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Loss of power
http://classiccamaroclub.mfatw.com/viewtopic.php?f=9&t=4922		 Page 1 of 2
Author:  Gearjammer [Wed Apr 20, 2016 8:28 pm ]
Post subject:  Loss of power
My 77 305 has been getting driven nightly as the weathers been good.....twice it has started to lose power under acceleration in top gear(turbo 350).....tonight I thought it was going to conk out...I'm not caning it....was doing around 40 accelerating and it stated to fail...now I know there could be many reasons.....I've looked a nd checked plug leadsto make sure they're on properly....and the battery con's look fine...so any suggestions would be great.
Author:  78 Camaro [Thu Apr 21, 2016 9:47 am ]
Post subject:  Re: Loss of power
Bugger that's not good to hear!
There are people on here far more skilled than me, so i'll throw in a few basic suggestions to get started with.
Timing - are you able to check to see if it's kept timing, sometimes it can slip?
Vacuum leak - i'm not sure how to test this, but i've heard about using a smoke machine and then i guess you look for areas where the smoke gets sucked into the engine. This could be at vacuum line connections or gaskets.
That's all i can think of right now, hope it helps!
Author:  Gearjammer [Thu Apr 21, 2016 5:10 pm ]
Post subject:  Re: Loss of power
Thanks...I don't have the kit do do either of these things at the mo......I had a similar prib years ago with a Vauxhall nova...turned out to be pin holes in the butterfly valve in the carb...my brake pressure variestoo...and someone had mentioned the vacuum....it starts brightly and runs fine apart from this odd occasional glitch.
Author:  chevy-stu [Thu Apr 21, 2016 6:04 pm ]
Post subject:  Re: Loss of power
I reckon vaccum is a good place to start if brake pressure is varying ... There'll be pipes from carb/inlet manifold to brake servo, and distributor, so check these are on ok and not rotten..
Author:  3rdGenmalc [Thu Apr 21, 2016 8:55 pm ]
Post subject:  Re: Loss of power
What carb have you got, does it idle okay ?
Author:  Gearjammer [Thu Apr 21, 2016 10:00 pm ]
Post subject:  Re: Loss of power
It has a misfire....I started it from cold tonight and could hear it from the exhaust....I don't know what carb it has...it has an edelbrock manifold....I'll look more closely at those pipes....at a glance they don't look obviously damaged as in split but I guess I maybe should take them off.....is it a cheapish fix to to replace those...it'll be a case of process of elimination I guess?
Author:  3rdGenmalc [Fri Apr 22, 2016 8:18 am ]
Post subject:  Re: Loss of power
With the motor idling, spray carb cleaner around all the gasket joints, manifold to heads, carb to manifold etc., use a can with the thin tube to get in close.
You still did'nt tell me what carb you have.
Do you have a load of vacuum pipes etc., if so spray those too.
Don't lather up the areas with cleaner just enough, if the idle changes you've found the leak.
There could be an internal leak too, manifold to heads.
You could start off by tightening the manifold to head bolts, snug them down.
Author:  Gearjammer [Fri Apr 22, 2016 6:59 pm ]
Post subject:  Re: Loss of power
Thanks.....I had to check for identify on the carb...its a Rochester Quadrajet....I've attached pics of the pipes which all look relatively new....the engine was rebuilt so the dealer told me although dates unknown....the only pipe that lookssuss is the engine to air filter one as it has a rubber sleeve around it as you'll see and felt sloppy fit as I gently pulled it...maybe if it was rebuilt it needs head bolts retorqued?

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Author:  3rdGenmalc [Fri Apr 22, 2016 7:58 pm ]
Post subject:  Re: Loss of power
The "engine" to air filter is your PCV and that´s correct how it is.

"does it idle okay ?"

big job to retorque the heads, valve covers off, all the rockers of too.
then you have to reset all the valves afterwards.

I must say the motor looks pretty clean.
Author:  3rdGenmalc [Fri Apr 22, 2016 8:28 pm ]
Post subject:  Re: Loss of power
Image


Bottom right on the manifold under the air cleaner, what´s the plate held down by two bolts ?
It has a pipe sticking out, looks like it needs connecting to something.......or plugging.
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