273 hi-po has problems, please help....
#1374238
01/22/13 01:49 PM
01/22/13 01:49 PM
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Joined: Jul 2009
Posts: 209 Arkansas
beatupcuda
OP
enthusiast
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OP
enthusiast
Joined: Jul 2009
Posts: 209
Arkansas
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If anyone can provide me with some possible fixes for my 1966 273, Hi-Po 4 bbl. I will be happy to call evenings. The engine has probs, would prefer to discuss on phone as it will be quite lengthy.
Engine was rebuilt a few thousand miles ago (so i was told) and the guy said he installed a Hyd cam vs the original solid, but "did not replace the adj rockers." Which being a shadetree mech, I saw no prob, except harder to adjust properly. The engine has a new Edelbrock 500, on the stock intake. When you first start it, the engine rocks like it's going to come out of it's mounts, like a terrible vacumm leak, then once it begins to warm up, the rock & roll settles down, to acceptable but not smooth as it should be. it definitely has a peppy cam, the guy said a little over stock. SO, that being said, does the ratio of the solid adj rockers have anything to do with the prob. ?? It is almost like the lifters are adj too tight, but then it gets better, as it warms up. Timing on 12 before, New electronic dist & ign. carb is NEW and adjusted correctly. I have adj the rockers from 1/4 turn to 1/2 turn, never gone the full turn. Once the engine reaches temp, it runs fine, but still a lil rockin.
thanks
68 Hemi 4 speed Cuda,,,,building ?
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Re: 273 hi-po has problems, please help....
[Re: dogdays]
#1374240
01/22/13 03:45 PM
01/22/13 03:45 PM
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Joined: Jul 2009
Posts: 209 Arkansas
beatupcuda
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enthusiast
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OP
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Posts: 209
Arkansas
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Dogdays, cars runs great after warms up, but still idles a little rough still, it is NOT missing. thanks
68 Hemi 4 speed Cuda,,,,building ?
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Re: 273 hi-po has problems, please help....
[Re: beatupcuda]
#1374243
01/22/13 03:59 PM
01/22/13 03:59 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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I would say you have a carb issue... more than likely its running lean on the warm up.. I will guess its running at a lower than normal rpm when cold(just staying running) and would be a choke issue
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Re: 273 hi-po has problems, please help....
[Re: Kevins493]
#1374244
01/22/13 04:00 PM
01/22/13 04:00 PM
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Joined: Jul 2009
Posts: 209 Arkansas
beatupcuda
OP
enthusiast
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OP
enthusiast
Joined: Jul 2009
Posts: 209
Arkansas
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Have had plugs out, checked cap, wires, rockers, pushrods, timing, carb is new, disassembled anyway, adjusted perfect, choke works fine, cars runs GREAT after warmed up, but still has minor shake, not a miss, like a vacumm leak. sprayed intake & carb no change, checked all bolts..... so that's why i am here,,,,,,, Start car, idles w/choke at 12-1500, no miss no pop, nothing except shaking until warm.....
68 Hemi 4 speed Cuda,,,,building ?
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Re: 273 hi-po has problems, please help....
[Re: beatupcuda]
#1374245
01/22/13 04:09 PM
01/22/13 04:09 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Have had plugs out, checked cap, wires, rockers, pushrods, timing, carb is new, disassembled anyway, adjusted perfect, choke works fine, cars runs GREAT after warmed up, but still has minor shake, not a miss, like a vacumm leak. sprayed intake & carb no change, checked all bolts..... so that's why i am here,,,,,,, Start car, idles w/choke at 12-1500, no miss no pop, nothing except shaking until warm.....
How did you adjust the choke door when it was cold.. there is a spec(usually a drill size) and that will be a tad lean... then once the door is set then you set the cold idle rpm on the choke cam
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Re: 273 hi-po has problems, please help....
[Re: MR_P_BODY]
#1374246
01/22/13 04:09 PM
01/22/13 04:09 PM
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Joined: Aug 2003
Posts: 43,190 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,190
Bend,OR USA
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Quote:
I would say you have a carb issue... more than likely its running lean on the warm up.. I will guess its running at a lower than normal rpm when cold(just staying running) and would be a choke issue
I agree on the choke issue but I have seen the opposite with chokes, there adjusted to rich, when their adjusted lean they die and won't stay running, at least it is that way west of the big muddy OP, you say you changed the carb or it doesn't have the original carb. on it still look at the choke adjustment, even if it has the original carb. on it look at the choke adjustment When cold you should see the choke plate almost closed to the divider in between the front and back barrel, it should not be closed all the way and tight Look at it with the air cleaner off, open the throttle about a 1/4 of the way to full throttle and let it close, look at the choke plate then . Start the car up and see if the choke pull off is pulling the choke blade open some when running or if it is not doing anything Let us know what you find
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: 273 hi-po has problems, please help....
