Valve Seats 45 vs 30 single angle multi angle ??
Turbo Mini Forums

Well about to have the shop do seats and guides for my turbo 1098

we got talking at the shop and never made a call as to what was happening so left it to think about it some

the engine is intentended to be for weekend play use and not really do a lot of miles altho when used will be up it quite a lot

in short its a small bore block and rods with the 1098 crank and flat tops that come flush in the block
cam is the kent md274 rockers will be med 1.3 turbo carb on short cast manifold long 3-1 style ex mani 2" out from turbo with glass pack

now before going to the shop i had in my mind decided on 30 degree intake and 45 ex with hardened seat the 30 would follow vizards "trick 30 seat" being 0.01"x15, 0.05"x30, 0.02"x45, 0.04x60 and 70 into port not thats a load of work just for one seat

i had thought yeah lets do it as the flow is up all the way from a few tho off the seat to about 350 before it starts to lose out to the 45 so knowing my cam lifts about 270 or so thats some good 10-13 percent increase below 100 lift and 7 percent for 150 so it should breath more sooner seen how peak lift is momenteary compared to the duration i think it might be worth the hasstle

on the other hand a good 60 wide 45 has proven good resolts aswell and much less work

haveing the valves cut to 30 is also a thing id prefer not to do

they have a few insert cutters that have your typical 15,45,70 or what ever

also valve wedgeng/sealing is difrent

so is anyone useing 30 seats or messed with them?

I personally would not bother with 30 degree seats and use a fat 45 and a back cut on the valve . that is pretty foolproof, seals well cools well and is easy to do.

trouble with a lot of fancy seat configurations is that they are very finicky and you have to get it spot on to work. while just any back cut on a stock seat will work very well just about every time . 15 minutes work

Edited by Sir Yun on 15th Jul, 2015.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

I think the issue of poor sealing is enough to put most folks off using a 30degree seat. Looks good on paper but in reality on a road car it's probably not worth the hassle.
A basic 3angle job will work well enough and will be reliable with a decent width seat.

Phil.

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