FuzzayD Posted September 14, 2009 Share Posted September 14, 2009 I have been told by a few of me wee friends that if you wan't more power out of a carb'd car that you can "Do the secondary's" on the carb but none of them can explain to me what that entails. I have thought maybe larger jets or maybe a secondary fuel circuit but i recently bought a wreck off one of these wee friends who told me it's had the secondary's done. The only thing i can see is that the choke butterfly is linked to the throttle butterfly. Any one know anything about secondary's? Are they real? Are my wee friends using a term out of context? Does linking the choke to the throttle make it go hard? Quote Link to comment Share on other sites More sharing options...
Testament Posted September 14, 2009 Share Posted September 14, 2009 if the only information they can give you is that you should "do the secondarys bro" then they probably don't really know what the f' they're talking about. My guess though would be that they probably mean something like taking a 2 barrel progressive opening carb with vacuum operated secondarys and altering the linkages to give it mechanical operated secondarys. This may give the car a more sporty feel/sound (less smooth response) but wont really make it any faster and wont make it any more powerful at all(provided the carb was working correctly to being with). re jetting and changing choke sizes may give you more power but it depends on what else has been done to the engine. But thats no called "doing the secondarys", it's tuning the carb to get the most out of the engine package. So final answer is - "doing the secondarys" does squat. If the stock carb is a piece (some stock carbs are) then maybe put a suitable type of weber on it. But ultimately changing carbs/modding carbs isn't going to give a very large increase in power unless going to a 1 thottle per cylinder setup or some factory setup where the carb is a huge restriction. Quote Link to comment Share on other sites More sharing options...
bubblegoose Posted September 14, 2009 Share Posted September 14, 2009 choke butterfly is linked to the throttle butterfly. ? appaerntly this can help remove flat spots on some cars but ive never tryed it "Do the secondary's" is that some kind of dance? Quote Link to comment Share on other sites More sharing options...
forced Posted September 14, 2009 Share Posted September 14, 2009 It pays to never listen to your mates unless they can proove that they know something. In this case they're just muppets, but then the same goes for mechanics too, even at the best of times. Steve Quote Link to comment Share on other sites More sharing options...
Spencer Posted September 14, 2009 Share Posted September 14, 2009 Yea as above best thing you could do is get a carb kit and rebuild that spare carb you have and make sure its running well to factory specs, bigger jets or stuffing with the secondary's isn't going to make it run better or 'go harder' Go to a second hand book store and try find an old book about carbs/engine maintenance, got one when I was starting out with cars. Learn about all the different circuits in a carb and what engine/air speeds/conditions they apply to. Then shut your mates up by knowing what your talking about Quote Link to comment Share on other sites More sharing options...
tortron Posted September 15, 2009 Share Posted September 15, 2009 what car is this hopefully its running S.U's in which case you can buy some jets off rusty Quote Link to comment Share on other sites More sharing options...
Unclejake Posted September 15, 2009 Share Posted September 15, 2009 We used to "do the secondarys" on 4.2 litre petrol Landcruisers. Where "do the secondarys" = wire them closed in an attempt to save fuel. It didn't help much. /Spam Quote Link to comment Share on other sites More sharing options...
cletus Posted September 15, 2009 Share Posted September 15, 2009 have seen a couple of rotary engined veehicles with carb secondarys modified to open mechanically, thus giving the illusion of more power due to the fact there is a big flat spot and then surge. = wanky. the reason a holley carb with mechanical secondaries is known as a double pumper is because it has two accelerator pumps to stop the lean condition when the second throttles are opened Quote Link to comment Share on other sites More sharing options...
FuzzayD Posted September 15, 2009 Author Share Posted September 15, 2009 Thanks guys. Yeah i thought it sounded like turd talk but I'm no pro just needed to know for piece of mind. ^^ Quote Link to comment Share on other sites More sharing options...
sholdowa Posted September 15, 2009 Share Posted September 15, 2009 Well, I sort of disagree a bit. Simple things like removing the choke flap from the 2nd venturi can allow for more air flow = more power. But really, you want to increase the choke size and rejet. The thinking behind it is that the stock carb design is restricted by fuel consumption rather than outright power, so you can improve one at the loss of the other. Quote Link to comment Share on other sites More sharing options...
forced Posted September 15, 2009 Share Posted September 15, 2009 Most carbys don't have a choke flap on the secondary. In fact I can't think of one that does, because there's no need . Steve Quote Link to comment Share on other sites More sharing options...
My name is Russell Posted September 16, 2009 Share Posted September 16, 2009 Doesn't a 32/36? Quote Link to comment Share on other sites More sharing options...
Gaz Posted September 16, 2009 Share Posted September 16, 2009 yes Quote Link to comment Share on other sites More sharing options...
Burntrubber Posted September 16, 2009 Share Posted September 16, 2009 Changing vacume secondarys to mechanical makes a differance in low down power it effects smoothness and fuel consumption though. If you time them to early it will have quite the flat spot need to get it just right.. Quote Link to comment Share on other sites More sharing options...
CaMpylobacter Posted September 16, 2009 Share Posted September 16, 2009 vac secondarys ftw. cable tied open choke flaps ftw Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.