Better intake Valves for stock heads?

[Brian Mc]

OK, i have engine out and am doing some low cost mods in search of performance. i have pocket ported the heads and gasket matched the intakes and will finish this, was wondering if there are better intake valves to use. teh stock ones have a sharp ridge on tehm that looks like it will block flow. also, is a five angle valve job worth anything?

 

[qwknuf6 jr]

Manley has stock replacment intake valve 1.7 and a larger 1.77 intake valve , not sure you will pick up much w/just the valve upgrage

 

[Nick Micale]

The gain with larger valves will mainly come with the associated machining for them and the bowl work. Obviously NOT a drop in item. We only use them when doing a full port and polish job on iron heads, and find noticable gains.

Further, we have found the 5-angle job has insignificant difference over a 3-angle. The 5-angle also has very narrow lines on the iron heads and will not last very long.

 

[Brian Mc]

i'm not talking larger valves, i'm referring to the ridge on the stock intake valves just above the seat surface. can it be cut down for better flow?

 

[UNGN]

Originally posted by Brian Mc
i'm not talking larger valves, i'm referring to the ridge on the stock intake valves just above the seat surface. can it be cut down for better flow?

Yes. The machine shop I deal with does this as part of their valve job. It's referred to as "back cutting" the valve. It will noticeably improve flow, especially at low lifts.

 

[Brian Mc]

should i back cut inakes only?

 

[UNGN]

Originally posted by Brian Mc
should i back cut inakes only?

Both intake and exhaust flow will improve with back cutting the valves.

 

[Brian Mc]

thanks i have access to a valve grinding machine at a friend's house so i'll do both intake and exhaust