Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - 1977 Chevy K20: Engine Suffers from Hesitation/Power Loss When In Drive
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Old 02-21-2012, 01:39 PM
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Hey Chet,
Originally Posted by T-bucket23
First let me say I agree that you need to get the timing correct. Second I will say I dont think it is your issue. In past posts you have said that you took it for a ride and sometimes it is fine.
Everything you have posted points to fuel, choke or carburation issues.
In one post you said the choke goes to half way closed then went back to 3/4. This is not right.

I would recommend as your next test you disconnect the choke and wire it open, warm it up and take it for a spin.

Note if the engine is cold it will be hard to start with the choke wide open and you may need to baby the accelerator for a few minutes to keep it running.
If it still runs poorly you have eliminated one thing, the choke. Then move on from there.
I will try this the next time I fire it up.


I did make a video of the truck starting and warming up for nine minutes today.

In Case You Can't See the Video:
- Engine starts on the third try.

- Truck is allowed to warm up on its own for the first 8 minutes.

- Choke-pull off closes and the choke plate open up at the 00:15 mark.

- Camera is panned towards the firewall at the 3:45 mark. Light smoke can be seen coming out from the rear exhaust manifold area. Oil seems to be back there. Might explain the fouled plugs on the passenger side?

- Idle cam falls at 8:00 mark when the accelerator pedal is pressed for the first time.

- Coolant starts leaking out of the upper radiator hose at the 8:04 mark. One of the bolts for the water neck wasn't tightened down all the way. Tightened up afterwards.

I then took the truck for a spin on a couple of nearby streets. The video is made from inside the truck and hopefully you can hear the engine hissing and hesitating when gas is given. The video is chopped up to shorten the time.

In Case You Can't See the Video:

- Truck ran under its own power at approximately 20 mph, except when gas given at : 00:14, 00:16, 00:20, 1:23, 1:26, 1:54, and 1:56. Hissing can be heard.

- Truck was parked and revved a three times from 2:20 to 2:43. Engine revved fine, except for the unnoticeable hesitation at 2,500 rpm.

- Truck allowed to run under its own power again. Gas given at 2:51 and 2:59. Hissing heard.

- Truck parked again. Revved at 3:09 mark. Engine revved with the hesitation at 2,500 rpm mark.

Last edited by lt1silverhawk; 02-21-2012 at 01:47 PM.
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