Re: LA 360 - Hits a wall at 4,000rpm
[Re: GoodysGotaCuda]
#2555619
09/27/18 05:33 PM
09/27/18 05:33 PM
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Joined: Jul 2011
Posts: 972 Chicago
PurpleBeeper
super stock
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super stock
Joined: Jul 2011
Posts: 972
Chicago
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Geez.....looking at the video, it is starting to look like a cam timing or distributor timing issue to me. Have you taken a timing light to it to see exactly what your timing is doing at various rpm's? I'd try that first (easiest). 2nd, if the timing all looked good, I think I'd pull the timing cover and see what I see. It's not that major of a job.
OK, just to be clear.... is this a relatively new build or recent overhaul OR did the engine run great for years & now all of a sudden it won't rev past 4 grand?
70 Roadrunner convt. street car
440+6, NOS, 4-spd, SS springs
'96 Mustang GT convt. street car
'04 4.6 SOHC, NOS, auto, lowered
"Officer, that button is for short on-ramps"
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Re: LA 360 - Hits a wall at 4,000rpm
[Re: GoodysGotaCuda]
#2555653
09/27/18 07:20 PM
09/27/18 07:20 PM
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Joined: Sep 2014
Posts: 4,457 Washington
madscientist
master
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master
Joined: Sep 2014
Posts: 4,457
Washington
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I will eyeball the rockers but will likely go ahead and pull the timing cover. The more it sinks in the more I think it’s in there wrong. I just am crossing my fingers that valves didn’t kiss pistons.
Rookie move! Thanks all, I’ll keep you posted You may get lucky as most of this mostly stock stuff has piston to valve clearance that can be measured with a yardstick. Hopefully you get lucky. Again, this is why you always degree the cam. Not only can there be errors in machining and tolerance stack up but there can be human error. If you degree the cam you eliminate all but the human error and reduce the human error to almost zero. We can never eliminate human error. We are...human after all.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: LA 360 - Hits a wall at 4,000rpm
[Re: madscientist]
#2555714
09/27/18 09:55 PM
09/27/18 09:55 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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Are you sure you dont wanna check "rockover" as opposed to pulling the dampener/pump/tcover/new gaskets? (that's alot of work!) You know I ain't sure how a way advanced cam would affect compression but just me (I'm lazy) I would pull the plugs & do a compression test & even just (1) cyl would tell something (assuming a compression test will be way off if the cam is way off). I ain't a cam guy but if my thinking/math is right with a 23/46 tooth SB timing set, one tooth adv would adv the cam 15.7 degrees in addition to the built in adv (from LCA). Holler how it turns out, this is the weirdest one I have seen in a long time! I cant wait...
live every 24 hour block of time like it's your last day on earth
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Re: LA 360 - Hits a wall at 4,000rpm - video added
[Re: GoodysGotaCuda]
#2555739
09/27/18 11:05 PM
09/27/18 11:05 PM
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Joined: Jun 2005
Posts: 5,126 Western Md.
skicker
"The Champ"
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"The Champ"
Joined: Jun 2005
Posts: 5,126
Western Md.
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All this talk reminded me that this happened to me in 1991. I had a short block assembled at what should have been a respectable shop...Was charged on the invoice for degreeing in the cam and everything... This was a dirt track 340 motor with a 284-484 Mopar Performance camshaft. There were 3 marks on the timing gears the triangle...the square and the dot. They lined up the dots but the dot on the outside of the crank gear wasn't stamped well. After two weeks of no RPM's...Changing intakes and carbs and distributor I pulled the timing cover... Instead of the crank keyway being at about 2:00 and the cam at 4:00 and the dots aligning the cam was at 4:00 and the crank was at 12:00. The dots were aligned but it was the wrong dot on the crank gear. When I pulled the "X" heads after finding this it had lightly hit the valves... I remember that motor had a very small sweet spot where it would start easy and if the timing was off just a little it wouldn't start... Worst thing about getting old is the things you forget...
...FAFO...
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Re: LA 360 - Hits a wall at 4,000rpm - video added
[Re: skicker]
#2555774
09/27/18 11:46 PM
09/27/18 11:46 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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What Madscientist said made me think of something to try: bump the dampener to TDC on the tab & look at the dist rotor & if it is at #1 then pull the pass VC & see if the #6 rockers are even & if rotor is at #6 then pull the dr VC & see if the #1 cyls' rockers are even. Alot of chain slop might mess this up, but just a thought.
live every 24 hour block of time like it's your last day on earth
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Re: LA 360 - Hits a wall at 4,000rpm
[Re: fastmark]
#2555857
09/28/18 08:36 AM
09/28/18 08:36 AM
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Joined: Nov 2004
Posts: 25,050 Texas
GoodysGotaCuda
OP
5.7L Hemi, 6spd
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OP
5.7L Hemi, 6spd
Joined: Nov 2004
Posts: 25,050
Texas
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You are up late. This must really be digging at you, huh ? This stuff can really suck...You don't want to let them WIN... Yep. With two little kids I'm stuck working on things late at night, unfortunately this vehicle stays outside, so that adds to the fun. I’ve been building motors for a long time. I did not always have the tools to degree a cam. I have run across it twice in my lifetime where the cam gears were not marked correctly. One motor was off 8 degrees and the other was off 16. These were factory assembled motors that had been running. Both were 340s and both were dogs. You must always degree your cams. Statistically another gear set would almost guarantee me to not have that problem, if it were the case. I'm only partially kidding, however I need to see what it takes to degree a cam, with the head on, and the intake on, in the truck....
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Re: LA 360 - Hits a wall at 4,000rpm
[Re: GoodysGotaCuda]
#2555889
09/28/18 10:37 AM
09/28/18 10:37 AM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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There is a simple way to degree a cam using feeler gauges.
Essentially when the cam is installed "straight up" the intake and exhaust lifters should be at the same height at TDC. Put a straight edge across both (sometimes you may need to substitute deep well sockets to get enough height)and measure any gap. No gap means straight up installation. If there is a gap then it's not installed straight up. How much gap and which one is low will determine advanced/retarded and how much. But I forget those details it's been a long time.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: LA 360 - Hits a wall at 4,000rpm
[Re: GoodysGotaCuda]
#2555903
09/28/18 11:12 AM
09/28/18 11:12 AM
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Joined: Oct 2004
Posts: 2,849 Connecticut
FurryStump
master
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master
Joined: Oct 2004
Posts: 2,849
Connecticut
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That tach might have a rev limiter in it, move the redline needle higher.
Last edited by FurryStump; 09/28/18 11:13 AM.
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Re: LA 360 - Hits a wall at 4,000rpm - *not cam timing*
[Re: GoodysGotaCuda]
#2555993
09/28/18 02:31 PM
09/28/18 02:31 PM
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Joined: Jan 2003
Posts: 8,082 Tulsa OK
Bad340fish
master
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master
Joined: Jan 2003
Posts: 8,082
Tulsa OK
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The AFR going lean makes me want to say ignition, coils are cheap and easy.
68 Barracuda Formula S 340
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