Thoughts about adding EGR
Thread Starter
|
Fleet Mechanic
Joined: Dec 2016
Posts: 1,261
Likes: 714
Does it ping/rattle/knock at wide open (zero" vacuum), at part throttle (say 8-10"), or under both conditions?
Higher-octane gas would likely fix the former, less vacuum advance might fix the latter. You can determine if you have too much vacuum advance at part throttle by removing and plugging the vacuum hose. If that helps, maybe experiment by adjusting the vacuum pot to get less total advance to the distributor.
Some guys swear by mechanical-only spark advance even knowing they use more fuel at cruise.
Higher-octane gas would likely fix the former, less vacuum advance might fix the latter. You can determine if you have too much vacuum advance at part throttle by removing and plugging the vacuum hose. If that helps, maybe experiment by adjusting the vacuum pot to get less total advance to the distributor.
Some guys swear by mechanical-only spark advance even knowing they use more fuel at cruise.
AFAIK, any aluminum heads for the FE will have smaller combustion chamber and therefore raise compression.
Logistics Pro
Joined: May 2015
Posts: 4,474
Likes: 974
From: Tri Cities, TN
What distributor and vacuum canister are you using? The vacuum advance is only there to increase fuel milage. The higher the vacuum the more advance it adds up to the max for that particular canister, they come in a gazillion different flavors. It should not be adding advance if the engine is under a load. On medium and heavy-duty trucks, the distributors are usually set up with the centrifugal advance set in the 18-degree notch with very strong springs and a vacuum canister that only adds 8 or so degrees of advance at very high vacuum. This is to keep the advance low while the engine is under a heavy load. Disconnecting the vacuum advance won't do anything but decrease the fuel milage.
If your distributor is set up for a performance curve you may have to change to stronger springs. Or recurve it completely. Decreasing the initial advance from the optimum will only screw up the idle quality and make it harder to start.
If your distributor is set up for a performance curve you may have to change to stronger springs. Or recurve it completely. Decreasing the initial advance from the optimum will only screw up the idle quality and make it harder to start.
Thread Starter
|
Fleet Mechanic
Joined: Dec 2016
Posts: 1,261
Likes: 714
What distributor and vacuum canister are you using? The vacuum advance is only there to increase fuel milage. The higher the vacuum the more advance it adds up to the max for that particular canister, they come in a gazillion different flavors. It should not be adding advance if the engine is under a load..
If it helps, this is what have been running since day 1.
Logistics Pro
Joined: May 2015
Posts: 4,474
Likes: 974
From: Tri Cities, TN
Single wire going in so it is either an original points or a Pertronix no difference in the operation. Other than not having to replace points.
Do you have a dial back timing light with a tach feature? If so, you can plot the curve yourself just to verify when and how much centrifugal advance it's putting in.
If you want to do that, I can tell you what to do.
I don't have the specifications for all the distributors Ford used in 390's but some of those things put in as much as 36 degrees at 2500 rpm. Which is way too much for a truck pulling a heavy load up hill especially if you have high dynamic compression.
Do you have a dial back timing light with a tach feature? If so, you can plot the curve yourself just to verify when and how much centrifugal advance it's putting in.
If you want to do that, I can tell you what to do.
I don't have the specifications for all the distributors Ford used in 390's but some of those things put in as much as 36 degrees at 2500 rpm. Which is way too much for a truck pulling a heavy load up hill especially if you have high dynamic compression.
Thread Starter
|
Fleet Mechanic
Joined: Dec 2016
Posts: 1,261
Likes: 714
Single wire going in so it is either an original points or a Pertronix no difference in the operation. Other than not having to replace points.
Do you have a dial back timing light with a tach feature? If so, you can plot the curve yourself just to verify when and how much centrifugal advance it's putting in.
If you want to do that, I can tell you what to do.
I don't have the specifications for all the distributors Ford used in 390's but some of those things put in as much as 36 degrees at 2500 rpm. Which is way too much for a truck pulling a heavy load up hill especially if you have high dynamic compression.
Do you have a dial back timing light with a tach feature? If so, you can plot the curve yourself just to verify when and how much centrifugal advance it's putting in.
If you want to do that, I can tell you what to do.
I don't have the specifications for all the distributors Ford used in 390's but some of those things put in as much as 36 degrees at 2500 rpm. Which is way too much for a truck pulling a heavy load up hill especially if you have high dynamic compression.
This should do the trick
Has advance control and assuming same as dial back. If not, can get 1.
