Picked up another van

[Rockwerx]

Thanks for the tips Alex. I will check to see if the knocker is a "W" engine. My donor is a "Z" engine. So what you are saying is that I maybe able to convert it to a "W" engine with a cam and head swap or is it just a different cam? I was not going to modify this van, but a cam change is just so easy...even easier once I get the engine onto a stand. I have to swap oil pans and a few things so it may get a few other parts while it is out. I have a few sets of used forged pistons from a 350... same bore and stroke so maybe I can use 6 of them to really wake it up!

[GEJ]

Rocky,
The 4.3 with split cranks have offset connecting rods where they don't line up with the bore centers.Not sure about the piston pin size either.It was a long time ago,but I do remember once I went with a common pin crank,I was able to use any 350 piston.I at the time bought a NASCAR brush V6 from Childress Racing at a Indy auction that included a bowtie unfinshed block,18 degree heads and the crank.If I remember right the stock pistons are offset also where the inside of the pistons set the rods.One thing for sure I do remember it almost cost me my partnership in the racing operation because once the engine was done it cost about 2 1/2 times what a SB race engine costs.

[Rockwerx]

Rocky,
The 4.3 with split cranks have offset connecting rods where they don't line up with the bore centers.Not sure about the piston pin size either.It was a long time ago,but I do remember once I went with a common pin crank,I was able to use any 350 piston.I at the time bought a NASCAR brush V6 from Childress Racing at a Indy auction that included a bowtie unfinshed block,18 degree heads and the crank.If I remember right the stock pistons are offset also where the inside of the pistons set the rods.One thing for sure I do remember it almost cost me my partnership in the racing operation because once the engine was done it cost about 2 1/2 times what a SB race engine costs.

Sounds like it may be more trouble than I first thought to use some forged 350 pistons. If the wrist pins are the same diameter then I would just need to check for clearance room inside the piston for the rod offset? It has been a few years since I had a 4.3 apart and I did not look at the rods very closely. I will have a look inside the knocker soon though.

My wife just wants a clean reliable winter vehicle. A Nascar Busch engine would be cool though! I am leaning more towards doing all of the almost free (time consuming and some abrasives) mods on this van engine now. Porting the heads like Alex suggested might help it gain some fuel economy as well as porting and polishing the TBI unit.

If it is too much of a dog I can still fix it later.

[GEJ]

Yep,
Most of mods are the top end anyways.Anything short of a compression increase are to let it live long term.I still don't remember if the piston end is offset or the rod small end was.You must be sure to number the rods and the direction of the caps for sure.If you order rod bearings you will see what I am talking about.

[Mr_Roboto]

Rocky,
The 4.3 with split cranks have offset connecting rods where they don't line up with the bore centers.Not sure about the piston pin size either.It was a long time ago,but I do remember once I went with a common pin crank,I was able to use any 350 piston.I at the time bought a NASCAR brush V6 from Childress Racing at a Indy auction that included a bowtie unfinshed block,18 degree heads and the crank.If I remember right the stock pistons are offset also where the inside of the pistons set the rods.One thing for sure I do remember it almost cost me my partnership in the racing operation because once the engine was done it cost about 2 1/2 times what a SB race engine costs.

Sounds like it may be more trouble than I first thought to use some forged 350 pistons. If the wrist pins are the same diameter then I would just need to check for clearance room inside the piston for the rod offset? It has been a few years since I had a 4.3 apart and I did not look at the rods very closely. I will have a look inside the knocker soon though.

My wife just wants a clean reliable winter vehicle. A Nascar Busch engine would be cool though! I am leaning more towards doing all of the almost free (time consuming and some abrasives) mods on this van engine now. Porting the heads like Alex suggested might help it gain some fuel economy as well as porting and polishing the TBI unit.

If it is too much of a dog I can still fix it later.

As long as you're using 23 degree heads the pistons are basic SB Chevy pistons. A lot of Sy/Ty guys use L2441F30s in their engines. Rods do not interchange however, and it's not unusual to have the con rods "off center" especially in a V6. Common pin cranks are a bit of an oddball these days, and may be "fun" to get to work with the EFI. Certain 200s and 229s would have them. however if you were ever looking to go crazy with the engine some time, they would probably be a good choice. I'd probably end up doing the 267 if you have all the parts there for it, just because it's oddball and would probably still not kill the mpg especially with that 4 speed behind it.

[Rockwerx]

I did a bit of research and found a good write up on differences in the Chevy V6 engines. I have the old 229 V6 out of my friend's 81 Malibu. It probably has the splayed crank throws though.

http://engine.firebirdv6.com/V690.html

[GEJ]

One of things my machine shop told me they found about 4.3's with over 70,000 miles on them was number three bore was found to be oval in almost all the blocks they rebuilt.Centered pistons with the offset and the rod bearings don't run completely flat on the crank(more towards the edge of the rod bearings)or center the rod bearings and the pistons wear the bores out of round.Common pin forged cranks straighten the problem out but ended up with the odd firing you found out about.The long and the short of it is the 4.3 isn't really a 350 with two cyclinders cut out of it.The link you found brought back some of what I remember about mine.Even thro the 4.3 does use some of the 350 parts,the split crank does make it a much different engine than the 350.Also bowtie blocks are the only real way to use a common pin crank.To finish machine those ruff castings cost a bundle.They didn't for the 4.3's have any bolt holes at all and are just like they came out of the forge plants.

Like you said and so did Roboto-head and cam change,keep it simple.

I got roped into wanting to do something different and found out how much different costs.

[Rockwerx]

I find it interesting to read that some cylinders go out of round so much. For fun I will check the bores on the knocker and my donor also if I pull the heads on it. Is it just the number three cylinder that wears the most?

I am not sure if I ever posted this pic. A friend was cleaning up his barn and gave me these SBC parts. After we finished loading up the van there were 14 heads, 4 cranks and one block in the back of the Safari.


I stripped all of the heads down one by one to determine if any of them were any good. All of the thin walled castings had problems and went for scrap metal. I salvaged only 6 heads out of the bunch. I was able to salvage 2 sets of sodium filled valves that I installed into some heads that I had already.

I traded two of the cranks that were good still for a gasket kit and an aluminum intake. The other 2 cranks were too rusted and pitted to regrind. The engine block was very rusty. The reason was that someone had taken a grinder and removed all of the casting marks and then they did not oil it down properly or paint it. I took a wire wheel on an angle grinder to it and in no time it polished up to a shine. The person who was polishing up this engine even did the lifter gallery. Then I ran an old ball hone through the cylinders to clean them up. Unfortunately there was some pitting on a couple of cylinders so it will need a bore job. I have some used .060 11.5 to 1 forged pistons that will work well in this engine though.

[GEJ]

Rocky,
I would be very interested in hearing what you find once you open up the knocker.