Engine issues.
01-23-2017, 07:54 PM
#1
Thread Starter
Join Date: Jan 2017
Location: Utah
Posts: 4
Engine issues.
I purchased a 1978 Mustang II Base hardtop edition, the previous owner made some modifications to the engine however and I don't understand very much about this kind of stuff beyond repair and maintenance.
First thing is he put in a 1968 302, he replaced the stock blaster coil with an MSD one, replaced the distributer cap but left the stock distributer, which he modified to a pointless one. he also replaced the original air intake manifold with the edelbrock performer 289 and bolted on an edelbrock 1406 which is 600cfm w/ electric choke. He left the original ford motor craft ignition control module however. far as I have been able to tell everything else in the engine and ignition is still stock.
Some of the issues I am having is performance and power, my mechanic could only get it to idle properly at 700 to 900 rpm with a full mechanical advance timing of 32 degrees and running a rich mixture in the carburetor, If we run a less rich mixture the car drives fine till you hit a certain RPM then it acts like the engine lost all power the car will slow down to about 35-40mph and the engine will sound/feel odd, like its sluggish with no power.
I have talked to several mechanics about this and most of them put it off to the engines age, our altitude (about 4500feet) or any excuse they can imagine to not have a look at the engine for me. however one place I found online told me the timing is too advanced and said that it sounds like whoever modified the distributer didn't tune it for my engine and that I should send it to them (along with any information on all the modifications to my engine and ignition system) so they can tune it and replace my vacuum chamber with a tunable one etc and all I have to do is drop it in retime the engine to 30 degrees and after that its all about tuning the carburetor. This sounds kind of fishy or funny to me but however like I stated I know nothing about this stuff so any input would be very helpful.
Thanks in advance - Ren
First thing is he put in a 1968 302, he replaced the stock blaster coil with an MSD one, replaced the distributer cap but left the stock distributer, which he modified to a pointless one. he also replaced the original air intake manifold with the edelbrock performer 289 and bolted on an edelbrock 1406 which is 600cfm w/ electric choke. He left the original ford motor craft ignition control module however. far as I have been able to tell everything else in the engine and ignition is still stock.
Some of the issues I am having is performance and power, my mechanic could only get it to idle properly at 700 to 900 rpm with a full mechanical advance timing of 32 degrees and running a rich mixture in the carburetor, If we run a less rich mixture the car drives fine till you hit a certain RPM then it acts like the engine lost all power the car will slow down to about 35-40mph and the engine will sound/feel odd, like its sluggish with no power.
I have talked to several mechanics about this and most of them put it off to the engines age, our altitude (about 4500feet) or any excuse they can imagine to not have a look at the engine for me. however one place I found online told me the timing is too advanced and said that it sounds like whoever modified the distributer didn't tune it for my engine and that I should send it to them (along with any information on all the modifications to my engine and ignition system) so they can tune it and replace my vacuum chamber with a tunable one etc and all I have to do is drop it in retime the engine to 30 degrees and after that its all about tuning the carburetor. This sounds kind of fishy or funny to me but however like I stated I know nothing about this stuff so any input would be very helpful.
Thanks in advance - Ren
01-23-2017, 09:22 PM
#3
Join Date: Jan 2017
Location: California
Posts: 9
None of the modifications you describe should cause you the problems you are experiencing. A virtually stock motor with your Edelbrock combination should run like a top. Any competent mechanic should be able to tune what you have and/or diagnose which of the components need to be rebuilt or replaced.
Age is irrelevant if the engine has been maintained and does not show the telltale signs of excess wear (i.e. rings,valves, seals etc.). Lastly, why would any mechanic from the upper elevations of Utah not know how to tune for that elevation?
Time to start looking for a new "Wrench".
Age is irrelevant if the engine has been maintained and does not show the telltale signs of excess wear (i.e. rings,valves, seals etc.). Lastly, why would any mechanic from the upper elevations of Utah not know how to tune for that elevation?
Time to start looking for a new "Wrench".
01-23-2017, 10:58 PM
#6
Thread Starter
Join Date: Jan 2017
Location: Utah
Posts: 4
@gun jam, I'm not certain what would b causing fuel starvation, I've had the carb cleaner and rebuilt, I personally replaced all the fuel lines, fuel filter and fuel pump. Only thing I haven't done is have the tank completely cleaned and treated as I haven't decided if I want to keep it or replace it. I know the down pipe isn't installed properly, it's sealed properly to the tank but it might have issues up at the top allowing air. Can an unpressurized fuel system be a problem for a fuel system that only creates 1.5 - 3lbs of presure? Also I noted that the old charcoal box is still connected to the exhaust system but not the carb as the carb has no connection for one. A partially connected HC collector shouldn't cause issues should it?
