SBC won't fire/run!

[AFRIKANZ]

Put sbc into my 40, was running ok, little missfire & rich.

Now, won't start! There is fuel & have spark. Twiddled with carb (holley) and have both rich/lean screws out 2 turns.

What should I be looking at for fault?

 

[cmiller114]

Timing?

 

[Shawn Russell]

A little rich? How rich? Did you foul your plugs?

Shawn

 

[AFRIKANZ]

Timming- assume ok as it was running ok previous

Took out plugs, they're not wet............

 

[zags]

an engine needs three things to run: compression, spark an fuel. The easiest thing to check first is fuel. Look down the front two holes of the carb and work the throttle to wide open. There should be two small jets of fuel from the accelerator pump. If you see fuel, the carburator has fuel in it. Next, check for spark. take off a plug wire at a spark plug. Take a screwdriver and insert it into the wire, hold it a 1/4" or so from a metal part of the engine, and have someone try to start it. A spark should jump from the screwdriver to the engine. If so, you have spark. If those 2 are O.K. you may need to check the compression.

 

[justacruiser]

Do you have a points style or HEI distributor? If it's points style, check the points. I was getting a very bad 3 cylinder misfire on mine despite having fuel, spark and correct timing. I checked the points and found that they were so burned that they had a hole in the contacts! Instead of wasting money on the points and a dwell meter, I ditched them and put a new HEI in with a new set of properly gapped plugs and good wires. Starts on the first crank now, with no gas given, and runs smoother than my 2007 truck does and has WAY more power than it had before. The others here are right, it can be only one of the three problems. You need a compression test done as well if you have spark and fuel, that could cause a problem.

 

[AFRIKANZ]

It's running HEI

What should the plug gap be for a 305?

 

[justacruiser]

I'm running mine at .045, whereas a points style calls for .035 I believe. With an HEI, you could have a bad control module in the distributor. That would cause a misfire in it too. You'd need a special tool to tell if it's bad or not though, that's the prob.

 

[RMC73FJ40]

zags is on it......spark, fuel, timing............should be able to put a timing light on it and see if you're close there.......unless no spark. Since it's HEI make sure you have power on the distributor terminal that's not marked TACH. I have had a problem before with stuck floats on a Holley.....

You could manually check timing by pulling #1 plug.....move to TDC and check timing mark....may take 2 rotations of crank......when harmonic balancer and piston are at TDC....see where rotor button is pointing.

When checking for spark....you may want to get away from spark plug hole if its full of fuel.

 

[zags]

Failed control modules are very common on HEI distributers. If you have 12V to the distributer and no spark, put a module in it. I would spend the extra $ for an AC Delco one.

 

[pbgbottle]

i would check the module also . i used to carry a spare in my tool box. until i picked up a MSD box from a buddy ,hope the MSD box never packs it in .

...

 

[zags]

i would check the module also . i used to carry a spare in my tool box. until i picked up a MSD box from a buddy ,hope the MSD box never packs it in .

...

MSD boxes do fail pretty frequently. be sure you know how to bypass it on the trail if you need to. I set up my electrical connectors so I could just unplug the MSD and plug in to the harness on my rock buggy. I needed do just that in the middle of a competition.

 

[AFRIKANZ]

Will start by checking timming & then check hei as per instructions i downloaded frtom net

Thanks guys. Fingers crossed

 

[AFRIKANZ]

Been away on holiday............... problem still persists even with new module :-(

 

[FishNinJay]

Did you ever check the timing? i don't see any reply on that.
Prob know this already, (but I didn't). just put on the induc pick-up on the wire, as close as possible to the #1 plug. Also, if no timing gun available, you could always do it "ol'school" and just try adjusting the dizzy to see if the knock goes away. Never done this, but I've heard it works. Prob gap is ok.. I don't think it's that crucial with HEI, right?

Just reread top post, this is an SBC install? Could you have mixed up the firing order?

 

[Elbert]

Do you have fuel at the carb? and Spark at the plugs? Assumption is that engine ran before so no issue with timing chain. Did you remove the distributor during the engine swap?

 

[TEXASgirl]

Had the exact same problem. Ran, then just wouldn't crank. No spark to the plugs. Cleaned up the contacts inside the HEI cap and Replaced the module in HEI...nothing. Replaced the coil inside of the distributor and it fired right up first try. Did it 3 more times and it fired right up every time....knock on wood.

Good luck

 

[Elbert]

Had the exact same problem. Ran, then just wouldn't crank. No spark to the plugs. Cleaned up the contacts inside the HEI cap and Replaced the module in HEI...nothing. Replaced the coil inside of the distributor and it fired right up first try. Did it 3 more times and it fired right up every time....knock on wood.

Good luck

agree I would just go buy a new dist cap, rotor button and coil...just for fun..to rule those out.

 

[Elbert]

what exactly is happening when you try to start?

does engine simple turn over and not fire at all.... does it pop and spit but never really fire?...

Does it sound like it wants to start?

If you removed the distributor you may have a timeing issue.

 

[loosechange]

I had a broken spark plug connector that went to from my coil to the dist. ( im using a Msd sys...I had Intermitant running at best...try to not to test this out by pulling that cable off as your friend cranks engine..Its gonna wake you in a bad way.

Engine cranks will not start. Fuel? Spark? and air etc.. If you got fuel is it getting to the dist at the right time. I read earlier post that it ran for a bit...very strange. I say maybe the little peice of Metal under the dist cap is not making contact with the rotor...Your getting poiwer to the Fist not to the rotor it sounds like.