350X Engine Build Thread

[lndy650]

ok so over the winter im doing some stuff to my 452x engine. heres a couple pics of the porting ( Still rough not polished yet) i went by a TC racing head from a 425 bigbore and took it a bit farther than TC did. well quite a bit farther lol i wish i had pics of before...
so all together im doing full race porting welding and grinding my own cam lightening the flywheel boondocker nitrous and having a custom CDI programed. and maybe more....more to come over the next couple months

first 3 are intake last ones exhaust

[lndy650]

the pics arent very good its hard to get a good shot of the ports... you cant really tell but i ground a a$sload of material out of the exhaust ports so theres not so much of a bend anymore

[Yamada]

What tools do you use to port a head?

[lndy650]

Snap-On porting bits and i got 2 regular size die grinders and 2 straight and right angle pencil grinders

[The Goat]

so you prolly should have known I'm going to ask this... what size exhaust are you running since you have the exhaust ports so large?

also...is there any worry that the flow is going to be so much it's going to push the power into RPMs beyond the reliable range of the valves?

[lndy650]

im building a custom exhaust i have to do some measurements to see how big i can go but im looking at 1 1/2 inch on each 5 inches long going into 2 1/4 to 2 1/2 inch single back to a TC Supertrapp silencer. Im not going too crazy with the cam and i have hardened rockers and new heavy duty valve springs so the valves will be fine. the CDI will have a rev limit built in also once i figure out mean piston speed at desired rpm and how much i think the valves can handle. lots of calculations to do.

[lndy650]

the new exhaust will be similar to this one but made with stainless and less welds... this one is pretty much a mock up.

[fabiodriven]

Let me start out by saying I'm no expert on porting, but from everything I've ever heard and read porting is more than just opening up the ports and removing material. I think to truly do it right you either need a ton of experience and/or a flow bench. You didn't say, Indy, but maybe you've done this before and/or have a flow bench? Either way, I'm curious about how that baby's gonna run. I know you're no dummy, so my guess is it'll just fine.:D

[lndy650]

ive been porting for years... its defenitly a lot more than just making everything bigger! with 4 strokes a lot of it is making a straight path for the mix to flow which is hard on a 2 valve single carb intake...im more experienced with 2 strokes but ive had very good results with my own porting on 4 strokes also. a flow bench isnt always helpful because it just shows how fast air/fuel flows but it dosent take into effect how long and at what times the valves open/close and how much the engine can suck in before it just blows it back out the intake. you want the intake valve to close before that point. i have used a flow bench in school but theres a lot more to it.

[fabiodriven]

Roger dodger. Sounds like you've got it under control.

[lndy650]

ya it should work out ok