02blackbeauty19

iTrader: (22)

I am putting together a motor combo to go with TT's and I'm wondering if you guys think I might gain either efficiency or power by doing some light bowl blending and a good 3 angle valve job on a set of milled 317 heads?

JRENIGAR

iTrader: (37)

I think it would gain all over the board in both efficiency and power. I have been told most of the power in head porting is from a good valve job anyways, anything extra from blending the bowls would only add to the benifits of the VJ.

02blackbeauty19

iTrader: (22)

That's exactly what would think, but did a search and don't see much about good valve jobs and gains. Most just rant and rave about CNC porting, etc.

dschmittie1

iTrader: (64)

I know crazy power can be made on stock heads. I personally made 676rwhp with stock 241 heads on an old Procharged set up. That being said. I don't think something as minimal as just a valve job is going to net you a big gain on a FI set up. obviously there will be more power had from porting the heads as well.

If you are going to pay for a valve job and some bowl work you may as well just have them do some minor clean up the the runners. I think it would be worth it.

02blackbeauty19

iTrader: (22)

I've read the opposite on a couple occasions, but like I said, there isn't a whole lot out there from what I could find. I made mid-700's on these stock heads, but I was hoping to do some low-cost things to make them flow better.

I've read that doing a really good 3-angle valve job in conjunction with porting, that the majority of the flow/power comes from the valve job itself. That's one of the reasons I've thrown this thread out there.

nxfirebird

iTrader: (1)

opening up the ports never hurts, a fancy valve job on forced induction motor doesn't do alot though. once your in to boost it doesn't really care, it's going to push the air in no matter what the valve job is. does it make more, a little, but not enough that i'd spend real money on it.

02blackbeauty19

iTrader: (22)

Makes sense.

It may be far better to spend the money on porting the LS2 intake. I know these things don't flow for ****.

Nitroused383

iTrader: (10)

I have read some stuff about guys running a 50-55 degree valve seat on the exhaust side of a turbo setup. I'm not 100% sure on the theory but I believe the 50+ valve angle kills low lift flow (.200-.400) lift and helps cut back on the over scavenging the port during the overlap period. This supposedly can help reduce back pressure and increase spool on a turbo setup. No doubt there are nice gains to be had in the proper valvejob. With that being said I honestly don't feel too many people have any clue about what a proper valve job is. I can tell you it's not the standard 30-45-60 angles.

02blackbeauty19

iTrader: (22)

So, is doing the standard 30-45-60 angles on valves what separates a standard valve job to a "competition" valve job?

Shawn @ VA Speed

iTrader: (3)

anything that promotes airflow in a cylinder head is good whether it be an n/a engine or fi. Anybody who thinks that good port work and good valve jobs on forced induction is a waste is sadly mistaken. Anytime you increase the efficiency of an engine , you increase power and wear and tear on the engine

turbo'd stang

VJ are very important. By the time you read about it on the internet, people have moved on to better things.....

02blackbeauty19

iTrader: (22)

Thank you, Shawn.

Now I'm sure you have your builder secrets, but could you advise us [me] on any angles I should stay away from? ie - Standard valve job vs. competition valve job?

Nitroused383

iTrader: (10)

It seperates average small block chevy engine builder from the people who understand 15 degree ls stuff.

Shawn @ VA Speed

iTrader: (3)

alot of valve job depends on the heads and the valves. Generally speaking any good 3-5 angle valve job will pick up airflow. But a great valve job varies by the head. I know the trickflow heads likes a way different valve job than a mast head, and stock heads will act differently depending on the size of the valve and the type of valve. With that being said, I really don't know the best on a stock head as I really don't hardly use stock heads-but we have used a std 30-45-60 with good results.

sorry for rambling

02blackbeauty19

iTrader: (22)

No worries, Shawn.
I appreciate your input.