Valve job on os valves

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Slant Six Bumblebee

Slant Six Bumblebee

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SOry for the multitude of posts recently but i am rebuilding my head and converting to a super six currently. I was wondering if i should get a multi angle valve job with my new oversize valves. they are the 1.7/1.44 valves from orgen cams (just up the street) and if the hp gains are minimal or with the cost.
 
I did on mine. I'm fortunate in that I have a friend who does really high end machine work for dirt track guys. He has a very new Rottler and can set it up to cut eight, ten angles at once. It's pretty badass. That's what he cut my head with. The only way I could see the 45 was when I lapped the valves in. The valve seat area looks convex in a round shape there are so many cuts. It's pretty dang nice. The valves he said only really the 45 and a 25 back cut on the intakes, so that's what we did. It turned out nice.
 
RustyRatRod said:
I did on mine. I'm fortunate in that I have a friend who does really high end machine work for dirt track guys. He has a very new Rottler and can set it up to cut eight, ten angles at once. It's pretty badass. That's what he cut my head with. The only way I could see the 45 was when I lapped the valves in. The valve seat area looks convex in a round shape there are so many cuts. It's pretty dang nice. The valves he said only really the 45 and a 25 back cut on the intakes, so that's what we did. It turned out nice.
Click to expand...
do you have a baseline on before the valve job. I am just wondering if it is worth the ~400 it will cost. I also ported my head. ( I will post pictures latter i am very proud of it this is the first time i have ever had a engine apart)
 
Slant Six Bumblebee said:
do you have a baseline on before the valve job. I am just wondering if it is worth the ~400 it will cost. I also ported my head. ( I will post pictures latter i am very proud of it this is the first time i have ever had a engine apart)
Click to expand...
If you look in the thread "I might have found something kinda cool" The flow sheets are in there. That is all before the valve job was finished out and with just one rough cut 45. I don't have an after, as all it will do is add to, It is whatever it is and I really didn't give a ****. lol
 
Here you go. Flow sheets are in there somewhere. @MOPAROFFICIAL can probably give you a good "guess" as to what a good valve job will add percentage wise. I don't know why you're trying to be picky. Just do it, because the slant 6 needs all the help it can get. In for a penny in for a pound. lol
I Might Have Found Something Pretty Cool.....
 
Is that a $400 difference in valve job cost over a plain old "standard" valve job? As even that, won't be free.
The labor on the valve job I had done on the head on my latest slant was $425 total, and that was with a 70 thou mill, new exhaust seats, cutting seats for the oversized valves, finishing up my porting, a magnaflux to be sure we didn't oops and hit a water jacket, cut down tops of guides for positive seals and also for length so that I don't crash the retainers at full lift. Unsure if they had to put new guides in, don't remember any talk about that.
I supplied the valves (same ones you are talking about from Oregon cams) the positive seals and the 318 springs I had them install.
All total I have between $600-650 in this head. Parts included. Double what I spent on the last pair of 318 "302" casting heads with this same machine shop, that they got me all new valves for and they got me the positive type seals, they just did a regular standard valve job on those heads and only took 7 thou off the deck surface of (1/10 the amount I had them take off of this slant head)
I had the 318 heads done about a year and a half before they did the slant 6 head for me. But I figure that since the /6 is about 90-some CID less than what a 318 is, and my /6 is in a 1/2 ton truck, that this engine needed all the help it can get.
BTW the 318 is in a B body.
 
what cam are you running, I have a 270 redone cam I picked up when I bought a spare engine, came with a rebuilt head (spare ) and a the cam .
 
What people don't realize it that when machine shops talk about "three angle" valve jobs, they're not talking about anything special. Every single automotive and light truck engine from our era came with a three angle valve job. That's a stock factory valve job. Machine shops have cut that corner for DECADES acting like when they grind or cut a three angle valve job, you're gettin somethin special, when you're not. They grind or cut a simple single angle for the speed of gettin it done and out the door and lower total cost. You can verify this easily in most any factory service manual that details a factory valve job and gives an explanation of those angles. Most shops refer to it as a "competition" valve job, but there's nothing competition about it, although certainly it takes more labor to do.
 