01-24-2017, 12:40 AM
#7
Moderator
Join Date: Dec 2005
Location: Hills of California
Posts: 5,208
First of 4,500 feet is nothing. Tuned for sea level a properly running system will also operate just fine at 4,500 feet..If I was going to drive a lot at 4,500 I would simply lean each of my 4 idle screws 1/16th to 1/8th of a turn...Done. I driven my well tuned system at 400ft to 9,000 feet and it was still running....actually well.
Your issue is not altitude related.
Yeah it could be a timing issue...but 35 all in is not too advanced. You could weld those adv plates shut and it would run just dandy at 35deg from idle to WOT although startups would be tough. (assuming 9:1 ish compression maybe a bit less for 35 deg)
Im still of the opinion that its fuel related..but its not unreasonable to assume that is has multiple issues.
So
1) since you have owned it the car has never run right?
2) How long had the car sat before you became the owner?
3) Is the fuel fresh?
4) what carb is on the engine?
5) How do you know its actually advancing 32deg?
Yes having the distributor curved for the engine would be helpful but its unlikely its going to solve the problem unless is not advancing 32deg as you claim.
If you are only making 1.5lbs of fuel pressure that would be why its starving. That system needs to generate 5 to 7psi
If it wont idle that could be due to a plugged idle jet in the carb...thats a great explanation for that issue...but a vacuum leak would cause that issue as well. Maybe checking for vac leaks would be a good idea. There could be other issues as well..yes including timing or fouled plugs, could even have a worn cam or totally shot rings and only makes 50 psi of cylinder pressure.
with that in mind if a mechanic says it runs crap because
1) altitude (4,500) Find a new mechanic
2) the engine is old ( my engine is a 65 with aftermarket parts it gaps some WRX subarus makes 294Hp with 310ftlbs torque) Old is irrelevant...If the mechanic says the engine is old fine a new mechanic (not to be confused with worn out that is independent of age)
3) If the mechanic is making claims like the engine is worn out without having actually checked compression, valve lift and perhaps timing there is no way to make that call...find a new mechanic.
4) it might be a good idea to get some basic tools, A timing light, A compression gauge a fuel pressure gauge. Use them and see if something is well out of spec...like compression or timing.
-Gun
Your issue is not altitude related.
Yeah it could be a timing issue...but 35 all in is not too advanced. You could weld those adv plates shut and it would run just dandy at 35deg from idle to WOT although startups would be tough. (assuming 9:1 ish compression maybe a bit less for 35 deg)
Im still of the opinion that its fuel related..but its not unreasonable to assume that is has multiple issues.
So
1) since you have owned it the car has never run right?
2) How long had the car sat before you became the owner?
3) Is the fuel fresh?
4) what carb is on the engine?
5) How do you know its actually advancing 32deg?
Yes having the distributor curved for the engine would be helpful but its unlikely its going to solve the problem unless is not advancing 32deg as you claim.
If you are only making 1.5lbs of fuel pressure that would be why its starving. That system needs to generate 5 to 7psi
If it wont idle that could be due to a plugged idle jet in the carb...thats a great explanation for that issue...but a vacuum leak would cause that issue as well. Maybe checking for vac leaks would be a good idea. There could be other issues as well..yes including timing or fouled plugs, could even have a worn cam or totally shot rings and only makes 50 psi of cylinder pressure.
with that in mind if a mechanic says it runs crap because
1) altitude (4,500) Find a new mechanic
2) the engine is old ( my engine is a 65 with aftermarket parts it gaps some WRX subarus makes 294Hp with 310ftlbs torque) Old is irrelevant...If the mechanic says the engine is old fine a new mechanic (not to be confused with worn out that is independent of age)
3) If the mechanic is making claims like the engine is worn out without having actually checked compression, valve lift and perhaps timing there is no way to make that call...find a new mechanic.
4) it might be a good idea to get some basic tools, A timing light, A compression gauge a fuel pressure gauge. Use them and see if something is well out of spec...like compression or timing.
-Gun
01-24-2017, 04:38 PM
#8
2nd Gear Member
Join Date: Apr 2014
Location: PA
Posts: 424
Does it still have a CAT? If so sounds like it is plugged. The tank isn't pressurized. It is vented through the carbon canister if that is connected. If not it is vented to the air. A seal fuel tank could develop quite a vacuum and reduce the flow of fuel at higher rates of fuel pump. Try it with the tank cap off.
01-30-2017, 02:17 AM
#9
1st Gear Member
Join Date: Jan 2017
Location: Nebraska
Posts: 55
Yep, it definitely sounds like a fuel issue. I have built a lot of these older Ford 302 engines for drag racing and just hot rodding around. A couple of things I don't like about what you have described.