Pertronix has replaced old points and do believe currently set for all in mechanical advance 36° but beyond that don't know. So yes, would be interested in plotting curve.
That being said, truck currently in shop for warranty repair on transmission, so actual hands on will have to wait a bit.
Logistics Pro
Joined: May 2015
Posts: 4,474
Likes: 974
From: Tri Cities, TN
Thats an impressive piece of machinery. If it has a timing light, I suppose it will work. Is that 36 degrees total counting the initial or 36 degrees of just mechanical?
A dial back timing light gives you the ability to have the light flash when the timing pointer is only on TDC. In other words, if I wanted 10 degrees of initial, I would set the light at 10 advanced and adjust the distributor until the pointer was on TDC. And if I want to see what my total centrifugal advance is at say 2500 rpm. I would bring the engine up to that RPM then adjust the light to read at TDC. Whatever number is showing on the light is the number of degrees advance. With the vacuum can disconnected you can run the engine in increments of 500 rpm, 500-1000-1500 etc. writing down the numbers until you reach an RPM that the distributor isn't advancing anymore. Those numbers will be the curve of the mechanical advance. You can add stronger springs to slow the curve down and move it to a higher RPM. Way more to it than this but I got to clean my shop stove out, chop some kindling and bring some coal in before the cold rain shows up tomorrow. Just doing my part for global warming, pine trees to palm trees is my hope.
A dial back timing light gives you the ability to have the light flash when the timing pointer is only on TDC. In other words, if I wanted 10 degrees of initial, I would set the light at 10 advanced and adjust the distributor until the pointer was on TDC. And if I want to see what my total centrifugal advance is at say 2500 rpm. I would bring the engine up to that RPM then adjust the light to read at TDC. Whatever number is showing on the light is the number of degrees advance. With the vacuum can disconnected you can run the engine in increments of 500 rpm, 500-1000-1500 etc. writing down the numbers until you reach an RPM that the distributor isn't advancing anymore. Those numbers will be the curve of the mechanical advance. You can add stronger springs to slow the curve down and move it to a higher RPM. Way more to it than this but I got to clean my shop stove out, chop some kindling and bring some coal in before the cold rain shows up tomorrow. Just doing my part for global warming, pine trees to palm trees is my hope.
Thread Starter
|
Fleet Mechanic
Joined: Dec 2016
Posts: 1,261
Likes: 714
Thats an impressive piece of machinery. If it has a timing light, I suppose it will work. Is that 36 degrees total counting the initial or 36 degrees of just mechanical?
A dial back timing light gives you the ability to have the light flash when the timing pointer is only on TDC. In other words, if I wanted 10 degrees of initial, I would set the light at 10 advanced and adjust the distributor until the pointer was on TDC. And if I want to see what my total centrifugal advance is at say 2500 rpm. I would bring the engine up to that RPM then adjust the light to read at TDC. Whatever number is showing on the light is the number of degrees advance. With the vacuum can disconnected you can run the engine in increments of 500 rpm, 500-1000-1500 etc. writing down the numbers until you reach an RPM that the distributor isn't advancing anymore. Those numbers will be the curve of the mechanical advance. You can add stronger springs to slow the curve down and move it to a higher RPM. Way more to it than this but I got to clean my shop stove out, chop some kindling and bring some coal in before the cold rain shows up tomorrow. Just doing my part for global warming, pine trees to palm trees is my hope.
A dial back timing light gives you the ability to have the light flash when the timing pointer is only on TDC. In other words, if I wanted 10 degrees of initial, I would set the light at 10 advanced and adjust the distributor until the pointer was on TDC. And if I want to see what my total centrifugal advance is at say 2500 rpm. I would bring the engine up to that RPM then adjust the light to read at TDC. Whatever number is showing on the light is the number of degrees advance. With the vacuum can disconnected you can run the engine in increments of 500 rpm, 500-1000-1500 etc. writing down the numbers until you reach an RPM that the distributor isn't advancing anymore. Those numbers will be the curve of the mechanical advance. You can add stronger springs to slow the curve down and move it to a higher RPM. Way more to it than this but I got to clean my shop stove out, chop some kindling and bring some coal in before the cold rain shows up tomorrow. Just doing my part for global warming, pine trees to palm trees is my hope.
At least when I get the truck back I'll have a starting point now. What should the curve look like?
Need to get some global warming here. About 15° worth should bring us up to about normal. Apparently AZ hasn't gotten it's share this year.
