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Discussion Starter · #1 ·
Hey all. So I have a 79 camaro, 350, HEI distributor. I just finished assembling the motor and wiring and when I'm trying to start it, it just keeps cranking and seems to spit puffs of gas out of the carb. To me it sounds like the cam and crank timing is out of whack and unfortunately I didn't check it since I got it back from the engine builder as a long block. My mistake.

So i've triple checked my distributor install as well as my wires tried turning it 180 deg., I'm on the compression stroke for sure, I'm definitely getting gas, and I checked that I'm getting spark, however, the spark appears to be weak even though I'm getting a full 12 volts into the dist. Bad coil?

I'm worried that the engine shop got my internal timing wrong and really don't want to tear apart the whole front of the motor I've come way too far to have to go all the way back. Especially since its pretty unlikely that an engine shop would get timing wrong on a 350. Another bit of info on this, I did the "finger test" to assure that I was on the comp stroke, and I checked again with a scribe in the chamber to see when the piston started going down in reference to TDC mark on harm. balancer And it was at like 22 after on my timing tape when it started moving down. That cant be right.

So long story short, could the weak spark be a bad coil? and cause it not to start? And also, how can I check that my cam and crank are correctly aligned without tearing my motor apart?

Help is definitely appreciated, because I did it by the book and now I dont know what the hell is wrong, haha :confused:. Thank you!
 

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Discussion Starter · #2 ·
Update

UPDATE: Got it to run although rough, by turning the dist very hard CCW. So i figured Id move all the wires CCW one post and adjust from there. didn't run at all then. still not sure if the timing is right internally though...

Anyway, do you guys think that I'm off a tooth or two on the distributor gear?? And thats why I had to turn it CCW so much??
 

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Discussion Starter · #4 ·
I will definitely give it another go tomorrow, thanks. The harmonic balancer line being way off, is that fairly common? its the right size but its aftermarket.
 

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1st, talk to the shop that assembled it to ask them about the balancer timing mark. I would doubt they timed the crank and cam incorrectly, but anything is possible. You MUST know where #1 TDC mark is within a degree or two of accuracy with your balancer mark.

2nd, you need a timing light (dial back would be best).Hook it up to #1 wire and start spinning the distributor until you see it's advanced 10-20 degrees- it will start and idle at that point. This might involve moving the wires on the distributor or re-stabbing it as Bob mentioned.

FWIW, I fresh start every motor with a timing light (even COP) to confirm the timing is close.

Anyway, once it starts move the timing to 25-30 degrees and break in the cam. Not enough timing when idling and the manifolds will turn a bright orange.
 

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It appears the cam timing could be "180 out"

Meaning....The camshaft gear dot was installed at 6 o'clock and the crankshaft gear dot was installed at 12 o'clock and the engine builder forgot to rotate the crank one revolution before setting the valves with #1 at TDC.
 

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Timing light suggestion about is right on the mark, dont guess if it is right.

Second common issue for new motors is valve lash being too tight, not sure how you set the valves. If you used the spin the push rod technique it is very easy to over tighten the lash and when you get full oil pressure the valves hang open and no compression. I like to leave them loose for initial start up, and then adjust them with the engine running.
 

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Discussion Starter · #8 ·
would it even run if the cam was 180 out though? Ok so I'm going to pull the valve cover to find exactly where TDC is, then put my timing tape on the balancer to know where actual TDC is, try and re install the distributor. And go from there. When I insall the dist, I should install it where I ballpark want my initial timing correct? lets say I'm shooting for 12 BTDC. So I'd set the motor to 12 BTDC then install my dist with the rotor on the no. 1 post right? Because if so, I think i set it way wrong.
 

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I test drove a 1966 GTO when the timing chain and valves were installed and set 180 out. It drove terrible for about a mile before I drove it back the the shop.

Pulled the engine and the Pistons had marks on them where the valves were hitting the Pistons!
 

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Discussion Starter · #10 ·
Update

I went out and verified by the compression stroke and the valve placement that I am at TDC. My timing tape was accurate. Then I put the motor at about 12 BTDC. From there set my dist. up and marked where the rotor is and tightened the dist down and installed the cap so that the rotor and post lined up. This should get it to fire correct? id not I have to assume my internal timing is bad?
 

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would it even run if the cam was 180 out though? Ok so I'm going to pull the valve cover to find exactly where TDC is, then put my timing tape on the balancer to know where actual TDC is, try and re install the distributor. And go from there. When I insall the dist, I should install it where I ballpark want my initial timing correct? lets say I'm shooting for 12 BTDC. So I'd set the motor to 12 BTDC then install my dist with the rotor on the no. 1 post right? Because if so, I think i set it way wrong.

This goes back to Mousefink's comment; when setting the SBC up the pip marks when both are pointing in the 12 o'clock position the engine's internals are set to fire number one. The problem this causes is it's difficult to see that the marks are aligned, so builders set the marks facing each other that is crank gear at 12 o'clock and cam gear at 6 o'clock. This then is ready to fire number 6 which is half way through the firing order.


