I have a 305 TPI, and I just got a set of 30 lb motorcraft injectors. What do i need to do to make sure i get the most out of these? Can i just put them in and go?

 

No, do not use those in that engine.
For a 305 without boost, and one that's getting at least 300 horsepower to the ground, I'd recommend a 24 lb injector at most.

For your reference, most naturally aspirated 383 engines run just fine with 24 lb injectors. Going too big for your engine size will cause you nothing but problems.

Do a search on this site, and/or take a look at this thread (link below) for some explanation as to what kind of problems to expect, even with the proper tune.
https://www.thirdgen.org/forums/tech...injectors.html

If you had an ECM that could run in sequential mode at low RPM, then you could get away with the 30 lb injectors without any problems.

On the other hand, if you have a typical 230 RWHP 305 with the factory batch-fire, then you would have big problems running 30 lb injectors, and it would likely lead to engine damage due to excess fuel diluting the engine oil.

 

To trade them for something more appropriate to your CID.

24 lb is marginally too big. 30 lb, and you probably won't even get it all the way started before it fouls all 8 plugs.

Turn them into cash.... it's easier to modify cash into the parts you need, than to modify (or modify around) parts that don't work.

 

What would i have to upgrade to run them in it?

 

see post #2

 

Your cubic inches (to about 383) and your induction system (to something other than TPI).

Other than that, you're ready to roll.

 

If you where to burn a chip with the new injector constant, they may work. But, the real issue here is the small amount of fuel thats needed at idle. The injectors will be open for so little time that they may not deliver the fuel. You have an early TPI batch fire system which fires the injectors each engine rev., IIRC. Normally those would be used on an SFI system, which fires each injector once per 2 engine revs. This means they would fire at 2x their normal rate on your motor. This causes the pulsewidth to get real short. So short that they may not open.

Im running Ford 36 lb injectors because 30 lb ones where too small, and those have a pretty short PW on my 350 at idle. Like 1.2 milliseconds. On your engine, that would be .6 msecs, which is too short under most conditions. If you REALLY knew what you where doing, you could probably get it to work by tinkering with the injector offset, but its too much work for a stock 305 that only needs 19 PPH injectors.

 

Don't use them! you are going to have problems with flooding at idle and probably wash the rings and destroy the engine. Especially without changing the constant in programming.

 

Okay so there not going in guys. thanks guys im just going to sell them and get 27 lb. If anyone want to buy or trade for them PM. They'll be posted in parts for sale later today

 

It seems that you missed a great deal of information that was given to you in this thread, or you're intentionally pranking us.

The proper sized injector for a 305 is 19 lb/hr.
Once your 305 is built up enough to the point of getting 300 horsepower to the rear wheels (not so common), then it is reasonable to upgrade to 22 lb/hr or 24 lb/hr injectors IF you then also get the proper calibration for your chip so that they will work properly for you.

If you have a power adder creating boost, and are not using an FMU, then an injector upgrade is also in order, but will also absolutely require recalibration of your chip to work properly.

If you have an average 305 making 230 horsepower or less to the rear wheels, and you install 24 - 27 lb/hr injectors, then you are going to run slower than before, probably have idle issues (even after tuning), and probably eventually cause internal engine damage.

This has been said.
Learning by doing is the best teacher.
There's no need for me to post again in this thread.
Good luck.

 

Get the 19 lb and be done with it. Or, if you can do the programming 22lb.

 

DO NOT CHANGE THE INJECTORS. LEAVE THE STOCK ONES IN THERE. If you have a 350 then you need 22-24lbs. If you change the cam in the 305 then 22lbs but you will need a chip tune for those injectors. GET IT?

 

If you JUST HAVE TO change the injectors, get yourself a set (or a couple of sets, to make sure you get 8 good ones) of used Frod 19 #ers such as out of a Mustang. Cheeeeeepest kind you can get, I usually pay $30 - 35 A SET on the usual auction site. Make sure they're all the same style, I prefer the "Gen 3" (thin) ones myself. You might have to file a bit off of where the fuel rails sit to make them fit but usually not. Put GM O-rings on em obviously. Soak em in a coffee can full of lacquer thinner for a few days before putting em on.

You don't seem to be listening. Large injectors pour in more fuel. Your engine can only ingest just so much air. Too much fuel and not enough air = go slow, foul plugs, waste gas, wash down rings, contaminate oil, and besides all that if that's not enough, do some bad things too. Don't use your own money as the weapon to shoot yourself in the shorts with.

 

Okay thanks guys im going to go with the 19lb and sell the 30lb.