Slant Six Head Mill

[rustyratrod]

Any time you remove. 090 from the deck or head combination you will need a custom length pushrods. With that much removed the pushrods will be too long and the rockers will not be pushing on the center of the valve stem.

Well somebody better tell me, because I just assembled this with a head that was cut .155" and the original pushrods fit just fine. Pushrod length has squat to do with where the rockers engage the valve stem. Nothing. Nada. Zilch. Zero. As long as they are not too long and will FIT between the rocker and lifter and will adjust to the correct lash, they do not affect geometry one iota.

Now, I have a factory closed chamber head I am installing 318 valves in. THAT affects geometry, because of the longer valve stems.

So I will have to get with Mike at B3 Racing Engines and get some custom shims from him to relocate the rocker shaft. Once that's done, it will be fine.

 

[rustyratrod]

Pre '80 /6 with adjustable rocker arms (I should say, also needs to be cleaned). There are a couple of different versions but differences are minor.
View attachment 42254

This is a '80 and up non-adjustable rocker arm (looks somewhat similar). You can see the internal oil passageway cast into the part.
View attachment 42255

Some part stores say this rocker arm will fit.
View attachment 42256
It might fit (never tried), but there is no oil passageway to the lifters (so DO NOT try to use).

BudW

That looks like a small block rocker. They won't fit. I WISH! Big block rockers don't fit either. The slant six's rockers are a good bit longer than both the small and big block. I wish they would interchange, then slanters could have some decently affordable HP rockers available, instead of 1500 dollar shiny things from T&D Rockers.

 

[Duke5A]

Ooooh, shiny. What's the story on that build?

 

[rustyratrod]

Ooooh, shiny. What's the story on that build?

Nothing, really. It's a stock fresh rebuilt short block that I put a heavily (.155") milled head on. I had originally planned on the obligatory .100" head mill....BUT on the last cut, the head slipped off one of the clamps on the broach and the machinist didn't catch it in time. He tried to reset it back up and it cut it crooked. So I took it to a friend with a Rottler and he set it up off the valve cover rail and milled it until it was straight again. The total off is .155" Chambers are 34cc. Static compression came in at 9.8. Dynamic 7.8. Custom grind Oregon camshaft with .465 lift and 250 @ .050" duration ground on a 108 LSA. Head is otherwise stock unported with stock valves. Should still be pretty peppy with the Offy intake and 450 QFT four barrel with exhaust manifold outlet opened up to 2.5 and a full 2.5 exhaust system. Going in my 64 Valiant.

 

[Oldiron440]

Well somebody better tell me, because I just assembled this with a head that was cut .155" and the original pushrods fit just fine. Pushrod length has squat to do with where the rockers engage the valve stem. Nothing. Nada. Zilch. Zero. As long as they are not too long and will FIT between the rocker and lifter and will adjust to the correct lash, they do not

You are totally incorrect! Anytime you change the height of the valve or the pushrod you must adjust the height of the other, this is very basic knowledge.

 

[rustyratrod]

You are totally incorrect! Anytime you change the height of the valve or the pushrod you must adjust the height of the other, this is very basic knowledge.

No sir, I'm not, but I'm not going to argue about it either. Thanks for your opinion.

 

[rustyratrod]

You are totally incorrect! Anytime you change the height of the valve or the pushrod you must adjust the height of the other, this is very basic knowledge.

And just so you know, I am specifically speaking about "THIS" particular engine and "ANY" slant six engine that "I" build.

I checked geometry with the stock head. It was actually almost spot on. So much so, I decided to leave it unchanged with the heavily milled head.

I did that, by communicating that same .155" that was taken off the head, plus the head gasket thickness with my camshaft grinder, Ken Heard.

Normally, just hacking off a big chunk of the head, effectively makes the pushrods too long. Since I let Ken know how much was removed from the head, he positioned the camshaft lobes in accordance with the removed amount from the cylinder head, thus not affecting valve train geometry.