67belevdere/225 said:
what cam are you running, I have a 270 redone cam I picked up when I bought a spare engine, came with a rebuilt head (spare ) and a the cam .
Click to expand...
You talking to me? I've talked about this build all over the place, I'm sure some here are "blue in the face" from hearing about it.
But back to talking about heads, it was pretty much a moot point on the slant 6 head being as how I brought them oversized valves from the get go, so the machine shop knew they would be cutting my seats oversized (and replacing the exhausts anyway regardless of save ability of the originals as put in by the factory.
Add in my oop'ses from being a novice head porter, where I bumped the original seats so many times it was a foregone conclusion, they had alot of seat cutting to do.
But back up for a minute to when they did both those "302" heads and my "Ready out of the box" EQ heads (that weren't) that I got for my Durango the machine shop went on and on about how Chrysler couldn't cut a true and concentric seat at the factory "to save their lives". Even though the aftermarket EQ heads weren't factory heads they had the same complaint about those as the mid 80s "302" heads they did for me.
 
Ok thanks all for the good info i have a better idea of what i need to do now. I have another question about how much to shave off the head. I am keeping the stock bottom end and using a .040 felpro and want to have a target compresion of 8.5:1 but dont know how much to take off. I know there are calculators but shaving the head will affect teh cc and i dont know how to calculate the new cc.
 
another point where there's lots of info on the site about. Look around, even just within the /6 topic area.
On mine, I used an Aussie head gasket (0.060" out of pkg, 0.050" compressed-- actually measured, "my68barracuda" pointed out a spot to me, at back of head/block with a little room for the edge of feeler gauge blades so you can measure what your head gasket ends up at, while compressed) Many are listed by various members right here. so you can get a pretty good idea from reading the posts where yours "should" fall.
and 0.100" combined, shaved off the head and block/ I wound up right at 8.4:1/ I was hoping for a little more. I had a thread not too long ago about "that came up short". With my particular head gasket I had to run (for other reasons) and its larger fire ring, plus its added thickness the 30- thou I had taken off the block "just" makes up for the added head gasket thickness, vs how it was at the factory. It doesn't help that most "rebuilder grade" pistons actually come up short of where the original pistons sat, "in the hole" at TDC, mine are just about where most guys find theirs on a stock unrebuilt engine, even with that 0.030" I had taken off the block.
I don't know that I could measure the actual deck height on my engine, that may be a "machine shop guy's" job. but it is known what the design spec was supposed to be for deck height as built brand new back in the day. But even considering all that, at the end of the day that 8.4:1 CR is better than my engine ever was from new, by virtue of all that milling/machine work. It just sucks to have had to do "all of that," to even get to "design spec". on my particular combo, that means there was an extra 0.070" "somewhere," that wasn't supposed to be there. though granted, I did use a newer "peanut" head, I want to measure the original head's chamber size, and plug that into an online CR calculator. That original head hasn't as of yet, been milled or machined at all, since new.

Depends on assembly line tolerance stackup, how tall your block was when new, and actual size of chamber. They seemed to vary alot on these engines, over the years. All of the old school auto repair manuals would have a person working on their car believe that most all /6s came from the factory at 8.4, but most were really truly in the 7's to 1. You're gonna have to make a few measurements off of YOUR engine, to see where you stand now. plus who knows who has been inside of that engine, over the years?

That 40-thou head gasket will crush a bit, 40 isnt the "installed thickness. Id guess it would end up at 30-35 thou. (wont mean THAT much at the end of the day)
but you need to know where YOUR pistons sit at extreme TDC on YOUR engine, (how far below deck) as well as to measure CCs on YOUR head that you are gonna use on it to figure that out. I was hoping to be closer (but not quite "to") 9:1.
 
Slant Six Bumblebee said:
SOry for the multitude of posts recently but i am rebuilding my head and converting to a super six currently. I was wondering if i should get a multi angle valve job with my new oversize valves. they are the 1.7/1.44 valves from orgen cams (just up the street) and if the hp gains are minimal or with the cost.
Click to expand...

