Go Back   Ford Truck Enthusiasts Forums > Older, Classic & Antique Trucks > 1973 - 1979 F-100 & Larger F-Series Trucks
Sign in using an external account
Register Forgot Password?


1973 - 1979 F-100 & Larger F-Series Trucks Discuss the Dentsides Ford Truck

Welcome to Ford-Trucks Forums!
Welcome to Ford-Trucks.com.

You are currently viewing our forums as a guest, which gives you limited access to view most discussions and access our other features. By joining our community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join the Ford-Trucks Forums community today!





 
Reply
 
 
 
 
LinkBack Thread Tools Search this Thread
  #1  
Old 06-25-2014, 06:33 PM
0ldman 0ldman is offline
Senior User
 
Join Date: Jan 2013
Posts: 239
0ldman is starting off with a positive reputation.
glen.waldrop
My economic 390 project

Just a quick overview, I got a 1974 F100 with a 390 from a friend of mine.

390 .060 over, fairly fresh build
compression ratio is unknown, been told it was built with extremely high compression, then told he was getting his builder to set it up for a blower... ??
Edel intake
Edel 650 (so I've been told) carb
Edel Performer cam
C8AE-H heads, not sure if they're ported or not, conflicting stories
Hooker Super Comps 1 3/4 longtubes
2.5 full duals
I think Flowmasters
C6
3:1 rear

When I got it, I put a set of points in it and drove it home. Rough mileage on it was 8mpg.

When I got some time, I set the points correctly, set the timing by ear, fuel filter, etc, just quick stuff trying to get it back running, got somewhere around 6mpg.

I cleaned the Edelbrock carb and put it back together, set the timing as high as it would go and still crank, any higher and the starter would bog. 4mpg.

I rebuilt my old Holley 600 that got 24mpg on my 302 on my Comet, decent little carb. I found the vacuum advance was busted, replaced it with a Crane adjustable kit. Swapped the carb, got it going, 6.9mpg.

Fine tuning the timing, finding and fixing vacuum leaks, 7.47mpg.

Further tuning the vacuum advance, dialing in the carb better, 7.8mpg.

I haven't gotten the engine to ping since I cleaned the Edelbrock carb. I'm pretty sure the only reason I got it to ping before was due to it leaning out because of the trash in the carb.

Right now initial is somewhere around 12-14*, mechanical advance is in the mid 20s around 1500-2000rpm (haven't got a tach on it yet), full advance with the vacuum shoots well past the 30* mark on the balancer.

I'm looking for advice on getting the mileage up a bit. My goal is 20mpg, I realize this is probably impossible, but I figure aim high and pull back as needed. I got 24mpg out of my 74 Comet, so I figure I can at least get this truck comparable to my sister in law's Jeep, 4.7 (or 4.8, whatever) that gets 14mpg.

Right now it seems I need to back the vacuum advance down a bit, kind of sputters when accelerating after fixing a vacuum leak. Before I fixed the leak it would burn the tires until it shifted into second @ 55-60mph.

The next thing I plan on doing is getting a vacuum gauge, tinkering with the idle and timing a bit, get a set of smaller jets and a looser power valve since this engine has more vacuum than anything I've ever worked on. I'm pretty sure the power valve never kicks in.

I am a little concerned/confused since I have not gotten the engine to ping at all since cleaning the Edelbrock carb. I've pushed the timing to ridiculous extremes and it might misfire, but it it will not ping.

I'm wondering if the jets that ran fine on the 302 might be a little rich considering how much more vacuum this engine has.

I'd appreciate any input.
Reply With Quote
  #2  
Old 06-25-2014, 07:42 PM
HIO Silver's Avatar
HIO Silver HIO Silver is online now
Post Fiend
 
Join Date: Dec 2009
Location: NorCal
Posts: 10,849
HIO Silver is a splendid one to beholdHIO Silver is a splendid one to beholdHIO Silver is a splendid one to beholdHIO Silver is a splendid one to beholdHIO Silver is a splendid one to beholdHIO Silver is a splendid one to beholdHIO Silver is a splendid one to behold
Quote:
Originally Posted by 0ldman View Post
Just a quick overview, I got a 1974 F100 with a 390 from a friend of mine.

