Valve seat angles

[RevTheory]

Didn't Billy Godbold say something along the lines of 30* degree seats up to about .25/D, 45* from there up to ~.37/D and 50* beyond that? I'm sure the port needs to be worked around that.

[CGT]

I have a good friend with a LS7 corvette, he did a little lower of the ssr and a 50 degree Vj. .650 lift cam. Runs very good. To me, your application has 50 degree or steeper seats written all over it.

[user-9274568]

I'd put a 40 top 45 seat on that head....

[user-30257]

I'd put a 40 top 45 seat on that head....

Just sink the valve job some more why doesn't he.
If he has a 50 degree seat, the top cut is probably 46. In order for that to come in they must have sunk the valve job quite a lot. So are you suggesting to sink the valve job even more? Will the bottom angles come in? Does it need new seats in order to do the job properly? Most likely.

Id say grind the valves 50 if the seats are already concentric.

[user-9274568]

I'd put a 40 top 45 seat on that head....

Just sink the valve job some more why doesn't he.
If he has a 50 degree seat, the top cut is probably 46. In order for that to come in they must have sunk the valve job quite a lot. So are you suggesting to sink the valve job even more? Will the bottom angles come in? Does it need new seats in order to do the job properly? Most likely.

Id say grind the valves 50 if the seats are already concentric.

I'm saying I would but that on it if it was a head that left here. That head doesn't need a 50 degree, period.

I'd put the valves in it and run it like it is. But that's just me.

[randy331]

I would use 30* seats on almost every application.

Need all the controversial low lift flow you can get.

Randy

Dammit Randy....you poking the bear this early in the morning?????

You know this will start a pissing match.

I love it. Thank you. Should make the day go better!!!!!

Your not a fan of controversial low lift flow in your builds ??

Randy

[induction apprentice]

a 30 deg top cut in a LS7 head would kill the head.

[mag2555]

Any of you folks experiencing seats falling out with valve angles above 45 and spring seat pressures above 350?

[statsystems]

I would use 30* seats on almost every application.

Need all the controversial low lift flow you can get.

Randy

Dammit Randy....you poking the bear this early in the morning?????

You know this will start a pissing match.

I love it. Thank you. Should make the day go better!!!!!

Your not a fan of controversial low lift flow in your builds ??

Randy

Nope. Before I bought a flow bench I'd fret about .100 lift to the point of my hair falling out. Then I got the bench and learned there is way more to a flow bench then the paper the guy doing the flow works gives you.

I test at different pressures for diffent lifts. I also spend a lot of time doing other unconventional testing. Most of it shows if you get anal retentive about low lift flow you're probably going to lose power.

[ProPower engines]

Any of you folks experiencing seats falling out with valve angles above 45 and spring seat pressures above 350?

Are we talking about stock OEM installed seats? And it what material of Cylinder head??
There is only a couple good reasons seats drop out and a steeper angle I don't believe would affect the retention in the head unless the head annealed and relaxed the press fit on an aluminum head.Iron may take severe detonation to loosen the seats if they had .005 or better press fit. .006-.007 on aluminum depending on the head heat treat

[GARY C]

Ok, when is necessary to go to 50 deg or 52 deg valve seat angle?? The guy that done my heads last time had 50 deg seats with steel valves,
am using Del West Ti valves this time and they are 45 deg, am i going backwards going back to the 45 deg seats ? Pros and cons ?? heads are GM LS7, 0.740" lift lashed on the intake. Thanks in advance.

Regards, Garry

Your widow area at TDC will be more with a 45 than with a 50 so it may require a later IVO or a shorter seat duration then what worked before with your previous combo to prevent unnecessary reversion.

Your head and valve size would have more low lift flow on a flow bench with a 50* seat than a conventional head and vale size would have with a 45*.. but what it flows on a bench is not as important as what it does on the engine in relation to the piston...but you probably already know that.

If you are using the same cam as before you could probably map the window area from seat to TDC and get an idea of before and after widow area so you could adjust IVO accordingly.

[GARY C]

Dammit Randy....you poking the bear this early in the morning?????

You know this will start a pissing match.

I love it. Thank you. Should make the day go better!!!!!

Your not a fan of controversial low lift flow in your builds ??

Randy

Nope. Before I bought a flow bench I'd fret about .100 lift to the point of my hair falling out. Then I got the bench and learned there is way more to a flow bench then the paper the guy doing the flow works gives you.

I test at different pressures for diffent lifts. I also spend a lot of time doing other unconventional testing. Most of it shows if you get [Blank Post] retentive about low lift flow you're probably going to lose power.

Then again if you ignore it you also loose important data in relation to what takes place from IVO to TDC.

[steve316]

what important data?

[GARY C]

what important data?

data in relation to what takes place from IVO to TDC....

[steve316]

care to share?