76 360 timeing issue

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Feb 28, 2011 | 07:27 PM

supercabfreak

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From: High Point NC

76 360 timeing issue

ive got a 76 f350 with a 360. the issue im haveing is with the ignition timeing. ive been told that my dizzy should be set somewhere between 6-8 degrees atdc. when i set it at 8 degrees atdc it backfires under acceleration, doesnt have much power, and smells horrificly rich. to get her to run right im keeping it timed between 0tdc and 2 degrees atdc any help is much appreciated.

im running stock duraspark ign. and an autolite 4100 4bbl

Feb 28, 2011 | 08:30 PM

mustang_gt_350

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I would say you want it BTDC not AFTC. Have you tried setting it anything more advanced than 0? I would guess its a MAJOR dog with the timing set at that.

Feb 28, 2011 | 09:27 PM

Death85e

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From: Grand Junction, Colo.

You definately want to time it before top dead center not after. A good starting point is 6 degrees BTDC then tune it from there.

Mar 1, 2011 | 07:09 PM

supercabfreak

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From: High Point NC

sorry guys i goofed up i am timeing it btdc it becomes evil atdc and at 2-3 degrees btdc it is a dog but if i advance it on up to 6 degrees or so it backfires and hickups

Mar 2, 2011 | 09:34 AM

mustang_gt_350

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Is this a freshly built engine? or are you just playing with the timing?

Mar 2, 2011 | 10:07 PM

supercabfreak

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From: High Point NC

i bought this truck a lil over a year ago the PO told me it was a 390 that had been recently warmed over (obviously but the rtv mashed out around the intake )

i learned that all 360s magicly become 390's on sale day and i have every reason to beleive it IS a 360 based on vin and data decodes

the carb was rebuilt back in dec. it got new plugs, wires, dizzy cap, rotor button, new ignition module, coil, distributor and engine harness

ive had the same set of semptoms since i bought it......depending on what i do/change makes it better or worse

Mar 2, 2011 | 11:03 PM

Sleepy445FE

Fleet Mechanic

Joined: Nov 2010

Posts: 1,501

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From: Axtell, TX

well there is an easy way to measure the stroke to know what you have. Just pull a spark plug and put a dowel in and rotate crank. Make a mark at tdc and bdc on the dowel and measure the difference. 3.5" = 352/360, 3.78" = 390

doesnt change anything about your timing issue but you'll at least know your cid, ffr.

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Mar 3, 2011 | 06:51 PM

supercabfreak

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From: High Point NC

worked on it a little today and found that the vacume advance is inconsistant....thus explains random setting changes.

i removed the vacume line from the advance and timed it at 10 degress btdc, pluged the advance back it and watched the timeing advance itself close to 2 degrees............normal right? or so i was told

i took her out and drove 2-3 miles of "average" driveing some hard some easy broght it back and threw the timeing ligt on and saw that the advance wasnt advanceing the spark when i pluged it in.

re-seting the timeing fixed almost all of my problems but now i need to figure out why the vacume advance is randomly changeing at idle?

Mar 3, 2011 | 07:24 PM

#10

69cj

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Joined: Jul 2005

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From: Middle Tn.

Change the vacum advance unit. Speed shop here will then set you dist. curve up for 25 bucks.

Mar 3, 2011 | 07:42 PM

#11

arctic y block

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From: Island Southeast Alaska

Is the vac advance plugged into the carb or manifold? It should be on the carb. I would also look for vacuum leaks. The FE intake is known for vacuum leaks.

Mar 3, 2011 | 08:08 PM

#12

supercabfreak

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From: High Point NC

yes arctic the vacume advance is plugged into the carb and im pulling 15-20 inches of vacume from the advance port

Mar 3, 2011 | 08:32 PM

#13

Redmanbob

Logistics Pro

Joined: Oct 2005

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From: Mddl A MexCans

Quote:

Originally Posted by supercabfreak

i took her out and drove 2-3 miles of "average" driveing some hard some easy broght it back and threw the timeing ligt on and saw that the advance wasnt advanceing the spark when i pluged it in.

If the carb is setup correctly and idle is correct there will be no advance at idle.

Hence there should be no change when the vac line is reconnected.
As for the timing moving 8º in reverse when connecting the vac line back up. Sounds like you typoed or ? Are you disconnecting vac line while dist is loose making these timing changes and reconnecting the ac line while dist is loose? It's likely moving when you attach the hose..??? the more I read this either you are confused as to ATDC/BTDC or you have some seriously odd shiate going on. A pict or two would help all of us understand where you are at on this.
JMO