a 2 angle valve job?

[ziggy]

regaurding my 72 IL6, chevy 250cid. i got the head into the headshop guy. says he's gonna R&R the valve seats with some hard ones so i can run unleaded fuel. headshop guy says, just by lookin at how high or low a valve sits in the head he can say that i need new seats hard or not. seems like the hard ones are the way to go. my question is. i guess i thought that most valve jobs did a 3 angle valve seat job. headshop guy is gonna do a 2 angle. his reasoning sounds good. says that the new hard seats don't have the material to grind to a 3 angle job. says the seat width will be not enough. will burn the valves w/o enough seat width. the headshop guy seems like he's pretty hip to what he's doing. even had a few marine parts layin around, and says he loves marine. even had some other persons IL6 (mercruiser)head in his millin machine...so is this 2 angle valve job what i need? any ramifications between a 3 angle and 2 angle seat?....just wondering if anyone had any insight to this notion.....i guess my thought is that if the seat is the proper width and in the middle of the valve seat face, it must be ok. but thats my only slightly educated thoughts though....

 

[mkast]

Re: a 2 angle valve job?

Three angle valve jobs are usually reserved for racing applications. Considering your engine will never see anything over 5000 RPM, you won't get anything in return for the money spent.

 

[Bondo]

Re: a 2 angle valve job?

It wasn't All That Long Ago, that a Valve Job only Included 1 Angle..............45*s.....<br /><br />Go with Whatever Your Head Guy is Set-Up For.....

 

[ziggy]

Re: a 2 angle valve job?

thanks guys for the input. yer probably both right.<br /><br />

mkast<br />Member # 17290 - posted April 25, 2006 08:09 AM Three angle valve jobs are usually reserved for racing applications. Considering your engine will never see anything over 5000 RPM

thats certainly true. i was hopeing to see 3900-4400. <br /><br />

Bondo<br />Member # 8448 - posted April 25, 2006 12:12 PM It wasn't All That Long Ago, that a Valve Job only Included 1 Angle..............45*s.....

like perhaps in 1972 for the one angle bondo. was readin vol.1 and that would be the spec it seems for my engine. 45* for the valve and 46* for the seats.... thanks for the input....it apears my machineist is on the right track....

 

[rodbolt]

Re: a 2 angle valve job?

what the angles mean is hard to describe but to raise or lower the valve seat 2 angles are nessasary the third angle is under the seat area. its to open up the area below the valve seat angle to allow more gas flow both in and out.<br /> for everyday use a single angle is best as it leaves more metal to keep things cool.<br /> I hope your machinist is good or the seats may fall out.<br />most stock motors wont pound the seats out, quite a bit of motors with .500+lift cams and 300+PSI open pressure springs turning more than 6K will . <br /> yours should be fine.<br />the seat and face are normally ground 1-2 degrees different to aid in sealing and keeping the faces clean.<br /> get a good shop and let them go

 

[ziggy]

Re: a 2 angle valve job?

rodbolt<br /> what the angles mean is hard to describe but to raise or lower the valve seat 2 angles are nessasary the third angle is under the seat area. its to open up the area below the valve seat angle to allow more gas flow both in and out.

i guess this was what i was thinking about was this third angle to help it breath better for lack of a better way to explain it. i just remember talking about it in (oh my, he's not gonna say it is he) auto shop class. i know i'm supposed to forget auto shop class. . anyways, <br />

rodbolt<br /> <br />for everyday use a single angle is best as it leaves more metal to keep things cool.

this is what the machineist also was talking about was the fact that the valves only get cooled when they are in contact with the head. so i guess the more the merrier for seat contact width it seems, within spec that is...i hope he's good too as i go back and reread about doing a valve job there are many things to take into consideration. i guess i have to assume that he's checkin all the appropriate parts for wear and excessive clearances.....he's the machinst, so i expect him to know the realationship of these parts when they're reassembled....he did seem to talk knowlegeabley about his trade and was proud to show me some of his work in progress, includeing someone elses mercruiser IL6 head that had just been planed and a couple of weld jobs on marine blocks and manifolds (also the IL6 manifold which had internal freeze damage that he said he could not repair). so far i'm impressed, he at least seems to know the difference between servicable and not servicable, but time will tell for me....guess i need to start cleanin up the parts i got left for when the heads done....thanks peoples.....