The Camaro Club (UK)

Fit a wideband lambda sensor and gauge and get tuning. Or for a quick and dirty method pull a couple of spark plugs. They should 've tan/beige in colour.

I'd expect your combo to return 10-12 mpg on average. Sounds like it's running very rich.

To give you an idea my car with ~450hp, 4.11 gears, 3000 stall and 700r4 returns on average 18mpg. If I keep it out of OD then I get 12-14. And I don't drive slowly. But I do have fuel injection and its set up properly.

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My '80 progress thread - hugger orange! Now with LQ9 power - forged pistons, LS2 rods, 236/242, .621/.612, flowed and milled 317 heads. MS3X

4L80e, 12 bolt, 4.11, Moroso brute strength posi, steel shafts.

Subframe connectors, g-braces, solid body bushes, carbon hood and front bumper, custom door cards, Autometer gauges.

Sounds like a few good options have been brought up. I guess step 1 would be what Flak Monkey suggests - "wideband lambda sensor and gauge and get tuning" Then you can get it towards the 10's. In regards to what tuning involves, i'm not too sure, sorry. I believe tinkering with the carb - jets / fuel amount etc. I have a PDF for the Edelbrock carb which shows you where to make adjustments, what jet setup to use etc. Do you have one for your carb? That could be a good starting block, coupled with the wideband sensor. For what it's worth, a friend had a double pumper and took it off as it was quite thirsty, giving him under 10mpg.

For the gearing, a 400R sounds like a good option if you want to keep the rear gearing as is. This may not help too much with town style driving as you'll never get to the 4th gear. So another option would be a bolt on overdrive unit? I posted a video about a week ago - HotRod Garage on youtube fitted one and explain it, see if you can find that vid. It's not a cheap unit but you can engage it any point, so even in first, giving you 0.75 output... say you're doing 3,000rpm in 2nd gear to stick to a 40mph zone, engage the overdrive unit and it will drop the revs to 2,250 RPM.

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A 700r4 will be on it's limit at close to 500hp. They can be built to handle it though - if you can find a transmission and want it building to suit, give me a shout.

Carb tuning with a wideband is pretty simple - just understanding what jets are in play at any given throttle position/load is important.

Figure on buying something like an Innovate LC1 which has a gauge with integral controller - £250 sounds like a lot but it doesn't take long to pay back in gas mileage - and you'll notice a performance improvement as well.

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My '80 progress thread - hugger orange! Now with LQ9 power - forged pistons, LS2 rods, 236/242, .621/.612, flowed and milled 317 heads. MS3X

4L80e, 12 bolt, 4.11, Moroso brute strength posi, steel shafts.

Subframe connectors, g-braces, solid body bushes, carbon hood and front bumper, custom door cards, Autometer gauges.

There's a lot more to tuning a Holley than just jets once a WB Lambda is used. The fuel curve is usually upside-down so they are too rich at cruise and too weak for power. Bung in bigger mains to fix the power and you're now massively over-rich at cruise. What to do? That's where the secret squirrel sh1t comes in....................
Overdrives are great, as is FI and other upgrades but if you read my post, 20mpg, 12 second quarters (TS 114 so really 11's with traction) and good top speed for racing etc. No overdrive, no FI and 3.50 cogs. No magic, no rocket science and no weak-knees 5 speed or sludge-box to break.
OP: 'Loose' converter is dragracing language for a high-stall converter which tends to slip away much of it's power at lower speeds. They tend to be used to 'crutch' up poorly built engines that have no low-speed grunt, along with low axle gears. There goes all your fuel economy..........
Cheers, Martin

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I can handle 10-12 mpg no worries Thanks for the comparison.

Please excuse my ignorance but what exactly is a 400 R ? Plus where exactly is an overdrive unit fitted in or to? To be honest my lack of mechanical skill and knowledge normally points me in the direction of the local garage or specialist for work on my cars. I think tuning a carb (to me) seems a pretty intricate job and best left to those in the know.

You mention bigger mains, what's that?

He is referring to the main jets in the carb, the previous post I'm assuming they meant a TH 700 R4 gearbox which is extremley popular auto box fitted Into 3rd gen camaros amongst other things? Andy who I reccomended on the other thread would be worth phoning for a chat even if you decide to go elsewhere for the work to be done.

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1997 30th Anniversary SS SLP
1993 GMC Typhoon

I have been gone from England for a long time, but they tell me you now have emissions testing. If you can find a friendly tester get him to run an exhaust analysis to see if your engine is running rich.
But looking at the spec of your engine I don't think economy was on your mind when you put it together.
You want high performance, you pay for it

Thanks for the info there The TH 700 R4 seems to be a better option than the 350 I'm currently using, can it handle a lot of torque?