Help..Rebuilt 289 engine will not start, backfires thru carb, Cam setting wrong? - Vintage Mustang Forums

Thread Tools
post #1 of 16 (permalink) Old 10-22-2003, 11:40 AM Thread Starter
Senior Member
Join Date: Jul 2003
Location: Vestal,New York, zip 13850
Posts: 131
I just rebuilt, rings - bearings - valve job ect, a 289 motor, installed it into the car and went to start it,
has backfires thru the carb, checked timing with a timing light while engine cranks and timing is good
so i assume that must mean the dist is in the right setting, the points appear correct so its either
the 4100 type 4bl carb that has been sitting for years is screwed up or I somehow got the
cam set up wrong I tried to line a dot on the upper timing gear with the woodruf key pointing up
on the cam shaft, but the "how to rebuild your engine book" showed the eccentric cam that
runs the fuel pump having the detent in it pointing down towards the woodruff key.
mine did not line up that way...Need some help on what to do..thanks Bob

1965 Mustang Convertible - Driver
1966 Mustang Fastback - Shelby Clone Project car
KC2DSS is offline  
Sponsored Links
post #2 of 16 (permalink) Old 10-22-2003, 11:53 AM
Sick of Corporations
dodgestang's Avatar
Join Date: Aug 2002
Location: Omnipresent
Posts: 17,126
Checked timing while cranking? That's a new one to me, I've never heard of such a thing.

Why don't you just hand rotate the dizzy while someone cranks until you can get the car to run and then try to set the timing?

1965 Fastback 410c AOD - DT
1967 Fastback 347 T5- Cruiser
1968 Fastback 408w T5 - Brute
1991 GT Hatch - Fauxbra
1996 Dodge Viper GTS
dodgestang is offline  
post #3 of 16 (permalink) Old 10-22-2003, 12:00 PM
Senior Member
RTM's Avatar
Join Date: Dec 2001
Location: Cape Coral, FL
Posts: 4,511
Did you replace the cam and if so what is the firing order of them? It could be a 302 or a 351W firing order.

1965 fastback
RTM is offline  
post #4 of 16 (permalink) Old 10-22-2003, 12:03 PM
Senior Member
Join Date: Dec 2002
Location: Palm Bay, Florida
Posts: 216
I'm with dodgestang on this one. Sounds like timing to me.

- Keith A.

'73 Convertible - 351C 2V - FMX - daily driver

"Beer is proof that God loves us and wants us to be happy." - Benjamin Franklin
Verbal is offline  
post #5 of 16 (permalink) Old 10-22-2003, 12:09 PM
Senior Member
gt350clone's Avatar
Join Date: Aug 2002
Location: KANSAS!
Posts: 5,196
Sounds like it's 180* out of time.

Swap each of the sparkplug wires at the distributor cap with the wire that's directly across from it.

Anytime you're dealing with backfires, keep a fire extinguisher handy.

Ye old 65 Clone - (Car & Tech Pages)
The young stud -
gt350clone is offline  
post #6 of 16 (permalink) Old 10-22-2003, 12:10 PM
Senior Member
sykesk's Avatar
Join Date: Aug 2000
Location: Huntsville, AL
Posts: 4,279
I'll take this one....been there, done that.

Either your distributor is 180 degrees out or your cam is a 302 late model cam. Sometime around 1983 or so, the firing order on the 302's was changed. My engine was recently rebuilt and the shop ordered the later model cam. I built the engine and once I tried to start it up, it backfired out the carb. Once I went back and saw the part number of the cam they ordered, I relized the firing order was different. I redid the plug wires to the new firing order and it started right up...

Good luck.
sykesk is offline  
post #7 of 16 (permalink) Old 10-22-2003, 12:23 PM
Posts: n/a
You didn't state that you changed the distributor, so it will be assumed that it is the old dizzy you had on the car when you tore it down. Most likely you are 180 degrees out, so take your dizzy out and turn it around. After you get the car started, you can adjust the timing. You can't do that unless the car is running. Then adjust your points, then go back and re-adjust your timingl.
post #8 of 16 (permalink) Old 10-22-2003, 12:26 PM
Moderatly Old Fart
Gene_J's Avatar
Join Date: Mar 2001
Location: Wheaton, IL
Posts: 4,428
Just went through the same thing as have many of us. Are the plug wires on the distributor counter clock wise?

