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Are tripowers kicking in??

jims427400

Well-known member
Joined
Jun 7, 2005
Messages
763
Location
Temperance Michigan
Corvette
67 427 tripower,68 427 tripower,04 Z16, 62 340hp
Just broke in the cam on the 427/400 and it seems to be running ok BUT.. I'm not sure the tripowers are kicking in completely. On my 67 (same set up) I can feel when the 2 carbs kick in. If I wanted to test the carbs on the 68, can I just disconnect the vacuum lines feeding the front and back carbs and run it that way or is there a better way to check them?
If I do this it should just begin to hesitate when I accelorate right?
 
Did you check the throttle linkage travel? Have someone press the gas pedal (car can be off) to the floor and you can confirm that the linkage has the full travel.
 
Can you change the springs in the vacuum canisters on the secondary carbs to tailor their opening rate like on a vacuum secondary 4-barrel? Your 67 may have light springs and your 68 could have heavier springs making the secondaries open later. You should be able to rev it up at idle and look down the carbs to see if they open(hopefully it won't backfire.:))
 
I have reved it up and dont see any jets opening in secondaries. I've never seen springs available for vacuum canisters. Where can I buy them and what type do you suggest.
Linkage is set per assemby manual.
Great ideas,
Thanks
 
You can hook up a vacuum pump to the outer carbs and verify they move and don't have leaks.make sure they move and verify at what vacuum level that occurs.
 
You can get springs anywhere that sells Holley parts. The yellow spring is the lightest and will open the fastest(but could cause a bog)and there are many different colors all the way to the black spring. You could try taking the springs out of you 67 and put them in the 68 to test them.
 
Eelco still makes adjustable mechanical linkage for them and prices are still very reasonable, if you want to go that way.
Mike
 
I have reved it up and dont see any jets opening in secondaries.

You won't be able to open the end carburetors by revving up the engine in the driveway; the engine has to be under load to generate an adequate venturi vacuum signal to open them, just like a vacuum-secondary Holley 4-barrel. You need to drive it to open them.

:beer
 
You won't be able to open the end carburetors by revving up the engine in the driveway; the engine has to be under load to generate an adequate venturi vacuum signal to open them, just like a vacuum-secondary Holley 4-barrel. You need to drive it to open them.

:beer


A vacuum hand pump hooked up to the carb will create vacuum when the car is off.
 
I'm surprised you can't feel them. My 69 was originally a tri-power. at 70 MPH, drop 1 gear and jump on it and the passenger side floor mat would roll up.
 

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