Lots of 454 Issues... - Chevelle Tech
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post #1 of 25 (permalink) Old Jun 16th, 17, 4:41 PM Thread Starter
Scott
 
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Lots of 454 Issues...

Hello All,


I am having some major problems with the 454 in my 64 Chevelle. A little background, I bought the car as a half done project, and thought the engine was actually solid and good to go. Everything else had to be done to the car, but I thought I was free of engine work. Also, I bought the car from a guys wife (she got it in a divorce) so I really don't know much about the engine, except that it is a 454, possibly bored out, with a more aggressive cam than stock (no idea what it is), Holley 650 DP, Edelbrock dual plane intake manifold, and headers. I have done some research on it by the casting numbers and it looks to have come out of a 72 era Corvette. It took a while for me to get it running, but I have gotten it to run and drive, and it seems to drive pretty smooth, but there always seemed to be a huge lack in power. With what I know about this motor, it should be blowing the doors off this car.


Here's a list of what I have done to the engine:
-Rebuilt the carb
-Adjusted the valves
-Installed a new MSD ignition system
-New Accel 8.5mm wires
-Multiple sets of new plugs
-Installed a AEM Air/Fuel Ratio gauge to help with tuning the carb
-Increased the carb jet size based on the initial A/F gauge reading


Here's a list of the issues I am having with it:
-Vacuum is all over the place. I have hooked up a gauge to multiple manifold vacuum ports and the needle is bouncing all over the place. When I say bouncing, I mean bouncing, between 2-12" Hg. It seems to smooth out a little, and go out to 15" Hg when I rev it up, but at idle it isn't even readable.
-Multiple dead cylinders. The idle is pretty rough at cold startup, I thought it might just be the cam, but the other day I used my infrared thermometer and read the temp on the header tubes while it was running. Most were reading pretty close (cant exactly remember the value, but around 270-290 I think), but then a few of them were around 130, much lower than the others. I then pulled the plug wires while it was running on #1, nothing happened. I think the other cylinders that seemed dead were #4, #5, and #7 possibly more, nothing happened to the idle when those were pulled too. I know I have spark to all the cylinders because I hooked up my timing light to all of them, and it triggered. Could this be an issue with the carb, half of it not working properly due to the dual plane intake feeding different cylinders?
-Exhaust popping bad around 3k RPM. I think this has to do with the dead cylinders dumping too much fuel into the exhaust once the secondaries open and it is igniting in the exhaust.


My question is what kind of problem does this seem like and what's the best way to start investigating? I have a lot of experience with cars, but not too much with old carbed BBCs, I am learning as much as I can, and am enjoying it, but a lot of the research I have done has lead me to many different possible problems. Could it be a massive vacuum leak somewhere, rounded off cam, burnt/bent valves, bad valve guides, fuel issue in the carb with the dual plane intake? How can I investigate some possible "easy" solutions with the engine still in the car, and not having to take it all apart?


Any help is greatly appreciated!


Thank You,
Scott
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post #2 of 25 (permalink) Old Jun 16th, 17, 6:37 PM
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Chris
 
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Re: Lots of 454 Issues...

Try perusing this link.Also,what are the head casting numbers?
Vac Visual: Quick Guide to Vacuum Gauge Readings - OnAllCylinders

GenVI 454,Autogear M-22W,Moser 12 w/3.42s


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http://www.chevelles.com/forums/142-...esto-67-a.html
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post #3 of 25 (permalink) Old Jun 16th, 17, 7:17 PM
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Re: Lots of 454 Issues...

start at the beginning. make sure the battery is up, pull all the plugs, run a compression check. Look at all those plugs to see that they have a decent gap. it'd be nice if all the cylinders are at least 150 and plus or minus 5-10 lbs. bring it up on TDC #1 by using the finger over the spark plug hole to feel the compression. follow the #1 plug wire to the dist cap, mark which tower it is with a sharpie. mark the dist body right below the that tower. pull the cap to see if the rotor is pointed to that mark on the dist body. if it's not you're going to need to re-drop the dist until it is. I would work it till the rotor physically points at #! cylinder. Make sure there's a gasket on the dist and that it is properly engaged in the oil pump drive which allows it seat completely on the manifold. Install the plugs, using brake clean to clean any that are oily or wet. when you've got the dist in properly installed the plug wires starting at #1 going clockwise 18436572. be careful about mixing up 4 and 8, 6 and 4 and 5 and 7. 5 and 7 are always the most popular for getting crossed. if there's a vacuum advance urn the dist till it points at #4 and #6.

make sure the gas in the tank, lines and carb is fresh, not over a year old. If needed drain it install 5 gals of new fresh premium. At this point if you haven't skipped any steps it should start up and run more or less normally. If it doesn't post back here with what happens.

Did I mention not skipping any steps?
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post #4 of 25 (permalink) Old Jun 16th, 17, 7:19 PM
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Re: Lots of 454 Issues...