The way to get back from where you are at is to pull the left (drivers) side rocker cover off. Put a 1/2 drive ratchet with a socket big enough to engage the damper bolt's head. Then standing on the left side pull the wrench toward you while observing the rocker motion. When the intake and exhaust are both closed you should see the timing mark coming to zero. Do this a couple three times to get a feel for what you are looking at because the overlap period looks a lot the same but if you keep going once the exhaust is closed the intake will open so till you see this event a couple times it is a little difficult to be sure which stroke you're on when it appears that both valves are closed. Once your confident that number one is on firing then set your distributor up to fire number one.


There is a cheater way out of all of this by assuming the distributor is 180 out, then put the number 1 wire into the number 6 terminal and reposition the firing order from there done right the number 6 wire will be in the number 1 terminal when you get there,,,, like I've never done this. It get's you there without a lot of hassel if the distributor is 180 out.


Bogie
 

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Discussion Starter · #12 ·
Very bad news.

So, I reinstalled the dist properly and also rebuilt the carb. I had to advance the timing a lot to get it to fire. Since im doing cam break in I set the idle really high. Then all of a sudden the whole dr side of my motor literally burst into flames and it looks like It started internally then spread from the carb out. fried my spark plug wires and a few other things. this cannot simply be the distributor not being right. This is an absolute nightmare.
 

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The fire described is a gas fire - hopefully you're OK. I'd guess you had a fuel leak of some nature somewhere.

Why did you rebuild the carb???! What is it and what do you mean exactly by rebuilding it?

You set the idle really high - how high is 'really high'?

I'd guess really high was too high, you're rebuilt carb or install had a leak and you experienced a backfire through the carb. Where was the timing thorugh all of this when the idle was 'really high'?
 

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So, I reinstalled the dist properly and also rebuilt the carb. I had to advance the timing a lot to get it to fire. Since im doing cam break in I set the idle really high. Then all of a sudden the whole dr side of my motor literally burst into flames and it looks like It started internally then spread from the carb out. fried my spark plug wires and a few other things. this cannot simply be the distributor not being right. This is an absolute nightmare.


Too much cranking this puts a lot of fuel past the rings and into the oil pan. I've seen this blow the rocker covers clean off the engine. Yes it can be the distributor not being right, go back to my immediately previous post read and follow the directions. Especially the first about pulling the rocker cover and hand walking it through so you know for sure what you've got. If you can't match the conditions as I describe them then the crank and cam are off time or at least you have enough information to take the next step which would be to open up the timing cover to see what the set up is.


Hopefully neither you the vehicle or the shop have sustained damage. This is freaky but it does happen once and a while.


Bogie
 

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Discussion Starter · #15 ·
Nailhead, thank you I am ok although now am missing quite a few arm hairs. To answer your questions, I rebuilt the carb(edelbrock 1406) because I was starting to think that maybe there was something wrong with it. There were actually a few issues with it. Missing the accelerator pump spring and some other minor stuff. I threw in a rebuild kit and set it according to the guide it came with. The idle was set at roughly 2500 rpm for cam break in. As far as where the timing was, well the distributor was still pretty advanced. I unfortunately didnt have time to retard it before it caught.

Bogie, I didn't read your previous post in time before I ran it, however what you described is basically what i did. And when I found TDC after checking a few times and ensuring both valves were closed on the comp stroke I found TDC was still 22 degrees before(as in BTDC) the timing mark on the balancer. I just figured the balancer was not marked in the right place and adjusted my timing tape.

I really think my cam is off. Because I have spent a lot of time timing this thing and it should've been running perfect. Granted, I've never timed a motor but I'm not a new mechanic even though it probably sounds like it with this disastrous post. the only variable as far as I see is the cam timing. either it jumped a few teeth or was installed wrong. I'm just gonna pull my stupid timing cover soon and see whats up.

So I guess another question is, lets say my cam has been off this whole time, it ran for maybe 3-5 minutes before the fire... Do I need to be in the market for a new cam?

BTW everyone's knowledge and help is very appreciated. Thank you!
 

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My strongest recommendation before you start tearing apart someone else's work is to talk to them. If they made a mistake, then they will be standup and help you out.

I've been in your shoes (minus the fire). I would get the timing set correctly before I wanted to tear anything apart. Many here will describe a system that puts the distributor in within a couple degrees. I have to admit that I've never been able to pull that off consistently. I try to get it close and spin it as needed. I've had to move wires one location clockwise or counterclockwise many times. But the key is getting it to run smoothly as quick as possible to get the cam broke in. You can pull the distributor later and get the wires in the locations you want.

I've never had what Bogie described happen to me, but I wouldn't doubt him. Change the oil and good luck.

