Bore and Stroke ?

[gectek]

Ok so tell me if my thinking is correct...
stock bore size and stroke size is
3.62 " bore
3.31 stroke right

so that pretty much nets a 3.35 liter or 204 cu in right...the 3400
so then a 3.6 stroke on a 3.65 (.030 over) is a 3.7l or 224 cu in
then a 3.8 in stroke is a 3.9l does that sound about right?

I would think about .040 over, but that just seems like too much...but i dont think the outer limits of the 3400 have been set have they??? maybe .040 is ok?

Yes to answer any ?s i do have a stroker idea in the plans...I like the idea of a 3.5/6/7/8/9 stroker...but i would like to stay within the confines of reliable(haha) and ease of finding a machine shop that will build up the crank and grind it for me...this would be a stock 3400 crank that would be stroked and offset ground, then prob some manley or scat rods machined and then block clearancing when i get all that back. then i would take it to my local shop with all that and have it balanced...that way its a monster of a v6 hehe...

[geoffinbc]

Use a 3500 crank and have the large rod bearings offset ground down to the size of 3400 bearings. You can get them in the forged variety too.

[Superdave]

Bah.. pick up a 3500, bore it .030 and use SBC 305 pistons, offset grind the crank +.25" and have a 3800..

Desktop dyno dosen't show much of a HP increase, just more torque.

[Joseph Upson]

Bah.. pick up a 3500, bore it .030 and use SBC 305 pistons, offset grind the crank +.25" and have a 3800..

Desktop dyno dosen't show much of a HP increase, just more torque.

You can only offset grind the crank to ~.100 increase, you have to divide the .250 by 2 giving .1125 and then clean up the crank after the offset which will net about a .100 offset.

[gectek]

well that would be .1 up .1 down...so .2 total...and yah i might think about the 3500 and then getting the TCE trigger. i really want a very clean install...but its still just a musing

[Superdave]

You can only offset grind the crank to ~.100 increase, you have to divide the .250 by 2 giving .1125 and then clean up the crank after the offset which will net about a .100 offset.

if you cut .25" off the backside and use 2" journal rods it should work.. or maybe i'm thinking wrong...

[Joseph Upson]

if you cut .25" off the backside and use 2" journal rods it should work.. or maybe i'm thinking wrong...

You're dealing with a circle so if you start at center you have .1125" above and below the 2" perimeter inside the 2.250 crank pin. You can't offset grind a total of .250" as in the piston moves .250 inches further up in the bore with the same rod.

If you count the added distance of .1 above and below then yes, but I'm talking about the pin circle center being shifted the indicated distance of .250", you can't do that without welding the crank or going to a journal diameter smaller than 2.00". I guess we're just looking at it from two different aspects that are in a sense correct.

[gectek]

im talking about welding it up and offset grinding then redrilling the oil holes and then having it chamfered, polished and balanced accordingly, of course with custom pistons with the pin height already compensated...i like the thought of the 3500, but i really want a clean and easy install. if i can get mile high to cut the timing marks into the crank, then that would be better...then i wouldnt have to worry about the difference in the timing reference, and it would be a drop in engine, but otherwise ill have to go with the TCE piece, which wouldnt be that bad. I am torn between two ideas...but a stroker would be very nice...esp a 3.8 or 3.9 stroker...yah the rod ratio might have gone a little off, but even a 383 has a not so average rod ratio and they still produce good power

[Joseph Upson]

im talking about welding it up and offset grinding then redrilling the oil holes and then having it chamfered, polished and balanced accordingly, of course with custom pistons with the pin height already compensated...i like the thought of the 3500, but i really want a clean and easy install. if i can get mile high to cut the timing marks into the crank, then that would be better...then i wouldnt have to worry about the difference in the timing reference, and it would be a drop in engine, but otherwise ill have to go with the TCE piece, which wouldnt be that bad. I am torn between two ideas...but a stroker would be very nice...esp a 3.8 or 3.9 stroker...yah the rod ratio might have gone a little off, but even a 383 has a not so average rod ratio and they still produce good power

If you do this with a 3900 block, rod ratio will not be a problem because you can use LS1 pistons which come with several different compression heights as low as 1.030 still leaving room for use with a 6" connecting rod. Welding up the crank and regrinding will run in the $600 ball park due to the need to address 6 individual throws, I've already looked into this in an effort to create a 60 degree 4.3L.

[gectek]

that might be a better option...but a little on the expensive side. oh well...i have the resources to do it if i want i guess. I think itll be exciting. I can see it already, lots of TQ and revvin it to 7 grand...sounds like fun esp with lightweight pistons and rods

[geoffinbc]

If your talking about welding up the older model cranks like the 3400 then I would be very cautious. Cast iron is particular metal and unless the welder properly pre heats and post heats it you could be in for some problems.

[Joseph Upson]

If your talking about welding up the older model cranks like the 3400 then I would be very cautious. Cast iron is particular metal and unless the welder properly pre heats and post heats it you could be in for some problems.

Not to mention it will cost about twice as much to do considering the price quotes I've received for welding the steel crank in an effort to achieve the 3.48" stroke, over $650 as opposed to as low as $225 to offset grind the steel crank to the max possible.

[gectek]

well i have a few connections at some awesome crank builders...and yah you are talking about stress relieveing if i am correct....maybe

[montess408]

Not to mention it will cost about twice as much to do considering the price quotes I've received for welding the steel crank in an effort to achieve the 3.48" stroke, over $650 as opposed to as low as $225 to offset grind the steel crank to the max possible.

how much can you off set a 3400 crank b4 you get problems ? .125 ?

i was talking to a guy that has a stroker motor and he said that his stroke is now 3.510 and as far as i know he is using stock lengt rods and pistons

[Joseph Upson]

how much can you off set a 3400 crank b4 you get problems ? .125 ?

i was talking to a guy that has a stroker motor and he said that his stroke is now 3.510 and as far as i know he is using stock lengt rods and pistons

Impossible, you can't use the same piston and rod in any engine that has crank stroke increased unless you have at least that much clearance plus some above the piston in the stock engine at TDC before hitting the cylinder head.