I recently rebuilt the carb on my 66 L79. Everything seems to be good except for the secondaries. When the engine is idling and I start advancing the throttle, the secondaries do not open on thier own. Should they open gradually or do they open all at once? The secondary shaft rotates freely. It seems that there is not vacum to open the secondaries. Does anyone have any ideas?
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Re: C2 Carb Secondary
It's virtually impossible to 'force' the secondaries to open in the shop... You'd have to rev the engine SO hard/long that without a load on the engine, you'd be flirting with thowing a rod!
Get inside, take 'er out on the street and punch the accelerator. I guarantee you if the engine climbs above 4000 RPM, the secondaries ARE opening! -
Re: C2 Carb Secondary
Frank,
I have a '66 L79, and was wondering if the secondaries were functioning properly on mine. I recently had several postings with the same concern. Holley recommends putting a "bobby pin" on the secondary shaft lever in a position so that you can see if it has moved from them opening. Is it the rpm that makes you think they're not opening, the lack of acceleration or both? I also got a tip on the discussion to put a dab of grease on the secondeary shaft lever where it will be smeared if they fully open. I'm still trying to decide if mine are fully opening. Regarding Jack's response, I'll see if my rpm goes past 4000 next time I drive it.Comment
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Re: C2 Carb Secondary
Rob, I will try the suggestions you and Jack have suggested and get back to you. Where did you get the tip from Holley? I have one of thier books.
Thanks for the help,
FrankComment
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Re: C2 Carb Secondary
Frank,
Their tech dept. suggested the "bobby pin". Tomorrow I'm going to use a thin wire on the secondary plate lever to hold them closed and see If feel the difference in performance. That should let me know for sure if they've been opening properly or not.Comment
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just put a little dab of grease
where the secondary linkage wide open throttle stop on the vacuum diaphram side hits the throttle base plate and check to see if there it a mark in the grease dab after a full throttle run. this will tell you if the secondary is opening all the way because some secondary spring setups will not allow full opening.Comment
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Re: C2 Carb Secondary
Rob:
You will not see the secondaries open by "flooring" the throttle, because they work on vacuum, and the engine must be under load to cause them to open.There are three ways that I know of, to actually check whether or not your secondaries are opening fully, and I particularly like the third method, which is by far the most fun:
1. Try the above mentioned "dab of grease" method.
2. Put the car on a chassis dyno, and observe the secondaries with the engine loaded.
3. This method requires a friend, and a length of stout rope. After removing the air cleaner and hood of the vehicle, have a (trusted) friend lash you to the passenger side fender using the stout rope. A series of half hitches, a bowline-on-a-bight, and possibly a sheepshank are required to shorten up on the stout rope. Position your face within clear view of the carburetor, but far enough away to protect your eyebrows in case of backfire. Have your friend now drive the car briskly on the highway, and observe the secondaries opening and closing. They should be full open at WOT with engine approaching "redline".
Here is a link to Holley's website:
http://www.holley.com
Here is a link to other useful engine/vehicle information:
I hope this helps.
JoeComment
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Re: C2 Carb Secondary
Joe,
I tried method #3....my friend driving the car got a speeding ticket...and I was given one while still lashed to the fender for not wearing a seat belt..Comment
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