Hey. I'm considering getting some new valves for my heads. The vavles I'm looking at are the Manley street flo series. I'm going to stay with my stock valve sizes (1.94 and 1.5). Would I have to do any maching to the valve seats to accept these valves? I know they are the same size but I'm not sure if there is a seat angle difference or something that would need reworking. I searched and couldn't find anything about it. I hope its not something known to everyone but me.

Thanks,
David

 

Nothing special or weird like that.

Get a good-quality valve job done on the heads, and lap them in like any other valves.

 

Are you sure you don't want the Race-Flos? The price is nearly the same, and they are more than durable enough for street use.

 

I had considered them but I'm trying hard to keep the price down, expecially if I have to machine the heads to accept the valves. I'm in college so money is tight. How much does a good multiangle valve job run? I'm new to machine work.

Thanks,
David

 

Just my opinion, but a multi-angle valve grind on a street engine provides little benefit for the reduced durability. You might want to ask your machinist about a radius grind on the front margin edge of the intake valve to help flow into th echamber. This doesn't affect seat wear at all, so there is no detriment. Around here, the concensus among short-trackers is that the front radius is good for about an extra 5 HP in a 358 SBC (with a NASCAR 2 barrel).

You should be able to get both heads hot tanked, crack tested, and have the valve seats machined for under $100. Be sure to check the valve stem clearance before you assemble the heads and install them.

 

Ok. I wasn't sure about the multiangle valve job. I had heard it helped out flow, but I wasn't sure how much it did. $100 ain't that bad. I probably wont have the crack checked since I just pulled them off of my car and they were doing well. Will I see a bit of improvement for the $200 for the valves and machine work or is my $200 better spent else where.

Are the seats a difference angle on the head than where they would touch the valve? I'm not gonna try to do it myself, I'm just curious what exactly is done.

Thanks,
David

 

A "regular" valve grind usually involves facing the valves at 45° while grinding the seats at 46°. Actually, the factory doesn't grind them any more, but uses an indexable ceramic tool to machine them to the depth and angle. Surface finish from common machining can be held to tolerances almost as good as grinding any more, so they eliminate the extra process. I'm not sure if the valves are lapped in or not. I still do it on replacement. I guess old habit die hard.

Watching an Ingersoll sequntial automated milling line crank out a small block in seconds is an amazing friggin' thing.

As for your valves, the Street-Flos are O.K. The Race-Flos are a little better for stem flow and are all stainless steel. They are $9.12 (2.02") and $9.24 (1.60") from Scoggin Dickey, so it's not a great deal of cost difference.