91 Chevy TBI, need suggestions for performance/ fuel mileage

I have a 89 4x4 burg that i have had since new with 175k on it now, It will get 18 to 19mpg on highway consistently still. The trick with it is I run timing at 8 BTDC and I use premium fuel. TO seriously boost MPG you need to raise engine efficiency and there is only so much you can do with 87 octane fuel in a modern engine. You want to raise CR to at least

10 to 1 and keep cam mild and use good gas to get maximum efficiency from engine and with this come good power too.

learning

sellers.

Big question is, How do you use this truck. If you use it as a truck then you want to boost low end torque. If you use it as a car and never haul anything then you could drop in the LT1 and get more HP but don't expect any mpg increase.

Also DON'T buy the parts off EBAY. Buy them from a local shop, better service and less hassle when you have questions. Plus the local shop can provide suggestions as to which parts work well together and which don't. Just tossing parts together WILL get you an engine that may run but will probably run like crap. Happens all the time.

As to my suggestion, I would buy a 383 kit from a good company and install it. Roller cam is an OK idea if there is one that will work with the parts you have. Roller rockers are a waste of money for the street.

Keep in mind that EVERY change has to be accounted for with the computer.

Thanks for the input on the timing and compression all the options are just so overwhelming. I finally found a great article on retro fitting roller cams at

Would also consider wether or not you have to pass an emmisions test or not.

Keep it simple. Your eng.block is already machined for a roller cam.You can buy a complete roller cam kit from comp cams.Get a cam slightly larger than stock. Add a set of GM Vortec cyl. heads,& Vortec intake manafold for TBI .Also add an adjustable fuel pressure regulator to TBI unit.You will need more fuel pressure than stock.Set ign.timing to 8 Deg.BTDC, & use 89 octaine fuel.It really depends on how much you want to spend.You can add roller rockers,but you than have to buy larger valve covers for clearance.You can add headers but don`t. You need the hot air tube to the air cleaner housing to keep intake manafold from iceing in cold weather.If you want you also can buy a ported TBI base that has a larger CFM rating. & a hot chip for the computer.Get on EBAY & tipe in serch TBI. Good luck.