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Old 05-20-2009, 01:49 PM
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Vortec heads on an old block, fine tuning help

I finally got the Vortec heads working, it was a pain. Needed a new starter, I was out on a few teeth when I dropped the HEI back in. Idles really well. Exhaust sounds different too.....bigger exhaust valves? here nor there

When accelerating I notice a studder from 1500-3500 on WOT. I have an Edelbrock performer 600 CFM with offroad needles and seats. Last night I tried to richen it up, seemed to help a little, however, not entirely. It is set at 8 BTDC.

Should I adjust timing a bit? Richen it up again? Check spark plugs? SWITCH TO TBI!!!!

thanks
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Old 05-20-2009, 05:53 PM
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I wouldn't go TBI

Edelbrock carbs tend to be notoriously lean from the factory. I would look there first, especially because you mentioned that richening it helped some. I might also (depending on the cam) try to get the initial timing up out of the basement. More like 10-14 initial is more in the range of most combos.
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Old 05-21-2009, 08:49 PM
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the saga continues

I advanced the timing to 8 and it ran wonderfully for about 15 minutes, then it started to start to sputter and cough. I continued to run it and it started to hiccup? burp out of the carb. From the cabin it almost sounds like an exhaust leak. Once I took of the air cleaner I could see that I was getting some back discharge up through the carb.

To make sure I did this right, when I timed it, the mark on the balancer was below the timing marks, I reset the dizzy/timing so it came up past the marks to 8. Is this correct? I advanced it right?

any help as always appreciated.
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Old 05-21-2009, 08:56 PM
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Quote:
Originally Posted by ryankalel
I advanced the timing to 8 and it ran wonderfully for about 15 minutes, then it started to start to sputter and cough. I continued to run it and it started to hiccup? burp out of the carb. From the cabin it almost sounds like an exhaust leak. Once I took of the air cleaner I could see that I was getting some back discharge up through the carb.

To make sure I did this right, when I timed it, the mark on the balancer was below the timing marks, I reset the dizzy/timing so it came up past the marks to 8. Is this correct? I advanced it right?

any help as always appreciated.
No, you moved it to 8* ATDC AfterTopDeadCenter. You need to be before the 0/TDC or center mark at 8-10 BTDC BeforeTopDeadCenter.
You have the timing Retarded 8*.
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Old 05-21-2009, 09:08 PM
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Quote:
Originally Posted by SSedan64
No, you moved it to 8* ATDC AfterTopDeadCenter. You need to be before the 0/TDC or center mark at 8-10 BTDC BeforeTopDeadCenter.
You have the timing Retarded 8*.
Ok, that is fixed. Still having the burping almost clanging noise still.I wonder if I have a rocker arm that is out of adjustment....
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Old 05-21-2009, 09:33 PM
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Quote:
Originally Posted by ryankalel
Ok, that is fixed. Still having the burping almost clanging noise still.I wonder if I have a rocker arm that is out of adjustment....
try changing the step up springs in the carburetor.
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Old 05-21-2009, 09:41 PM
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Quote:
Originally Posted by SSedan64
No, you moved it to 8* ATDC AfterTopDeadCenter. You need to be before the 0/TDC or center mark at 8-10 BTDC BeforeTopDeadCenter.
You have the timing Retarded 8*.
I went out again to look at the timing and I think that I do have it adjusted correctly. Just to the engine side of the marks, of where I set it, it says BEFORE.
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Old 05-21-2009, 09:47 PM
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Quote:
Originally Posted by ryankalel
I went out again to look at the timing and I think that I do have it adjusted correctly. Just to the engine side of the marks, of where I set it, it says BEFORE.
Sounds like you have it right.
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Old 05-21-2009, 09:50 PM
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Is it possible that if I don't have a valve adjusted right that it gas could come back up the carb?
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Old 05-22-2009, 12:17 AM
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Timing and carb looked fine.

I pulled of the right side valve cover and the #7 exhaust rocker was off of the valve. I spun the engine around until I knew that it had opened and closed and the same of the intake, tightened it up to zero lash plus 1/2 turn. Started it up and could still here some rattling. I checked and now the intake on #7 was loose.....Tightened it up to zero lash plus half a turn. Going to bed now, to tired to dick with it anymore.

I have a set of arm ball and nuts for the rocker arms, not very impressed with them. I have already had a few rockers come loose.

Are poly's any better?
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Old 05-22-2009, 07:02 AM
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Quote:
Originally Posted by ryankalel
Are poly's any better?
They work, as will NEW self-locking rocker arm nuts.

If you reuse the original self-locking nuts, expect them to back off. Even though they will sometimes work OK with only one on-off-on sequence, it's just not worth it IMO. They only cost a couple bucks.
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Old 05-22-2009, 08:20 AM
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Vortecs require self aligning rockers, don't they? Are you using self aligning rockers?
Also, No one has asked if this is a new cam. Almost sounds like number seven lobes are going away.
JA
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Old 05-22-2009, 08:44 AM
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Thanks for the replies

It is not a new cam, I kept the older one in there.

The rocker arm nuts I speak of I got through summit, Here

I'll see how she goes today!
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Old 05-22-2009, 08:46 AM
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Quote:
Originally Posted by johnnya
Vortecs require self aligning rockers, don't they? Are you using self aligning rockers?
Also, No one has asked if this is a new cam. Almost sounds like number seven lobes are going away.
JA
Sorry forgot to mention that I am using self aligning rockers. Before I started in on this project I made sure to ask on this forum and they told me.

weird that it would work its way off.
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Old 05-22-2009, 08:52 AM
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Quote:
Originally Posted by ryankalel
Sorry forgot to mention that I am using self aligning rockers. Before I started in on this project I made sure to ask on this forum and they told me.

weird that it would work its way off.
Another thing to check is to see if the stud is pulling out. Measure w/a straight edge across the tops of the studs- they should all be very close to the same height.

Good luck!
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