Go Back   Ford Truck Enthusiasts Forums > Performance, Engines & Troubleshooting > 335 Series- 5.8/351M, 6.6/400, 351 Cleveland
Sign in using an external account
Register Forgot Password?


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 12-19-2009, 11:07 PM
flashover604 flashover604 is offline
Freshman User
 
Join Date: Feb 2007
Posts: 40
flashover604 is starting off with a positive reputation.
351M ignition/timing/carb trouble

Hi all. I recently posted in the dentside forum with my problems. I'll post here the trouble and suggested causes. Hopefully I can get a handle on where to go from here.

The truck is a 79 f250 with a 351M with a Performer intake and Edelbrock 1406 600 cfm carb to a C6 to Dana 60's front and rear. The engine is apparently not original, or the distributor isn't as it a points type.

Up until a week ago it got 13 mpg at it's best (highway), but it pinged pretty bad on hills or heavy acceleration. I knew it didn't have the hose from the carb to the vacuum advance on the distributor. I bought and installed the hose on the passenger side port of the carb. When I went to install it on the distributor, the whole distributor turned. The hold down bolt had loosened. I put it back where I thought it was before. It didn't run any different. The next day I set the timing to 11 btdc. It was near 20 btdc when I started. I set the points to .017 per the Haynes manual and checked the dwell. It read 15 degrees instead of 24-30 degrees like the manual called for, so I OPENED the points gap until the dwell got to 25 and locked it down. I also put a vacuum gauge on the drivers side port of the carb. The needle bounced between 17 and 13 rapidly. I averaged it at 15 and turned one side screw until the engine started sputtering, then backed the screw out until the vacuum got the highest, around 16 in/hg average due to bounce. After all that, the detonation ping is gone, but I'm down to about 8 mpg. Crap....

So, where do I start?

(I'd like to thank montanahighboy for all of his help up to this point!)
Reply With Quote
  #2  
Old 01-31-2010, 09:29 PM
Dave 77's Avatar
Dave 77 Dave 77 is offline
New User
 
Join Date: Jan 2010
Posts: 10
Dave 77 is starting off with a positive reputation.
does vac adv work
Reply With Quote
  #3  
Old 02-09-2010, 04:39 AM
walkee's Avatar
walkee walkee is offline
Senior User
 
Join Date: Jan 2001
Posts: 203
walkee is starting off with a positive reputation.
Hi, I have the same intake/carb combination on my 400.

Yes, I agree with your describtion of the adjustments you did - so far.

Guess it´s not the distributor it´s the carb makes the mpg go down.
Have you checked the colour of the spark plugs ? Are they light brown
or more white or black. Plugs colour is an easy indicator to check the engine is running too lean or too rich.

Watch for the vacuum hose, you must connect it to the ported vacuum at the carb ( passenger side ). The drivers side port delivers full vacuum from accelerating over idle. Had this issue by myself and ever wondered why had no power over 2k rpm ....

You wrote the engine had 20 BTDC .... didn`t you have backfires ?
Check your air/fuel ratio, the best A/F ratio should be between 14 and 17.
Start adjusting the carb carefully with both crews, not more than 1/2 a turn on both crews than check again. Screw in = leanm screw out = rich.
The edelbrock homepage has a carb manual for download, this may help.

Remember : lean does not mean high mpg, the right carb-setup depends on your whole engine setup. You´ve changed something by adjusting the dizzy and timing, now it looks like you have to adjust some other components.
__________________
Tom
1960 F100 /400/C6
Reply With Quote
Old 02-09-2010, 04:39 AM
Reply

Go Back   Ford Truck Enthusiasts Forums > Performance, Engines & Troubleshooting > 335 Series- 5.8/351M, 6.6/400, 351 Cleveland

Tags
351m, adjustments, advance, btdc, carb, degrees, elderbrock, engine, f150, ford, pinging, porting, spec, specs, timing, vacuum

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



All times are GMT -5. The time now is 09:36 AM.


Powered by vBulletin® Version 3.7.5
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