3 angle valve job vs 5 angle valve job

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Dan the man

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I've been reading more about people using 5 angle valve job on their cylinder heads. Is there a advantage to this on a mild build? With going to a 3 or a 5 angle valve job should the seat's / valve's be replaced? On the 5 angle valve job what are the preferred angles?
 
It’s not the angles, it’s how it opens the port and smooths the way into the chamber.

If you need a valve job, it’s worth the added effort, but it’s not just pulling your engine apart to do it. Usually adds a 15 deg and 75 deg angle to a 3 angle seat.
 
For your stated usage in a previous post, seeing as how your engine will rarely be at WOT, never mind at high rpm, IMO, unless the heads are coming off anyway, I agree with ch1ll, in post #2.
Now, if you were to pull out the hiway gears, and stick 4.30s in the back, Ok, now we're in a new arena.
But consider this;
3500 rpm with 2.76 hiway gears, an A904, and 26"tires at 10% TC slip, makes, 37.4mph; and Not to be mean, Brother, but Ima thinking your car will have been stuffed into Second gear, long before that.
I think I know what you want.
You want a lil kick in the azz off the line, and a snappy throttle.
and I'm pretty sure that's all you want. If I got that right, then all you need is a 2800 stall, and maybe some 3.23s, and a tune.
After that, a 4bbl and a free-flowing exhaust; both at the same time; but, unless the tires spin, that will only pick up where the stall leaves off. No need to open the engine up, unless she's tired.
Throttle response, in an 8/1 2bbl engine is gonna be more the the stall, and the tune.
If you install a 4bbl, without a higher stall, please let it be a small-port intake with a spreadbore, with triple boosters in the Primaries..
I realize this probably not the answer you wanted,
but it might be the answer you need. friend
 
Guess you never heard of mid range power 3000-5000 rpm you act like all mods only happen to add hp to 5500-6500+ rpms.
 
273 said:
Guess you never heard of mid range power 3000-5000 rpm you act like all mods only happen to add hp to 5500-6500+ rpms.
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woulda been better off posting a recipe for pozole than whatever that mumbo jumbo was up there.

ask about a 5 angle cut on the valves and get a manifesto about 4.88 gears and 3500 converters.
 
If the angles get too narrow and/or you have too many angles the valve job will act like it’s a radius.

Bye bye power when that happens.

For low port heads 4 angles is about it. You can get more but it’s not worth it.

There are huge differences in even 3 angle valve jobs.
 
junkyardhero said:
woulda been better off posting a recipe for pozole than whatever that mumbo jumbo was up there.

ask about a 5 angle cut on the valves and get a manifesto about 4.88 gears and 3500 converters.
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It's cause of his performance philosophy, a street car don't need lots of power and what power it does make should be between 2000-4000 rpms. Gearing, stall, exhaust, cr, tuning timing and carb are only allow everything else makes power 6000+ rpm seem to be the philosophy.
 
273 said:
It's cause of his performance philosophy, a street car don't need lots of power and what power it does make should be between 2000-4000 rpms. Gearing, stall, exhaust, cr, tuning timing and carb are only allow everything else makes power 6000+ rpm seem to be the philosophy.
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That’s the problem with philosophy. There isn’t a one size fits all.
 
ch1ll said:
It’s not the angles, it’s how it opens the port and smooths the way into the chamber.

If you need a valve job, it’s worth the added effort, but it’s not just pulling your engine apart to do it. Usually adds a 15 deg and 75 deg angle to a 3 angle seat.
Click to expand...
And backcutting the valves can help as well.
 
Dan the man said:
I've been reading more about people using 5 angle valve job on their cylinder heads. Is there a advantage to this on a mild build? With going to a 3 or a 5 angle valve job should the seat's / valve's be replaced? On the 5 angle valve job what are the preferred angles?
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On a mild build, probably not, but, it would depend on what it would cost you to do it. If it's cheap (your definition on that), why not? When I was grinding my own stuff, I used 15, 30, 45, and 75 degree cuts. Just those 4. The 15 and 75 were mainly just to clean up rough or protruding edges and throat the bowl area a bit. If I wasn't doing any porting, I also buzzed any rough casting flaws especially on the exhaust side.
 
Don’t think your going to get boatloads of cfm increase or hp increase by going to a 5 angle from a 3 angle.
 
Dan the man said:
Was just asking a question
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Question is to open ended. A,real answer would require intended use. A stock/slant, 318, 340, 360 with mild cam, mild big block, lawn equipment engine? Mild street strip, race? Totally dependent on what the engine use intendedto be used for.
You night as well ask what a favorite color is......
 
ch1ll said:
I agree, but intake only as a vapor ridge on exhaust can help stop reversion.
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Good to know. My 273 heads were done on the Serdi. Now I find a radius may not be the best thing. Intake or exhaust?
 
toolmanmike said:
Good to know. My 273 heads were done on the Serdi. Now I find a radius may not be the best thing. Intake or exhaust?
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On the seat? Most porters I know of on YouTube radius to the 60 deg on both and smooth the chamber to the 30 deg.

I’m thinking the 5 angle is the machinist way to make a better transition into and out of the valve seat when not porting with a die grinder.

If you have faith in your porter and he has a good rep, trust him that he did what was best. Most folks of modest means can’t afford a set of heads ported by Darren Morgan. Is it worth it to you for that 5-10 hp more? If you have the cabbage, get to Darren.

I like champagne,but I’m still drinking beer.

Even though the valve and seat is the greatest point of restriction in the head port, there are other things to consider like efficiency and port energy. A ported intake and the right sized carburetor properly massaged greatly enhances your combination.
 
Depends on the chamber, valve, app, lift range.

Blanket statement would be to simply say it'll increase the flow at all lifts.
Sometimes small increases in flow don't equate to power increases.
The diff can be negligible in some instances.

Testing helps.
 
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