Just wondering! ::
Gene_J is offline  
post #9 of 16 (permalink) Old 10-22-2003, 12:34 PM
Senior Member
Join Date: Oct 2002
Location: Houston, TX
Posts: 2,523
I'm with everyone else. Check your dizzy. Make sure you aren't 180 out. Also look at your cam specs.


Slade & The KaStang

200 CI, T5, Comp Cam 260H ,Dual Exhaust Headers, OZ 250/2V head, Holley 390 4V, DS2 Ignition w/ MSD Digital 6+, GT 5 lug disc brakes, 8" rear end, V-8 Steering

Current Project:
5.0 EFI with Megasquirt, BBK SSI intake Manifold, Trickflow TW170 AL Heads, TF Stage 1 Cam...and a quiet as hell exhaust. Want it to sound like an I6...

"It's not how fast you go...but how go you fast"
CobraSix is offline  
post #10 of 16 (permalink) Old 10-22-2003, 01:05 PM
Senior Member
JerseysBest's Avatar
Join Date: May 2003
Posts: 1,426
i went through something like that... turn the crank over and watch the rockers to be positive on which cam you have. If you have the right fireing order its, just one less variable to worry about


JerseysBest is offline  
post #11 of 16 (permalink) Old 10-22-2003, 01:15 PM
Senior Member
Join Date: Aug 2001
Location: Calgary
Posts: 399
Sorry, I'm not sure I understand how you set your cam? Did you align the the timing marks? Are you just saying the key was off compared to the book? Oh, did you replace any of the cam, timing chain or gears? Its possible the timing is off but you can verify it is the ballpark by removing the valve cover and watching the valves on #1 as you turn the engine (by hand) to TDC . No offense but you might also want to check that the valves are not set too tight and are closing completely.

65 2+2, 289 C4
65acode is offline  
post #12 of 16 (permalink) Old 10-22-2003, 01:45 PM
Senior Member
Join Date: Aug 2002
Location: Austin,Tx
Posts: 162
If you have 1 or more intake valves not closing all the way, it will back fire through the carb.

A lean condition can also cause backfire.

73 351CJ Mach 1
68DARKHORSE is offline  
post #13 of 16 (permalink) Old 10-22-2003, 02:19 PM
Just some guy
GypsyR's Avatar
Join Date: Jun 2001
Location: SC foothills, USA
Posts: 15,380
If you lined up the marks on the timing gears correctly, the position of the fuel pump eccentric makes no difference.
My vote is for something simple, like wrong firing order, or crossed spark plug wires. Easy to check and fix, best to start there.
If you timed it while cranking, I doubt the distributor timing is too far out (for you unbelievers, that's exactly why you would do this. Not to time the engine, just to make sure it's in the ballpark and NOT 180 out-a useful trick).
Of course the trouble may lie in the other stuff mentioned and more besides. Start with the simplest things and go from there. Carb trouble is possible, but considereing what you've been doing to the engine, it would about last on my list. Much more likely you didn't get something back together just right. Happens to everybody.

.... it wouldn't be the first time reality took theory and conjecture out behind the woodshed and gave them a good thrashing.
GypsyR is offline  
post #14 of 16 (permalink) Old 10-22-2003, 02:31 PM
Senior Member
gt350clone's Avatar
Join Date: Aug 2002
Location: KANSAS!
Posts: 5,196
At 180* out, the timing marks will still line up - remember, the crank turns twice as fast as the cam in a 4-cycle engine.

BTW, I've always used a timing light while crank to get things "close enough".

Ye old 65 Clone - (Car & Tech Pages)
The young stud -
gt350clone is offline  
post #15 of 16 (permalink) Old 10-22-2003, 02:39 PM
TFOB's Avatar
Join Date: Jul 2000
Location: West Michigan
Posts: 2,987
Send a message via AIM to TFOB
I am with Gene_J on This one, DO the easy thing first MAKE SURE THE WIRES ARE ON COUNTER CLOCKWISE.
I did the same thing on the 429.

I have always been among those who believed that the greatest freedom of speech was the greatest safety, because if a man is a fool, the best thing to do is to encourage him to advertise the fact by speaking.
Woodrow T. Wilson

You have a friend in Jesus!
TFOB is offline  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the Vintage Mustang Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Posting Rules  
You may post new threads
You may 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 Off

For the best viewing experience please update your browser to Google Chrome