I have no idea how that double post happened but if a mod could delete one, I'd appriciate it. Never happened before. Sorry.

Yeah I was just throwing out what most do. Agree on the weight and space of a larger block and all the goodies. I always like the idea of building onto the 4.3 than a swap. There very resilent and acceptive of forced induction and nitrous if used properly. Man this is making me wish I had time and money. lol

 

nope. that's the main weak point with a split-pin designed crank.

i didn't even get really deep into the last 4.3 i built, just opened everything up as much as possible, matched all the ports (in & out), taller cam, etc., and i got less than 18K on the engine before it broke the crank.

if you really want to build reliable power in a 4.3, spend the coin on a Marine crank. they're not cheap by any means, but that's the route i'm going when my engine pops.

 

to find out what a 4.3 can do without Forced-Induction, look at some folks who have ran in IHRA and NHRA stock classes.... Some neat stuff.

Anyway.... The 6.0 rod won't net you inches. You need a stroker crank....and to my knowledge the only ones of those that did exist were used up. A custom crank can cost $$$$.

The 4.3 isn't a horsepower motor. It is mostly a 350 with 2 cylinders loped off and most parts will translate.

For the 4.3s beyond the TBI years, cams are few unless you get comp or someone to turn you one (and that is their normal day-to-day offering).

I plan to do my TBI S-10 first and will use a tried and true plan. I am not sure if I can translate this to my 2000, but I will try when the time comes...or sooner.

My '94 has headers and that's fine, but I will not put them on the 2000. 2wd vs 4wd....I don't need the fuss on my DD anyway (and this coming from a guy who used his LT1 firebird as a daily-driver for 12 years....).

The plan:
W-code heads and mild port with focus on the short side and NOT PORT MATCHING. Port-matching (making the port volume higher) slows the incoming charge which is exactly what you don't want on a low-speed torque mini-monster. Screw-in studs and 1.5 RR w/ guideplates. 1.94 and 1.60 valves w/ 3 angle and backcut. Mild cam with 114-115 ls, ~200 deg dur @ .050, .500 lift. My 94 already has an edelbrock intake and AFPR. I'll keep compression in the 9.0-9.5 range and run ARP rod bolts and such. I'll probably adjust the redline up some, but not get crazy with it. I'll switch to a little higher stall speed and the 4L60 already has a transGo kit in it (that will kick the tires on the 2-3).

On the 2000 I'll use the factory heads and clean up a set of factory manifolds and otherwise follow the same path as the 94. No, it won't put down 300 rwhp, but it will be more than the 165 or 190 flywheel net they put out stock (the 94 is over that now) and make gobs (technical term) more torque. Since I am going offroad with one and playing autox/on the street with the other......that's just what I need.

On porting....for low to mid-range speed power you need to focus on the area under the curve and flow under 1/2 total lift at the valve. the larger valves, backcut, short-side and maintaining low-speed flow/draw on the intake side and increasing the intake signal from the exhaust side will help all this.

If you are going to run a 5,000 stall and 5.30 gears on a 26" tire at the strip you can make 300hp plus, but that power doesn't translate to what you can use on the street or even enjoy on the daily drive or trails. My 94 with all it's bolt-ons and tuning is more fun to drive than my 12-sec firebird around town and it makes a lot less power (weighs less too, but that's another story).

You'll also note in the HotRod article that the dyno numbers show a torque curve that is flat as a pancake.... that's ALL useable power. With their cam choice changed to less lobe separation and less duration you'd move the power down more making it more effective for the trails and street. I didn't know there were pushrod alignment issues so I'd defer to the SA rockers (what I use on my LT1 f-body) and be sure to use a louis tool or equivalent because the stock pushrod holes in the heads won't work with increased lift or larger rocker ratios. The 2.00 or 2.02 valves are about all you can get away with unless you jump through some hoops.

Good article and good power. I've read some other articles with a TBI and a blower making about 350 RWHP..... so it's completely doable. A buddy had a bolt-on S-10 SS using a 75-shot and ran 12.99. It's all in what you want to do.

 

I have heard that you can bore the 4.3 to the stock 350 bore and then use a hi-po build kit for the 350. Use 6 of the 8 pistons of course, rumour has it that you need to turn two of the pistons around for some reason, guessing a clearance thing. I have heard that this can make upwards of 300-350 hp. I am not sure of the cam. Like I said this is all things that I have heard, some local guy has been building these.

 

the discussion has never been about what can be achived, but what can be done for a street truck that can be a DD, and have some length of life to it.

 

Well, I guess I'm gonna try it. I've got a POS half-ton '96 that's REALLY tired...I'll be changing the crank though...sounds kinda interesting!

 

be sure that's the first thing you do before you start getting into your build.


you're gonna be surprised @ how much that little chunk of steel is!

 

K...found my crank...actually, an entire engine out of a little Bayliner with a broken keel. Pretty low hours on the engine, so I'm gonna swap everything off the motors (I hope). I'm worried the assembly rotates the wrong way though...

 

4.3 and a 350 have the same bore stock... In all honesty, just get a v8. There is no replacement for displacement. I have made a 4.3 fast before but it costed twice the amount and had half the horsepower of what a 350 would of had. If its 2wd, just go turbo and call it a day. Makind lots of power NA with small cubes is pointless and a money pit.

 

Came across this
http://www.speedomotive.com/ps-502-8...crank-kit.aspx

I'm picking up a 98 Jimmy to take its tranny (cause mine is completely done), so I was thinking seems how its engine isn't in use i could rebuild it and try this
But that's if i have an extra $1600 laying around...