Ok so I'm in the process of building a 305 tbi motor for my car. The current parts list are as follows.
ported aluminium L98 corvette heads with 2.02/1.6 valves (I could be wrong about the valve size)
Edlebrock performer RPM intake gasket matched to the heads
Howard cams 207/213 @ .05 lift and 450/465 lift on 1.5 rockers
Hooker competition headers

My questions are what kind of power should this combination make? Also what kind of upgrades will I need to make to the fuel system to support the engine, bigger injectors? bigger fuel pump? adjustable fpr? Ive heard all kinds of different ways to make the tbi unit support more power but my question is which ones do I need? Once everything is said and done i will have the car tuned my a very reputable tuner. Thanks

 

Stringbean: do L98 heads/valves clear the 305 cid cylinder?

 

If a large lift cam is used no they wont clear but with the cam that I am using there will be right .050 clearance between the valve and the deck of the block. That should be enough clearance as long as the valves don't float right? Sorry for all the questions I'm kinda a newby to building engines but I gota start somewhere.

 

A lot depends on the porting of the heads, but I would think you could be in the 275+ fwhp range. I would recommend you use the 350 injectors with probably 16-20 psi fuel pressure. So, you will need a better fuel pump (probably could use a tpi pump) and modify the fpr for adjustability and a higher spring rate.

 

Man what you are telling him makes me thing I need more fuel for my engine. lol. its way more aggressive than his. but back to subject.

your right about running the smaller cam lift with 2.02 but you still shrouding the valve too much. You really dont want to go 350?

 

I would consider a 350 swap but right now this is my only car so fuel economy is a bit of a concern can you say broke highschool kid...Ive worked my butt off to get the parts that ive got right now and trying to buy the right parts not to mension theres still alot of small things that I need to buy. so to answer you question yes im shure I dont want a 350 besides "everyones got a 350" i know there is a reason for this but hell why not be diffrent. so now for another question an probably one i should have asked a long time ago will my bottom end hold up to the power level il be putting out? am im aware of the valve shrouding but hey they will be than the stock heads for sure.

 

i'm out of fuel with the stock fuel system with just headers a 3" ccat back an open element an a tune ....

 

Yup, the stock fuel pump only puts out 15 psi on a really good day. If you look on ebay you can find a spring that's adjustable from 10-40+psi and one92rs can link you to a decent fuel pump, as I'm not home to get the part number.

As long as you tune it well you should be able to make between 325 and 375hp with your combination.
40psi through the stock 55 lb/hr will support about 350fwhp but in order to retain driveability you need to mod the fuel pressure regulator to make it Vacuum Referenced https://www.thirdgen.org/forums/tbi/...tbi-vrfpr.html
And of course, at that fuel pressure a new diaphragm is an absolute must.

I also have the IAC mostly sealed off (don't want it completely sealed) with a piece of black RTV shoved in just before the divide between the channels. I've heard this will improve idle quality by drawing more vacuum at idle. However, this has not been tested by any members of TGO so as far as my car isn't running yet lol.

 

Don't think this combination will come anywhere close to 375hp. Not enough head flow or cam to make that kind of hp on a 305. VRFPR should not be needed for this setup and idle quality should not be a problem with proper tuning. Stock tb should handle the power level of this combination, but the ultimate tbi mods might give you a little extra.

 

ok so il definitly pick up some 350 injectors and a tpi pump to keep this thing fueled. as far as the fuel economy once its tuned it should be fairly easy on gas because the tune will get the injectors back in check with the rest of the motor right?

 

That is correct and mileage should be good if you can keep your foot out of it.

 

i'm getting 21 mpg on the highway at 80-85 mph ....
what are you gonna tune with ?

 

I am having James short of Shortuning do my tuning. He is located in hardosburg KY and is considered one of the best tuners around here for the longest time he would tune your car going down the road but now has a dyno to tune with so as soon as everything's buttoned up I'll have some numbers for you guys.

 

ugh i hate the I cant afford the 350 right now so I am going to go with the 305 to be differnt routine..seems like one of these pops up every month. You can get a 350 tbi on ccraigslist for 300-500 bucks all day..

 

Dont get me wrong Id rather have a 350 in my car and the added power would be a real plus but right now the 305 will suit my needs very well and its a low milage motor. so for right now all things considered the 305 is the best choice for me and if i change my mind down the road everything can be changed right over to a 350. Once i get the money a 383 will be in the works but thats something eles all together.

 

what other mods have you done to the car? You can make all the power in the world but if you can't put it to the pavement it doesn't mean squat. I have much more cam than you do and all i'm running are the stock 55lb injectors with the fuel pressure bumped up to 21 psi. I'm running a stock TPI AC Delco fuel pump and it's a direct bolt in number. I would go that route. Plus, bump up the cam size, it's too small,lol

 

i really wanted to go with a slightly bigger cam but my heads wouldnt allow it because of interfierence issues with the valves and the top of the block, but it suits my needs well. as far as the rest of the car its all stock right now but soon it will be getting 3.43 or 3.73 gears and a limited slip diff and better springs for up front...its setting high in the front due to weight loss.