4.3L displacement

[paulrfrancisco]

First forgive me for getting off topic and perhaps being dense, but I've been following the Captianloud thread about the harmonic balancer of the 4/3L V6, and read the .pdf file near the end where it gives the specs on the 4.3L. I was amazed at the 4" bore and 4" stroke geometry of this motor so I got to thinking about the math to figure the cu in displacement. And calculating this out it comes to 301ci. (PI * Radius squared (bore 4"/2) * 4" (stroke) * 6 (# of Cyl) = 301 cu. in. The 4.3L is like 268ci. No? Where 4.3L divided by 62.5 = 268ci. Am I missing something? 1 cubic inch (1*1*1) is = to 16.38 cu centermeters (2.54cm * 2.54cm * 2.54cm)... Right?<br /><br />Ok I have too much time on my hands....LOL

 

[Haut Medoc]

Re: 4.3L displacement

Something like that....A 302-305 is a 5.0....JK

 

[paulrfrancisco]

Re: 4.3L displacement

HM, I get the rounding... however 4 inch bore, and 4 inch stroke times 6 cylenders comes to 301 ci. The 4x4" geometry is for the 4.3 L V6 (268ci)so something doesn't jive.

 

[coalbucket]

Re: 4.3L displacement

A 4.3 has the same bore and stroke of a 350. 4" bore and a 3.48" stroke.

 

[QC]

Re: 4.3L displacement

Paul,<br /><br />I found your prah dude. Where you got messed up was that the specs show that the block is desigend for a "maximum" stroke of 4.00". If you look lower at the crankshaft specs it shows a stroke of 3.48" for the "standard" displacement of 4.3L.<br /><br />Using your formula I get 262 CID . . .<br /><br />Edit: Sorry coalbucket. I was composing while you posted

 

[paulrfrancisco]

Re: 4.3L displacement

OK.. I see it now.. Thanks everyone.. I didn't think my math was bad.

 

[coalbucket]

Re: 4.3L displacement

No problem QC

 

[Silvertip]

Re: 4.3L displacement

4.3 liters is also not 268 cubic inches. Its 262 (61 cubic inches/liter).

 

[WillyBWright]

Re: 4.3L displacement

I WISH! They have Stroker Kits for 350s. 4.3s are 350s minus 2 cyls. 350ci Stroker pistons would fit. 350ci stroker rods would fit. All that's left is a stroker crank. Yet nobody makes one. SUCKS!!!!!!!<br /><br />Addendum: Just Googled 4.3 stroker kit and ran accross this...<br /> "Note : The Original design of the 4.3 Crankshaft's make them too weak to stroke. The only option available is the Billet Steel Crank at this time. We are aware of companies that are stroking the stock 4.3 cranks, but with any serious power these cranks will break."<br /><br />If they break in automotive applications, they wouldn't have a prayer in a boat.

 

[Bondo]

Re: 4.3L displacement

Ayuh,.....<br /><br />They have Off Set Pins........The Big ends of the Rods,.... Don't line up.......<br /><br />Pretty Weird Looking the 1st time you see 1.......

 

[Silvertip]

Re: 4.3L displacement

The weird crank is necessary to make a 90 degree V6 smooth. Those of you who are old enough should remember the 1961 Buick Skylark V6 which was an odd-fire 90 degree V6. That engine bobbled under the hood like mad. Soft mounts were used to isolate the shake. The crank was later changed to the offset pin style as was the Chevy V6 so they run smoother. There simply is not enough time in two engine revs to get all the valves and pistons through the "suck-squeeze-bang-blow" process we like to call four-cycle. The included angle in the offset pins fixed this. Just a little history from a "duffer".

 

[Reel Poor]

Re: 4.3L displacement

Originally posted by WillyBWright:<br /> I WISH! They have Stroker Kits for 350s. 4.3s are 350s minus 2 cyls. 350ci Stroker pistons would fit. 350ci stroker rods would fit. All that's left is a stroker crank. Yet nobody makes one. SUCKS!!!!!!!<br /><br />Addendum: Just Googled 4.3 stroker kit and ran accross this...<br /> "Note : The Original design of the 4.3 Crankshaft's make them too weak to stroke. The only option available is the Billet Steel Crank at this time. We are aware of companies that are stroking the stock 4.3 cranks, but with any serious power these cranks will break."<br />If they break in automotive applications, they wouldn't have a prayer in a boat.

You can use this crank<br /><br />14044838 — Raw Crankshaft Forging Common pin “odd-fire” crankshafts are recommended for all Chevrolet V6/90°competition engines. The rod journals on this unmachined forging arenot offset like a production crankshaft; each pair of adjacent connecting rods shares a common journal. This design produces a 150/900firing sequence.An odd-fire crankshaft uses wider rod bearings than a production crankshaft,and has less rod offset.<br /><br />Technical Notes: <br />This raw crankshaft is forged from vacuum degassed 5140steel. It will accommodate strokes from 3.25" to 3.75". This forging uses a two-piece rear main seal; use crankshaft seal adapter P/N 10051118 wheninstalling this crank in a heavy-duty Bow Tie block which is machined for a one-piece seal. Forging ID #14044838.<br /><br />Then uses regular 350 rods. <br /><br />Might could even get a little more if you used the old small journal 327 rods Just my opinion <br /><br />Came from here down by the crank shaft section