Qjet falling flat
Tech Contributor
Joined: Aug 1999
Posts: 14,377
Likes: 6,377
From: At my Bar drinking and wrenching in Lafayette Colorado
Been out of town for a few days - just got back. If you drop me an e-mail, I'll send you my phone number so you can give me a call and chat about the tuning & setup. A stumble upon acceleration is almost always a lean issue. But the lean issue can be caused by several different problems.
The Olds carb is jetted very lean in its stock configuration. The Olds engines were cammed and set up from the factory very conservatively so they would produce glass-smooth idle and a good throttle feel at low rpm. Set up like this, they produced gobs of vacuum signal to the carb. This is very different from your Vette engine, and can give you some tuning difficulties when using the Olds carb on your application. But the key is going to be to richen it up a bit so you get fuel flow during throttle transition.
Lars
V8FastCars@msn.com
The Olds carb is jetted very lean in its stock configuration. The Olds engines were cammed and set up from the factory very conservatively so they would produce glass-smooth idle and a good throttle feel at low rpm. Set up like this, they produced gobs of vacuum signal to the carb. This is very different from your Vette engine, and can give you some tuning difficulties when using the Olds carb on your application. But the key is going to be to richen it up a bit so you get fuel flow during throttle transition.
Lars
V8FastCars@msn.com
Tech Contributor
Joined: Aug 1999
Posts: 14,377
Likes: 6,377
From: At my Bar drinking and wrenching in Lafayette Colorado
Racer
Joined: Jun 2000
Posts: 473
Likes: 18
From: Holland MI
Been out of town for a few days - just got back. If you drop me an e-mail, I'll send you my phone number so you can give me a call and chat about the tuning & setup. A stumble upon acceleration is almost always a lean issue. But the lean issue can be caused by several different problems.
The Olds carb is jetted very lean in its stock configuration. The Olds engines were cammed and set up from the factory very conservatively so they would produce glass-smooth idle and a good throttle feel at low rpm. Set up like this, they produced gobs of vacuum signal to the carb. This is very different from your Vette engine, and can give you some tuning difficulties when using the Olds carb on your application. But the key is going to be to richen it up a bit so you get fuel flow during throttle transition.
Lars
V8FastCars@msn.com
The Olds carb is jetted very lean in its stock configuration. The Olds engines were cammed and set up from the factory very conservatively so they would produce glass-smooth idle and a good throttle feel at low rpm. Set up like this, they produced gobs of vacuum signal to the carb. This is very different from your Vette engine, and can give you some tuning difficulties when using the Olds carb on your application. But the key is going to be to richen it up a bit so you get fuel flow during throttle transition.
Lars
V8FastCars@msn.com
Interesting. I've been having a similar issue with my '70 Olds 350 and was trying to determine what my next step should be. I was thinking larger jets, and it seems that you've confirmed that.
Also swapping to a different accelerator pump made a huge difference. I installed one with the spring inside the cup, and it gives a much better shot of fuel than the brand new one the carb had in it from the restorer.
Patrick