Short answer,Yes.
More detailed answer, ask if they will add a 4th 70 degree to open the throat to size for the 1.7 valve.
Gasket match the head, port the floor from the window in about a fat inch ish..then quick roll down/decend into the floor about .060 ish straight/toward the valve...then go from the bowl side and work the ssr to the floor work...that's your new and improved short turn. It will have 3 parts, entrance,runner, desension ramp.
 
volaredon said:
another point where there's lots of info on the site about. Look around, even just within the /6 topic area.
On mine, I used an Aussie head gasket (0.060" out of pkg, 0.050" compressed-- actually measured, "my68barracuda" pointed out a spot to me, at back of head/block with a little room for the edge of feeler gauge blades so you can measure what your head gasket ends up at, while compressed) Many are listed by various members right here. so you can get a pretty good idea from reading the posts where yours "should" fall.
and 0.100" combined, shaved off the head and block/ I wound up right at 8.4:1/ I was hoping for a little more. I had a thread not too long ago about "that came up short". With my particular head gasket I had to run (for other reasons) and its larger fire ring, plus its added thickness the 30- thou I had taken off the block "just" makes up for the added head gasket thickness, vs how it was at the factory. It doesn't help that most "rebuilder grade" pistons actually come up short of where the original pistons sat, "in the hole" at TDC, mine are just about where most guys find theirs on a stock unrebuilt engine, even with that 0.030" I had taken off the block.
I don't know that I could measure the actual deck height on my engine, that may be a "machine shop guy's" job. but it is known what the design spec was supposed to be for deck height as built brand new back in the day. But even considering all that, at the end of the day that 8.4:1 CR is better than my engine ever was from new, by virtue of all that milling/machine work. It just sucks to have had to do "all of that," to even get to "design spec". on my particular combo, that means there was an extra 0.070" "somewhere," that wasn't supposed to be there. though granted, I did use a newer "peanut" head, I want to measure the original head's chamber size, and plug that into an online CR calculator. That original head hasn't as of yet, been milled or machined at all, since new.

Depends on assembly line tolerance stackup, how tall your block was when new, and actual size of chamber. They seemed to vary alot on these engines, over the years. All of the old school auto repair manuals would have a person working on their car believe that most all /6s came from the factory at 8.4, but most were really truly in the 7's to 1. You're gonna have to make a few measurements off of YOUR engine, to see where you stand now. plus who knows who has been inside of that engine, over the years?

That 40-thou head gasket will crush a bit, 40 isnt the "installed thickness. Id guess it would end up at 30-35 thou. (wont mean THAT much at the end of the day)
but you need to know where YOUR pistons sit at extreme TDC on YOUR engine, (how far below deck) as well as to measure CCs on YOUR head that you are gonna use on it to figure that out. I was hoping to be closer (but not quite "to") 9:1.
Click to expand...
The stock pistons are 0 cc right? If i find the deck height can i take it into the machine shop and tell them what cc i want on my head and have them figure out how much to take off for my targeted compresion?

Screenshot 2022-03-13 2.57.17 PM.png

I did not hit calculate the actual CR should be 7.87
 
Slant Six Bumblebee said:
The stock pistons are 0 cc right? If i find the deck height can i take it into the machine shop and tell them what cc i want on my head and have them figure out how much to take off for my targeted compresion?

View attachment 1715887661
I did not hit calculate the actual CR should be 7.87
Click to expand...
Are you 100% on that deck clearance? I ask because normally it's around 175" - .180".
 
RustyRatRod said:
Are you 100% on that deck clearance? I ask because normally it's around 175" - .180".
Click to expand...
no this is just theoritical its raining hard outside and im just waiting for it to clear up. Also my pistons have a lot of carbon build up how should i clean that off for a corect reading.
Also am i putting that in correctly because when i put in a higher number for deck clearance it raises the cr wouldn't it be the opposite
 
Slant Six Bumblebee said:
no this is just theoritical its raining hard outside and im just waiting for it to clear up. Also my pistons have a lot of carbon build up how should i clean that off for a corect reading.
Also am i putting that in correctly because when i put in a higher number for deck clearance it raises the cr wouldn't it be the opposite
Click to expand...
A razor blade scraper works good.
 
