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Originally Posted by 1992camarors  Please shifty or Fast355 respond to my question and give me your ideas. |
I honestly would not do 081s or 416s. 601s are good. 187s are good. I would do a pair of 187s over 081s. The 081s are tough to get power out of. The only reason I put them on my 350 is because I had them, they were already reworked, and my 350 has 18cc dished pistons.
The 081 and 416 heads BOTH have CRAPPY open style 58cc chambers.
The 601s have a closed style, twisted 52cc chambers.
The 187s are a hybrid style, almost open chamber, but twisted like the 601s. In extensive testing by David Vizard, he concluded that the 492 style chamber used by the 601 heads was worth 25-30 ft/lbs of torque across the whole operating range, with no other changes.
For a performance 305 it is very tough to beat a pair of nicely reworked 601s with 1.94 intake and 1.60" exhaust valves.
For strictly economy, torque, and towing it is very hard to beat the swirl ports.
I would not do the LT1 heads, too much work, too much $$ and not enough gain over other heads.
I would would find a pair of 601s and do some work to them. There are several threads about porting 601 heads.
I would deck the heads .020", which will bring them down to about 49cc. Install the heads with a .016" compressed head gasket will give you about .040" quench with the stock block and pistons. The stock pistons are about 8 cc dished. Deshrouding the chamber will likely bring the heads back up to 52-54 cc, should you elect to deshroud. If you leave the chambers stock, you will end up at about 10.7:1 compression with a .020" cut on the heads. If you deshroud the chamber you are looking at about 10:1 compression. Both will work equally well on 93 octane gas with the appropriate camshaft.
The GM Production LT4 cam is plenty for the daily driver 305 and is easy to tune, especially for beginners.
An Edelbrock 2701 EGR Performer will fit nicely onto the 601s. You will need the throttle cable, throttle cable bracket, and TV cable from a carbed thirdgen. An EGR valve from a carbed 3rd gen would be needed as well.
Your stock 305 injectors will work fine, you just need a TPI pump in the tank and the GM 30 PSI TBI fuel pressure regulator.
Mount the TBI on a Projection TBI-Carb adapter on the standard carb Performer intake.
Extremefi makes a nice throttle body that is bored to 46mm and flows 590 cfm @ 3.0 in/hg pressure drop. The stock throttle body flows about 425 CFM @ 3.0 in/hg. With ultimate TBI mods that will climb to about 490-500 cfm @ 3.0 in/hg. For up to 375 HP, I see no problem with the 590 CFM TBI unit. The stock TBI unit will work up to about 300 HP.
Match the intake and the 601s to a standard 305 Felpro intake gasket.
You will want some Hooker 2460 Headers and increase the size of the pre Y-pipes to Dual 2 1/2 or Dual 3" pipes. You should then merge the pipes into a 3 or 3.5" sinble pipe. Flowmaster makes a nice Y to do this with. Then out a single inlet, single outlet muffler of sufficient size and flow. 3.5" pipe is ideal, 3" is OK, 2 1/2 is too small.
You will need lots of prom tuning, and I highly recomeend swapping over to the later model 1993-1995 TBI truck PCM. Your 700r4 will eventually take a dump, when that happens, I would definately take the opportunity to put in a 4L60E. A 4L60E from a 1995-1997 F-car will drop right in and be right at home with a 1995-1996 TBI Van/Truck ECM. Both have pulsewidth modulated torque converter clutches. If you choose a 1994 4L60E, you have to use the 1993-1994 TBI truck PCM. The 1993 F-car transmssion was a 4L60, non electronic, better known as the 700r4.
The end result is about 315 HP @ 5,500 and 360 ft/lbs of torque at 3,750. Power will come in strong almost off idle and pull through 6,000 rpm.
Oh and BTW, I am not suggesting anything I have not done.
The little 305 TBI can make damn good power, torque, while retaining very good fuel mileage and clean emissions.
http://www.youtube.com/watch?v=Oi_n0goatA8
(240 RWHP 305 TBI, 700r4 w/2,000 rpm converter, 3.08 gears, P255/70/R15s)
My build was very similar, but used a Federal Mogul CS1014R cam and my 305 had factory flattop pistons with only about 5-6cc of valve relief to them. I cut my heads .015" to compensate. It ran great at 10.5:1 compression with the mild cam and the TBI setup.
