Fuel consupmtion with a Weber?

[sigma]

Hi All
First of all I'm a Newbie to this forum and so far it looks pretty good......informative and most people seem happy to help....pretty much what a good forum is about
I have a question about fitting a Weber to a 1984 Tercel 4WD with a 4AC engine......what sort of fuel consumption figures can I expect?
The engine is currently running what I assume is the stock carb (jap looking carb with 1/2 million vacuum hoses) and I am getting around 8.2 ltrs/100Kms (28.61miles/US gals)
Do you guys think the fuel consumption will improve with a Weber and if so will the increase make the cost of fitting the Weber worthwhile? The majority of my driving is in the 50-65mph range and I have no plans to sell the Beast just yet......as long as she keeps working I will keep driving!!!
Thanks in advance for any help
Will

[Mattel]

Hi, I had about the same fuel use with a good carb and with the weber. I wouldn't change over unless your old carb really needed a service and you found a cheap weber. The performance wasn't much better with the weber. It was harder to start. (needed to install manual choke) had a little better pickup but bogged down every now and then.

Probably a better mod for Aus Tercels it an electronic pointless distributor from a AE82 to replace the mechanical one in the aus spec 3ac.. should cost about $25 on ebay or wreckers!

[sigma]

HI Mattel

Thanks for the info.....if the fuel consumption I am getting will be the same with a Weber then I probably won't bother with the conversion, but I have seen a few people have done the electronic ignition conversion so I think I will do that one
You said that the distributor from the AE82 will fit the Aus spec 3AC My block is 4ac but the head looks the same as the 3AC but I'm not 100% sure as the 4AC was already in it when I bought it so will the AE82 distributor still fit ok?

Cheers
Will

[dlb]

welcome, sigma. fuel economy is about the same between stock and weber carbs if both are running correctly. it can be a pain to confirm all the vacuum-operated components of the stock carb are working properly but i find once they are sorted out, it is a better all-round system than the weber. the weber has a bit more power but ices up in the first few minutes of cold weather driving. probably not an issue in australia but in canada it made the short drive to work in the winter a pain.

28.6 mpg is still a little low, though, presuming you are not a leadfoot. here is my list of things to check that affect mpg.

tire pressure
wheel alignment
dragging brakes
extra cargo weight
ignition timing
air filter
dizzy rotor
dizzy cap
spark plug wires
spark plugs
vacuum leaks
correct vacuum routing
choke wide open once warm
AAP diaphragm
worn out TVSV (directs vacuum to AAP at all heat ranges)

the 3a and 4ac heads are the same. the only difference is the outer shape of the heads, which means you must keep 3a valve covers on 3a heads, and 4a valve covers on 4a heads. so a point-less dizzy will fit just fine.

[overs10ded]

I agree with dlb, my Aisin carb ran pretty strong without any stumble although the mpg was BAD! So w/ Weber, I get over 30mpg combined regularly and am satisfied with the performance and the tiny bog off idle. I lost 10#'s of weight when I stripped the egr system and aisin carb items also. I don't have much cold weather running where I live and haven't run a choke yet. A little time warming up first start in the a.m. is all it needs. My Aisin needed rebuilding and the Weber was the route for me vs rebuilding the Aisin carb.

[Petros]

If you switch to the weber, do not do it for the economy, you will not improve your economy enough (if at all) to make the cost worth it. You can improve the fuel econmy by making sure the stock carb, and all the vac operated equipment, is working properly. when working good, the stock carb has good drivablity and economy, and operates well in all conditions from sub freezing, high altitudes, to very hot and humid sea level operation. Rebuilding the stock carb is not too difficlut and kits are available for about $30. But first work your way though the tests in the FSM for each of the systems (not difficlut, it just takes you going though each system one at a time), make sure the vac lines are all routed correctly and everything is working properly.

to improve the econmy further you can also set your ignition timing at 10 deg btdc, disable the EGR system, and remove the catalytic conveter and install a bypass tube (if your state law allows it).

good luck.