4bbl carb on 300
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Joined: Dec 2002
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From: Gainesville
4bbl carb on 300
I have an 86 Bronco that with the 300 ci straight 6 and I am thinking of installing an Offenhauser manifold and Holley 390. What I would like to know is how this combo has worked out for other people. The truck is primarily for use off-road, so I need nice low-range power.
Another question is this,...I am told the engine is remanufactured but it seems a little under-powered and usually diesels when you shut it off hot. It also only gets about 11 mpg on the road. It starts up pretty quickly but runs pretty choppy until has it warmed up for about 2 minutes. I bought it from a lady whose husband died and so I obviously can't get much info about what has been done in there. THe truck currently is entirely stock minus some emissions equipment. I am thinking replace the spark plugs, check the timing,...can the mixture be adjusted on this truck? Any other suggestions?
Thanks
Another question is this,...I am told the engine is remanufactured but it seems a little under-powered and usually diesels when you shut it off hot. It also only gets about 11 mpg on the road. It starts up pretty quickly but runs pretty choppy until has it warmed up for about 2 minutes. I bought it from a lady whose husband died and so I obviously can't get much info about what has been done in there. THe truck currently is entirely stock minus some emissions equipment. I am thinking replace the spark plugs, check the timing,...can the mixture be adjusted on this truck? Any other suggestions?
Thanks
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Joined: Jan 2001
Posts: 56,990
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From: Virginia
4bbl carb on 300
usually diesels when you shut it off hot
Most of the time this is caused by the idle speed being too high. Of course if there is another problem causing it to run rough, somebody may have raised the idle speed to keep it running. Your general check-up/tune-up thing you are going to do is a good start.
Most of the time this is caused by the idle speed being too high. Of course if there is another problem causing it to run rough, somebody may have raised the idle speed to keep it running. Your general check-up/tune-up thing you are going to do is a good start.
Posting Guru
Joined: Jul 2002
Posts: 1,785
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From: Paola, KS
4bbl carb on 300
The 300 I-6 is a very good running motor with a 4bbl carb and intake and it will definetly wake it up if you install a header and the same time. The stock manifold in pretty restrictive.
If you want some more out of it put a RV cam in it.
If you want some more out of it put a RV cam in it.
Hotshot
Joined: Oct 2002
Posts: 18,488
Likes: 22
From: The Big, Oregon
4bbl carb on 300
I would recommend against the 4BBL and cam. With EFI duals, the Offey intake, and a 350 2BBL, these engines wake up very nicely, and gain more low end torque. You wind up pushing 260-280lbs at 2000rpm, vs. the same at 2600+rpm. You sacrifice a little top end, but mine set up like that still pulls to 5500 rpm, and quite nicely too. Plus, you need to run a spacer with the 4BBL, or you wind up having to mount it backwards and run a long throttle cable. The spacer almost totally defeats the dual-plane design of this manifold.
Jared
Jared
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