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  #16 (permalink)  
Old 08-11-2017, 05:11 AM
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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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  #17 (permalink)  
Old 08-11-2017, 07:57 AM
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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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Old 08-11-2017, 11:48 AM
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Quote:
Originally Posted by tmillz1293 View Post
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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  #19 (permalink)  
Old 08-11-2017, 02:22 PM
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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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Old 08-11-2017, 02:24 PM
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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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  #21 (permalink)  
Old 08-13-2017, 12:12 AM
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Ok, Well I'll definitely make 100 percent sure that I know where TDC is my using a more legitimate method. But, I think I know why its so far off from the mark. It looks like depending on the year of the engine the timing mark would be in different positions in reference to the keyway. So it looks like i have a balancer that it meant for an earlier 350. So the balancer fits, and is the correct diameter but is marked wrong. But we'll see when i check for TDC again.
Here is where I got that info: http://www.crankshaftcoalition.com/w..._TDC_lines_SBC

And I'm definitely going to do a compression test. My friend is coming over to help and he has a tester. And I think whoever said that the fire was caused by fire coming out of the cylinder when it was ignited, I think they are correct, based off what happened and the damage caused. But, once i get it running I'm not going to forget to post here first thing. I'm looking at my mistakes and I think this was one of those things that was a "perfect storm" if you know what I mean. A bunch of small factors basically lined up perfectly and caused a big problem.

And thank you all for the help, I'm glad I posted here you guys have helped me a lot.
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Old 08-13-2017, 08:47 AM
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If you dont have a piston stop tool, and cant find one locally, you can make one by knocking out the center of a spark plug with a punch. Then drill and tap the center for a 5/16 or 3/8th bolt. thread a nut on a long bolt first and then thread it through the spark plug. Once you get the blot positioned use the nut to tighten the bolt to the spark plug, This keeps the bolt from rocking and makes your position more accurate.

When you are doing this do not use the starter to turn the engine over, only by hand. The starter is strong enough to push the piston right through the stop.

Lastly before you attempt to start the engine again CHANGE YOUR OIL!. The fuel that is in the oil know destroys its ability to lubricate and you will ruin your new engine faster than you can believe.

I think your on the right path and i doubt there has been any internal engine damage done.
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Old 08-14-2017, 03:53 PM
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I feel very confident that next time I fire it up it will go a lot better. I mean hell it can only get better from literally catching on fire right?

Now don't get me wrong I'll change the oil, because why risk a $1500 rebuild over 40 bucks. But WHY are you guys so sure there is definitely gas in it? I only know of gas in oil from bad rings. Just curious, Thanks!
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Old 08-14-2017, 05:04 PM
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Quote:
Originally Posted by tmillz1293 View Post
I feel very confident that next time I fire it up it will go a lot better. I mean hell it can only get better from literally catching on fire right?

Now don't get me wrong I'll change the oil, because why risk a $1500 rebuild over 40 bucks. But WHY are you guys so sure there is definitely gas in it? I only know of gas in oil from bad rings. Just curious, Thanks!
When compression occurs without ignition the gas liquefies and is forced past the rings. The rings don't seal very tight in a cold non-running engine. They and the pistons need to get to running clearances but having achieved that they really need the pressures developed by combustion in the power cycle to seal. The other three cycles they are quite loose. So cranking and fueling with more of the same and no ignition pushes a lot of fuel into the crankcase.

Following the burn off I don't know if you need to change the oil, but you have got to get this timed correctly, if you need confidence that the cam is timed correctly now is a good time to look, far better than another fire or explosion. To repeat with both gear marks pointing to each other with the crank at noon and the cam gear at 6 the TDC mark should be on TDC firing cylinder 6 you need them pointing at each other to see the timing is correct. When both timing marks are at noon the timing mark is also at TDC and the engine is ready to fire cylinder 1. But in this position it is a bit difficult to tell if the gears are synched. Frankly at this point I'd chase these possibilities before trying to light it off again. To add to you fun this wouldn't be the first miss marked timing set. So I suppose going through the find true TDC drill with a positive stop and degree wheel would be worth the time. Directions are on the web.

Bogie
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Old 08-16-2017, 08:21 PM
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UPDATE: Well on ya'll's advice I changed the oil and damn. I am glad I did. There was absolutely gas in it. For sure. But no horrible slivers of metal or anything as far as i saw. So That's good. The motor is ready to go. I'm trying to locally source a piston stop but worse case scenario, I'll just buy one spark plug to sacrifice to a home job. but I really would rather not fab one.

Anyway, my motor is ready to roll and my retired master mechanic friend is coming by tomorrow to give me a hand. So hopefully everything goes well. I'll let everyone know.

Thanks for the valuable advice guys!
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  #26 (permalink)  
Old 08-16-2017, 08:46 PM
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Be sure you remove the rocker arms before you turn the motor over with a piston stop installed, otherwise valve damage may occur.
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Old 08-16-2017, 09:19 PM
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Here's another way of finding TDC without chance of valve or piston damage;
Attached Files
File Type: pdf S.B.C. HOW TO VERIFY T.D.C..pdf (801.0 KB, 12 views)
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Old 08-16-2017, 10:22 PM
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Good call on taking the rockers off with a piston stop installed, probably not a big deal with a mild cam, but if Murphy lives in your garage like he does in mine cant hurt. Also pull all of the plugs so you are not having to work against compression in other cylinders, you want the crank to spin as easy as possible. I could make a case for pulling all of the rockers so you are not pushing against valve spring pressure.

If you do that reset the rockers by just taking up the slack until the push rod is not moving up and down. Do not use the spin the push rod until there is drag method you stand a high chance of rockers being over tightened. Once the engine is running and the cam broken in you can always go back and readjust the valves, a little loose will not hurt anything in the beginning.

Once the valves are readjusted then you can set the motor up for timing the distributor.

Did you every do a compression test? Just wondering the results if you have.
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Old 08-17-2017, 10:21 PM
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UPDATE: Success!

Hello all, well we got the cam broken in today without much trouble. However, there appears to be some sort of vacuum issue with the carb. But thats not a big deal. Basically I had way too much advance like I thought and there were some other factors that contributed but that was the main one. But she ran and it's good to go, from here I'll button up the drive train, do a full oil change. And I should be on my merry way. However, let me tell you, next time I get a motor rebuilt... I'm getting a roller cam set and timing gears!! Hahaha no more break in night mare.

Thank you all for the help, it was invaluable. I'll be coming back here if I get into a pickle again. So probably tomorrow haha
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Old 08-18-2017, 04:37 AM
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Quote:
Originally Posted by tmillz1293 View Post
Hello all, well we got the cam broken in today without much trouble. However, there appears to be some sort of vacuum issue with the carb. But thats not a big deal. Basically I had way too much advance like I thought and there were some other factors that contributed but that was the main one. But she ran and it's good to go, from here I'll button up the drive train, do a full oil change. And I should be on my merry way. However, let me tell you, next time I get a motor rebuilt... I'm getting a roller cam set and timing gears!! Hahaha no more break in night mare.

Thank you all for the help, it was invaluable. I'll be coming back here if I get into a pickle again. So probably tomorrow haha
If the vacuum advance was hooked up to a full manifold source during breakin, then you could see as much of 50 degrees of advance. It won't hurt anything as long as no detonation is present. I would STRONGLY recommend getting your carb and distributor dialed in with the vacuum advance unhooked and the hose plugged.

Let us know what you think the vacuum issue is or describe what it's doing. Post a picture or two of your carb, distributor and vacuum lines.
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