3500 crank

[blkalero]

so correct me if im wrong because I prolly am

the crank can be offset ground down to the earlier engines size so you can now use the early SBC rods without much work and since the sbc rods come in the same shorter length as the earlier 3x00 rods then that should fix the length issue you would have with offset grinding and a stock 3500 length rod, correct? also, wouldn't the different length needed also change the effective stroke?

the 3.7 i remember though had a stock bore IIRC, maybe he was .020 over though?

I started the 3.7L strocker for my alero.. as of right now its not on my to do or finish list.
the engine is bored .020 over the rest was done with the crank.
they miscalculated how much we could go so we ended up welding the crank to get our longer stroke. this was only an option because the crank is foreged steel.

but we started with the jbody crank which I have found is a 3500 crank with part number removed and modified crank sensor wheel to work in the 3.1/3100/3400 engines
they sent it to me with the journals untouched so they had to be ground to take the sbc or 3400 rods. This is why i decided to offset grind and do a stroker. since the miscalculation was not on my part the only added expinse is a little more time to ballence. psitons were custom either way with no additional cost for different placement of the wristpin hole

[34blazer]

Ford 4.6 engines have a 92mm bore, and I'll bet a set of forged pistons for that would be lots cheaper then a custom set from Ross or JE. That was my line of thinking, not cheaping out.

do those use a pin that will work with the sbc rods?

[Monzsta]

in the case of building a stroker motor like this it isnt cheap, so why cheap out and use stock pistons, even if they are for something else???

Ford 4.6 engines have a 92mm bore, and I'll bet a set of forged pistons for that would be lots cheaper then a custom set from Ross or JE. That was my line of thinking, not cheaping out.

[sharkey]

in the case of building a stroker motor like this it isnt cheap, so why cheap out and use stock pistons, even if they are for something else???

another thing to keep in mind here is the idea rod ratio, wich is supposed to be 1.72. a 5.7" rod with a 3.56 stroke is 1.60, however the 5.9" rod puts you at 1.65, a little closer. in theory a 6.1" rod would be ideal, however that leaves you with a pin height of .989, the top of the pin bore would be .525" from the top of the piston.

just some numbers to think about

[Monzsta]

Found the GAGT thread on 3.7's...

http://www.grandamgt.com/forum/showthread.php?t=61383

[Monzsta]

The 3500 rod is 5.9", I coudn't find the rod length of a 3400 on Alldata or Mitchell. Chevy rods are stock length at 5.7", altho nearly any length can be ordered. The difference of .200" leaves the stock height 3400 piston about -.075" in the hole..

Lots of engines share the 92mm (3.62") bore, so it would only be a matter of searching to yeild a piston with the correct pin height to get zero deck.

With the 60 degree deck height of 8.818", minus the stroke divided by 2, minus the rod length, and you need a piston with around 1.333" pin height. The stock 3500 piston has a 1.263" pin height.
(8.818 -(3.56/2)-5.7=1.333)

[El_Diablo]

so correct me if im wrong because i prolly am

the crank can be offset ground down to the earlier engines size so you can now use the early SBC rods without much work and since the sbc rods come in the same shorter length as the earlier 3x00 rods then that should fix the length issue you would have with offset grinding and a stock 3500 length rod, correct? also, wouldn't the different length needed also change the effective stroke?

the 3.7 i remember though had a stock bore IIRC, maybe he was .020 over though?

[Monzsta]

On the subject of the 3500, the rod journal is a monster 2.249", vs the 1.999" of the 3400. A full 1/4 inch. That would give you an increased stroke of ..250" if offset ground for a displacement of 220 ci, or 3.6l up from the 204(calculated)ci of a stock 3400. Now you have to shorten your rod/piston combo .125" or your piston will be hanging out the top of the bore 1/8".

By offset grinding (0 off the top, -.250 off the bottom of the journal) you raised the effective center of the circle 1/8 of an inch. Now X2 because you're swinging it in a circle. 1/8 up + 1/8 down = 1/4 total stroke. Do the math. I used to do this for a living..

From the literature the GM tech on the Fiero forum posted the Steel crank is forged steel;

"The crankshaft is forged steel with deep rolled fillets on all 6 crankpins and all 4 main journals. Four steel-backed aluminum bearings are used. The #3 bearing is the end-thrust bearing."

also;

"The connecting rods are made of forged steel. Full pressure lubrication is directed to the connecting rods by drilled oil passages from the adjacent main bearing journal."

I don't know if a rod swap is justified, especially not for older refurbished chevy rods.

Sense you are dealing with a circle you can't offset grind a total of .250" from the crank and end up with a 2.00" journal, you have to divide the .250" oversize which will give a .125" offset increase in stroke since you are dealing with the stock 3.31" stroke. The big end of the rod is centered, otherwise you'll have to have metal added to accomplish the .250" stroke and I provided a source in another thread that would do it for $400, without metal added $200.

I believe clearancing of the block will be required for the 3500/3900 crank in the 3400 block. When you get right down to it the cost effectiveness to retain the 3400 block and modify the 3500 crank to fit probably borders on or exceeds the cost of using the complete engine and having the room for future stroke increase that GM already stated there is room for in the newer motor.

http://www.flatlanderracing.com/crankshaft_services.html#weldedstrokers

The larger journals are a benefit to rod bearing durability so you may want to consider added metal to keep the journal size and using custom pistons with the stock 3500/3900 rods, the parts in these motors should be better over all than the earlier stuff.

[ForcedFirebird]

I'm very interested in stroking now. If the 3500 crank will fit in a 3.4/3400 block 3.605l would be had with a stock bore.

Was was done for rod length?

[bszopi]

http://www.grandamgt.com/forum/showthread.php?t=62278&page=3

Babalouie is the guy's name. Although I guess there is still some questions on his motor. I thought he used a reground crank, but others say the 3.7L was accomplished with the bore. And of course, he never really comes clean to explain it.

[silvergtjrad]

Guy I am thinking about with the 3.7L is a guy on GAGT (not John) that had an engine built by either RSM or JBP. Many people have disputed his engine though...

Ive never even heard of this guy or rumors of this engine before and I spend quite a bit of time on GAGT. Interesting.

[bszopi]

Guy I am thinking about with the 3.7L is a guy on GAGT (not John) that had an engine built by either RSM or JBP. Many people have disputed his engine though...

[sharkey]

but the question is, is it still possible to do a "3600" stroke using existing off the shelf parts such as the small journal SBC rods? i suck at remembering the measurements of such things... thats why i always kept a lil cheat book handy at the machine shop, lol

also, i remember some guy on GAGT talking about a 3.7l stroker? anyone remember the guy and how he achieved this?

.250" longer stroke and .040" overbore gives 3.72L.

[El_Diablo]

i remember he also had another set of pistons built for an even larger engine aswell? 3.9 after the overbore IIRC? same guy? last time i heard about this was atleast a year or more ago