so i decided to stay on the efi system for my truck, but have some questions id like to clear up:

1. an upgrade for it should be an injector swap out of an 302, how efficient will this be

2. i'm burning 98 octane fuel, should i retard timing to 12 (or more)

3. coupled on question 2, i also run propane/butane mixture on it? same question for timing.

4. i heard throttle body of a 302 should fit but would it be a gain or even a no fitter.

5. long skinny intakes should give some low end torque, since my air filter is now at prox 4inch of my throttle body would it help to make it +-double the length?

6. air filter is now fitted on a impco 300A carburator, (this is for the PB setup) does k&n air filters really work.

7. exhaust is now an open pipe behind the cat, i would remove the cat make a true dual exhaust the size of the pipes coming from the headers. then have some good mufflers on it. which brand and type would be good?

8. since egr system is no longer functional i'm removing it, is the cilinder shaped canister on the pass side fender part of this system? if not what is i for?

9. are there any chrome parts for an 4.9 efi?

10. should i install a tc which has lower stall speed?

11. would a camshaft which has +-10° difference make change in mid power band?

12. i also read somewhere that the 1st and 2nd gear of an AOD can be put into a C6 anyone done this? is it an easy swap?

13. have a C6 that need a rebuild and saw somewhere (sorry can't be precise on anything) they changed bushings by bearings to gain a bit of hptorque extra to the rear axle.

all these questions come because i like the six-inline however i sometimes need it to climb hills and instead of going up the speedo goes down. and i always have to manually shift between 2nd and D to get uphill: 2nd makes too high rpm but after a while in D it looses too much. also don't want to change rear diff ratio because it already does 3000rpm at 65mph and even if possible would put in a diff making this 2700rpm so need more torque on the band between 1400 and 2700 rpm. (doesn't have to drive faster then 85)
i know there are a bunch of question but any help would be great

I can answer just a few questions since i dont know much about the i6. The 5.0 injectors are 19lb vs your 14lbers. If going this route get injectors with 4 pintel holes, this helps with fuel atomazation. You would need to chip or reprogram your computer for larger injectors. Is your truck speed desitety or mass air?

Also your stock intake is the best as it is already a cold air intake. If you swapped it out for something else swap it back. You can use a k&n drop in but if its mass air they dont like the recharge oil. The k&n fipk is a waist of money as it ups air intake temps alot. It has bin proven many times.

You also dont need a duel exaust. Your not pushing enough out of that engine to warrent one. As for a muffler i like flowmaster but if i was you i would search for sound clips of differant brands. The wrong muffler on an i6 makes it sound like rice.

The coffee can is part of your emissions its a vacuum canister. It can be removed if your removed your tab/tad silinoids. This should have bin done with special resistors to fool the computer into thinking they are there. Same with the egr valve. On the 5.0/5.8 there are smog ports on the back of the heads that need to be plugged, im unsure if the 300 has one.

Hope this helps and good luck with the trans.

thanks for the answers already

i actually have no idea if its maf or map, how can i see this.

can i reprogram the computer myself? what do i need for it?

since i be building the exhaust myself it will cost less than a new stock which it need also: old one is rusted up.

i can't put the stock air inlet on because of the second fuel system:


i'll already try to put this upside down but am thinking of longer intake tubing with heat reflective tape around it or will this bring performance down?

Looks to be speed density. There are ways to tune them but usually not yourself. As for the intake where its at it is sucking hot air from the engine. The closer to the front of the truck the better. I would shoot for behind the headlight. Insulating it with reflective material will help bring down intake temps just make sure its flame retardant.

That truck is speed density.... Not worth tuning it for a 300 I6. Go MAF swap. Much easier..

19# injectors may be overkill on a stock 300 unless you up compression, change cam and open up te heads some..



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any links on this kind of swap?

Oldfuelinjection.com is the place to read up.. A lot of it is 302/351 specific but can be applied to the 300.. Just different Pin-out on ecu..


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Don`t even waste your time as far as an MAF conversion. It has the potential to improve idle qaulity and maybe raise your fuel mileage, but unless you plan on doing some serious work to the engine (massively ported head, cam, what not) youl`ll be fine with the stock speed density. 5.0Flareside`s combo is a whole lot more serious than your straight 6 can be as far as off the shelf parts, and he`s getting by with speed density. Does he need mass air (MAF), yeah, but it should still be tuned even then.

Your dual fuel setup adds a deggree of difficulty, but I would try and fab some kind of cold air set up, and add a header and freer flowing exhaust. If that doesn`t make you happy, you are going to have to dig into the engine.

Lower gears in the C-6 comes from swapping in the 1/2 gearset from the E40D, not the AOD, off the line, it`s like going from 3.55s to 4.10s. But, second gear will also be lower.

I`m tossing out some thoughts.

primetime said:

Don`t even waste your time as far as an MAF conversion. It has the potential to improve idle qaulity and maybe raise your fuel mileage, but unless you plan on doing some serious work to the engine (massively ported head, cam, what not) youl`ll be fine with the stock speed density. 5.0Flareside`s combo is a whole lot more serious than your straight 6 can be as far as off the shelf parts, and he`s getting by with speed density. Does he need mass air (MAF), yeah, but it should still be tuned even then.

Your dual fuel setup adds a deggree of difficulty, but I would try and fab some kind of cold air set up, and add a header and freer flowing exhaust. If that doesn`t make you happy, you are going to have to dig into the engine.

Lower gears in the C-6 comes from swapping in the 1/2 gearset from the E40D, not the AOD, off the line, it`s like going from 3.55s to 4.10s. But, second gear will also be lower.

I`m tossing out some thoughts.

Click to expand...

honestly, i forget my propane system is a carburator so maf/map conversion won't give extra power nor will an injector swap will.
but will camshaft make any difference? and tc? also thinking of 3G alt upgrade + e-fan