Advice on engine vacuum...or lack of..
I am breaking the stride of the Hammond barn news 'cause I am frustrated.....
My engine won't suck!!!!
Here is the situation.
My rebuilt 261 was started by Dan.. the Wizard Man....
since then I have tweak the timing and it starts easy...but.. after all efforts I can only get about 9 inches of vacuum at idle and ONLY with the choke on full.....
Mixture screw is at 1 1/2...... further adjustments + or - made no difference.....
Comment by Dan was that I might be overcarburated..... yeah like having too much sex.....
I was running at the time Dan was here a NOS 7015011 Rochester B carb listed as suitable for a 261. In fact the same carburator on Stew's 261 works fine.
I checked the fuel pump for sufficient delivery of fuel..... squirts like the devil..... I checked every vacuum line and even removed the PCV in case it allowed too much air into the manifold... no changes.
Then I changed the carburator for the original 261 Rochester B carb that I rebuilt and got the same no idle response.
Now I can get a reasonable idle speed with a very steady 9 inch vacuum but only with full the choke on... with that setting it runs reasonably good.... racing the engine raises the vacuum to the 15 - 18 inch easily.... but again only with the choke on.
I do have a small ( I think) leak in the front intake manifold at port 1&2..... engine races in RPM when I squirt raw gas with a syringe near that port and an exhaust gas leak underneath at the rear port 3&4......
After engine was hot the bolts were retightened from center outward as recommended.
New one piece special thick manifold gasket is ordered and on the way....
I almost seems that, without the choke on, the engine does not develope enough vacuum to run......
Help.....What did I overlook....????
BooB
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Bob Carriere....B.T.B
C15a Cab 11
Hammond, Ontario
Canada
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