Can you make the secondaries, 2nd barrel, whateveritscalled open earlier in the rpm range, or under a lighter load? If so, how?
Thanks
Thanks
Can you make the 2nd Barrel open earlier?
- Thread starter FJ60Cam
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This is reason number one on a long list of reasons why I hate Aisin carbs. Flame away.
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http://www.edelbrock.com/automotive_new/misc/tech_center/install/1000/1406_manual.pdf
More info than you will ever want to know about carb's in general with good theory info. Should be able to find an aisin(or whatever carb you have) specific tuning info. I'm not sure you can make them open earlier in throttle position but you can make your primaries deliver more fuel all the time with metering rods/jets or change the step up spring to allow for a quicker transition into the "power mode" of the metering rod. If your looking for more CFM all the time might have to change to a different carb.
Disclaimer: Don't have an aisin carb and have only worked with edelbrocks and am still learning
More info than you will ever want to know about carb's in general with good theory info. Should be able to find an aisin(or whatever carb you have) specific tuning info. I'm not sure you can make them open earlier in throttle position but you can make your primaries deliver more fuel all the time with metering rods/jets or change the step up spring to allow for a quicker transition into the "power mode" of the metering rod. If your looking for more CFM all the time might have to change to a different carb.
Disclaimer: Don't have an aisin carb and have only worked with edelbrocks and am still learning
The question is what is holding it closed. Does manifold vacuum hold it closed or does ported vacuum overcome a spring in order to open it? Once you determine what is keeping it closed, you can tweek it to make it open sooner. Mine went in the garbage 14 years ago, so I can't help you with that.
Drill and tap the top of the secondary diaphram housing, then run a small vacuum line over to the vacuum advance on the dizzy and tee in there. It's ghetto but the secondaries will open immediately. Oh, and MPG will decrease. ALOT.
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OK, yeah, don't do that.
Secondary opening is controlled by the vacuum from the carb barrels and the spring.
Softer spring or increased vacuum signal will open earlier.
Think of it as a Holley 4V sawed in half.
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Aisin makes driveline parts, not carbs. ;p
What is reason number one? Because the secondary vac spring is interchangeable w/ Holley 4V?
Aisin makes driveline parts, not carbs. ;p
What is reason number one? Because the secondary vac spring is interchangeable w/ Holley 4V?
I'm into simple. Asian carbs afflicted with smog stuff are anything but that, but then again so were domestic products of that era which also make me want to empty a clip full of lead into them.
LOL !
Yeah - for those of us who cut our teeth on 80's era domestics, I know exactly what you mean...
Yeah - for those of us who cut our teeth on 80's era domestics, I know exactly what you mean...
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Smog era carbs suck. I had a 1984-ish F150 300CID here recently that ran like dog doo, had electronic timing and some kinda feedback 1-bbl carb and smog stuff all over, like an FJ60.
The fix: Called Vatozone, ordered a reman carb & dissy for a 1977-ish F100. Installed non smog parts, blocked off extra smog fittings, runs better than new. Customer even returned the cores to the store.
FWIW, the worst smog carb vehicle ever:
<drumroll>
</drumroll>
OMG, it's a tie!
1981 RX7 4bbl
and
1985 Mitsu 2.6L 2bbl
They both get to wear the Crown of Shame...
The fix: Called Vatozone, ordered a reman carb & dissy for a 1977-ish F100. Installed non smog parts, blocked off extra smog fittings, runs better than new. Customer even returned the cores to the store.
FWIW, the worst smog carb vehicle ever:
<drumroll>
</drumroll>
OMG, it's a tie!
1981 RX7 4bbl
and
1985 Mitsu 2.6L 2bbl
They both get to wear the Crown of Shame...
This thread is turning out fUnNiE !
got me LOL-ing again !
got me LOL-ing again !
Yes, actually, I can. (Thanks for asking) Just one reason why I prefer my '74 Aisan with the mechanical secondary. By bending or straightening the linkage to the secondary I can make the secondary open just about whenever I want.
I'm amazed that you seem to understand this stuff. I always went for the nuclear option; rip it off and start over. In so saying I reveal myself as the simpleton that I truely am, but hey, I can make SIMPLE carbs run like crazy.
Wasn't Chrysler buying the Mitsu 2.6 for the old K cars?
Oh wait, new category! Worst Engines Ever Sold to Another Manufacturer! I'm going with the GM 2.8 that was, despite it being a flaming turd ball, sold to both Jeep and Isuzu. I think that engine could be ordered with a rod already portruding from the block. Saves the effort of installing it in order to throw a rod.
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OK, yeah, don't do that.
Secondary opening is controlled by the vacuum from the carb barrels and the spring.
Softer spring or increased vacuum signal will open earlier.
Think of it as a Holley 4V sawed in half.
Aisin makes driveline parts, not carbs. ;p
What is reason number one? Because the secondary vac spring is interchangeable w/ Holley 4V?
So, do I need to get Holley 4V spring and cut it down?
So, do I need to get Holley 4V spring and cut it down?
Cutting a spring is a bad idea, it results in a stiffer spring for the given height and throws all your efforts out the window. If I were you, I would remove the one you have, find an auto shop that does old-school performance stuff and get a softer spring than the one you have. Place your spring against the new spring and push them together. the softer one will compress before the stiffer one. Or if you're lucky, Jim will give you the part number and save you some work.
yeah back in the hot-rod days...you could "tune" the holly secondaries (vaccum ops) buy swapping out to a different spring. Use to be a box of 5 or 6 that were color coded as I recall. Of course the real "race cars" ran the mechanical secondaries w/double pumper.
Smog Carbs suck..no matter who makes them. All of that emissions crap back in the 70's & 80's sucked.
Its amazing how much power the cars make now and how clean they run. OF course fuel injection has come along way....to include all the sensors and other crap.
Smog Carbs suck..no matter who makes them. All of that emissions crap back in the 70's & 80's sucked.
Its amazing how much power the cars make now and how clean they run. OF course fuel injection has come along way....to include all the sensors and other crap.
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A non-smog carb still has a stock secondary spring. The OP wanted to know how to adjust the secondary opening timing.
There are a bunch of secondary springs available for the Holley/Aisan vac secondary carb. Take a stock spring to the hotrod store, and compare to the holley springs. They can be rated using a small diet/postal scale and squishing the spring almost to the stack point and reading the force (weight) on the scale.