whoa prepare for a lot of money and work. Contrary to belief, a carb setup cost approxiamately the same as any other NA setup.
Carbs: you'll need a set of carbs. as kits are very hard to find...and when you do find them, they are grossly over-priced...you'll need to source out some good side drafts. Webbers, Mikunis and Keihin FCR's are a few. While Webbers are most common and most affordable, they lack in performance as they do not side-load very well. 4ag tuners had the most success with the latter two as both Mikuni and Keihin side-load very well. However, both come at a price...both literally and figuratively. Mikuni's are getting harder to find as the company doesn't exist...so YOU WILL be buying used ones. Keihins have proved to be the best carbs for the 4ag and are tried and true in japan. The problem: keihins are found off of motorcycles...cbr900, suzuki 1200 r (predecessor to the gsx r), and others. This means you will be essentially trying to fit and work a motorcycle carb on a car engine...tuff job. There are kits for this in japan, but they come at a dear price. Dellorotos are another brand but they fair worse than the Webbers. Don't get the wrong impression though, many use Webbers and they are probably the best bang for your buck.
You'll need to link the carbs together as they are duals or singles and you need to make all four work in perfect harmony. Pick a good size carb also...many opt for 45's on webbers as its said that 40's are too restrictive. Then comes the jets and chokes...its alot of trial and error, but you can minimise yer costsa and errors if you do ALOT of research. Check http://www.club4ag.com/faq%20and%20tech_pages/Carburators%20for%20the%204A-GE.htm pretty good article on carbs. You'll also want to invest in a mercury synchronizer and AFR gauge...and not one of those cheap, ricey autometer ones!!!! they are innacurate and will not measure your AFR properly!! get a high quality one...even an aircarft AFR or go ol' skool and get a FPR gauge and Exhaust Temp gauge and do the math. Remember to also get a good manifold.
Cams: okay so you got the carbs, now you neeed cams. Carbs are useless withought cams as you are increasing the volumetric efficiency so you need to increase your engine's breathing capability. If necessary, this means upgrading your exhaust system.
Fuel: Use stock fuel pump but you will have to make a manual relay. simple on off switch attached to the power lines that will get it to start pumping. You could also opt for a manual fuel pump (ie: vortech, holley, etc.), but i've read many that find the oem one perfect. goto club4ag to find out how to do the mod. you'll also want a FPR gauge too.
Ignition: MSD 6AL should do. you need an ignition amplifier that has the ability to adjust the ignition timing. You could also opt for a magnetic distributor. Ask Neil85ae86 about this as he has experience with carbs...myself..this is just regurgitated info.
The biggest task is converting your electronics over. All the fuel and ignition mapping that your ecu does will now rest in your hands. So you have to be prepared for a lot of tinkering and futzing.
Well, with carbs you dont have to think where to pull all the ECU wires and where to stick the box, although there are few mechanical injection units from bosch, but I've heard nothing good about them. Plus with carbs you dont have to buy an ECU unit and spend even more on that.
mmm...people belive that the lack of an ecu and wiring equates to cheaper setup. wrong. i've done the research and talked to owners and carbs are not cheap. a set of carbs wil cost anywhere from $600 - $1200 for all four. On top of that, you'll have to get jets, the linkage, manifold, air horns, cams, header, exhaust, ign. amplifier, fuel lines, etc. With all those combined the price is probably comprable if not greater than getting an ecu and quad throttles! We haven't even calcualated in dyno time or tuning time (if you do not know how to jet the carbs yourself)or if you cannot synch all four butterflys together.
Carb guys will tell you its easy to jet the carbs and get them to idle and peak perfectly. In my opinion though, its as easy as mapping your fuel and ignition with a standalone. In my case, either would be a long arduous and learnign process. If you have very little experience on TUNING cars, i suggest plenty reading and indepth research or you will pay dearly.
one thing...my car is carbed right now...the 4ac is a top fed single carbed motor...so ecu and wiring is no problem...the guys at toyosport said i need their carb kit, multiple discharge ignition and it should run with the rest of the gear in it is this true...oh andi have the jet settings already...anything else
I'd still argue about the fact that carbs would be cheaper. Now if you had to buy an Ecu, Injectors...and if you bought an standalone fuel management system, well heck I'd think the price would go over a set of webers and their jets ;P
first of all, the problem with carbs is, setup. you can't just buy the biggest injectors like efi, and then use the computer to control the flow. with carbs, too big = flood the engine =(
No offense, but going with a standalone could end cheaper in the long run. Lets say you got a decent standalone, and can map your fuel curves and can do all those little kool things that come with that standalone.
lets also say that you already have a boost ready engine. With carbies, good luck with tuning, unless you got a lot of theory in that tiny head, not to mention alot of money. With a standalone, its not as hard. You just change around a few settings and there you go. with carbbies, oh boy. (just generalizing here)
imo, carbs are too much work for the power they produce. I'd go with an standalone anyday, it's easier! especially if i didn't have a family of mechanics. i'd wouldn't recommend carbs for those that have little experience with cars in general, and esp if you don't know jack all about carbs, like me. I'd leave going back to carbs to those who can tell pinpoint all those little problems and where they are comming from on a car. I'm pretty sure the majority of people on this board don't know the difference between a brake pad lurching and abs in normal. or even the difference between engine revs in ignition timing.
If you don't have a knack for cars, don't bother with the headache of carbs, esp if your driving it everyday.
mind you, a knack doesn't mean able to install a damn cold air intake..
don't fool yourself, cuz you'll know you don't have that knack when you thousands in the hole. :smile:
As for that 4ac. ya its carbed, but it never runs efficiently like how you would want it to. you ever notice that theres barely a difference in the first barrel and the second barrel in opening? all the second barrel does is use more gas =D, and it still goes nowhere!
btw: nick, aren't the jets on the carbs dependent on the atmospheric pressure and temp etc?
<font size=-1>[ This Message was edited by: fatredcircle on 2002-01-31 23:16 ]</font>
flashman, in your arguement about costs...an sds or electromotive go for about 1200 - 1400. RC injectors i think are like 250 a pop...2400 for injector and ecu. a brand new set of webbers, un jetted and no choke or floats....800-1000. manifold..500-1000. linkage. app. 200. airhorns app. 160. and we still haven't bought jets or chokes to make the damn thing run!
toysport has a full carb kit for 900...thats everything and then i buy a jet set...how does that cost as much as fuel injection...wire harness is 350...ecu is 350...other wiring god only knows
because, jsut having a carb kit and jets doesn;t mean it will run!!!!! thats waht ppl think, but little do they know what else is involved!!! standalone ecu...1200cdn so lets say 800usd...thats it...nothing else needed...go...have fun...get some injectors, go crazy with the curves.
carbs....900...now get the jets...200 - 300...now get the manifold....now get them linked....now get them synchronized....now get the afr straightened out...now go buy cams....now go buy a multipled discharge ignition....tinker, tinker, tinker....then go have fun.
dude, do whatever you want...i'm just letting you know the dilly...whether you want to listen...hey its up to you...you asked the question right????
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