taylor91rs

What kind of horsepower gains will my 305 get by puting ona holley 670 tbi.

PyRo9862

I beleive your stock TBI will support the power you have and some. Which means not much.

2kickassbirds

iTrader: (3)

what have you done to it if it is stock you will have no power.

ShiftyCapone

iTrader: (7)

You will lose power and drivabilty. The bigger TBI units have 2" bores which will not work with your stock intake. To really implement one you need an intake that can support it, heads and cam that is can feed, and tuning to adjust for the added air, changed vacuum, and larger injectors. This thread should help you out a lot. A larger TBI unit is about the last mod you should do to your car. The stock can go a long way on a 305.

https://www.thirdgen.org/techbb2/sho...hreadid=205713

cas0484

Would one benefit from the holley TBI on an otherwise stock 350? Because right now I feel that the stock TBI and manifold are really holding my motor back. The car really has now upper RPM power. I know it's not a powerhouse but I'm hoping the Holley and a better manifold well help out somewhat. What does everyone think?

89fastlookinRS

Maybe, but I would definately try the ultimate tbi mods in the tech section first. They are free, and do help out. I just now got a 670 because I believe it's the last bottle neck on my motor besides alittle more tuning. If you want to get alittle crazy go ahead and buy a carb intake with a tbi adapter plate, then later on you can add a 670. I would say headers, cam, intake, and ultimate tbi mods should all be done first. Although a mild 350 may run descent and gain alittle with a 670, it's up to you.

ShiftyCapone

iTrader: (7)

A weak cam is what is holding you back. You should only look into the 670 after you get into tuning with a new cam.

IROCaholic

cas0484 I would definetly reccomend going with a better manifold, the stock tbi manifold sucks. Just before I pulled my motor out this winter I put a performer RPM intake on and I felt a pretty good improvement in power I would say it probably knocked a few tenths off my quarter,but I didnt get any times before I pulled the motor so I dont know for sure. As for the holley 670, it really improved the ET's on my car but like I tell everyone I dont know if the guy I bought my Lo5 from did any headwork or changed the cam before he sold me the motor so I dont know if they are stock. Your biggest limitations are your heads and cam on that motor. you could try installing 1.6 roller rockers to raise the lift on your cam a little. You will see a decent gain from that. Also I saw that you ran a 15.0 @ 97 mph , with that trap speed you should easily be in the mid 14's, so your engine is probably doing as well as mine was when I got the times in my sig, I had about the same setup you have now. Good Luck.