390 .060 over, fairly fresh build
compression ratio is unknown, been told it was built with extremely high compression, then told he was getting his builder to set it up for a blower... ??
Edel intake
Edel 650 (so I've been told) carb
Edel Performer cam
C8AE-H heads, not sure if they're ported or not, conflicting stories
Hooker Super Comps 1 3/4 longtubes
2.5 full duals
I think Flowmasters
C6
3:1 rear

When I got it, I put a set of points in it and drove it home. Rough mileage on it was 8mpg.

When I got some time, I set the points correctly, set the timing by ear, fuel filter, etc, just quick stuff trying to get it back running, got somewhere around 6mpg.

I cleaned the Edelbrock carb and put it back together, set the timing as high as it would go and still crank, any higher and the starter would bog. 4mpg.

I rebuilt my old Holley 600 that got 24mpg on my 302 on my Comet, decent little carb. I found the vacuum advance was busted, replaced it with a Crane adjustable kit. Swapped the carb, got it going, 6.9mpg.

Fine tuning the timing, finding and fixing vacuum leaks, 7.47mpg.

Further tuning the vacuum advance, dialing in the carb better, 7.8mpg.

I haven't gotten the engine to ping since I cleaned the Edelbrock carb. I'm pretty sure the only reason I got it to ping before was due to it leaning out because of the trash in the carb.

Right now initial is somewhere around 12-14*, mechanical advance is in the mid 20s around 1500-2000rpm (haven't got a tach on it yet), full advance with the vacuum shoots well past the 30* mark on the balancer.

I'm looking for advice on getting the mileage up a bit. Goal is 20 mpg, I realize this is probably impossible, but I figure aim high and pull back as needed. I got 24mpg out of my 74 Comet, so I figure I can at least get this truck comparable to my sister in law's Jeep, 4.7 (or 4.8, whatever) that gets 14mpg.

Right now it seems I need to back the vacuum advance down a bit, kind of sputters when accelerating after fixing a vacuum leak. Before I fixed the leak it would burn the tires until it shifted into second @ 55-60mph.

The next thing I plan on doing is getting a vacuum gauge, tinkering with the idle and timing a bit, get a set of smaller jets and a looser power valve since this engine has more vacuum than anything I've ever worked on. I'm pretty sure the power valve never kicks in.

I am a little concerned/confused since I have not gotten the engine to ping at all since cleaning the Edelbrock carb. I've pushed the timing to ridiculous extremes and it might misfire, but it it will not ping.

I'm wondering if the jets that ran fine on the 302 might be a little rich considering how much more vacuum this engine has.

I'd appreciate any input.
Input? Sure. Get yourself some diagnostic tools and do it "right". the **best** you'll get, under ideal conditions, is probably around 15 mpg.

Last edited by HIO Silver; 06-25-2014 at 07:44 PM. Reason: Cat walked on the keyboard right when I posted...
Reply With Quote
  #3  
Old 06-25-2014, 09:10 PM
0ldman 0ldman is offline
Senior User
 
Join Date: Jan 2013
Posts: 239
0ldman is starting off with a positive reputation.
glen.waldrop
What diagnostic tools do you recommend?
Reply With Quote
  #4  
Old 06-25-2014, 10:10 PM
mikeo0o0o0's Avatar
mikeo0o0o0 mikeo0o0o0 is offline
Post Fiend
 
Join Date: Apr 2009
Location: Davenport, Fl
Posts: 10,085
mikeo0o0o0 is a splendid one to beholdmikeo0o0o0 is a splendid one to beholdmikeo0o0o0 is a splendid one to beholdmikeo0o0o0 is a splendid one to beholdmikeo0o0o0 is a splendid one to beholdmikeo0o0o0 is a splendid one to beholdmikeo0o0o0 is a splendid one to beholdmikeo0o0o0 is a splendid one to behold
Quote:
Originally Posted by 0ldman View Post
What diagnostic tools do you recommend?
To start, a timing light, vacuum gauge and dwell meter.
Reply With Quote
  #5  
Old 06-25-2014, 10:36 PM
61steven's Avatar
61steven 61steven is offline
Elder User
 
Join Date: Jun 2013
Posts: 547
61steven is starting off with a positive reputation.
What type of ignition setup is the truck running? Stock style, or has it been upgraded to an MSD? New plugs and ignition components could pick up a small gain.

