one more photo... and the performance system is:

comp cams Extreme energy 274

Edelbrock RPM performer

Hooker headers following 2 x 3 " exhaust line with single dampers at the rear

MSD street fire 5520 with rpm adjustment

MSD Tach adapter to run the original tach

MSD coil Blaster 3

MSD distributor 8477 with vacuum adjustment

Hurst 4 speed Toploader

Detroit locker

I cant wait to get it on the road :)
IMAG0175[1].jpg

IMAG0178[1].jpg

 
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Lots of good suggestiong where to start with. I would also chance the coil location since you're boiling the coil. Simply bolt it off and bolt it vertical postition to the end of the head away from the engine's top. You can use the same bolt to attach the coil bracket to one of the four boltholes in the end of the head and 99 % of cases you can use your existing coil wires. My 900 miles driven MSD made coild buked the oils out, so there's no quarantie for any chinese crap to work even when new.

Good to hear your project going forward and closer for the shakedown runs!!

 
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is that Holley new?? if so,.. open it up, check for debri's from the manufacturing process,.. you're not the first who's carb is full with drilling/casting residu.. had the same thing with an 600cfm holley, car wouldnt run for the life of it,.. finally opened up the carb, which was brandnew, found little bits of castings and drilling parts in the bowls and inside the main body, cleaned it out, and it ran beautiful after that..

 
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