I was born on a Monday, not last Monday.

 

[ChryslerCruiser]

And just so you know, I am specifically speaking about "THIS" particular engine and "ANY" slant six engine that "I" build.

I checked geometry with the stock head. It was actually almost spot on. So much so, I decided to leave it unchanged with the heavily milled head.

I did that, by communicating that same .155" that was taken off the head, plus the head gasket thickness with my camshaft grinder, Ken Heard.

Normally, just hacking off a big chunk of the head, effectively makes the pushrods too long. Since I let Ken know how much was removed from the head, he positioned the camshaft lobes in accordance with the removed amount from the cylinder head, thus not affecting valve train geometry.

I was born on a Monday, not last Monday.

Rusty, I appreciate your sharing of HOW you have accomplished making corrections to the valve train geometry after taking .155 off the cylinder head. Such information tells us that you have depth of knowledge and creativity behind your efforts.... And in this above post you also allow that Oldiron440 had a valid point.

What I am trying to bring into this discussion is not about the rightness or wrongness of anything.. Only stating that 3 years from now some one who was born more recently, and does not understand the nuances of engine building, could read about taking .155 of of their head, and run into big troubles.

Again I am wanting to be clear, creative and deep reasoning is wonderful, and I applaud your thinking process... Just please lightly consider the 17 year old, who is interested in cars, and is using the internet as a mentor. It is my perspective that Oldiron440 was speaking up, to alert those who do not have the depth you possess. Respectfully submitted, C.C.

 

[rustyratrod]

Rusty, I appreciate your sharing of HOW you have accomplished making corrections to the valve train geometry after taking .155 off the cylinder head. Such information tells us that you have depth of knowledge and creativity behind your efforts.... And in this above post you also allow that Oldiron440 had a valid point.

What I am trying to bring into this discussion is not about the rightness or wrongness of anything.. Only stating that 3 years from now some one who was born more recently, and does not understand the nuances of engine building, could read about taking .155 of of their head, and run into big troubles.

Again I am wanting to be clear, creative and deep reasoning is wonderful, and I applaud your thinking process... Just please lightly consider the 17 year old, who is interested in cars, and is using the internet as a mentor. It is my perspective that Oldiron440 was speaking up, to alert those who do not have the depth you possess. Respectfully submitted, C.C.

Oh trust me, I'm not out to prove me right and someone else wrong. How small minded is that? I just realized I failed to include relevant information and came back and did so. Remember, there's always more than one way to skin a dog.....I like cats. lol But in this instance, pushrod length is irrelevant since I compensated for it. I already knew ahead of time I was milling the head......just not .155" <rolls eyes>. But since it "happened" and the rest of the head (seats and guides) was pristine, I had to utilize it. I already knew since the cam was a regrind, it would have a reduced base circle, which would make up "some" of the pushrod length, plus, since I was going low lift to save money on expensive valve springs and machining necessary for them, I knew I "had more lobe left" to work with, if that makes since, so I asked Ken if he could make it up when he ground the cam and he was able to. It just kinda came together. Honestly, this motor is intended to "bridge the gap" between this and the long rod motor I am building.....but as good as it's turned out, the long rod motor may be a while.

 

[ChryslerCruiser]

Oh trust me, I'm not out to prove me right and someone else wrong. How small minded is that? I just realized I failed to include relevant information and came back and did so. Remember, there's always more than one way to skin a dog.....I like cats. lol But in this instance, pushrod length is irrelevant since I compensated for it. I already knew ahead of time I was milling the head......just not .155" <rolls eyes>. But since it "happened" and the rest of the head (seats and guides) was pristine, I had to utilize it. I already knew since the cam was a regrind, it would have a reduced base circle, which would make up "some" of the pushrod length, plus, since I was going low lift to save money on expensive valve springs and machining necessary for them, I knew I "had more lobe left" to work with, if that makes since, so I asked Ken if he could make it up when he ground the cam and he was able to. It just kinda came together. Honestly, this motor is intended to "bridge the gap" between this and the long rod motor I am building.....but as good as it's turned out, the long rod motor may be a while.

