Slant Six Forum :: 390 Carb problem

: Hello,
: I am new to this site and have a question for
: you gear heads. My problem is
: that I have gone radical with the engine:
: rebuilt engine and put a 260 cam in it, new
: dual headers/manifold from cliffords, holley
: 390 4 bbl., msd ignition. With the new carb,
: the engine seems to really boog down when i
: get on it. I have replaced the jets, power
: valve, discharge noozle. I am about to
: replace the pump cam in hopes to solve my
: problem. Any help would really help!

: Boy, this sounds a lot like the question elam
: just asked. You may want to read through the
: following message thread for some ideas.
:
: <A HREF="http://www.slantsix.org/cgi-bin/webbbs_ ... ad=8987</A>
: My guess is that your new cam has knocked the
: effective cylinder pressure way down. Did
: you increase compression during the rebuild?
: What is the cranking psi? What happens when you
: run the carb. with the secondaries
: disconnected?
: DD

:
: Boy, this sounds a lot like the question elam
: just asked. You may want to read through the
: following message thread for some ideas.
:
: <A HREF="http://www.slantsix.org/cgi-bin/webbbs_config.pl?read=8987">http://www.slantsix.org/cgi-bin/webbbs_config.pl?read=8987</A>
: My guess is that your new cam has knocked the
: effective cylinder pressure way down. Did
: you increase compression during the rebuild?
: What is the cranking psi? What happens when you
: run the carb. with the secondaries
: disconnected?
: DD

Author:	EKVSaxMan [ Wed Jun 19, 2002 11:58 am ]
Post subject:	390 Carb problem
Hello, I am new to this site and have a question for you gear heads. I know that I dont have a slant six, but I do have a Chevy 250 six in a 68 Camaro(ALL original). My problem is that I have gone radical with the engine: rebuilt engine and put a 260 cam in it, new dual headers/manifold from cliffords, holley 390 4 bbl., msd ignition. With the new carb, the engine seems to really boog down when i get on it. I have replaced the jets, power valve, discharge noozle. I am about to replace the pump cam in hopes to solve my problem. Any help would really help! EKVSaxMan@comcast.net

Author:	Doc. [ Wed Jun 19, 2002 2:20 pm ]
Post subject:	Re: 390 Carb problem
Quote: : Hello, : I am new to this site and have a question for : you gear heads. My problem is : that I have gone radical with the engine: : rebuilt engine and put a 260 cam in it, new : dual headers/manifold from cliffords, holley : 390 4 bbl., msd ignition. With the new carb, : the engine seems to really boog down when i : get on it. I have replaced the jets, power : valve, discharge noozle. I am about to : replace the pump cam in hopes to solve my : problem. Any help would really help! Boy, this sounds a lot like the question elam just asked. You may want to read through the following message thread for some ideas. <A HREF="http://www.slantsix.org/cgi-bin/webbbs_config.pl?read=8987">http://www.slantsix.org/cgi-bin/webbbs_config.pl?read=8987</A> My guess is that your new cam has knocked the effective cylinder pressure way down. Did you increase compression during the rebuild? What is the cranking psi? What happens when you run the carb. with the secondaries disconnected? DD

Author:	elam [ Thu Jun 20, 2002 10:10 am ]
Post subject:	Re: 390 Carb problem
Quote: : Boy, this sounds a lot like the question elam : just asked. You may want to read through the : following message thread for some ideas. : : <A HREF="http://www.slantsix.org/cgi-bin/webbbs_ ... ad=8987</A> : My guess is that your new cam has knocked the : effective cylinder pressure way down. Did : you increase compression during the rebuild? : What is the cranking psi? What happens when you : run the carb. with the secondaries : disconnected? : DD Hang on a few days and I will have the new midwest converter I ordered today. I think that will fix the 390 problem. At least put it in a place I can fix it with timing and carb adjustments. I'll come back and let you know. melam@nxs.net

Author:	richard [ Tue Jul 02, 2002 7:37 am ]
Post subject:	Re: 390 Carb problem
there is a spring kit to adjust the vacuum operated secondaries fo lower vacuum engines. Mine is doing the same thing. Quote: : : Boy, this sounds a lot like the question elam : just asked. You may want to read through the : following message thread for some ideas. : : <A HREF="http://www.slantsix.org/cgi-bin/webbbs_config.pl?read=8987">http://www.slantsix.org/cgi-bin/webbbs_config.pl?read=8987</A> : My guess is that your new cam has knocked the : effective cylinder pressure way down. Did : you increase compression during the rebuild? : What is the cranking psi? What happens when you : run the carb. with the secondaries : disconnected? : DD

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