Hey Tom

You're sposta be werkin on mah stearin bocks

..........................................
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post #5 of 25 (permalink) Old Jun 16th, 17, 7:20 PM
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rick
 
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Re: Lots of 454 Issues...

What's your timing?

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post #6 of 25 (permalink) Old Jun 16th, 17, 7:25 PM
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Tom Terrific II
 
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Re: Lots of 454 Issues...

ignore the AEM gauge till you get it on the road. They're pretty much useless at idle or if there a misfire condition.

Tom Terrific or Terrible Tom, depending on the phase of the moon, passing cosmic rays or other factors not fully understood except by my wife.
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post #7 of 25 (permalink) Old Jun 16th, 17, 7:27 PM
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Tom Terrific II
 
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Re: Lots of 454 Issues...

don't use any platinum or other fancy plugs, just regular old plugs will be fine.

Tom Terrific or Terrible Tom, depending on the phase of the moon, passing cosmic rays or other factors not fully understood except by my wife.
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post #8 of 25 (permalink) Old Jun 16th, 17, 7:41 PM
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Re: Lots of 454 Issues...

You say you adjusted the valves. What did you set them to? Since you dont know what cam is in there how do you know you got the adjustment right? Bouncing vacuum gauge leads to valve spring hence the valve adjustment question.

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post #9 of 25 (permalink) Old Jun 16th, 17, 7:43 PM
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Tom
 
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Re: Lots of 454 Issues...

Are you sure you didn't wipe out the cam? Did the other guy have it running? If no or unknown, did you break in the cam? What oil is in it? Should be something with high zinc. It's easy to kill a flat tappet cam on modern oils. When you adjusted the valve were a bunch loose? I'd pull the valve covers and see how much the rockers are moving.
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post #10 of 25 (permalink) Old Jun 17th, 17, 5:39 PM
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Re: Lots of 454 Issues...

Quote:
Originally Posted by dream66 View Post
Hey Tom

You're sposta be werkin on mah stearin bocks

I is or I wuz or im gonna Real Soon Now.

Soon as I get this Muncie finished up, your box is next on the bench.
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post #11 of 25 (permalink) Old Jun 17th, 17, 6:06 PM
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Re: Lots of 454 Issues...

Quote:
Originally Posted by Tom Mobley View Post
I is or I wuz or im gonna Real Soon Now.

Soon as I get this Muncie finished up, your box is next on the bench.
Lmao eye iz eye wuz eye gonna...perfect..

I'm the Haught guy...
haughty is the nic, not the attitude....
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post #12 of 25 (permalink) Old Jun 17th, 17, 7:12 PM
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Re: Lots of 454 Issues...

The cold cylinders is a sign of either a wiped cam or broken valve springs or it could be a bad collapsed lifter. Maybe pull valve cover and rotate engine see if rocker arms move (or move as much as good cylinders) on the cold cylinders.
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post #13 of 25 (permalink) Old Jun 18th, 17, 1:06 AM
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Daron
 
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Re: Lots of 454 Issues...

I would think the bouncing vacuum gauge would mean at least 1 lobe on the cam is wiped. That's what my issue was.


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post #14 of 25 (permalink) Old Jun 18th, 17, 11:00 AM Thread Starter
Scott
 
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Re: Lots of 454 Issues...

Thanks for all the advice guys, appreciate it! Ill try to address all the comments so far...

Timing - 18* initial, 19* mechanical advance, all in by 3000
Plugs - I've used both AC Delco and Autolite, both just your standard plug, nothing fancy. Ive gapped them to .045, which I have heard should work just fine with the MSD ignition
Distributor - I have it installed correctly, it points at #1 when its at top dead center, and it is fully seated with a gasket. The timing mark lines up perfectly on the balancer when the rotor is pointing at #1 @ TDC too.
Cam - I will be the first to admit I may have wiped the cam out myself, I changed the oil right away when I got the car, not knowing how old it was, I put in just standard Valvoline 5W-30, don't know the zinc content of that... Once I did get it running I did let it idle a lot while I was fiddling with it, which I also read is not good for a new cam...
Valves - I adjusted them with the engine warm, I loosened the rockers a bit, and then spun the pushrod as I tightened the rocker down until I felt a change in resistance. Then I gave it 1/4 more turn and then moved onto the next one. It did seem to quiet down the engine quite a bit. *Note* The first time I adjusted the valves I went way too tight, I mean pretty damn tight, would that have hurt the cam/valves/valve springs when trying to start it?

Next steps I'm going to try today:
-Remove and check plugs
-Compression test
-Remove carb and investigate carb & intake manifold to make sure there isn't something weird going on with the dual plane intake starving the one set of cylinders
-Double check plug wires and make sure they're going to the correct cylinder
-Remove valve covers and measure how much the rockers are moving on the dead cylinders vs the good ones

Ill report back with what I find!

Thanks,
Scott
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post #15 of 25 (permalink) Old Jun 18th, 17, 12:54 PM
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Re: Lots of 454 Issues...

What about that power wire that feeds the dist? Don't you run a different wire from a known 12v source?

New oil is cheaper than new parts
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