More really good info here Rusty. Thanks for including this, and everything else you have contributed to this thread.

 

[BudW]

I should probably side-step this conversation before I get dirty...but I can't.

There is an element of truth in what the different parties are saying.

If Rusty's engine uses solid lifters (ie: have adjustable rocker arms). There should be plenty of adjustment in the rocker arms to allow for the 0.155” machining. Most adjustable rocker arms – NO, but I think these might be OK.

The second aspect is the other end of the rocker arm tip, where it contacts the valve tip. The goal is to have:

At both ends of valve travel – in the center of the valve (to prevent wear to valves/valve guides/rocker arms).
That said, again, I “believe" (nothing to back this up) the rocker arm tip is both long enough/rounded enough that this might not be a concern. It doesn't hurt to check, though.
If the checks have been done – then I'm in no position to argue with the results.I do know if the valve tips are not in position (in middle part of valve tip) – then excessive wear will take place at an accelerated pace (to sometimes a very accelerated pace).

If he is using hydraulic lifters (ie: non-adjustable rockers), then I think he will experience a few problems. I don't know nor has he said which type he has. Again, an important fact – but not worth being disagreeable about.

There is a lot about valve train geometry that can fill a good sized book (about how “A” affects “X”, “Y” and “Z”, but I won't go into it.
All I will say is if he has checked It and is happy with findings, then I won't say a thing more. If he hasn't checked it and it causes problem(s) for him down the road, then I also won't say a thing – sense it was mentioned. It is not worth getting into an argument about.
BudW

 

[rustyratrod]

I'm running a mechanical camshaft. That's really the only way to go on a slant six.

 

[BudW]

No disagreement there. I'm not a fan of hydraulics - but in some cases, you have no choice.

 

[rustyratrod]

No disagreement there. I'm not a fan of hydraulics - but in some cases, you have no choice.

I don't mind hydraulic lifters. The problem with the slant is, it was never redesigned to use hydraulic lifters. The lifters do not get pressurized oil from an oil galley. They rely on "backwards oiling". Through the block, through the head, into the rocker shaft, through the rockers, down the pushrods and finally into the lifter. It just never worked very well and I've always surmised it was because of the pressure loss before the lifters, but what the heck do I know? lol

 

[Oldiron440]

COMP Cams Valve Train Geometry
Push rod length changes where the rocker contacts the valve, among other things it can cause valve guide and seat wear. To say it has no effect on the geometry is just incorrect.

 

[rustyratrod]

COMP Cams Valve Train Geometry
Push rod length changes where the rocker contacts the valve, among other things it can cause valve guide and seat wear. To say it has no effect on the geometry is just incorrect.

"In my case" it does not, since I corrected it as outlined in my post. Apologies for leaving that out.

 

[MiradaMegacab]

Lol

 

[Oldiron440]

This is what hammers are for. Lol

 

[volaredon]

I would seriously doubt that your original engine as it left the factory is 8.4:1 compression. If you measure things out id bet you are closer to 7.5:1.
Due to tolerance stack up and such. Even with the stock original shim steel head gasket which is half or less, of the installed thickness of any head gasket you will find commercially. That said, the first 0.020 cut off the face of the head, will put you exactly back to what the compression ratio was on that engine when it was built from the factory. Look at FABO or slant six.org websites, common knowledge among those who have been messing with slant 6s since they were still available new. So measure where you stand now, actually cutting the head to "blueprint" the engine to the advertised compression ratio will give you a noticeable performance improvement. So will converting to a super 6 setup.
I too have an 80 volare that originally had a slant 6 in it, I sold the engine long ago planning on putting in a V8 but may wind up putting a built up slant 6 back in it, once I get the body work done on it.