TB42 & TB45 Fuel Economy

[Throbbinhood]

@mudnut what'd it cost to get your carby rebuilt and the dyno tuning time?

[dom14]

@mudnut what'd it cost to get your carby rebuilt and the dyno tuning time?

Yeah, mudnut, how much did it cost mate? The rebuild kit is around 80 bucks, but rebuild usually cost as much as a new carby, hence the reason I'm not too keen on getting professionally rebuilt. Spending that money on a brand new carby is a better option I reckon.

As for the dyno, closest I've got so far to that is by investing on an AFR gauge kit which cost me around 200 bucks and I fitted it myself. The best money I've spent so far. I just need to work on the carby & the LPG gear to get the best out of my AFR gauge.

[dom14]

I took my carby and kit to the local dyno guy. and it really ran a lot sweeter on the dyno, even before he tuned it. You haven't got any brake pads dragging?

Not sure. I'm gonna have to check it. I wonder whether the rear bearings might be dragging as well. Need to check that as well.

[mudnut]

Not a lot, to be honest, as it is a case of not what you know but who you know. He didn't use the whole kit, either. Just parts the parts he knew were toast. It probably only took him half an hour to have the carby on and running.

[dom14]

Not a lot, to be honest, as it is a case of not what you know but who you know. He didn't use the whole kit, either. Just parts the parts he knew were toast. It probably only took him half an hour to have the carby on and running.

I can do it now in half hour 'cos I've been tearing apart this Nikki carby for like million times.
But, still it amazes me that I pretty much know nothing about it's internals and how everything work together to produce a good AFR.
All in all, it's been a great fun exercise for me.
It's that I don't always enjoy having to tune the carbies all the time, 'cos older worn out carbies need attention all the time, and
there are times you get sick of it, while the other times you enjoy it.
I know, mine needs a needle seat and needle again, but it pizzes me off, 'cos the current kit is only four years old.
The issue is that some of these aftermarket rebuild kits are crap, particularly the needle and seat(the most important and delicate part of the kit). There are no jets in the kit. The accelerator pumping plunger and the rubber boot is also important, but all the gaskets I learned to cut myself. It's not an arm and a leg cost for me to buy another kit for $78 trade price from Burson. It's that I can't justify it. It's either a new carby or 'new' EFI engine for me. And if I put an EFI engine in it, then it will be a matter of time before I put turbo in it. . I just wanna fiddle around with carby bit longer I rekcon.

Another thing that amazes me about carbies is that a perfectly working carby starts crapping itself when it is faced with a totally different weather conditions.

[dom14]

Not a lot, to be honest, as it is a case of not what you know but who you know. He didn't use the whole kit, either. Just parts the parts he knew were toast. It probably only took him half an hour to have the carby on and running.

If you do know a bloke who fully rebuild carbies under $200, do let me know.

[mudnut]

This bloke is very much into racing and his knowledge is extensive. He has even built a vaccuum test bench, so he can achieve maximum gas flow for the heads he builds.

[billyj]

before you go buying a new carbie, go get a dyno shop to do a couple of power runs then they can actually see what the afrs are doing in real time under load.

an afr gauge is only half the battle to getting a tune right while 14.7:1 may be stoich and ideal at cruise you will be loosing power under load as best power is made at about 11-13:1 so if everything is working right you should be running rich under wot then lean off when at cruise. if your only at 14.7:1 under load then your at a much higher risk of pinging and proobly running less timing than ideal to compensate. the point being that if your down on power your going to be using full throttle or more throttle more often trying to pick up and maintain speed

11351133_10153391028716133_6811608451076355849_n.jpg this is the 355 holden stroker i hand built for my old vs ute made about 240kw with a cam suited to low end torque

[dom14]

before you go buying a new carbie, go get a dyno shop to do a couple of power runs then they can actually see what the afrs are doing in real time under load.

an afr gauge is only half the battle to getting a tune right while 14.7:1 may be stoich and ideal at cruise you will be loosing power under load as best power is made at about 11-13:1 so if everything is working right you should be running rich under wot then lean off when at cruise. if your only at 14.7:1 under load then your at a much higher risk of pinging and proobly running less timing than ideal to compensate. the point being that if your down on power your going to be using full throttle or more throttle more often trying to pick up and maintain speed

Thanx for the tip mate. I'll richen up the AFR a bit and see what it does.
I leaned the LPG mixture under cruising 'cos I was told to do so.
The intermittent nature of the issue baffles me a bit.
Carbies(two of them) have issues.
I need to spend some time on dismantling them and playing with the jets, etc.

Yeah, a dyno run is way overdue. I wanted to be confident with the carby & ignition system and LPG gear(mixer, converter, etc) before I take it to a dyno. I'm not sure that's the best approach.