TermnEatr

iTrader: (24)

I have a 370 with stock crank, diamond pistons and 6.100 rpm rods if I was to take it to a 408 could I use the same pistons with a 6.125 rod and 4 inch crank?

dodson55

iTrader: (18)

nope it wont work in order to use them pistons you would need a shorter rod due to the stroke being longer the rod would need to be a 5.911 which i dont think they make your best bet will be to keep the rods you have and sale the pistond you have and purchase ones with the propper pin height

TermnEatr

iTrader: (24)

So what would u do I wanna go with a bullet rod cause I'm not happy with what I have now but if I do that I'm gonna throw a dragonslayer crank in it also should I just keep the pistons and the 370 ci or sell the pistons and buy new crank pistons and rods?

Sales2@Texas-speed

iTrader: (5)

If you want to go 408, sell your current pistons and buy the correct ones for sure!

Gunslinger09

I would get a stroker kit that came with the crank, rods and pistons all matched to work together. Probably come out cheaper than putting it together piecemeal too.

TermnEatr

iTrader: (24)

How much would I benefit though going 408 from 370 I'm running a f1a at 16-18 psi

PREDATOR-Z

Yes 6.100 rods will work, pistons will be .025 more "in hole" than with 6.125 rods. (depending on pin position in piston).
Ideally a custom rod to have piston flush with block could be ordered but not necessary.
Regarding OP, block could be decked to reduce in hole height of piston. IMO mock build it and then make the proper decision.


Hi Matt, this is a quote from your site.

Texas Speed & Performance rotating assemblies offer the best durability with the best pricing available! Our 408 C.I.D. rotating assemblies come standard with a forged Lunati 4.00" stroke crankshaft, Texas Speed & Performance H-Beam 6.125" connecting rods with ARP 8740 rod bolts, and Mahle -4cc flat-top pistons, wrist pins, and plasma moly piston ring set. You can choose from a variety of upgrades for the crankshaft, connecting rods, and pistons! FYI, All Wiseco piston sets will come standard with their steel top/napier 2nd ring set! Bearings are not included in the base price but can be added to your rotating assembly package. Give us a call, and we will be happy to spec out a rotating assembly that will match your needs!

Sales2@Texas-speed

iTrader: (5)

^^What's your point? Out kits have aftermarket rods, he wants to use an existing piston. What are you trying to get at? He could use the 370's pistons with roughly a 1.330" CD, a 4.00" crank, and those 6.100" rods...his pistons would be about .19x" OUT of the hole. Or he could go with a 6.125" rod and the same pistons with the 4.00" crank and they'd be about .21x" OUT of the hole.

So, I'm not trying to be a dick, but I guess I'm just trying to figure out what you were trying to show by quoting our site

TermnEatr

iTrader: (24)

They are .007 out the hole right now correct? Or in that ballpark..... What im getting at is no matter what I'm going with different rods probaly a compstar or howards possibly depending on funds but if there won't be much to gain from a 370 to a 408 then I will just swap rods and be done with it and keep my stock crank and diamond pistons or possibly get a forged stock size crank and keep the same pistons.

KCS

iTrader: (20)

I think you've got it backwards, he wants to use pistons intended for a 370ci engine and use them with a 4.00" crank to make a 408ci engine.

PREDATOR-Z

The usual correct common combo

Sales2@Texas-speed

iTrader: (5)

Gotcha. Thanks for clarifying, and again, I hope that didn't come across too dick-headish.

PREDATOR-Z

No problem Matt, you protect your interests and I am passionate about LS modding. I just try to make less experienced members to follow more proper build protocols instead of just slapping stuff together and hope for the best.

TermnEatr

iTrader: (24)

Asking ?s doesn't mean I'm slapping stuff together im just trying to educate myself the right way by asking questions and not learning from mistakes.

PREDATOR-Z

Please do not take that personally. I was just making a general comment not solely directed at you.

bww3588

iTrader: (49)

If I recall, 408 pistons have a 1.115 compression height, my 370 pistons have a 1.3045 compression height.

To use 408 pistons (1.115 compression height) with a stock stroke crank, you will need 6.314 rods to bring it to 0 deck.

Then you can swap rods out to 6.125 with the 4 inch crank and have the same pistons at 0 deck.

My opinion on this, do it once, do it right.

lemons12

iTrader: (71)

F1, I would make sure I had a forged crank.