351W Troubles........................

BroncoMan83 · #1 (**permalink**) 02-04-2004, 09:49 AM

Engine 1983
351W
I have replaced the coil, wires, distributer cap and rotor, and the spark plugs. Removed varible venturi carb and put on a older 2 barrel carb from a 91' f-350 with a 351W. All I'm getting it 12 gauge gun shot gun blasts from the engine once every 30 15 seconds. What should I try and do? Is my timing off? It could be....... But would that prevent the engine from running NOT at all?? I was told there was a pick up coil and after taking the bottom on the distributer apart I found NO "pick-up" coil. I have NO vacum advance on the distbuter, When I bought the bronc a few hoses are plugeed here and there with screws, nothing out of the ordinary for an old vehical. What vital things am i missing? Getting good spurts of fuel from the pump when turrning the engine over. Step by step process? Thanks guys! Engine is in a Ford Bronco, Not the same make as you guys but same engine and concepts............ THANKS

Ron61 · #2 (**permalink**) 02-04-2004, 10:35 AM

Bronc,

I am not exactly sure of what distributor you have, but from what you are describing it would sound as if you have unburned fuel. Are these blasts out the exhaust pipe or back throught the carb? Also do you have any type of electronic or High Energy ignition on that motor? Does this happen when you are acclerating, backing off, or just sitting still? Was the distributor a vacuum advance type which has been plugged off? Maybe a good idea would be for you to go to your local parts store and get the manual on that year Bronco. They have them at our Franklin Auto Parts here in Redding or did the last time I was in. I looked at some of them and they didn't cost that much and showed the connections for all the hoses and everything on the motor. If your center piece in the distributor is sort of in a star shape then you most likely have an inductive distributor. If you have the optical type, they normally either work or don't work. I know this isn't going to help a lot but maybe you can give us a little more information on just what is happening now and some of the really knowledgable guys will be able to help you.

Ron

DAVID GAGNARD · #3 (**permalink**) 02-04-2004, 11:11 AM

BroncoMan;

If all your getting is a backfire every 15/30 seconds,I would think when you replaced the distributor you do not have it on #1 cylinder.. Your getting fuel,but if no fire or fire in the wrong sequence,it will not start....

Try checking and making sure #1 cylinder at TDC and see where your rotor is pointing,then go from there.... This is the easiest thing to check first.....

David

Bruce Edwards · #4 (**permalink**) 02-04-2004, 01:52 PM

One question I do not see and I did not read in your post. Did the engine run before and then die? Now when you turn it over it backfires out the tail pipe? If so how many miles on the engine? Over 100,000 ? If so sounds like the timing set has gone bad and the cam timing is now out of time.
Easy check is to run a compression test. Also as someone else said spin the engie to TDC mark on balancer and pull the cap. Is the rotor pointing at #1? You can check for number one compression by pulling #1 spark plug and checking for compression as you turn the engine BY HAND not with the starter. If the rotor is not pointing to #1 the timing has jumped.

lineslinger · #5 (**permalink**) 02-04-2004, 03:51 PM

I've had a similar problem although not on an 8cyl. Timing chain tensioner gave out and the chain was dancing around on the camshaft drive gear. I was lucky I didn't punch a hole in some pistons. It does sound like a timing problem though, regular firing at an irregular interval. Let us know when you figure it out.

BroncoMan83 · #6 (**permalink**) 02-04-2004, 05:16 PM

Blasts are coming from tail-pipes, Im pretty sure i dont have any kind of High Energy ignition, there is no vaccum advance hook up on the distributer, The engine ran...... ideled for awhile.....then i turned it off to open the garage...... went to start it again and it would not. Now i get the blasts, 150,000 on the engine, Whats my first step to go about wokring with the timing and fixing it??? Thanks

Jack21 · #7 (**permalink**) 02-04-2004, 05:21 PM

All the above are good suggestions, but a little more history on the engine on "How did we get to here" would help in where to look for the glitch. Was the engine running? Did it stop on its' own, or did you fix something before it stopped?

I suspect ignition problems. Distributor installed out of time, plug wires not on correct plug, if the engine is otherwise healthy. For a high mileage engine that just crapped out, timing chain and gearset likely needs replacement before anything elce will work.

The reluctor coil in the distributor can can go out due to corrosion and age. Better replacing it with a rebuilt rather than screwing with individual parts.

Ditto the shop manual. Manditory if you're going to try any diagnosis.

Bruce Edwards · #8 (**permalink**) 02-04-2004, 05:24 PM

If you have made sure that is your problem it is best to pull the pan and the front off the engine. The pan will be full of bits of timing gear as well as the oil pick up.
Make sure you check to be sure the chain has jumped before you dig in. Another thing you can do to check for "Play" in the timing set is move the crank back and forth and see how much free spin you get before you fell the cam start to turn. If the chain is in good shape it will not move much if the chain set is bad or going bad it can move up to and inch or more side to side.

