I have been looking at Manleys site and they list a 1.60 exhaust valve with a 30 deg tulip. Would this flow better than say a necked down raceflow valve? Also I am interested in knowing how big you can go with the valve size in a LT1 chamber. I was thinking about 2.08 int or 2.100 int and 1.625 exh and then have the serdi machine unshroud for the valves. Chime in and throw me some ideas

 

You'll need new seats to go that large, and 2.100/1.625 may require offset guides. If your using oem heads 2.00/1.56 seems to work out. Minimum unshrouding in the camber, can use stock seats. I'm pleased with my intake flow, 268@stall, the exhaust is lazy, only 201@stall. If I do these heads again I think I can get 210/215 on the exh side.
If you want big flow numbers start with aftermarket heads.

 

Yeah I was thinking that 2.10's and 1.625's might be too big, but I know that Lingenfelter goes with 2.08's and 1.60's with no problems. Granted I would need to unshroud the chamber to accomadate the valves with a Serdi machine or something equvilent. I guess I will buy one straight stem, race flo, pro flo and then the new 30 degree tulip valve they have and flow each one on the bench and see which one flows the best. Ill psot back when I get the results, thanks for the replies

 

I'll bet Manley has the data. Why not call them and ask? If you find out, please post it here. Enquiring minds want to know

Rich Krause

 

Cool, I was thinking of calling them this week, Ill let everyone know what there data said. Also I was wrong, Lingenfelter does use 2.00 1.56 in his heads. I thought he used to use 2.05 1.60's? Huh, anyway Phil has emailed me with some very useful things to think about so I might be going with some AFR LT4's, but I still want to see some flow differences so I will still do that experiment, thanks

 

Talk to any GOOD head porter and they will tell you that anything bigger than 2.00 in a LT1 head will have shrouding problems

 

Well, until you unshroud it, right

Yeh, I suggested he put his $ elsewhere.. the valves arent the restriction with the lt1.

 

I cant explain it, but you once you put in the larger valves there is a problem with the seats and shrouding of the chamber.

That is why you should really only go 2.00/1.55 on the valves

Look at George B's old LT1 heads.......one of my car club members bought his old LT1 heads and with a CC306 cam and those heads on a stock shortblock he was going mid 11s in a 6 speed and 10s on a 150shot

 

Well a 2.00 intake will flow more than enough in the LT1, so that's what goes in 90% of the sets we do. Like i told vx, the valve isnt the restriction, it's the port, but you can still unshroud it whether its a stock valve or a 2.100 valve, just takes more & isnt worth it on a lt1 casting w/o adding material IMO.