[Re: beatupcuda]
#1374247
01/22/13 05:54 PM
01/22/13 05:54 PM
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Joined: Jan 2005
Posts: 1,260 Las Vegas NV
moparmanjames
pro stock
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pro stock
Joined: Jan 2005
Posts: 1,260
Las Vegas NV
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Quote:
Have had plugs out, checked cap, wires, rockers, pushrods, timing, carb is new, disassembled anyway, adjusted perfect, choke works fine, cars runs GREAT after warmed up, but still has minor shake, not a miss, like a vacumm leak. sprayed intake & carb no change, checked all bolts..... so that's why i am here,,,,,,, Start car, idles w/choke at 12-1500, no miss no pop, nothing except shaking until warm.....
How are you adjusting the rockers? I would back them off to zero lash if not say about 10 thousanths lash and see if it stops shaking at warm up, it might just be that some of the lifters are holding the valves open during warm up while the oil is thick and then they are bleeding down when the oil warms up.
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Re: 273 hi-po has problems, please help....
[Re: MR_P_BODY]
#1374249
01/22/13 08:07 PM
01/22/13 08:07 PM
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Joined: Dec 2005
Posts: 1,495 Shelby mi.
JAKE68
pro stock
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pro stock
Joined: Dec 2005
Posts: 1,495
Shelby mi.
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That carb does not have a choke pull off. Next time when starting cold and it is running rough slightly open choke and see if it smooths out if it does lean out choke adjustment a little leaner. It is a too rich condition you are having.
JAKES AUTOMOTIVE
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Re: 273 hi-po has problems, please help....
[Re: formula S]
#1374251
01/24/13 01:12 PM
01/24/13 01:12 PM
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Joined: Jul 2009
Posts: 209 Arkansas
beatupcuda
OP
enthusiast
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OP
enthusiast
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Posts: 209
Arkansas
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My rockers can be backed off until there is gap, I adjusted the rockers in sequence of like a solid cam adjustment, zero lash then 1/4 and later 1/2 turn. the carbs choke appears to work properly, it's electric, the door/butterfly was closed to 1/8" when you start the car, the first full pedal sets the cam and the butterfly closes to within 1/8" of being fully closed, then you have to pedal and crank 3-4 times before it will run on its own. the rpms begin gradual like 800, then finally achieve 14-1500 after a minute or so, then it totally runs 90% good until you kick it down to 800 rpm idle, where it is still a lil rough, not bad, the idle mix screws are about 2 1/2-3 turns out.
68 Hemi 4 speed Cuda,,,,building ?
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Re: 273 hi-po has problems, please help....
[Re: stumpy]
#1374253
01/24/13 01:53 PM
01/24/13 01:53 PM
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Joined: Jul 2009
Posts: 209 Arkansas
beatupcuda
OP
enthusiast
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OP
enthusiast
Joined: Jul 2009
Posts: 209
Arkansas
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1 1/2 out begins to bring the idle down too low, it does not like that.
68 Hemi 4 speed Cuda,,,,building ?
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Re: 273 hi-po has problems, please help....
[Re: beatupcuda]
#1374254
01/24/13 10:09 PM
01/24/13 10:09 PM
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Joined: Jul 2003
Posts: 6,167 Maryland
GO_Fish
master
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master
Joined: Jul 2003
Posts: 6,167
Maryland
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Quote:
If anyone can provide me with some possible fixes for my 1966 273, Hi-Po 4 bbl. I will be happy to call evenings. The engine has probs, would prefer to discuss on phone as it will be quite lengthy.
Engine was rebuilt a few thousand miles ago (so i was told) and the guy said he installed a Hyd cam vs the original solid, but "did not replace the adj rockers." Which being a shadetree mech, I saw no prob, except harder to adjust properly. The engine has a new Edelbrock 500, on the stock intake. When you first start it, the engine rocks like it's going to come out of it's mounts, like a terrible vacumm leak, then once it begins to warm up, the rock & roll settles down, to acceptable but not smooth as it should be. it definitely has a peppy cam, the guy said a little over stock. SO, that being said, does the ratio of the solid adj rockers have anything to do with the prob. ?? It is almost like the lifters are adj too tight, but then it gets better, as it warms up. Timing on 12 before, New electronic dist & ign. carb is NEW and adjusted correctly. I have adj the rockers from 1/4 turn to 1/2 turn, never gone the full turn. Once the engine reaches temp, it runs fine, but still a lil rockin.
thanks
If the lifters (and cam) were changed from solid to hydro, you can use the same stock adjustable rocker arms, BUT you cannot re-use the original pushrods, as they will now be the wrong length. Find a set of pushrods out of a '70's 318 motor and try them for a test.
Scott B.
"I'm a self-made man... I started with nothing, and I still have most of it!"
68 360 rusty B'cuda 'vert (GO Fish)13.59@ 98.72 mph
69 340 GTS stock 14.18@ 95.60 mph
01 5.9L Ram 1500 Quad Cab 4x4
01 3.5L 300M 16.23@ 86.97 mph
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