RustyRatRod said:
What people don't realize it that when machine shops talk about "three angle" valve jobs, they're not talking about anything special. Every single automotive and light truck engine from our era came with a three angle valve job. That's a stock factory valve job. Machine shops have cut that corner for DECADES acting like when they grind or cut a three angle valve job, you're gettin somethin special, when you're not. They grind or cut a simple single angle for the speed of gettin it done and out the door and lower total cost. You can verify this easily in most any factory service manual that details a factory valve job and gives an explanation of those angles. Most shops refer to it as a "competition" valve job, but there's nothing competition about it, although certainly it takes more labor to do.
Click to expand...
I didn't think of that, either. All I remember from the FSM was that IF the 45* seat winds up being over "so" wide, to narrow it with another angle of cut. though it has been a while since I have had my head into that part of an FSM.
and back when I was 30-some years younger I remember from my Dad's old Chilton manuals in the back "unit repair" section I remember talk about a "competition" valve job. and alot of notes at the bottom of each step with a single star or a double star indicating "optional" extra steps, and I think the double star was " optional increased performance" things you could do but didn't have to. Among them, I remember a starred item along the way, was to "CC" the combustion chambers. which by, of, and for itself, does nothing for performance.

The OS valves can't hurt, especially with some porting.... something else I've had drilled into me, regarding the heads on the /6 was that they were originally specc'd out for the 170 CID version and unchanged and just "slapped onto" the 225s. Pretty much regardless of how the short block is built, or whether it's still as built by the factory/ or what you want to see different after, vs before. That, plus a compression boost/ which I can see that you are already talking about, can only help.

I dunno if he was being "funny"/ like people are when they claim a HP boost just by adding chrome, or serious/ but when the machine shop guy seen what I'd done to the head I'm running, he said that it was a "fantastic start" and that by itself, that my porting work "should add 20-30HP to my build by itself". He just "touched up" a few things, mainly finished the gasket match on the other end of the ports/ which I had barely touched. We shall see. Most of my performance measures will have to be limited to a before and after "butt dyno" comparison.
 
I've seen @IQ52 (Jim Laroy) make the comment that larger valves make more power everywhere in the RPM range. He oughtta know. lol I think the larger valves are certainly worth it, especially with a slant 6.
 
Slant Six Bumblebee said:
The stock pistons are 0 cc right? If i find the deck height can i take it into the machine shop and tell them what cc i want on my head and have them figure out how much to take off for my targeted compresion?

View attachment 1715887661
I did not hit calculate the actual CR should be 7.87
Click to expand...
It takes less than $6.00 worth of hardware to cc a combustion chamber.
1) get a 60cc or larger animal syringe from tractor supply.
2) a 4x4 piece of plexiglass, an old cd cover will work
3) an old sparkplug to fill the sparkplug hole
4) a teaspoon of vasoline
5) a couple or three drops of food coloring
6) water and a empty cup

position the plexiglas so it covers the combustion chamber evenly. Mark a spot on the plexiglass that is at 12:00 on the combustion chamber and it is at the very top and drill a 1/4 inch hole. You will use that hole to insert the tip of the syringe to fill the combustion chamber with the colored water.
Screw in the spark plug, the valves retained by springs need to also be in place.
Smear a bit of the vasoline around the outer edge of the combustion chamber to act as a seal.
Place the plexiglass over the combustion chamber with the drilled hole at 12:00 and the head angled back slightly so the chamber will fill evenly.
Mix the food coloring and water in the cup. With the syringe piston fully in, insert the nozzle of the syringe in the cup and pull back the piston slowly and evenly to fill the syringe past the 60cc mark. Tap on the sides of the syringe to dislodge any bubbles, and empty and refill till the syringe chamber is full and free of bubbles.
Push the syringe piston to the 60cc mark.
Insert the syringe nozzle into the drilled hole and evenly press the syringe piston in till the combustion chamber is filled.
Note how many cc’s are left in the syringe, typically for an un cut slant head it will be 1 to 4.
There are also YouTube videos on this subject.
On a slant head, the accepted formula is one cc of combustion chamber volume is removed for every .0069 removed from the head deck.

