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Chevy 4.3 Question

 
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JasonProspect
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Joined: 22 Jun 2009
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Location: Lake Forest CA
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PostPosted: Mon Jun 22, 2009 6:52 pm    Post subject: Chevy 4.3 Question Reply with quote

I have a 93 TBI motor that i need to replace. I found a 2000 short block that has had some work done to it. I would like to use my heads and intake on the new short block. Will this work? Thanks for the help. Dan
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squeeezer
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Joined: 02 Mar 2007
Posts: 2427
Location: new richmond WI
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1991 Chevrolet Camaro

PostPosted: Mon Jun 22, 2009 7:19 pm    Post subject: Reply with quote

im not sure if all is compatible but......
the newer stuff is better
the heads have the what we know these days as the vortec design same as the 350 heads fyi

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10sec.et
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Joined: 29 Mar 2006
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Location: Houston,Texas
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1969 Oldsmobile Cutlass

PostPosted: Mon Jun 22, 2009 10:34 pm    Post subject: Reply with quote

as far as i know, a 4.3 is a 4.3. the fleet trucks that come into the shop with the later 4.3 engines dont appear any different than those from the early 90s. i see no reason why it wouldnt work.
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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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Knarley Darley
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PostPosted: Mon Jun 22, 2009 10:43 pm    Post subject: Reply with quote

Only difference I know of is a balance shaft in the lifter valley.
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10sec.et
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Location: Houston,Texas
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1969 Oldsmobile Cutlass

PostPosted: Mon Jun 22, 2009 10:51 pm    Post subject: Reply with quote

Knarley Darley wrote:
Only difference I know of is a balance shaft in the lifter valley.
i like the ones with the balance shaft. they will rev smoothly until they float/bend the valves............ dont ask Embarassed
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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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Big Dave
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PostPosted: Tue Jun 23, 2009 10:40 am    Post subject: Reply with quote

Didn't they change from an even fire to an odd fire at some point? The engine was built originally as a Chevy 350 with a pair of cylinders left out when casting the block and used a sawed off 350 style crank with both cylinders on the same crank throw.

The newer crank has two different locations on each throw to try and smooth out the fact that you are trying to fit four crank throws into six holes and something has to give because of it. The four cycle engine doesn't like V motors that are not a multiple of the four cycles the engine runs on. In line motors can have a crank with the firing pulses spread out around the circle because each cylinder has it own crank throw.

Big Dave
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squeeezer
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1991 Chevrolet Camaro

PostPosted: Tue Jun 23, 2009 12:18 pm    Post subject: Reply with quote

the 96+ heads flow more
intake will not just bolt up (holes will not line up)
different set of gaskets (intake)
combustion chambers on newer is identicle to the l31 350 heads
older "vortec are not heart shaped

the typhoon and cyclone guys will take the newer stuff supposedly they flow almost twice that of the older stuff
i dont know if they are comparing older "vortec" (pre 96) or pre vortec heads

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240Z8
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Posts: 271
Location: Colorado
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1972 Datsun 240Z

PostPosted: Tue Jun 23, 2009 12:59 pm    Post subject: Reply with quote

Sorry I can't answer your question regarding the heads, but I used the 4.3 in two swaps. One N/A, the second Procharged.

Big Dave wrote:
Didn't they change from an even fire to an odd fire at some point? The engine was built originally as a Chevy 350 with a pair of cylinders left out when casting the block and used a sawed off 350 style crank with both cylinders on the same crank throw.

The newer crank has two different locations on each throw to try and smooth out the fact that you are trying to fit four crank throws into six holes and something has to give because of it. The four cycle engine doesn't like V motors that are not a multiple of the four cycles the engine runs on. In line motors can have a crank with the firing pulses spread out around the circle because each cylinder has it own crank throw.

Big Dave



Not quite sawed off, but two interior cylinders that were left out from the V8.
The move was from odd fire to a true even fire acheived with offset crank pins. I believe the first 4.3 was made in 1985.

Quote:
A production 4.3L V6-90 is a true even-fire engine. Achieving even firing pulses in a V-6 engine with a 90-degree cylinder-bank angle required GM to offset the connecting-rod throws 30 degrees to produce 120 degrees of crankshaft rotation between cylinder firings. Due to the journal offset, V6-90 rods as viewed from the side are narrower than V-8 rods, as are the rod-bearing inserts. V-8 rods and bearings won't work on a production V6-90 even-fire crank. However, most aftermarket forged or billet race cranks use odd-fire cranks with common-pin (nonoffset) crankshaft rod journals. These will accept V-8 rods, although vibrations induced by the odd-fire cranks' uneven firing impulses create considerable vibration on street-driven vehicles (that's not a concern on a race car).



I got lucky and found one in 86 from a wrecked 85 Astro, 10K miles, complete with Q-Jet four barrel. Thus began my first Mini Muscle Hilux Toyota. CC custom ground, and after a few years of pestering Holley, their first Large port 4.3 version of the Performer Manifold. I got it before they even started advertising it! Found a Marine distributor and drove the heck out of it for 250K miles.


Search the Syclone Ty forums. Lots of great experience there.

Lots of parts, but I found them expensive when you want more than 300hp. My final version was with forged pistons, promag rollers, custom CC blower cam and Procharger. Youth $$ and ignorance kept me from building the bottom end like I should have. Great fun, compact design. I lost track and interest once the newer balance shaft versions came out.

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JasonProspect
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PostPosted: Tue Jun 23, 2009 1:32 pm    Post subject: Reply with quote

It is listed as below:
.060 Over
60 over JE Ultra light Forged 10-1 pistons
Eagle Forged blown rods
Stroker crank
Needs oil pump

Motor has about 30K since build up. $1000

Is it worth it?
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squeeezer
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Joined: 02 Mar 2007
Posts: 2427
Location: new richmond WI
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1991 Chevrolet Camaro

PostPosted: Tue Jun 23, 2009 1:39 pm    Post subject: Reply with quote

there is a guy that drives around st.paul in a brown chevette with a 4.3
he has a bowtie aluminum 4.3 liter heads
he was /or did mount on a centrifical

i only talked to him once n/a and he said it was good for 315 horse
but now i cant remember if that was rear tire or crank.....pretty shur it was crank

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JasonProspect
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PostPosted: Tue Jun 23, 2009 1:51 pm    Post subject: Reply with quote

That is a whole lot better than the stock 165.
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240Z8
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Joined: 22 Jan 2006
Posts: 271
Location: Colorado
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1972 Datsun 240Z

PostPosted: Tue Jun 23, 2009 1:53 pm    Post subject: Reply with quote

JasonProspect wrote:
It is listed as below:
.060 Over
60 over JE Ultra light Forged 10-1 pistons
Eagle Forged blown rods
Stroker crank
Needs oil pump

Motor has about 30K since build up. $1000

Is it worth it?


Not going there, but sounds sweeet!
My demise was not having the 4 bolt mains and a bad dose of More's law on the boost Embarassed .
Letter to Hotrod re: 4.3s http://www.hotrod.com/pitstop/hrdp_0705_pitstop_chevrolet_v6_performance/index.html

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smashedfingers
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Joined: 29 Sep 2009
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Location: osceola indiana
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PostPosted: Tue Sep 29, 2009 2:47 pm    Post subject: Reply with quote

Knarley Darley wrote:
Only difference I know of is a balance shaft in the lifter valley.
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