Dwell on a 78 460?
#1
Dwell on a 78 460?
Howdy,
First time big truck owner. I just picked up a 78 F250 Camper Special 460 Auto and while it is running better than could be expected for the year, I'm trying it get it to purr.
Just did rotor, cap, plugs, PCV and fuel filter today. Definitely helped at idle and it's much more rev happy. Still missing a bit at idle though, and I feel like there is more power hiding in there somewhere. There is also some hesitation when I stomp on it, especially when cold.
So, I'm looking at dwell/timing next, then carb tweaking, but I wasn't sure if dwell was adjustable on this engine and if it was, what the range should be. Chilton doesn't seem to include that info.
Also, I've got a bit of a squeak in the dash. Constant pitch, only when bumpy. I've searched all through the forums and I think it might be either the speedo cable of the hood hinges/bumpers. Any other possibilities?
BTW, attaching a pic of the beast. Bone stock, great interior, very solid frame (no flaking rust), original paint with only a couple very small surface rust areas, drives perfect except for the above tune up issues.
First time big truck owner. I just picked up a 78 F250 Camper Special 460 Auto and while it is running better than could be expected for the year, I'm trying it get it to purr.
Just did rotor, cap, plugs, PCV and fuel filter today. Definitely helped at idle and it's much more rev happy. Still missing a bit at idle though, and I feel like there is more power hiding in there somewhere. There is also some hesitation when I stomp on it, especially when cold.
So, I'm looking at dwell/timing next, then carb tweaking, but I wasn't sure if dwell was adjustable on this engine and if it was, what the range should be. Chilton doesn't seem to include that info.
Also, I've got a bit of a squeak in the dash. Constant pitch, only when bumpy. I've searched all through the forums and I think it might be either the speedo cable of the hood hinges/bumpers. Any other possibilities?
BTW, attaching a pic of the beast. Bone stock, great interior, very solid frame (no flaking rust), original paint with only a couple very small surface rust areas, drives perfect except for the above tune up issues.
#2
Welcome to FTE! Nice looking SuperCab.
Dwell is ony applicable in a points type ignition. You should have a Duraspark electronic ignition, unless someone has swapped in a points ignition.
As far as hesitation, could be timing, make sure the distibutor advance is functioning properly. Also, check to make sure the accelerator pump is working. While looking down into the carb, move the throttle and verifiy good streams of fuel entering. My 77 still has some hesitation that I can't seem to track down.
Dwell is ony applicable in a points type ignition. You should have a Duraspark electronic ignition, unless someone has swapped in a points ignition.
As far as hesitation, could be timing, make sure the distibutor advance is functioning properly. Also, check to make sure the accelerator pump is working. While looking down into the carb, move the throttle and verifiy good streams of fuel entering. My 77 still has some hesitation that I can't seem to track down.
#3
First thing, aquire a small bottle of propane, and a $5 torch tip. Use the unlit propane torch to track down any vacuum leaks. The propane will make the engine run differently. Once you fix all of the vacuum leaks, make sure your timing is correct. Now take a vacuum gauge, hook it up to full manifopld vacuum, make sure you have at least 17" of vacuum.
if you don't, you need to adjust your carberator. I would adjust it just to say I did it. A flat spot (hesitation) in the carb can be fixed with a proper tune.
if you don't, you need to adjust your carberator. I would adjust it just to say I did it. A flat spot (hesitation) in the carb can be fixed with a proper tune.
#4
Make sure your carb accelerator rod is indexed correctly.
It makes a difference from idle to power up if it is set wrong.
You can find your engine specs here on my page.
http://mil1ion.clubfte.com/78Calibra...e-upSpecs.html
at the very bottom pf the page
.
Your calibration code is 8-97-R0
It makes a difference from idle to power up if it is set wrong.
You can find your engine specs here on my page.
http://mil1ion.clubfte.com/78Calibra...e-upSpecs.html
at the very bottom pf the page
.
Your calibration code is 8-97-R0
Last edited by Mil1ion; 11-19-2007 at 08:51 PM.
#5
Jason,
Kind of relieved that it isn't a points ignition. My only experience with them was tuning my dads old Chevy truck (62 I believe) about 15 years ago. I do get a bit nervous getting far enough into the engine compartment to peer down into the carb while running. Even at 6'3" that's a long way in. I suppose a mirror could make things easier though.
Tony,
Great advice on the vacuum leaks. I'll give that a shot tomorrow. With other engines, It has always been my experience to adjust the carb last. Too much risk of chasing the problem around in circles.
Follow up question. I'm not sure which rear end this has, but in general, how much grunt should the stock 460 have? Should I be lighting up the tires without trying, or is it more of a solid surge of power. Even as is, I hit 90 without trying driving it home and it got up to 65 on a 8% grade at 7000 feet. Seems decent, just curious what I should be shooting for.
Kind of relieved that it isn't a points ignition. My only experience with them was tuning my dads old Chevy truck (62 I believe) about 15 years ago. I do get a bit nervous getting far enough into the engine compartment to peer down into the carb while running. Even at 6'3" that's a long way in. I suppose a mirror could make things easier though.
Tony,
Great advice on the vacuum leaks. I'll give that a shot tomorrow. With other engines, It has always been my experience to adjust the carb last. Too much risk of chasing the problem around in circles.
Follow up question. I'm not sure which rear end this has, but in general, how much grunt should the stock 460 have? Should I be lighting up the tires without trying, or is it more of a solid surge of power. Even as is, I hit 90 without trying driving it home and it got up to 65 on a 8% grade at 7000 feet. Seems decent, just curious what I should be shooting for.
#7
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#8
Originally Posted by TheMule
Jason,
Kind of relieved that it isn't a points ignition. My only experience with them was tuning my dads old Chevy truck (62 I believe) about 15 years ago. I do get a bit nervous getting far enough into the engine compartment to peer down into the carb while running. Even at 6'3" that's a long way in. I suppose a mirror could make things easier though.
Tony,
Great advice on the vacuum leaks. I'll give that a shot tomorrow. With other engines, It has always been my experience to adjust the carb last. Too much risk of chasing the problem around in circles.
Follow up question. I'm not sure which rear end this has, but in general, how much grunt should the stock 460 have? Should I be lighting up the tires without trying, or is it more of a solid surge of power. Even as is, I hit 90 without trying driving it home and it got up to 65 on a 8% grade at 7000 feet. Seems decent, just curious what I should be shooting for.
Kind of relieved that it isn't a points ignition. My only experience with them was tuning my dads old Chevy truck (62 I believe) about 15 years ago. I do get a bit nervous getting far enough into the engine compartment to peer down into the carb while running. Even at 6'3" that's a long way in. I suppose a mirror could make things easier though.
Tony,
Great advice on the vacuum leaks. I'll give that a shot tomorrow. With other engines, It has always been my experience to adjust the carb last. Too much risk of chasing the problem around in circles.
Follow up question. I'm not sure which rear end this has, but in general, how much grunt should the stock 460 have? Should I be lighting up the tires without trying, or is it more of a solid surge of power. Even as is, I hit 90 without trying driving it home and it got up to 65 on a 8% grade at 7000 feet. Seems decent, just curious what I should be shooting for.
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