Jim
 

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I'm second the not tearing into the engine until you have done some more trouble shooting. I also say this as someone who has been in your shoes and has made most of these mistakes. This shouldn't take too long and should give you some answers, please let us know what you find .
1. Pull all of the plugs and set them in a piece of cardboard with the cylinders labeled. Mostly you look for differences between the cylinders, and as another piece of information with the other trouble shooting.
2. Do a compression test, if you don't have a compression tester you can usually get a loaner from the local auto parts store. If the cam is out of time there is a good chance you will see it here. More likely I think you will find that one or more cylinders have little or no compression. If you find a cylinder that has less than 50 psi of pressure, readjust the valves on that cylinder. First the INTAKE will open/close immediately followed by the EXHAUST open/close - Continue to rotate it over a bit and you are guaranteed to be on the "heel" for both valves. Adjust by pulling up on the pushrod, loosen until there is a small amount of play up and down, and leave it there. If the lifter was collapsed it will pump up when the engine fires. Re do the compression test.
I think the reason for your intake backfire was an intake valve that is hanging open and the combustion ignited the fuel in the intake manifold.
3. You said you think your TDC mark is off by 22 degrees, but I'm not sure how this can be. The balancer should have been installed with a keyway, this locks the balancer to the crankshaft. If the balancer was not installed with a key then it could be off but otherwise the mark will be TDC no matter what the cam timing is. The only other way to confirm this is with a piston stop installed through the spark plug hole. Install the stop and rotate the engine by hand until the piston hits the stop, mark the balancer, then rotate the engine the opposite direction until the piston hits the stop in the other direction, mark the balancer. TDC is half way between the two marks. You can double check the mark using this method.
4. When you go to fire the engine use a timing light to set the initial timing, I have never had any luck with the stab it in and get it close method. Have someone crank the engine with you running the timing light and adjusting the distributor, this will get it started the fastest.
5. I would change the oil since it looks like it was fuel contaminated and that will destroy a new engine very fast.

Good Luck Mike
 

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Nailhead, thank you I am ok although now am missing quite a few arm hairs. To answer your questions, I rebuilt the carb(edelbrock 1406) because I was starting to think that maybe there was something wrong with it. There were actually a few issues with it. Missing the accelerator pump spring and some other minor stuff. I threw in a rebuild kit and set it according to the guide it came with. The idle was set at roughly 2500 rpm for cam break in. As far as where the timing was, well the distributor was still pretty advanced. I unfortunately didnt have time to retard it before it caught.

Bogie, I didn't read your previous post in time before I ran it, however what you described is basically what i did. And when I found TDC after checking a few times and ensuring both valves were closed on the comp stroke I found TDC was still 22 degrees before(as in BTDC) the timing mark on the balancer. I just figured the balancer was not marked in the right place and adjusted my timing tape.

I really think my cam is off. Because I have spent a lot of time timing this thing and it should've been running perfect. Granted, I've never timed a motor but I'm not a new mechanic even though it probably sounds like it with this disastrous post. the only variable as far as I see is the cam timing. either it jumped a few teeth or was installed wrong. I'm just gonna pull my stupid timing cover soon and see whats up.

So I guess another question is, lets say my cam has been off this whole time, it ran for maybe 3-5 minutes before the fire... Do I need to be in the market for a new cam?

BTW everyone's knowledge and help is very appreciated. Thank you!
Distributor is probably off a tooth this is common this has the set up out of time by 27 degrees at the distributor.

What I left out was once you have confidence that the timing mark is correct for number one firing, then you set the distributor up so the rotor is pointed at the number 1 terminal. If you have space problems with the vacuum advance hitting the intake or a rocker cover then the distributor has to be removed and repositioned. The hidden headache is the oil pump drive also has to be moved the to the same position. This takes at least a long fairly wide blade screw driver to engage the slot in the end of its shaft. A super easy tool for doing this is a oil pump primer tool where it aligns its body as it drops into the distributor hole, then you turn the shaft till it engages the pump drive then make an estimate of how far it needs to rotate so the distributor will engage it and be positioned correctly. A primer like the one on this link works well and isn't costly.

Proform, Oil Pump Primer Shaft, Chev SB/BB - Competition Products

Bogie
 

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Your method of determining TDC, finger in the hole, scribe touching piston top, visual observation, etc is NOT GOOD ENOUGH to determine true TDC and confirm timing mark alignment. Many folks have been tripped up by this, the crank can be moved 15° from just slightly before to just slightly after TDC and piston movement is almost nothing as the piston dwells at TDC and the connecting rod goes over-center on the cranks rod journal.

Piston stop or dial indicator is the only true way's you can confirm TDC and balancer mark. Anything else is just a guess.
 

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The mile I drive the 1966 GTO when it was 180 degrees out of time did not hurt the camshaft. It was a Isky hydraulic flat tappet cam with only .440" valve lift with stock 1968 Pontiac Ram Air manual transmission valve springs with 126 lb closed and 300 lb open pressure. I used Crane cams moly break-in lube on the camshaft and that was in 1979 when motor oil still had some lead in it.

Now that would be very risky and you could ruin a camshaft.

In the sixties, I could break in a flat tappet camshaft with Lubriplate white grease. I broke in the camshaft a couple of SB Chevy engines with STP.
 
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