Cargo Master
Joined: Mar 2003
Posts: 2,333
Likes: 296
Many distributors that have the vacuum canisters with the octagonal shaped front can be adjusted for total advance with an allen wrench inserted into the vacuum nipple.
EDIT:
Basic procedure to adjusting vacuum advance:
EDIT:
Basic procedure to adjusting vacuum advance:
Test drive and listening for audible noise under load and at part throttle. If spark knock
occurs under load, at full throttle, retard the initial timing as required to eliminate it. If spark
knock occurs at part throttle an adjustment to the vacuum advance is necessary. This
adjustment is made by inserting the Allen wrench into the vacuum advance canister port
and turning it two turns clockwise. Test-drive the car and repeat the adjustment until the
spark knock is eliminated.
occurs under load, at full throttle, retard the initial timing as required to eliminate it. If spark
knock occurs at part throttle an adjustment to the vacuum advance is necessary. This
adjustment is made by inserting the Allen wrench into the vacuum advance canister port
and turning it two turns clockwise. Test-drive the car and repeat the adjustment until the
spark knock is eliminated.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Logistics Pro
Joined: Jun 2018
Posts: 3,554
Likes: 442
What about the Predator 6000 carb.
jpspecialties : PREDATOR 6000 VARIABLE VENTURI PERFORMANCE CARBURETOR (vendio.com)
jpspecialties : PREDATOR 6000 VARIABLE VENTURI PERFORMANCE CARBURETOR (vendio.com)
Logistics Pro
Joined: May 2015
Posts: 4,474
Likes: 974
From: Tri Cities, TN
Advance curve
36 is total. 12 initial plus 24 mechanical.
At least when I get the truck back I'll have a starting point now. What should the curve look like?
Need to get some global warming here. About 15° worth should bring us up to about normal. Apparently AZ hasn't gotten it's share this year.
At least when I get the truck back I'll have a starting point now. What should the curve look like?
Need to get some global warming here. About 15° worth should bring us up to about normal. Apparently AZ hasn't gotten it's share this year.
Without knowing what your dynamic compression is at sea level that is just a guess. Like I said before if it is over 8-1 more octane may be the only cure.
Stock Ford vacuum canisters are adjustable but only in the sense that you can change the amount of vacuum it takes to start it moving. The amount of advance they pull in is fixed by the slot in the arm. Most are stamped with a number that number represents the amount of camshaft degrees they will pull in. Double that for crank degrees.
And there are a gazillion different ones of these also.
You should look at that carb Christmas linked to. They look strange but they do work.
.
Thread Starter
|
Fleet Mechanic
Joined: Dec 2016
Posts: 1,261
Likes: 714
Lots of excellent advice here by all.
Agree that timing is main issue and will try and get that dialed in. I like the dial in timing control and the adjustable jet ideas as well. Combined with an a/f ratio meter becomes real easy to deal with changing altitudes. I remember those predator carbs. Knew a guy that swore by them. Others just swore at them.
Back to the effects of high compression. If higher octane reduces risk of detonation, (I did use 91 and octane boost at 1 point) it seems to me that on its own, taking spark timing out of the engine won't in and of itself cure the problem. I suppose octane/compression might not have been my problem but how can you know for sure? Short of reducing compression or even higher octane fuel, how much will lowering intake air or combustion temperature reduce risk of detonation caused by high compression? Engine ping due to timing and/or high compression seem to be 2 separate issues to me. Am I wrong? And, what's changing under load since that's when problems seem to start?
Agree that timing is main issue and will try and get that dialed in. I like the dial in timing control and the adjustable jet ideas as well. Combined with an a/f ratio meter becomes real easy to deal with changing altitudes. I remember those predator carbs. Knew a guy that swore by them. Others just swore at them.
Back to the effects of high compression. If higher octane reduces risk of detonation, (I did use 91 and octane boost at 1 point) it seems to me that on its own, taking spark timing out of the engine won't in and of itself cure the problem. I suppose octane/compression might not have been my problem but how can you know for sure? Short of reducing compression or even higher octane fuel, how much will lowering intake air or combustion temperature reduce risk of detonation caused by high compression? Engine ping due to timing and/or high compression seem to be 2 separate issues to me. Am I wrong? And, what's changing under load since that's when problems seem to start?
Laughing Gas
Joined: Nov 2001
Posts: 1,062
Likes: 78
From: Edmonton, Alberta
MSD make a BUNCH of products to enable adjusting your timing, but it might be worth the nickel to call their tech line and explain your issues, and have them suggest WHICH of their products will do what you want, for the least $$ expended.
https://www.summitracing.com/search?...ing%20adjuster
And stock CI heads are a huge heat sink, and sharp edges on the combustion chamber only make them more susceptible to detonation. They're a long way from free, but aftermarket aluminum heads will not only add some power from their higher flow, they will dissipate heat better....but again, far from a free fix.
