390 intake
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Senior User
Joined: Jan 2000
Posts: 259
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From: Mount Sunapee, NH
390 intake
I have a 67 390 2bbl thats stock except the carb wich is a 500 cfm holley. I have been having a lot of problems with the engine pinging going up hills and in some cases it backfires through the carb. I found out my intake gaskets were bad by spraying carb cleaner in the intake next to the valve covers and the idle speed changed when I sprayed the carb cleaner. I replaced the intake and valve cover gaskets, re-torqued them after it was warmed up and I still have the same problem with it pinging and backfireing going up hills and a serious loss of power due to this. I sprayed the intake again with the carb cleaner at idle and the RPM's changed so I'm think the intake gaskets are shot again. Is there anything I can do to help this problem. I really need this truck to haul gravel and there are a lot of hills around here.
Thanks
Jeff
Thanks
Jeff
Post Fiend
Joined: Jan 2003
Posts: 8,600
Likes: 4
From: Iowa
390 intake
Do you mean under the carburetor intake gasket or where it bolts to the head? If you can find exactly where the leak is, pull it apart and put a little silicone sealer on both sides of the gasket on that spot.
Thread Starter
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Senior User
Joined: Jan 2000
Posts: 259
Likes: 0
From: Mount Sunapee, NH
390 intake
I sprayed right where the valve covers meet the intake. I didn't spray the carb base, but i think that is good and sealed. I am gonna try and mess around with it a little more this weekend. Any other idea would be a big help.
Jeff
Jeff
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Joined: Aug 2003
Posts: 38
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390 intake
Also check your mixture, if you are running lean it can cause that condition. You might try some high octane gas, if that reduces the pinging then retard the timing.
I find it hard to believe you are just eating up intake gaskets, and even if you somehow are, that is a symptom - not the problem.
Also like rusty70 suggested, clean the metal and put some RTV on there if you do have a leak (could just be a warped or non-flat surface) to help seal it up.
I find it hard to believe you are just eating up intake gaskets, and even if you somehow are, that is a symptom - not the problem.
Also like rusty70 suggested, clean the metal and put some RTV on there if you do have a leak (could just be a warped or non-flat surface) to help seal it up.
