Rebuilt engine won't start..

[Anonymous]

I finally got my engine put back together, and now it wont start. I have sparks. I have fuel. I simply dont know what else to check. I have adjustable rockers, but i dont know if adjusting them might make a difference in firing. Also, my timing is probably off.

Ive cranked the engine a good 5 times for a few seconds, so now im worred that my cam lube is all wiped off...

Im very discouraged at this point, so if anyone has any clue or idea what to do, help me out. Thanks guys

 

[Anonymous]

I just adjusted my rocker arms. They were too tight, now they are adjusted right. I cranked the engine, and got a backfire out the exhaust, which is better than nothing. (i guess)

 

[Anonymous]

Have you set the timing?

 

[Anonymous]

does the engine turn over? if it doesnt, you may have it on the wrong commpression stroke. i had the same problem. you need to get it on the intake stroke. the easyist way to find this is if you take out one of the spark plugs and stick your finger into the spark hole and have a friend turn the engine by the crank untill you feal that your finger is being pushed out by real fast and hard.

 

[addo]

Backfire is probably late spark timing, or a massive (obvious) vacuum leak.

Set it at #1 TDC with both valves closed, check the plugs are dry and gapped, and line up the distributor so that the rotor points neatly to #1 terminal.

Did you set the cam with a dial gauge and degree wheel?

 

[Anonymous]

Alright, thanks for the replies. Im away in Austin for college for now, so i cant do much work on the engine.

Addo, My vaccum is all connected right without any leaks to my knowlege. I'm not too sure how to set my timing when I cant even get the engine to start. I also dont have a timing light handy, but I might be able to get ahold of one. I gapped the plugs at .45. They are autolite platinums. I used an extra bit of gap because i have the Pertronix I module and 40,000 Flamethrower coil, and I was told it could bridge the extra gap. If this is faulty info, let me know.

I did not put the cam in, the engine was actually put back together at a reputable engine shop in the Houston area, so im guessing they did everything. I simply slapped the head on, regasketed everything, and dropped the engine in.

Mustang owner, the engine turns over, it just doesnt start.

Steve, i havent set the timing. Not sure how to when i cant start the engine, so if you have insight, let me know.

I guess i should have warned you guys that Im limited in knowlege. Just a poor college student trying to fix up my old mustang. Layman terms would be best. Thanks so much.

 

[Anonymous]

Backfire is probably late spark timing, or a massive (obvious) vacuum leak.

Set it at #1 TDC with both valves closed, check the plugs are dry and gapped, and line up the distributor so that the rotor points neatly to #1 terminal.

Did you set the cam with a dial gauge and degree wheel?

What he is trying to say (I think), is to turn the crank (By hand) until the #1 piston is fully up (on the compression stroke), (You can do this with your finger in the hole while somebody turns the crank with a ratchet) You will know when your at tdc on the compression stroke when your finger blows out. Then take a screwdriver and put it in the spark plug hole and turn the crank slightly until you are sure that the piston is exatly at tdc (the screwdriver will be at it s highest point). Now take note where your #1 plugwire is on your distrubuter cap and mark it on the distrubuter, remove cap and check to make sure your rotor is pointing at the mark you just made on the distrubuter, if it is off slightly loosen the distrubuter and turn the distrubuter until the rotor lines up with your mark. If it is far off pull the distrubuter out and reinstall it with the rotor lining up with your mark and of course pointing towards the front of the engine.
Good luck
Steve

ADDO, If I missed anything please post it.

 

[BIGREDRASA]

You're probably experiencing the most common problem for novice engine rebuilders/assemblers. OK, basics. This is a 4 stroke or 4 cycle engine.

1st: intake stroke, intake opens, exhaust closes, piston goes down and sucks in air/fuel mix.

2nd: compression stroke, both valves close, piston goes up, compressing mixture, and spark ignites mixture nearing Top Dead Center (TDC).

3rd: power stroke, both valves closed, burning and expanding mixture pushes piston down, thus rotating the crankshaft and making power.

4th: exhaust stroke, intake closed, exhaust valve opens, and the rising piston forces out burned gases, until it reaches TDC, when intake opens and cycle starts all over.

The distributor makes one revolution for every two that the crankshaft does. Therefore ther are 2 times that the timing mark reaches the TDC mark. The trick is to set the rotor on the distributor pointing at the #1 plug when the engine is at TDC with both valves closed on #1 cylinder. That gets you close enough so you can set timing with a light. To get even closer, find the marking on the crankshaft pulley that reads 10* BTDC (Before Top Dead Center), and set the distributor rotor pointing at #1 plug wire. That should get you running

 

[Vaughano]

A friend of a friend of mine put his distributor in 180 degress out, 'cos he was too lazy to take the rocker cover off. I (I mean he) thought he would check it before startup, but had a sleep or two and forgot. Symptoms were as you describe...

Follow the advice above and you can eliminate this as a possible problem.

Vaughano

 

[Anonymous]

Alright, got it. What about the cam? Do i need to do anything to be sure I don't lose a lobe? Since I've been trying to start it, all the lube is probably wiped off, so what should I do?

 

[Anonymous]

Alright, got it. What about the cam? Do i need to do anything to be sure I don't lose a lobe? Since I've been trying to start it, all the lube is probably wiped off, so what should I do?

As long as your oil pump was working when you were cranking it over it should be fine.
Was your timing off?

 

[BIGREDRASA]

Don't worry about the lubrication. The oil pump pumps when you crank the engine over.

 

[Anonymous]

I don't know if any of you guys caught this, but he said the machine shop put the engine together and he slapped the head on...maybe his timing chain isn't lined up right? Just a thought.

 

[weeds]

Who put in the dizzy?

I'm going with the dizzy 180 out. Experience is the best teacher.

 

[Anonymous]

I don't know if any of you guys caught this, but he said the machine shop put the engine together and he slapped the head on...maybe his timing chain isn't lined up right? Just a thought.

I am going under the assumption that the shop new what they were doing. I guess we all know what assumption can do!

 

[Anonymous]

When I rebuilt my 300 I had a similar problem, it was getting fuel, it had spark, and it wouldn't start. I checked everything, my timing was right I know the cam was in right, etc. The problem turned out to be that I had tightened down my rockers too tight and had no compression, I would say to check that, a easy way to check to see if you have compression is to remove the number one cylinder spark plug wire and spark plug, and (VERY IMPORTANT!!!) make sure you disconnect the coil from the distributor, then put your thumb over the spark plug hole and have someone crank it up for about 2 or 3 seconds(be careful, there will be a huge spark coming out of the coil), if you have compression then your hand should go flying(and you'll probably jump a mile high, also)....after I loosened my rockers it fired right up. About the timing, the easiest way to get it close(notice i say close) is to have someone crank the engine and you turn the distributor until it starts and then once running adjust it by ear so it will stay running, that will do you fine for a start up. You cant do any damage by having the timing off, itll either start, wont start, or backfire, so you can just have someone turn the key and keep adjusting the distributor...