350x head on a 300ex jug?

[Cody_300ex]

Ok heres the deal guys (and gals), i was at the races the other night and i saw a 300ex in the pit area so i go over there to look at it. I was lookin at it and i saw 2 exhaust ports i was like wtf and i asked the guy how owned it and he said it was a 350x head. So does and bodywhat the performance gains are when you do this and how hard is it? thanks and yes i did a serch

[Cody_300ex]

anybody?

[TORO1968]

I imagine he had a 350x engine in his 300ex chassis.

-Jordan

[mersingt]

i know a guy who put a 350x head on a 300ex and bored it to a 450 and said it was really relieable hes a race shop guy and he also made alcohal burning ones starting at 45 hp

[Chanman420q]

Originally posted by TORO1968
I imagine he had a 350x engine in his 300ex chassis.

-Jordan

that would make more sence

[Cody_300ex]

Originally posted by TORO1968
I imagine he had a 350x engine in his 300ex chassis.

-Jordan

nope it was e-start, and there was no kicker, and i know for a fact it was a 300ex bottem end! :)

[ghak99]

Many believe with 2 exhaust ports they flow much better. I don't know for sure, but you would have to use a 350x cam and a custom header. One neg. would be that the 350x cam does not have bearings as the 250x or 300ex cam does.

[Cody_300ex]

does anybody know how to do this mod?

[TORO1968]

Sounds like a cool mod...anyone have more details?

[Honda250XRacer]

yea i know how to do it ......take the sh1t to monster garage , lol :cool:

[Mr.FDO]

This can be done.The head bolts right on. The piston will have to be modified for the bigger diameter valves , the combustion chamber will be to big for the 300ex bore (350x =81mm /300ex=74mm ), so compression ratio will be an issue. The 350x intake valves are 31mm compared to 25.5mm in the 300ex. This is a substantial increase in valve area , which should result in more air flow. The problem is that the 350x intake ports are actually smaller than the 300ex intake ports. So, to get the full benefit of this swap, you would need to build something 380cc's or bigger. This would allow the ports to opened up, so they would be more proportionate to the valve size. I really don't think this would be cost effective. I hope this helps.