rebuilt 455 startup--muffler blew apart

Old Jul 12, 2013 | 02:09 PM
  #1  
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rebuilt 455 startup--muffler blew apart

well...here is how the engine startup went.
day 1.

I had replaced the points with a petronix igniter and a flame thrower coil. I put the #1 at TDC by hand cranking and lined up the cap with #1 moved it slightly until it sparked.

I previously primed the oil pump with a drill for a few minutes and got lot of pressure. I filled to carb bowels and tried her out. After a couple of attemps se fired up...I kept the rpm's at 2000-2500 for about 20 min. It would not idle good but I figured I would look at that on day 2.

engine never got real hot...up to around 200 I am guessing.

day 2.

I turned the idle screw up on my 670 Holly and it idled faster but would stay running.

I wanted to use my timing light....with everything connected even the vacuum line to the dist it apperaed to be 10-12 deg advance. One I unpluged the vacuum from the dist and tried to plug it the engine would stall.

With the car shut off I tried to just move the dist about 1/8 to 1/4 " CCW but the thing would not start. I moved the dist back to orgional and tried the car...it seem to back fire a little and then with one loud bang...my muffler was toast....I may try and hammer it back together.

Now discouraged....I am here and having a drink thinking about what to do next. I should have had someone try to keep the rpm up while I took of the vacuum hose and checked the timing.

I have a HEI distributor here I am considering trying. Any suggestions ?
Old Jul 12, 2013 | 02:57 PM
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Here is a suggestion, try it or don't.
Unplug the vacuum advance from any vacuum port.
Get car started and turn the timing up to the top of the tab which is likely 15.
Tighten the dist down snug.
Now plug the vacuum advance vacuum line into a port that is pulling vacuum while the engine is at idle and loses vacuum once you start giving the engine the gas.
Now idle the carb down to where you want.
You have to leave it hooked to a vacuum source at idle or it will die set up like this.
Maybe someone can explain it a little better but its the same results.
Old Jul 12, 2013 | 03:27 PM
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Is your HEI hooked to 12v not using the resistor wire? Is your firing order correct? At what point did you get a back fire?
Old Jul 12, 2013 | 04:11 PM
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"I filled (the) carb bowels..."
================
You do that thru the tailpipe?
:-)

When you turned the dist'r body CCW, surely you realize you were retarding the timing which was, according to your story, set to TDC- very late already.

Don't be discouraged, muffler is an easy fix. Not like a broken crank.
Old Jul 12, 2013 | 04:13 PM
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Originally Posted by oldcutlass
Is your HEI hooked to 12v not using the resistor wire? Is your firing order correct? At what point did you get a back fire?

I do have 12 volts there and I am not using the resistor wire. I got a back fire after it would not start...attempted to start and then went bang. The firing order is correct.

I had some help keeping the idle up when I unplugged the vacuum. I set the rpm to 1100 and timing at 8 deg as per the CSM for a 68 delta 88. It seems a lot better in the garage but subsequent starts are hard. Seems to wind but not catch. I never gapped the plugs....not sure if that is an issue or not. I also have to check the vacuum lines..I am pulling over 15 " but I am not sure if they are all in the right place.
Old Jul 12, 2013 | 04:16 PM
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Originally Posted by Octania
"I filled (the) carb bowels..."
================
You do that thru the tailpipe?
:-)

When you turned the dist'r body CCW, surely you realize you were retarding the timing which was, according to your story, set to TDC- very late already.

Don't be discouraged, muffler is an easy fix. Not like a broken crank.

no sir surely I did not...when I think about it after yes I realize what I did. I agree...its only a muffler. I just hammered it back together....sounds pretty good. I'll replace it but I have a lot of work left to do.
Old Jul 12, 2013 | 04:29 PM
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All adjustments in moderation very easy. If the engine is not responding well go the other way until it gets better. Baby steps. If it quits and dies go back to where it last ran and try it again.
Old Jul 12, 2013 | 04:57 PM
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As mentioned earlier go ahead and set your timing around 15-17 btdc @ 6-700 rpm with no vacuum advance. Which should put your total timing around 33-36 btdc @ 3000-3500 rpm. See how it idles there.
Old Jul 12, 2013 | 05:53 PM
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Originally Posted by oldcutlass
As mentioned earlier go ahead and set your timing around 15-17 btdc @ 6-700 rpm with no vacuum advance. Which should put your total timing around 33-36 btdc @ 3000-3500 rpm. See how it idles there.
I'll give it a try and see what happens...tks
Old Jul 12, 2013 | 08:14 PM
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BTW, I agree the oil pressure is top priority.

Octania was commenting on your filling your carb through it's "bowels". Hence the tailpipe remark....
Old Jul 13, 2013 | 03:23 AM
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Originally Posted by oldcutlass
BTW, I agree the oil pressure is top priority.

Octania was commenting on your filling your carb through it's "bowels". Hence the tailpipe remark....
I got his joke the distributor I have is out of a 350. Is there a difference in the 2.
Old Jul 13, 2013 | 06:33 AM
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Well....f$/). I did have firing order messed up. Certainly explains the back fire....sounding really good now but I am going to try that timing setting. I'll keep you posted. I somehow had 2-7 switched.
Old Jul 13, 2013 | 06:47 AM
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It happens, so how's it running. Better I hope.
Old Jul 13, 2013 | 07:20 AM
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Originally Posted by CLcutlass
the distributor I have is out of a 350. Is there a difference in the 2.
There are 100's of different distributor numbers
But, the differences are typically subtle and slight tailoring specs-

Pretty much ANY Olds V8 dist'r will get you running, but for optimal performance the exact right mechanical and vacuum advance is required.

You may need to put on your engineer's hat and technician's pants and alter parts until the desired results are attained. I had to do this on the HEI in the HC 403.... learn how to read mechanical and vacuum advance figures by using calipers or whatnot... etc. It's not that difficult, but a distributor machine would be a damn lot handier.
Old Jul 13, 2013 | 07:32 AM
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Originally Posted by Octania
There are 100's of different distributor numbers
But, the differences are typically subtle and slight tailoring specs-

Pretty much ANY Olds V8 dist'r will get you running, but for optimal performance the exact right mechanical and vacuum advance is required.

You may need to put on your engineer's hat and technician's pants and alter parts until the desired results are attained. I had to do this on the HEI in the HC 403.... learn how to read mechanical and vacuum advance figures by using calipers or whatnot... etc. It's not that difficult, but a distributor machine would be a damn lot handier.
thanks...I have a hei that was the 455...but I like the look of the stock unit.
Old Jul 13, 2013 | 07:35 AM
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Originally Posted by oldcutlass
It happens, so how's it running. Better I hope.

much better but I have not tried the settings you recommended yet. I also have a new holly carb on there that I have not played with yet.

live and learn
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