Help, my engine still wont start

[jrprokop]

I am still trying to figure out why my 1970 4280 CJ will not start. All it does is backfire out the carb, which causes the carb to catch on fire. This Engine was running good before running rough briefly and then not starting again.

I have now tried several things. I think that it is not fuel related. It will not start with a shot of starter fluid. The carb does fill with fuel from the pump. I have tried a known carb from another 428, which behaves the same way on my engine. I have tried a different coil. I have replaced the distributer with a new one with standard points - still the same! It has been getting spark to the plugs the whole time and the distributer does turn counter clockwise when I crank the engine. My next idea is to pull a valve cover and see how the valves behave when starting. I would like to do a compression test but on a 428 it is very difticult to do so. I did put in rew irridium plugs last year, but it requires removing the smog tubes. I am wondering if something went drastically wrong with the timing chain. I can only guess that the timing is drastically off.

Any help would be most appreciated.

 

[truck90278]

Has this engine been rebuilt or is it still original? Not familiar with the 428 CJ timing chain/gears, but I have had a similar problem on a 289. The gears were plastic and a number of teeth went away, add a worn timing chain allowed the cam to get significantly out of time, needless to say it wouldnt want to start, some popping etc. Certainly if you have spark and fuel with close timing it should start. with popping back thru the carb, that would strongly indicate a serious timing problem

 

[jrprokop]

Thanks for your thoughts. It was professionally rebuilt with new timing chain about 12 years ago. I'm sure it does not have plastic gears. It has seen very very few miles since then. It is original even including original pistons, except for a mild crowler cam, and rhodes hydrolic lifters.

 

[SoCalCruising]

It does sound liek timing. Have you put a timing light to it? It sounds like the timing is retarded. If it is the distributor, you can correct it. If it is the timing chain, well ....

 

[D.Hearne]

Sounds to me like it's not timed correctly, ignition timing, not cam timing. The points aren't helping anything either. First chance you get, you should replace them with any of the electronic conversion units. To set the initial timing, rotate the crank till the timing marks line up to the pointer.(align the 12*BTC mark to the pointer) Make sure you're on the compression stroke for #1. (crank rotates twice for every one revolution of the cam) Stab the distributor to where the rotor is most closely pointing at the #1 cap terminal and the vacuum advance pod is pointing straight forward. Take the #1 plug wire off the plug, stick a phillips screw driver into the wire end. Then hold it close to a good ground. Turn the ignition on, but do not start it. Slowly rotate the distributor and watch for the spark jump from the screw driver to the ground. When you see it spark, stop turning the distributor immediately. Tighten down the distributor hold down bolt, make sure you don't move the distributor body while doing this. Timing should be dead on the money when checked with a light.

 

[jrprokop]

Thanks D.Hearne, I had never heard your trick with rotating the distributer to make it spark. I understand exactly what you are saying and I will use this great tip. In my old distributer, I did have pertronix, which I will put in the new distriburer as well. I actually replaced the distributer and electronic points to see if either might be my problem. I only replace the distributer when the ignition timing pointer is at my timing mark and the roror is pointing at #1. It is seeming to me that my cam timing some how went off though.

 

[PUNISHER RACING]

sounds to me like a lack of fuel, pump the **** outta that thing and when it fires keep it coming if it erupts in flames hold it to the floor it'll suck it down( a little fire will show em whos boss)

 

[D.Hearne]

sounds to me like a lack of fuel, pump the **** outta that thing and when it fires keep it coming if it erupts in flames hold it to the floor it'll suck it down( a little fire will show em whos boss)

Great way to treat a rare car like his.

 

[D.Hearne]

Thanks D.Hearne, I had never heard your trick with rotating the distributer to make it spark. I understand exactly what you are saying and I will use this great tip. In my old distributer, I did have pertronix, which I will put in the new distriburer as well. I actually replaced the distributer and electronic points to see if either might be my problem. I only replace the distributer when the ignition timing pointer is at my timing mark and the roror is pointing at #1. It is seeming to me that my cam timing some how went off though.

Jumped timing is a possibility, but a very, very, very remote one. Far more remote than the ignition timing being off.

 

[Rusty67]

Are you sure you have the right firing order ? It sounds to me like you have the wrong firing order setup. What you are describing is exactly what my 5.0 did when I unknowingly used the wrong (old 302) firing order when I swaped mine in.

 

[D.Hearne]

Only one firing order used in the FE's---- 1 5 4 2 6 3 7 8

 

[Rusty67]

That doesn't mean has has them on in the right order =-)

 

[Edbert]

That doesn't mean has has them on in the right order =-)

Or that the distro is 180 degrees out, TDC on the exhaust stroke.

 

[raleighstang65]

I had a similar issue recently after a cam install. It was backfiring/flaming through the carb. Turns out the timing was too retarded. After I advanced it enough it started right up.

 

[Mustang1.com]

We had a customer have the same Problem. Come to find out he had Plug wire 2 & 3 backwards and 5 & 6 Backwards. It hard to see with the valve covers on.

It sound like it was going to run , Big big back fires. Good Luck

 

[PUNISHER RACING]

why not he's already spraying ether at it, we all know how good that is for gas engines!

 

[dodgestang]

This is what it looks like when you are only a few degrees off on the timing for the car. The spark fires when the intake is still open shooting a fireball out the carb which then burns off any additional fuel it can find.

If your car was running just fine before you have a timing issue. Rotate the dizzy while someone starts the car (or use a remote starter on the solenoid). Sometimes the bolt holding the dizzy in loosens up a little and when you are working under the hood if you bump it you can loose your initial timing set.

 

[D.Hearne]

why not he's already spraying ether at it, we all know how good that is for gas engines!

Ether does nothing to a gas engine. A diesel now, that's a whole nother story.

 

[OonDeanisS]

i have the exact same problem in my 351w. When i checked for TDC, the spark plug hole was bigger than my finger, so i couldnt plug it firmly, so when i felt air coming out past my finger i stuck a screwdriver in and got it to the top, then put the dizzy in with the rotor facing the #1 on my cap, then wired them 13726548. Now i have spark and fuel, but all i get is backfires thru the carb, luckily with no flames. I dont know how to time it, but hopefully its just 180* off.

 

[woodsnake]

Back fire=timing.

Is there an update or progress report on this car?