Same goes for that OEM CI Intake, it takes a good man to lift one of those into/out of the engine bay! And it is also a big heat sink!! A craigslist Edelbrock performer would shave weight, flow more, and should lower the temp of your fuel @ the carb.
https://www.summitracing.com/search?...ing%20adjuster
And stock CI heads are a huge heat sink, and sharp edges on the combustion chamber only make them more susceptible to detonation. They're a long way from free, but aftermarket aluminum heads will not only add some power from their higher flow, they will dissipate heat better....but again, far from a free fix.
Same goes for that OEM CI Intake, it takes a good man to lift one of those into/out of the engine bay! And it is also a big heat sink!! A craigslist Edelbrock performer would shave weight, flow more, and should lower the temp of your fuel @ the carb.
Logistics Pro
Joined: May 2008
Posts: 3,670
Likes: 370
From: PHX AZ
Is the intake, heads made for EGR? Nope
If not how do you plan on adding it? Don't know. Haven't thought that far ahead
What carb & intake you running? Holley670 vac secondaries, cast iron Ford
I take it you are running cast iron heads? Yes
As far as how/what method is used to adjust timing, my concern is will it be enough to solve issue. Modern engines use multiple methods.
As far as EFI, basic and simple is what I prefer. Not sure the cost is justified especially when the occasional re-jet is simple to do. Would still need timing control and cost keeps climbing.
As far as changing cams goes, I have considered it but would open up another can. As things are now, based on altitude loss (remember I'm at 5300') my theoretical dynamic CR is just slightly over 8:1. That's how I can normally run on regular gas with no issues. How much compression would be lost with a different cam and at what point does the engine become a pig at higher elevations? 7000-8000' is not out of the question now too. Lower compression would help with the pinging but, also, with a different cam comes changes in power band and may be more appropriate for a car as opposed to a truck.
Yes, I want to have my cake and eat it too
If not how do you plan on adding it? Don't know. Haven't thought that far ahead
What carb & intake you running? Holley670 vac secondaries, cast iron Ford
I take it you are running cast iron heads? Yes
As far as how/what method is used to adjust timing, my concern is will it be enough to solve issue. Modern engines use multiple methods.
As far as EFI, basic and simple is what I prefer. Not sure the cost is justified especially when the occasional re-jet is simple to do. Would still need timing control and cost keeps climbing.
As far as changing cams goes, I have considered it but would open up another can. As things are now, based on altitude loss (remember I'm at 5300') my theoretical dynamic CR is just slightly over 8:1. That's how I can normally run on regular gas with no issues. How much compression would be lost with a different cam and at what point does the engine become a pig at higher elevations? 7000-8000' is not out of the question now too. Lower compression would help with the pinging but, also, with a different cam comes changes in power band and may be more appropriate for a car as opposed to a truck.
Yes, I want to have my cake and eat it too
What did you do to determine your compression ratio is 10.15 to 1? What heads are you using? , C8AE-H? Did you measure the combustion chamber size?
Someone asked what your deck height was you said ".037 quench ht" are you saying your crushed gasket thickness is .037" Or your pistons are .037 in the hole at TDC? Huge diff.
Did you measure actual deck height? (Piston at TDC to deck surface) Do you remember what part number head gaskets you used? You mentioned pistons with 8cc valve reliefs? Assuming it is a 4.080 bore?
What intake manifold are you using?
Assuming a C8AE-H head that is 74 cc zero deck with a 8cc valve relief in piston (8 cc valve relief sounds like a lot unless dished too and a .037 crushed head gasket your compression would be 9.98 to 1. That is why I am asking these questions. Also will assume you do not have anywhere near a zero deck height as it takes careful planning and usually a custom piston. Depending on year of engine It could be .050" in the hole or more. Some in excess of .100" in hole.
Edit add: Just re-read your post. 1968 390 4v from what? How did you arrive at the 360hp 460tq and what headers are you using? Is the cam the Melling CL-SYB-23 like from summit?
Logistics Pro
Joined: May 2008
Posts: 3,670
Likes: 370
From: PHX AZ
Lots of excellent advice here by all.
