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Head Building Questions
https://slantsix.org/forum/viewtopic.php?t=67607		 Page 1 of 2
Author:  Greg Ondayko [ Sun Jan 28, 2024 7:15 pm ]
Post subject:  Head Building Questions
Hello all

For the last few builds I have done, ('69 Dart, '79 Duster, Ruster and '64 Grüne Hölle), I either had a shop build me a head or I sent one to Mike J. for obvious reasons or I bought one second hand that had been done wiyh larger valves, port work etc.

My question here is about valves.. I want to use 1.5" & 1.8" valves, with new guides and cutting / flattening the valve spring pocket and lowering the valve guide height to permit a higher lift cam(s) as needed.

Does it matter if both valves are advertised for their OE Use (Chevy, I believe) that they are exhaust valves?

I.E.:
Original use/designation: Chevy 1.5" Exhaust valve - My Intended use: Slant 6 modified head Exhaust Valve
Original use/designation: Chevy 1.8" Exhaust valve - My Intended use: Slant 6 modified head Intake Valve


Thanks Sages!
Author:  slantzilla [ Sun Jan 28, 2024 9:56 pm ]
Post subject:  Re: Head Building Questions
Nope. Won't matter.
Author:  Dart270 [ Mon Jan 29, 2024 3:22 am ]
Post subject:  Re: Head Building Questions
Agreed. Note that Mike J settled on 1.76" valves for even big bore (0.100" or more over) due to valve shrouding. He told me he did substantial testing and the 1.76" he felt were the biggest that were useful. However, if you were to move the valve over, then 1.8 or bigger might be worth it? Or, just go for it and see how it works... :D

FWIW, I have a never-run head I bought from a guy in CA back in 1996 with stainless 1.84/1.54" Chev valves in it, and I will try to run it on a 0.104" over engine at some point...

Lou
Author:  Greg Ondayko [ Mon Jan 29, 2024 4:55 am ]
Post subject:  Re: Head Building Questions
Thanks, guys.

That's kind of what I thought, but I wanted to check to be sure.

Was not sure if there were some sort of special considerations for one valve over the other.

Greg
Author:  Greg Ondayko [ Tue Jan 30, 2024 8:34 am ]
Post subject:  Re: Head Building Questions
Okay Next question sages,

Where do you guys go to look / resource to utilize to find a specific valve spring based on seat pressure / instlled height open height and pressure?

I emailed Ken@ OCG about my cam and He gave me recommended pressures for seat and open, but I am having trouble finding the correct spring pressures/rate for my application at the installed height.

Thanks, sages!


Greg
Author:  hyper_pak [ Tue Jan 30, 2024 9:33 am ]
Post subject:  Re: Head Building Questions
I am going thru this now.
I downloaded the Isky PDF for all their springs.
Going to call tech for the confirmation.
I have a height micrometer that makes installed height easy.
And a spring scale so I can check and confirm what I have and what I am getting.
Author:  Greg Ondayko [ Tue Jan 30, 2024 10:20 am ]
Post subject:  Re: Head Building Questions
Quote:
I am going thru this now.
I downloaded the Isky PDF for all their springs.
Going to call tech for the confirmation.
I have a height micrometer that makes installed height easy.
And a spring scale so I can check and confirm what I have and what I am getting.
Yes I have that stuff.

I am setting up your old head that you sold me, thank you!
So far the valves seem good, I derusted the ports and have to replace a seal or 2. a few got smooshed somehow.

It has Chevy valves, springs, locks, retainers etc. which is not a problem. and I want to make sure it is matched to my cam and setup. so there are no issues.

My valve micrometer works best installed upside down due to the way it works with the retainer. - goofy.

Greg
Author:  Rick Covalt [ Tue Jan 30, 2024 1:35 pm ]
Post subject:  Re: Head Building Questions
I got mine from Mike Jeffrey! :D

Honestly there is probably a good bit of wiggle room in those numbers. I mean if you need 100#, 120 is not going to kill you. or 250# 275# should be fine. Especially on a street motor. As long as you can keep the lifters on the cam with a given pressure you should be Ok. Just my opinion.
Author:  slantzilla [ Tue Jan 30, 2024 2:53 pm ]
Post subject:  Re: Head Building Questions
Because of the small valves and lower rpm you can get away with a little less too.
Author:  hyper_pak [ Tue Jan 30, 2024 3:40 pm ]
Post subject:  Re: Head Building Questions
Glad the head is going to work out for you Greg.
Author:  ceej [ Thu Feb 01, 2024 9:54 pm ]
Post subject:  Re: Head Building Questions
Zilla,

Next time you talk to Mike, he tried some funky angles on the grind, he came up with some impressive numbers by changing the angles. But for the boost I was planning to run, it didn't pan out, IIRC.

It's been a while, but I'll bet he remembers what I'm trying to talk about. Naturally aspirated, he found a way to increase flow by using non-standard angles.

See if that stirs up any of his memories on the subject.

CJ
Author:  Rick Covalt [ Fri Feb 02, 2024 3:10 am ]
Post subject:  Re: Head Building Questions
I think he used 30 degrees instead of 45 on the intake to improve low lift flows.
Author:  Dart270 [ Fri Feb 02, 2024 3:40 am ]
Post subject:  Re: Head Building Questions
That's it. He did that on my turbo engine head.

Lou
Author:  Charrlie_S [ Fri Feb 02, 2024 4:05 am ]
Post subject:  Re: Head Building Questions
Thirty degree valve angles work well on "lower" rpm street/torque motors, with low(er) lift cams. I was doing that on my "stocker" type motors back in the '70's. Another thing we did back then was use cams with (for the time) very fast lift rates. We had to run stock duration and lift back then. We got more "area under the curve" with the lift rate. The limit on lift rate was dictated by the stock valve spring pressure. Today I think the lift rate (flat tappet) is more determined by the lifter diameter. I have always wanted to try a "mushroom" lifter/cam in a slant. I think it might be a good compromise instead of a roller cam.
Bush the lifter bores and spot face the under side. Use a mushroom lifter (Ford "Y" block/Volkswagen/etc) reground cam (Oregon cams?) 3/8 pushrods, beehive valve springs, 7mm valves.
Author:  slantzilla [ Fri Feb 02, 2024 10:11 am ]
Post subject:  Re: Head Building Questions
I believe Mr. Ondayko is in possession of 'The Book of Secrets' now. It will all be in there. :mrgreen:
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