|
|
Thread: How do I confirm my secondares are working?
|
jm1fd
Revvin Up
Posts: 83
|
posted March 19, 2012 03:58 PM |
|
How do I confirm my secondares are working?
How does one verify that the secondaries are opening properly on a stock Hitachi 4bbl? The truck seems slower than it should be (but my perception of "fast" is likely mis-calibrated since my daily driver has a Viper V-10 and my other car is an FD).
I tried manually taking the truck to near WOT for a brief second with the truck idling while looking down the carb throat, and I can't seem them opening, but since they're vacuum actuated, I'm not sure that is a valid test. I think I can feel a little more power come online at 5,000 RPM, but I'm just not sure.
|
|
Xp882
Redlining
Posts: 294
|
|
posted March 19, 2012 04:20 PM |
|
|
You should be able to hear them I know on my truck I could.... Time for a weber set up?
|
|
jm1fd
Revvin Up
Posts: 83
|
|
posted March 19, 2012 05:58 PM |
|
Hear them?? What do they sound like? I have the stock air cleaner...think that might be muffling the sound?
I'm going to try to stick with the stock carb for now...doesn't make sense to spend a bunch of money on a carb when my longer term objective is fuel injection.
|
|
paulsrepu
Hauling
Posts: 107
|
|
posted March 19, 2012 07:41 PM |
|
You should be able to see them open up as the tach needle swings past 4k and fuel should start spraying. They will not open fully when free revving.
You should also feel a noticable surge in power past 3500 rpm when in gear especially in 1st or 2nd.
Paul
|
|
sparky
Redlining
Posts: 299
|
|
posted March 19, 2012 07:44 PM |
|
If you dont mind revving the engine i used to check function this way.
Take off the air cleaner assembly so you can see the butterfly valves. Run the engine and quickly open the primary butterflys wide and watch for the secondaries begin to open. May need to over rev the engine a little. It may take some time. The airflow through the primary throats creats vacuum that is ported to the secondary diaphram actuator. I remember cutting down the spring on top of the diaphram to get the secondaries to open faster.
It's really easy to remove the diaphram actuator. 3 screws and a clip. Good thing to take off diapram assembly, push shaft up into the diaphram pot and plug vacuum hole. make sure the diaphram holds and isn't leaking. Also used to spray brake cleaner into hole thats feed diaphram on carburator and see if the circuit is clear back to sensing holes on primary throats. Sorry for the novel here. Used to spend alot of time dinking around with stock carbs. Went Dellorto and now Weber. Good luck.
|
|
jm1fd
Revvin Up
Posts: 83
|
|
posted March 20, 2012 04:46 AM |
|
|
Thanks guys! That's exactly the info I was looking for! I don't feel any more power around 3500 RPM...maybe, possibly I feel something a bit extra around 5000, but even then I'm not sure. Definitely can't see the secondaries doing anything when I manually yank the throttle open from idle. Sounds like I'll be taking the "lid" off the diaphragm to see what the condition is. I should probably get a rebuild kit for the whole blasted thing and go through it, but honestly I'm kinda scared. I'm a child of fuel injection. Most complex carb I've ever gone into is off a Briggs & Stratton. LOL
|
|
|
|
