3500 head swap

[xtremesunfire]

anybody got the part numbers for the 3500 valves?

[SappySE107]

He will be using the 65mm Billet TB. 4.3 is 70mm and way too touchy on the throttle. Ill get you the part numbers when I get home if no one else posts them up.

[Syn]

He will be using the 65mm Billet TB. 4.3 is 70mm and way too touchy on the throttle. Ill get you the part numbers when I get home if no one else posts them up.

hmm interesting, any specific reason why its so touchy?

i missed it in his post where it said 65mm t/b it was late lol

[xtremesunfire]

Ok now when I put the 3500 vavles into my 3400 heads what kind of springs should I use? LS1, LS2, LS6 or LS7 also I am thinking about turboing my 3400 and a other thing what keepers should I use and valve stems should I use?

[TurboGt]

What is the difference in the blocks?? 3400 vs 3500?

[Syn]

Ok now when I put the 3500 vavles into my 3400 heads what kind of springs should I use? LS1, LS2, LS6 or LS7 also I am thinking about turboing my 3400 and a other thing what keepers should I use and valve stems should I use?

theres a how to that covers the lsx spring swap

[xtremesunfire]

where is that how to at?

[SappySE107]

A 70mm TB lets too much air past at very low throttle openings which is why its so touchy.

Part numbers for the valves are

12568411 and 12568412

[SE'sarecool2]

Those valves are expensive! $17.68 each for the exhausts! Ouch! All i have to say is they better be worth it.

[xtremesunfire]

no they went down because when I checked the prices about 3 weeks ago it was like 21 dollars that is for the exhuast and I know the intake was about 12 dollars now its 10 dollars

[El_Diablo]

ben, do you have a set of heads yet? i would like to see how much you can get out of them compared to the 3400 heads

also, nobody has talked much about the 3500 LIM. does it flow any better? i wonder what numbers could be extracted from it over the 3400 LIM aswell

[SappySE107]

3500 lower flows a lot better than the 3400.

I did some cleanup work on a set of 3500 heads but it didn't do a damn thing for flow. I dont have 200 bucks to be buying a head to destroy with testing right now so it may be a while before I get into porting 3500 heads.

[AaronGTR]

Has anyone flow tested 3400 heads with 3500 valves in them yet? I keep hearing the 3500 valves are better. It would be nice to have some flow numbers. I have an extra set of 3400 heads I could send in for flow testing if someone wants to send him some valves.

[SappySE107]

Ive flowed the intake stock but I dont think I did it on the exhaust side. Exhaust valve isn't much different so I dont expect much on flow increase.

Stocck 3400 head with 3500 intake

0.0500 32.4
0.1000 58.5
0.1500 80.9
0.2000 102.7
0.2500 127.4
0.3000 151.4
0.3500 173.8
0.4000 191.8
0.4500 204.1
0.5000 212.1

Stock 3400 head with 3400 intake

CCFM
Lift No. 1
-------- -------
0.0500 32.8
0.1000 58.3
0.1500 82.0
0.2000 103.8
0.2500 127.6
0.3000 151.1
0.3500 172.2
0.4000 190.5
0.4500 204.0
0.5000 214.8

I dont think its the same port but you can see it doesn't do much on a stock head. Its a modified head that shows the difference. Ill have a set of 3500 valves tomorrow (i hope they are a direct copy...they are aftermarket meant for the 3500). Ill show you the difference on my level 2 heads with stock valves and with 3500 heads then.

This is stock intake port with combustion chamber deshrouding and 3500 intake valve.

CCFM
Lift No. 1
-------- -------
0.0500 34.6
0.1000 66.0
0.1500 94.4
0.2000 126.5
0.2500 154.0
0.3000 174.1
0.3500 189.7
0.4000 201.9
0.4500 209.0
0.5000 213.6

Picture for those that hate numbers:P Green is obvious I would hope...but its the deshroud with 3500 intake valve.

[El_Diablo]

ben- do you just need one 3500 head? or both? are they not usable once your done?