3 angle valve job question

[jdb85]

i just got a set of gt40's off a 351 lighning from ebay and sending them to the machin shop. i cant afford the port and polish but a 3 angle valve job is 50 bucks
is this worth doing to the heads? i'll be racing the car on the weekends other than that is a fun street car. will there a any power gains? if so any idea what it might be?

mods- roller 302, 650 edlbrock carb, performer rpm intake, e303 cam, 10:1 compression.

thanks

 

[Cobra_Dusten]

i maybe wrong, but 351 heads have larger head bolts than your 302 block, correct?
A 3 angle valve jobs cleans up the seats where the valves meet the heads. And yes, its worth the $50.

 

[347HO]

When done correctly, the 3 angles allow the air charge to flow through the bowl area, past the valve seat more efficiently.
If you can afford the small price to have the valve seat blended into the bowl along with the valve angle... that is a serious "bang for your buck" mod. If your machine shop doesn't know what this is, or doesn't do it, take your heads to a real machine shop/cylinder head shop.

Yes the bolt holes are 1/2" but you can use stepped washers such as Trick Flow offers. Some people actually just use the dowels already in the block to align the heads and use the normal 7/16" bolts. I'm using the stepped washers.

 

[Gearbanger 101]

If you can trust the quality of their work and all they're charging you for a 3-angle valve job is $50....take it and run!!!

 

[parrish5o]

I would be hesitant to let a shop I didn't know work on my heads if they only quoted me $50. But if it is a qualified establishment that does good work no doubt it will be worth the money.

 

[lang williams]

it is a good bang for the buck, so is a 30 degree cutback on the intake valves, an having the milled a little to bump compression. from the sounds of their pricing you might come away with these three items done for under 150. i paid $275 to have a three angle valve job, milled 30 thousanths, assembled with my supplied springs, they set the height an hand to get different exhaust retainers.

 

[jdb85]

sweet, thanks for the fast info,

its a little machin shop that does good work from what i seen, he was recomended from a co worker that has a hoped up dodge dart street car making 270 to the wheels.

the shop's rebuilding the heads and he said it'd be $50 more. so he's charging me a total of $300 that includes the 3 anglevalve job, magnaflux, new seats and some other stuff like making sure is flat on the bottom or somthin and installing my springs. as for my compression it should be 10:1 with the .200 dome pistons and 64cc heads, and since im wanting this to be streetable i figured it'd be better not to have them milled for even higher compression., but thanks for the recomendation.

also im getting the spacers or sleeves that adapts the 351 head to the 302.

as far as valve clearance and cam, what would be the best cam to run in a street/strip car were i could get alot of low end power and torqu for the street but will push me throu the whole powerband when drag racing on the weekends? i was thinking e303 or is there somthing better you guys might recomend? the piston company said i should be able to handle up to a .600 lift without vavle issues but i figured i wouldnt need to go that far for what i want. what do you all recomend?

 

[Cobra_Dusten]

milling heads for compression is the wrong way to do it. It's a lot better to do this with pistons.

 

[zm830101]

huh? if it is so wrong why have we been doing it for oh 60 years or so? qualify that statement PLEASE!

 

[Gearbanger 101]

huh? if it is so wrong why have we been doing it for oh 60 years or so? qualify that statement PLEASE!

It’s not necessarily “wrong” per say, but you're knocking .020-.030 off the deck of the head isn’t going to bump compression by any great degree and you increase the risk of piston to valve issues (especially if you deviate from the stock cam specs), as well as intake sealing problems. As it is, .030 will result in some creative silicone placement and the need to have your intake bolt holes elongated for fit. Milling the heads beyond that will require the need to have the intake milled as well for proper fitment.

Doing it with the pistons like Cobra_Dusten stated allows you to make more substantial increases in compression ratio, while still maintain the original valve train and intake geometry.

 

[347HO]

I agree with just about everything said "Gearbanger" which makes "Cobra_Dustin" 100% correct... milling heads to up compression is not the right way to do it.

 

[347HO]

huh? if it is so wrong why have we been doing it for oh 60 years or so? qualify that statement PLEASE!

It is now 2009.
There's now a large "following" of performance parts availabl for the SBF.
Doing things old school is no longer required, and will cost you more in the long run.

Today we have 18 year olds with daily drivers that would blow the doors off a similar "effort" setup of 30 years ago.

 

[zm830101]

while i agree it is less than ideal, saying it is the wrong way to do it is, well, wrong that is what bugged me about the statement.

 

[Gearbanger 101]

while i agree it is less than ideal, saying it is the wrong way to do it is, well, wrong that is what bugged me about the statement.

I wouldn't say that its wrong so much either, but its not the ideal way to do it. I would never deck heads to increase compression. I would however deck them to true the head surface....and probably take off a little extra for good measure (no more than .030 and only assuming it wouldn't cause piston to valve issues with whatever cam I was running).