What system are you using to draw in air? Getting to cooler air could also pick up a small gain.

Check out another thread on here on tuning a 351. He has posted some really good, in-depth data on fine tuning.
__________________
1961 f100 uni (project)
1979 f150 4x4 6" lift 400
1998 f150 (deceased)
Reply With Quote
  #6  
Old 06-25-2014, 11:39 PM
0ldman 0ldman is offline
Senior User
 
Join Date: Jan 2013
Posts: 239
0ldman is starting off with a positive reputation.
glen.waldrop
Got a timing light already, I figured that would be clear since I said what the timing was above. Vacuum gauge on the way, I'm replacing the points shortly, so I'm not too worried about the dwell meter. Never used one to set points in the past anyway. Maybe I've just been lucky.

Stock ignition setup right now, figured on installing Pertronix or one of the other drop in systems. Pertronix ran fine on my Comet until I hotwired it wrong. Not sure on the coil, but I think it is a stock-ish coil. Previous owner had an MSD on it and swears that old engines require old ignitions (because he couldn't make it work right), so he threw it away and put a points dizzy in there.

Right now it has a K&N 4x14 filter, chrome breather sucking in hot air from the engine bay. Any idea of an aftermarket breather assembly with ducts like the factory stuff?

I think I may have read that or a similar thread, get a hotter ignition setup, gap the plugs to .45, higher gauge, low loss plug wires?
Reply With Quote
  #7  
Old 06-30-2014, 04:47 PM
0ldman 0ldman is offline
Senior User
 
Join Date: Jan 2013
Posts: 239
0ldman is starting off with a positive reputation.
glen.waldrop
Got the Pertronix installed. Apparently the points were crap. I could set them and get it running fine but it all went to hell once I hooked up the vacuum advance. I worked on that for a few hours, thought I had it fixed. Regardless, the Pertronix has it purring like a kitten.

Got the vacuum guage, 18 at idle after I tinkered with the idle screws. Pretty sure it is still not quite there yet.

Initial is about 14, down from 20 on my test drive, vacuum hooked up to the manifold has it pulling more than 36 at idle. I'm fine tuning the vacuum advance again. I'll check the plug gaps later. My part throttle hesitation is just about gone. I'm hoping with the timing at 14 that has cleared it up.
Reply With Quote
  #8  
Old 06-30-2014, 05:42 PM
Blue and White Blue and White is offline
Elder User
 
Join Date: Nov 2011
Posts: 969
Blue and White is gaining momentum as a positive member of FTE.
Sounds like good progress. On the idle timing, not sure 36 degrees with vacuum helps it. I know its debated, but OE had the vacuum advance running on ported vacuum. May be worth trying both ways for your particular combo.
Reply With Quote
  #9  
Old 06-30-2014, 09:16 PM
0ldman 0ldman is offline
Senior User
 
Join Date: Jan 2013
Posts: 239
0ldman is starting off with a positive reputation.
glen.waldrop
That is the plan.

It is an adjustable advance, so I'll be tinkering with it for the foreseeable future.

With it connected to the carb vacuum it ran extremely warm in city traffic, warmer than I'm comfortable with, especially considering it wasn't a hot Alabama day yet.
Reply With Quote
  #10  
Old 06-30-2014, 09:23 PM
redroad's Avatar
redroad redroad is offline
Posting Guru
 
Join Date: Nov 2006
Location: Pa.
Posts: 2,150
redroad is gaining momentum as a positive member of FTE.redroad is gaining momentum as a positive member of FTE.
Quote:
Originally Posted by 0ldman View Post
That is the plan.

It is an adjustable advance, so I'll be tinkering with it for the foreseeable future.

With it connected to the carb vacuum it ran extremely warm in city traffic, warmer than I'm comfortable with, especially considering it wasn't a hot Alabama day yet.
Be careful advancing it to much by timing with the vacuum gauge ..

Using vacuum gauge to set timing

Slacken the distributor clamp bolt, and with the engine still at idle, advance or retard the ignition until the highest steady vacuum reading is obtained. Then retard the timing until the vacuum gauge reading drops slightly, approximately one half to one inch. In some cases, you may need to retard the timing up to two inches to prevent pre-ignition (pinging).