BroncoMan83 · #9 (**permalink**) 02-04-2004, 05:34 PM

So i should drop the oil pan? Then what?

Bruce Edwards · #10 (**permalink**) 02-04-2004, 06:09 PM

You first need to be sure that you have a jumped chain. Check your engine using some of the ideas I gave you to see what you find.

Jack21 · #11 (**permalink**) 02-04-2004, 07:04 PM

Like Bruce suggested, take both valve covers off. Remove the plugs so the crank is easier to turn by hand. Using a breaker bar and (If I recall correctly, a 15/16" socket) turn the crank in one direction until you have #1 piston on TDC. Now change the direction of rotation. Any movement of the crank should result in movement of the rocker arms, and distributor rotor. 2 - 4 degrees is typical "slop" on a high mileage timing chain. Substantially more than this indicates timing chain failure, and replacement time.

Fords of this vintage had sintered iron camshaft gears. They were brittle, but not particularly prone to catastrophic failure. Chevrolets, Pontiacs, and Oldsmobiles had nylon (plastic) camshaft gears and when they let go, they were done. I'd guess at this point against timing gear/chain failure.

If, however, you pull the front of the engine apart for a timing set replacement; replace cam, lifters, and distributor gear; and timing set with high quality aftermarket (Not OEM!) steel crank/cam gears, and roller timing chain. (My personal preference is Cloyce, but Crane, CompCams, and other steel/steel roller chain equivalents will work.)

lineslinger · #12 (**permalink**) 02-06-2004, 09:58 AM

Broncoman 83,
I reread one of your posts where you spoke of "blasts" coming fom the tailpipe. To me that sounds like an air/fuel ignition taking place while an exhaust valve is open with the combustible gases somewhere in your exhaust manifold or even in the tailpipe. An open exhaust valve during ignition could mean bad sync in regards to your timing. Hope this helps.

brainsboy · #13 (**permalink**) 02-06-2004, 12:23 PM

I had the same problem once... I cant remember what it was... hmmm... let me think... oh... sorry about the wait, i remeber now, well sorta remember it was either the wires out of order or the distributor, one of the two.. I cant tell you how many times i counted my firing order 3 or 4 times then on the 5th time it was wrong. Check the firing order 1st, then your distributor, if you have points use a dwell meter, they are only about 20 bucks.

Ben

Pete Munroe · #14 (**permalink**) 02-06-2004, 08:24 PM

I do not know if the age of the engine, late 80's means it has a Ford electronic igntion or not...it could have been removed if this is an engine pulled out of another car that isn't really smog legal.

On my 67" Vette, once I broke a condensor wire...the points were new, I didn't bother to change the condensor... but still managed to bend, crack and break it's wire...the engine would start, run a few seconds, (not 15 to 30) and stall, usually with a great spit back through the card.

If it is a high mileage engine, I would not waste money on a good roller chain...get a STOCK Ford replacement..this sounds like a almost worn out grocery getter...but maybe 20 or 30K left in it.

A stock chain and gear can go 100k+...this engine do not sound to have 100k left in it.

Just make sure there are no nylon teeth like the old GM stuff...my nylon gear let loose at 90K on the Vette and trashed the engine, many years back.

Check the simple stuff...wires, rotor...!!!!!!!!! ....the carbon nub in the top of the distributor cap...it is spring loaded, I have broken them too...oops.

hang in there, Pete

TonyMadrid · #15 (**permalink**) 02-07-2004, 06:49 AM

Try the simple stuff first.

I'd check the ignition timing first. Bring #1 piston to TDC and check to be sure that the distributor rotor is pointing to the #1 terminal of the distributor cap. Then follow the firing order to be sure that the firing sequence is in the correct order. Be sure to note the direction of rotation of the rotor so you don't set the sequence in reverse order. Once doen, be sure that you have the correct wires going to the correct plugs.

If that is not the problem then perform a compression test to be certain that you have good and consistent compression. If you find low or no compression in some of the cylinders you may be out of valve timing which may have been caused by a timing chain that may have jumped a tooth. Or it could be a sticking or incorrectly adjusted valve. Hopefully, it's not more serious internal trouble.

If the valve timing is off then you have to pull the front cover and re-align the cam and crank gears. If you go that route, replace the timing chain and cam sprocket.

Remember it is important that you set both the valve timing and ignition timing correctly so the turning system will be correctly in phase with the ignition firing system.

Remember the rule of thumb for what is needed to get engines running:

1. Cranking
2. Compression
3. Fuel
4. Ignition

If any of the above are not there or are there but at the wrong times the engine will not run or may run but backfire through intake or exhaust.

Good Luck,

Tony

BroncoMan83 · #16 (**permalink**) 02-10-2004, 09:30 AM

Thanks to all of you first and foremost! Please visit http://new.witek.net/PhotoBronco.htm I am placing all the pictures I have on my web site of the bronco engine pictures. Havent been in the garage for ever. Lossing time!!! GRRR Working on getting back in there and taking out plugs and working with the timing. I also have the valve covers off.