Re: why would a stock street hemi have only 5in vacuum ?
[Re: ogopogo]
#1533326
11/14/13 08:56 PM
11/14/13 08:56 PM
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Joined: Jan 2003
Posts: 21,123 Niles , Ohio
therocks
oh wait.but hey.lets see.oh yeah.
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oh wait.but hey.lets see.oh yeah.
Joined: Jan 2003
Posts: 21,123
Niles , Ohio
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With pushrods being almost 1/4 inch too long the valves might be bent a bit.It dosent take much to have them not seating completley.That compression is low also.Thats a lot of extra lift.Rocky
Chrysler Firepower
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Re: why would a stock street hemi have only 5in vacuum ?
[Re: pacifica]
#1533328
11/15/13 12:22 AM
11/15/13 12:22 AM
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Joined: Jan 2003
Posts: 42,714 Spokane Washington
ScottSmith_Harms
Mr Wizzard
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Mr Wizzard
Joined: Jan 2003
Posts: 42,714
Spokane Washington
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Quote:
and over until they don't take any more movement with a good inch lb. torque wrench, same thing after running the motor to warm it up, retighten those bolts many times until they stop tightening
I agree, just be sure to use an INCH LB wrench, I believe the spec is only 12 inch lbs? It isn't much that's for sure! You don't want to break off a chunk of cylinder head by over torqueing the intake bolts.
I also agree on the low vacuum failing to pull down the metering rods, no vacuum will = pig rich with those carbs.
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Re: why would a stock street hemi have only 5in vacuum ?
[Re: ScottSmith_Harms]
#1533329
11/15/13 12:54 AM
11/15/13 12:54 AM
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Joined: Aug 2003
Posts: 43,748 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,748
Bend,OR USA
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Quote:
Quote:
and over until they don't take any more movement with a good inch lb. torque wrench, same thing after running the motor to warm it up, retighten those bolts many times until they stop tightening
I agree, just be sure to use an INCH LB wrench, I believe the spec is only 12 inch lbs? It isn't much that's for sure! You don't want to break off a chunk of cylinder head by over torqueing the intake bolts.
I also agree on the low vacuum failing to pull down the metering rods, no vacuum will = pig rich with those carbs.
The FSM calls for 72 inch lbs(6 ft. lbs) on the center four intake bolts on both sides and 48 inch lbs(4 ft. lbs.) on the rest of the outer bolts and studs
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: why would a stock street hemi have only 5in vacuum ?
[Re: SNK-EYZ]
#1533332
11/15/13 12:51 PM
11/15/13 12:51 PM
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Joined: Mar 2006
Posts: 9,910 Eighty Four, PA
B G Racing
master
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master
Joined: Mar 2006
Posts: 9,910
Eighty Four, PA
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Don't over think the situation,start with the obivious things that can cause the problem. a.check all carb areas for vacume leaks and mixture settings. b.check intake for the same(tighten by hand,side to side and repeat till the bolts refuse to turn) use a small 1/4 ratch and socket. c.Check all electrical for voltage and strong spark and firing order. d.Check distributer for solid timing results.Set timing at 35* at 3000 RPM and no fluctuation at lower RPMs. e.Check valve settings f.If everything checks out,look to cam timing. We have seen bad fuel cause issues also.Cam design,cam timing,distributer timing,valve timing and compression can all effect engine vacume.If you can idle the engine at low RPMs then it is usually not a vacume leak unless the intake is pulling air from the crankcase and then you should see oil foul and smoke.If it shuts off at low idle the leak is above the manifold(carbs).Occasionally if you have a leak and adjust the blades open too far and uncover the idle slots the engine will siphon from the main jet wells and cause an overrich condition.
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Re: why would a stock street hemi have only 5in vacuum ?
[Re: ogopogo]
#1533338
11/17/13 02:37 PM
11/17/13 02:37 PM
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Joined: Aug 2003
Posts: 43,748 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,748
Bend,OR USA
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Quote:
so i spent the afternoon measuring lobe lift and duration,and checked degreeing of the cam and have determined I have a comp 292 in here,it appears to be out 2 degrees as well (timing events are 2 deg late) ,,specs:
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=754&sb=0
When you say late cam timing are you referring to opening and closing or te lobe seperation angle? If the cam has the intake lobe installed at max lift at 110 degrees after top dead center move it so it is at 104 to 106 before top dead center In other words if the cam is opening the intake lifters two degree later(closer to top dead center) than on the cam card move it forward (away from top dead center) to open sooner 6 to 8 degrees to help it have more bottome end I've never had any type of Mopar V8 motor like having the cam timing late, on the dyno or at the track Having the cam retarded will kill the bottom end dramatically Try moving it before replacing it That grind is not that big, trust me on that Hemiroid motor need an love more air to make more power
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: why would a stock street hemi have only 5in vacuum ?
[Re: racerhog]
#1533345
11/17/13 07:07 PM
11/17/13 07:07 PM
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Joined: Jan 2005
Posts: 2,540 Milwaukee WI
TRENDZ
master
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master
Joined: Jan 2005
Posts: 2,540
Milwaukee WI
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You say it's running rich, and you said the rpms climb with the booster vacuum line open. It's to rich. the engine wont run well if its blackening the plugs. Find somone that knows how to tune these carbs ON THE CAR. Everything you've stated tells that the engine wants more air. Get the Air/Fuel ratio where it needs to be, change the engine oil, and maybe the leak down numbers will also improve. You are chasing a tuning problem, not a mechanical issue.
"use it 'till it breaks, replace as needed"
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