if your the kind of guy wuo can find time to get serious abuot your engine i found a site that has some interesting ideas thinking .i have a 84 fullsize blazer 350 4 barrel its a plow for winter only so i have time to play with it im going to try it . go to (somender-singh.com-home) read his idea carfully it makes sense to me. good luck.
Thats kinda funny. That dyno on the TBI chevy 350 is a complete farce. He takes a motor with a 9.0:1 compression ratio, hacks the intake ports up with a dremel cutting blade, decks the heads, uses a thinner head gasket, and arrives at a 10.2:1 compression ratio. Not only is there no correlation between the two graphs since it's an apples to oranges comparison, but those grooves are way too deep and WAY too far away from the valve to make much if any difference. He could have probably gained more by gasket matching the intake and head than cutting those grooves in.
I have done a lot of computational fluid dynamics in my schooling and for work. Building up a turbulent boundary layer does increase flow, but it needs to be consistent.
Ok so I thought it was time to weigh in on this subject since I have been kinda called out.
Anyway... I have never said anything bad about iridium plugs, only that I won't use them until more is known about them as far as plug life. I want to know that the iridium plugs are worth the cost. From what I have read recently on them, they offer the benefits of a copper plug (stronger spark) with the life of a platinum. Maybe the next time I change plugs in the Bonneville I'll give 'em a try. It'll be next year. Just dropped in a set of 1 heat range colder NGK's a few weeks ago.
My negative comments on plugs have been made squarely at the Bosch +2/+4 line of plugs which are nothing but a gimic.
Now onto how you can save fuel...
One of the best things you can do to save fuel is to change your driving habits. Coast down hills and don't try to power back up hills if you don't have to. Coast to stop signs or lights if you are going to have to stop. Don't try to beat the lights. There are numerous other ways to save fuel by simply changing your habits.
Also, keep your vehicle in tip top shape. Make sure your plugs are properly gapped and are clean. That your wires, cap, and rotor are in good condition. Run a bottle of fuel injector cleaner through your tank at each oil change. Clean your MAF sensor. Try a can of seafoam through the intake to clean it out. Check your tire pressure and make sure that they are up to the proper pressure. Keep your alignment in check. If your vehicle starts to pull in one direction, it'll burn more fuel as you keep it straight. Keep your brakes up to par. If your sliders seize, you may be driving around with a brake pad against the rotor, introducing more drag.
I have heard good things about running synthetic fluids in your diffs and how it affects fuel mileage. I can't comment on that yet, but I have Mobil1 75w90 in my rear diff, but haven't changed the lube in my front diff yet. Plus I don't really drive the truck much in the summer time.
A throttle body spacer will tend to shift the torque curve down lower in the RPM range so you have more torque available off the line at the expense of higher rpm torque. If you tend to keep the rpms low, you should notice an increase in mileage.
And as always, if you are concerned with your mileage, don't race other people on the street.