Stock SBC 350 Crate Motor valve chatter under load - Page 3 - Hot Rod Forum : Hotrodders Bulletin Board
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  #31 (permalink)  
Old 02-26-2013, 12:34 PM
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What spec cam should I be looking at. I wouldn't mind gaining some MPG and additional power is never a bad thing.
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  #32 (permalink)  
Old 02-26-2013, 07:12 PM
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Stock SBC 350 Crate Motor valve chatter under load

Check out this Summit Racing camshaft and lifter kit. It should be all you need for the street. Summit Racing SUM-K1103 - Summit Racing® Cam and Lifter Kits
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  #33 (permalink)  
Old 03-02-2013, 07:06 PM
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Heads are back from the machine shop. The owner cleaned all the oil and crud off them and checked them out. He stated they did not need a full valve job and were just fine. There was a fair amount of oil burnt on to combustion chambers, but now their all clean. Got to love dealing with honest people. He could have just did the full work and charged me but instead it only cost me $40.00. I will be installing an oil catch can inline with the pcv valve as I'm suspecting that oil is being sucked in the intake manifold and causing detonation that sounds like the valve chatter. I've also clean off the piston faces so everything should be all set.
I'll be getting an early start tomorrow and should have my motor all back together my noon.
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  #34 (permalink)  
Old 03-02-2013, 10:10 PM
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awesome thats good to know, sometimes its better to spend a couple bucks and know what your working with, you do not need to run a pcv to the carb btw, all the pcv is way for the engine to vent combustable gasses back into the engine for better fuel economy so if this is not a pollution controlled engine then replace the pcv with a valve cover breather, and make sure there is one on each valve cover, i learned this the hard way
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Old 03-03-2013, 08:46 PM
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Well it's taking longer than I expected to put my motor back together. Ran into some delays cleaning off the burnt oil/carbon off the piston faces. The good news is I was able to really take a good look at every piston wall, all the lifters, and the cam lobes all check out fine.
The heads are installed, base valve adjustment complete.
Still need to install the intake manifold, carburetor, exhaust manifold, distributor, oil catch can set the timing, and do the final valve adustment.
Looks like I'm taking a day of tomorrow to finish.
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  #36 (permalink)  
Old 03-03-2013, 10:44 PM
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Before you continue the assembly it probably wouldn't hurt to redo a pressure test on cylinders 4 and 6 to make sure they are holding and something wasn't over looked
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  #37 (permalink)  
Old 03-04-2013, 07:48 AM
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All I can hear is a bunch of rearend noise and occasionally a faint ticking noise. Is there headers or manifolds on this vehicle?

peace
Hog
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Old 03-04-2013, 10:11 AM
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Quote:
Originally Posted by Hogg View Post
All I can hear is a bunch of rearend noise and occasionally a faint ticking noise. Is there headers or manifolds on this vehicle?

peace
Hog
Sanderson QP1000 cast iron headers
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  #39 (permalink)  
Old 03-04-2013, 10:11 AM
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Quote:
Originally Posted by Northern Chevy View Post
Before you continue the assembly it probably wouldn't hurt to redo a pressure test on cylinders 4 and 6 to make sure they are holding and something wasn't over looked
Good idea, I'll do that first thing this morning.
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Old 03-04-2013, 01:16 PM
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Quick update whitle I wait for the RTV to setup. I hooked up my airline adapter to the 4 and 6 cylinders and the air leak is gone. So it looks like it was either the built up crud in the head or the old head gasket that was the air leak issue.
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  #41 (permalink)  
Old 03-04-2013, 07:23 PM
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Too bad you did not take advantage of the situation and degree and advance the .450"in.460" ex camshaft in this motor.
( If you were to degree it you would find it is retarded (115in/113ex C/L's) 114LSA (retarded by 1deg)
Moving the cam to a new 107in/121ex C/L position (7degree advanced) will wake it up and make more torque in this low cr engine. as the intake valve will close sooner.
This cam was GM's origional 1969 11:1 ccompression 350-350HP L-46 cam.
As installed it is a mis match @8.5:1cr. It need to be advanced.

If the new head gasket is thicker than the old stock head gasket the compression ratio wil now be even lower.
Should have wacked some off the heads (.050") and used a felpro shim head gasket.
I would have home ported the heads too.
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  #42 (permalink)  
Old 03-04-2013, 09:46 PM
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Quote:
Originally Posted by F-BIRD'88 View Post
Too bad you did not take advantage of the situation and degree and advance the .450"in.460" ex camshaft in this motor.
( If you were to degree it you would find it is retarded (115in/113ex C/L's) 114LSA (retarded by 1deg)
Moving the cam to a new 107in/121ex C/L position (7degree advanced) will wake it up and make more torque in this low cr engine. as the intake valve will close sooner.
This cam was GM's origional 1969 11:1 ccompression 350-350HP L-46 cam.
As installed it is a mis match @8.5:1cr. It need to be advanced.

If the new head gasket is thicker than the old stock head gasket the compression ratio wil now be even lower.
Should have wacked some off the heads (.050") and used a felpro shim head gasket.
I would have home ported the heads too.
When I had the heads off I put it to TDC and it was already set to 6 degrees advance.
Unfortunately I ran into more delays today. Got everything put together, but when I fired her up she ran for about 20 second then died. Need to trouble shoot tomorrow and do the final dial in on the timing and valves.
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  #43 (permalink)  
Old 03-04-2013, 10:01 PM
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What was at 6deg advance? Did you degree in the cam with a degree wheel and dial indicator on the lifter or....?
6deg advance based on what/ ? the .050" lifter rise open close events? or...?

What is/was the .050" (@ the lifter) intake closing point ABDC?

Do not go by the point of max lift of the cam lobes or the point of split overlap as this cam is a non symetrical cam. The intake and exhaust sides of the lobes are different and the in and ex lobe is not the same lobe.
You cannot determine the advance/retard phasing of a non symetrical cam by laying a ruler across the lifters @ TDC
or comparing the points of max lobe lift.

You need to degree the cam to determine its installed position based on the .050" (lifter rise) open close event timings.

You are primarily concerned with the measured .050" (lifter rise) intake closing point ABDC.
It should check @ 47deg ABDC @.050" and you want to move that to 38deg ABDC.

Last edited by F-BIRD'88; 03-04-2013 at 10:13 PM.
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  #44 (permalink)  
Old 03-04-2013, 10:17 PM
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I think the cam can be advanced 6 by using the dot to A on the timing chain gear set. He could have checked that visually at tdc.
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  #45 (permalink)  
Old 03-04-2013, 10:32 PM
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Quote:
Originally Posted by spinn View Post
I think the cam can be advanced 6 by using the dot to A on the timing chain gear set. He could have checked that visually at tdc.
This is supposed to be a GM 350-290hp crate motor. It should not have a multi key crank gear on it.
Never assume the multi key crank gears actually will move the cam accurately,
by the desired amount. (they don't)
You want to move the cam accurately by first determining its real installed position first. By degreeing it.
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