So if you cc the head and find the chambers are 58 cc
And in working the compression calculators you find that a 48 cc chamber gets you to the desired static compression, you can tell the machine shop to cut .069 from the head deck.

to be the most accurate, do all combustion chamber polishing and valve deshrouding and valve seat work and use the valves that you plan to run when cc’ing the combustion chamber.
New valves and new seats will seal with a light smear of vasoline on them.
This may be an extra trip to and from the machine shop but this is how to get the amount to trim the head as accurate as possible to get the final numbers.
I always cc the head again after I get it back from the ms just to verify that they cut what I had requested.
 
Last edited:
my68barracuda said:
It takes less than $6.00 worth of hardware to cc a combustion chamber.
1) get a 60cc or larger animal syringe from tractor supply.
2) a 4x4 piece of plexiglass, an old cd cover will work
3) an old sparkplug to fill the sparkplug hole
4) a teaspoon of vasoline
5) a couple or three drops of food coloring
6) water and a empty cup

position the plexiglas so it covers the combustion chamber evenly. Mark a spot on the plexiglass that is at 12:00 on the combustion chamber and it is at the very top and drill a 1/4 inch hole. You will use that hole to insert the tip of the syringe to fill the combustion chamber with the colored water.
Screw in the spark plug, the valves retained by springs need to also be in place.
Smear a bit of the vasoline around the outer edge of the combustion chamber to act as a seal.
Place the plexiglass over the combustion chamber with the drilled hole at 12:00 and the head angled back slightly so the chamber will fill evenly.
Mix the food coloring and water in the cup. With the syringe piston fully in, insert the nozzle of the syringe in the cup and pull back the piston slowly and evenly to fill the syringe past the 60cc mark. Tap on the sides of the syringe to dislodge any bubbles, and empty and refill till the syringe chamber is full and free of bubbles.
Push the syringe piston to the 60cc mark.
Insert the syringe nozzle into the drilled hole and evenly press the syringe piston in till the combustion chamber is filled.
Note how many cc’s are left in the syringe, typically for an un cut slant head it will be 1 to 4.
There are also YouTube videos on this subject.
On a slant head, the accepted formula is one cc of combustion chamber volume is removed for every .0069 removed from the head deck.

So if you cc the head and find the chambers are 58 cc
And in working the compression calculators you find that a 48 cc chamber gets you to the desired static compression, you can tell the machine shop to cut .069 from the head deck.

to be the most accurate, do all combustion chamber polishing and valve deshrouding and valve seat work and use the valves that you plan to run when cc’ing the combustion chamber.
New valves and new seats will seal with a light smear of vasoline on them.
This may be an extra trip to and from the machine shop but this is how to get the amount to trim the head as accurate as possible to get the final numbers.
I always cc the head again after I get it back from the ms just to verify that they cut what I had requested.
Click to expand...
The calculating teh cc is not a issue for me it is knowing how much to cut off the deck to get the desired cc.
 
RustyRatRod said:
I've seen @IQ52 (Jim Laroy) make the comment that larger valves make more power everywhere in the RPM range. He oughtta know. lol I think the larger valves are certainly worth it, especially with a slant 6.
Click to expand...
I am going with larger valves positivevalve seals valve guides if needed 318 springs and have already ported the head the only uncertainty left is stated in my post above.
 
Slant Six Bumblebee said:
I am going with larger valves positivevalve seals valve guides if needed 318 springs and have already ported the head the only uncertainty left is stated in my post above.
Click to expand...
I forget if you've said so forgive me, have you chosen a camshaft?
 
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