I personally have had bad luck with any aftermarket coils paired with the factory stock ignition systems. I have also had bad luck with retrofitting the stock distributors to go pointless. I have always had better luck changing to either a high performance dual point system or an electronic. It has always worked best to pair the entire ignition system with parts of the same brand, like MSD or even Accel, although MSD would be my preferred choice. But keep in mind, the engines I used to build were for the drag strip or a dirt track. Typically the problem I have had with aftermarket coils paired with stock ignition parts is backfiring and poor spark. I still agree it is a fuel issue.
I have found todays mechanics do not like to work on anything unless they can plug a computer in and let the computer tell them what is wrong.
Now for the fuel issues. Your pump is not putting out enough pressure, but you also will need to check volume. Are you using the factory pump or an aftermarket electronic pump? Double check all of you vacuum lines to make sure you don't have a leak, but I don't think that is your problem either. Vacuum leaks typically show themselves more at lower rpm's.
One final thought, the edelbrock carb. I have not had good luck with these either. Out of probably a dozen of these carbs I have messed with I have had good luck with maybe 5 of them. One problem I have had with Edelbrock carbs is the bottom of the carb. I have found a couple of them new out of the box warped. They would suck air around the base of the carb. Again, this typically effects the low speed idle once the engine is warmed up. When you open the throttle it would surge ahead fine, then fall on its face once the rpm's level off. As long as the engine was accelerating the vacuum would hold the carb down tight to the intake and it would seal. I have also found a couple of these carbs with cracks in the body. I don't know if they were over tighetened at one point or if it was another manufacturer flaw. They are like the old carter or quadrajunk carbs, when they were on and good they ran great, but it didn't take much to make them fail.
If it were my car I would start with a timing light and verify the timing and the timing advance. Make sure it is advancing like it is supposed to. I am curious what the timing is set at. Your post said a full advance of 32 degrees. If my memory is correct on these, I would start with the timing between 8 and 10 degrees then fine tune from there by sound. Next I would verify fuel pressure and do a volume test. If it were me, I would probably install an inline fuel gauge so I could monitor the fuel pressure while it is running and while tuning it. I would probably even install a larger pump and a regulator to adjust the pressure.
Another thought I had, check your fuel lines between the pump and the tank. Are they rubber or steel? Often I have seen the rubber get soft and the pump will suck it shut, closing off the fuel supply.
I hope my rambling has made some sense.
I personally have had bad luck with any aftermarket coils paired with the factory stock ignition systems. I have also had bad luck with retrofitting the stock distributors to go pointless. I have always had better luck changing to either a high performance dual point system or an electronic. It has always worked best to pair the entire ignition system with parts of the same brand, like MSD or even Accel, although MSD would be my preferred choice. But keep in mind, the engines I used to build were for the drag strip or a dirt track. Typically the problem I have had with aftermarket coils paired with stock ignition parts is backfiring and poor spark. I still agree it is a fuel issue.
I have found todays mechanics do not like to work on anything unless they can plug a computer in and let the computer tell them what is wrong.
Now for the fuel issues. Your pump is not putting out enough pressure, but you also will need to check volume. Are you using the factory pump or an aftermarket electronic pump? Double check all of you vacuum lines to make sure you don't have a leak, but I don't think that is your problem either. Vacuum leaks typically show themselves more at lower rpm's.
One final thought, the edelbrock carb. I have not had good luck with these either. Out of probably a dozen of these carbs I have messed with I have had good luck with maybe 5 of them. One problem I have had with Edelbrock carbs is the bottom of the carb. I have found a couple of them new out of the box warped. They would suck air around the base of the carb. Again, this typically effects the low speed idle once the engine is warmed up. When you open the throttle it would surge ahead fine, then fall on its face once the rpm's level off. As long as the engine was accelerating the vacuum would hold the carb down tight to the intake and it would seal. I have also found a couple of these carbs with cracks in the body. I don't know if they were over tighetened at one point or if it was another manufacturer flaw. They are like the old carter or quadrajunk carbs, when they were on and good they ran great, but it didn't take much to make them fail.
If it were my car I would start with a timing light and verify the timing and the timing advance. Make sure it is advancing like it is supposed to. I am curious what the timing is set at. Your post said a full advance of 32 degrees. If my memory is correct on these, I would start with the timing between 8 and 10 degrees then fine tune from there by sound. Next I would verify fuel pressure and do a volume test. If it were me, I would probably install an inline fuel gauge so I could monitor the fuel pressure while it is running and while tuning it. I would probably even install a larger pump and a regulator to adjust the pressure.
Another thought I had, check your fuel lines between the pump and the tank. Are they rubber or steel? Often I have seen the rubber get soft and the pump will suck it shut, closing off the fuel supply.
I hope my rambling has made some sense.