Note: If you can't get the reading into the "normal" zone by adjusting the distributor then valve timing is the problem. Timing with a vacuum gauge will normally result in timing that is more advanced than what specifications call for, so you need to be alert for any pre-ignition (pinging) in the engine and adjust accordingly (retard the timing if needed).
Reply With Quote
  #11  
Old 06-30-2014, 09:48 PM
0ldman 0ldman is offline
Senior User
 
Join Date: Jan 2013
Posts: 239
0ldman is starting off with a positive reputation.
glen.waldrop
I'm just talking about the vacuum advance. I set the timing with the light, the vacuum advance has to be set by trial and error as far as I know. If anyone has a better way I'm all ears.

The directions say to turn it in two turns at a time until it stops pinging at part throttle and the go back one turn. I haven't heard this engine ping since I fixed a lean condition due to trash in the carb.
Reply With Quote
  #12  
Old 07-01-2014, 07:32 AM
redroad's Avatar
redroad redroad is offline
Posting Guru
 
Join Date: Nov 2006
Location: Pa.
Posts: 2,150
redroad is gaining momentum as a positive member of FTE.redroad is gaining momentum as a positive member of FTE.
Quote:
Originally Posted by 0ldman View Post
I'm just talking about the vacuum advance. I set the timing with the light, the vacuum advance has to be set by trial and error as far as I know. If anyone has a better way I'm all ears.

The directions say to turn it in two turns at a time until it stops pinging at part throttle and the go back one turn. I haven't heard this engine ping since I fixed a lean condition due to trash in the carb.
Here is some good info on tunning the vacuum advance ..
Reply With Quote
  #13  
Old 07-04-2014, 11:04 AM
0ldman 0ldman is offline
Senior User
 
Join Date: Jan 2013
Posts: 239
0ldman is starting off with a positive reputation.
glen.waldrop
I've been driving it a bit, timing is high, still can't make it ping.

I think the previous owner must have used bowls instead of pistons.

Still have a hesitation at part throttle, but I haven't narrowed it down to the carb or timing yet. I need to drive it with the vacuum advance disconnected and see.
Reply With Quote
  #14  
Old 07-04-2014, 06:52 PM
oddfordjunkie oddfordjunkie is online now
Elder User
 
Join Date: Dec 2012
Location: Olympia, Wa
Posts: 928
oddfordjunkie is starting off with a positive reputation.
Best MPG upgrade I did was a FULL CD ignition system. I use Jacob's products (which a lot of people don't like) a Duraspark II distributor and standard copper core plugs. I run my plugs at 0.090 and have tested with larger gaps but wanted to be safe in case of bad gas or towing over the mountains.
Reply With Quote
  #15  
Old 07-04-2014, 08:27 PM
0ldman 0ldman is offline
Senior User
 
Join Date: Jan 2013
Posts: 239
0ldman is starting off with a positive reputation.
glen.waldrop
Full CD?
I probably know it, but it isn't coming to me right now.
Reply With Quote
Old 07-04-2014, 08:27 PM
 
 
 
Reply

Go Back   Ford Truck Enthusiasts Forums > Older, Classic & Antique Trucks > 1973 - 1979 F-100 & Larger F-Series Trucks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
351M ignition/timing/carb trouble flashover604 335 Series- 5.8/351M, 6.6/400, 351 Cleveland 2 02-09-2010 04:39 AM
Can't seem to get rid of the ping. Help please. pidaster 1973 - 1979 F-100 & Larger F-Series Trucks 18 11-15-2009 12:21 PM
Fuel mileage help 72f2504x4390 1967 - 1972 F-100 & Larger F-Series Trucks 9 12-12-2006 08:18 PM
Detonation & Timing frankalonge 335 Series- 5.8/351M, 6.6/400, 351 Cleveland 6 11-07-2006 06:33 PM
390 timing gtex FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428) 2 08-22-2001 08:19 AM



All times are GMT -5. The time now is 11:53 PM.


Powered by vBulletin® Version 3.8.7 AC1
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Advertising - Terms of Use - Privacy Statement - Jobs
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. FordŽ is a registered trademark of the Ford Motor Company.

vbulletin Admin Backup