Agree that timing is main issue and will try and get that dialed in. I like the dial in timing control and the adjustable jet ideas as well. Combined with an a/f ratio meter becomes real easy to deal with changing altitudes. I remember those predator carbs. Knew a guy that swore by them. Others just swore at them.
Back to the effects of high compression. If higher octane reduces risk of detonation, (I did use 91 and octane boost at 1 point) it seems to me that on its own, taking spark timing out of the engine won't in and of itself cure the problem. I suppose octane/compression might not have been my problem but how can you know for sure? Short of reducing compression or even higher octane fuel, how much will lowering intake air or combustion temperature reduce risk of detonation caused by high compression? Engine ping due to timing and/or high compression seem to be 2 separate issues to me. Am I wrong? And, what's changing under load since that's when problems seem to start?
Agree that timing is main issue and will try and get that dialed in. I like the dial in timing control and the adjustable jet ideas as well. Combined with an a/f ratio meter becomes real easy to deal with changing altitudes. I remember those predator carbs. Knew a guy that swore by them. Others just swore at them.
Back to the effects of high compression. If higher octane reduces risk of detonation, (I did use 91 and octane boost at 1 point) it seems to me that on its own, taking spark timing out of the engine won't in and of itself cure the problem. I suppose octane/compression might not have been my problem but how can you know for sure? Short of reducing compression or even higher octane fuel, how much will lowering intake air or combustion temperature reduce risk of detonation caused by high compression? Engine ping due to timing and/or high compression seem to be 2 separate issues to me. Am I wrong? And, what's changing under load since that's when problems seem to start?
Thread Starter
|
Fleet Mechanic
Joined: Dec 2016
Posts: 1,261
Likes: 714
Lots of good info and questions here.
What did you do to determine your compression ratio is 10.15 to 1? What heads are you using? , C8AE-H? Yes Did you measure the combustion chamber size? Yes. Off-hand remember 76cc
Someone asked what your deck height was you said ".037 quench ht" are you saying your crushed gasket thickness is .037" Or your pistons are .037 in the hole at TDC? Huge diff. Neither. 360 rods put piston out of hole .040 + .077 gasket
Did you measure actual deck height? (Piston at TDC to deck surface) Do you remember what part number head gaskets you used? You mentioned pistons with 8cc valve reliefs? Assuming it is a 4.080 bore? 4.110 bore
What intake manifold are you using? Stock iron 4v
Assuming a C8AE-H head that is 74 cc zero deck with a 8cc valve relief in piston (8 cc valve relief sounds like a lot unless dished too and a .037 crushed head gasket your compression would be 9.98 to 1. That is why I am asking these questions. Also will assume you do not have anywhere near a zero deck height as it takes careful planning and usually a custom piston. Depending on year of engine It could be .050" in the hole or more. Some in excess of .100" in hole. See above
Edit add: Just re-read your post. 1968 390 4v from what? No clue. Parts sourced from different places. Was never a complete engine. Bought heads from youHow did you arrive at the 360hp 460tq Dyno2000 and what headers are you using? Garage sale special $5 long tubes Is the cam the Melling CL-SYB-23 like from summit? No. Melling MTF-4
What did you do to determine your compression ratio is 10.15 to 1? What heads are you using? , C8AE-H? Yes Did you measure the combustion chamber size? Yes. Off-hand remember 76cc
Someone asked what your deck height was you said ".037 quench ht" are you saying your crushed gasket thickness is .037" Or your pistons are .037 in the hole at TDC? Huge diff. Neither. 360 rods put piston out of hole .040 + .077 gasket
Did you measure actual deck height? (Piston at TDC to deck surface) Do you remember what part number head gaskets you used? You mentioned pistons with 8cc valve reliefs? Assuming it is a 4.080 bore? 4.110 bore
What intake manifold are you using? Stock iron 4v
Assuming a C8AE-H head that is 74 cc zero deck with a 8cc valve relief in piston (8 cc valve relief sounds like a lot unless dished too and a .037 crushed head gasket your compression would be 9.98 to 1. That is why I am asking these questions. Also will assume you do not have anywhere near a zero deck height as it takes careful planning and usually a custom piston. Depending on year of engine It could be .050" in the hole or more. Some in excess of .100" in hole. See above
Edit add: Just re-read your post. 1968 390 4v from what? No clue. Parts sourced from different places. Was never a complete engine. Bought heads from you
How did you arrive at the 360hp 460tq Dyno2000 and what headers are you using? Garage sale special $5 long tubes Is the cam the Melling CL-SYB-23 like from summit? No. Melling MTF-4Some info from memory but all was accurate at time of build.
