[fall-apart-dave]

Ok so I have a GMC Vandura, Chevy 350 block powered and currently has the stock EFI system on it. MPG is shocking (as I expected) but then 200 horses from about 8-12mpg is just silly. So, obviously swapping the factory fanimoulds for good headers will help, butwhat about fuel delivery? Carbs or injection? How tuneable is the stock injection system? Am i better using good carbs? I'm new to V8's, spent my time on old VW'S up to now.

 

[Kustom Jim]

I've just seen LPG for under 50p near the Tyne Bridge.
If you have room, I'd be inclined to install an lpg tank thing whilst it's still way cheaper than petrol!
No idea on cost or 'how to' though

 

[firebird68]

Is it the earlier throttle body type or the later tpi [multi point system]?
The throttle body type is not very efficient and not worth bothering with, the tpi system as used on corvettes and camaros is a good system which can deliver good performance and economy in the real world.
Other points to consider are gearbox type, and axle ratio. A 4 speed overdrive gearbox will help, as will a back axle ratio with high gearing to drop engine revs at cruising speed.
Like Custom Jim mentioned Lpg is a good way to lower fuel bills.

 

[fall-apart-dave]

I can cope with fuel economy being pants, i didn't buy it for economy. What i don't like is the power:economy ratio. That engine has a LOT more to give. It's the single throttle body injection. So, carbs it is then! I have overdrive but i think it's 3 speed. It ticks over at about 55 and to be fair, cruising to Santa pod with the cruise control on i did get 20mpg for the way there... on the way back though i was chasing my mate in his Rover V8 converted MK1 Celica (very nice motor and for sale...) so economy dropped a bit! Doh!

Well, headers, carb and 4 speed gearbox (and a bloody starter motor) on the shopping list. Oh and some 15" wide steel wheels too.

Related: what are stock Corvette headers like? Been offered a pair used for 60 quid.

 

[leepop633]

Tinleytech will sell you a self install LPG kit for about £500 and its a quality kit. Then take it an lpg installer like Fred Henderson in Durham and he will check it all and if all good will issue you a safety cert for about £40. At that mpg, you will recoup your money quite quickly but thee aint many lpg outlets in Northumberland.

 

[fall-apart-dave]

I'll have a look at LPG once i have fitted carbs etc. Thanks for that though really good info dude thank you!