Ever seen a 42° lifter angle?

 

I suspect that you are measuring incorrectly. See the chart below.

 

Check the pic again, if it is 39 or 45 the deck would be showing level or 6 degrees. Simple math, simple set up. Wouldn't have posted if came out to be what the charts show! Those are the stock lifter bores which we decided to put bushings in once the cam wouldn't dial in on opposite banks.

 

I don't understand what you are trying to show. Your angle cube has 300 measurement, I am assuming it means 3 degrees. The tool with the bubble is only showing a level condition with the bubble being level. Nothing shows what the lifter bank angle is by these measurements.

 

Are you sure the decks are accurate? And are both decks showing 3 degrees?

 

Angle cube is eating 3.00 degrees. If it was 45 lifter bore the angle cube would read 0 on the deck it was 39 it would read 6, 45-6=39. The bubble is showing the lifter bore to be plum.

 

Legit question, yessir the decks are 90 degrees, and the angel cube showed 3.00 on the vertical deck in that position.

 

Well, hard to argue then. Obviously there are manufacturing tolerances, but wow, never seen one like that.

 

Just out of curiosity, clearly you checked both decks, but have you checked all of the lifter bores? Are they all exactly the same?

There is no reason that they should not all be the same, but there is no reason why they'd all be 42 degrees either.

 

I just finished a 65 and it was definitely 45 deg. To be honest with you I do not trust those digital protractors. And your spirit level is probably not accurate enough either. I used a real machinsts protractor when I checked mine. I can certainly be wrong but I bet it is the way you are measuring.

 

So the decks have been trued by either a BHJ plate or CNC?

 

Are you really trusting a bubble level to prove the lifter bore is perpendicular to the deck to start with or did you confirm with the digital one? Don’t see a pic of that

what made you degree the cam on the opposite bank to start with? How many deg was the cam off to start with?

I hope you know the cam bank angle is from the cam Centerline not the deck. so if it’s a 39 deg block and you are going off a level lifter bore, the deck will be 3 deg off. 39+3 is 42. Your bubble is off 3, that’s why your getting what your getting

what cam and part #?

 

It’s a .921 39 deg block right?

 

Uh, better recheck your math. The lifter bore angle is measured relative to vertical. The 39 deg lifter bore is 39 degrees from vertical. The cylinder bore is 45 degrees from vertical. That's a SIX degree difference, not three. If you zero the bubble level in the lifter bore, the deck should be at six. Of course, this assumes all surfaces are machined properly and the measuring equipment is also accurate.

 

Are you assuming his bubble is not 3 deg off?

 

That's what I just said, it ASSUMES the measuring equipment is accurate. Can there be three degrees of error in that bubble level? Yeah, that is certainly possible.

 

then reread what I said.

If he is actually using the bubble to indicate 90deg, that’s so wrong

 

Yeah, now that you edited the original...

 

visually you can see it.

Draw a line across bottom of the digital level.. sure looks way more than 3 degrees to me.

looks like 6 right on 😁

 

What I would like to know is the level justified to the lifter bore or the top of the lifter boss? If it's not the actual bore you will have an issue.

 

There are NO 39 degree lifter bank angles in ANY Oldsmobile when measured from Vertical. There are 42 and 45 degree lifter bank angles. The 39 degrees comes from the way manual cam grinders would calculate the bank angle.

Berco Grinder Calculation: #2I = 50, #1I = 11 therefore 50-11=39
Actual Bank Angle Calculation: #8I = 140, #1I = 11 therefore ((140-11)-45)/2=42

 

Correct….. the lifter bores are 42deg from the cam centre line on whats called a “39” block

installing a “39” cam in a 45 deg lifter bore block will give a right bank 6 deg adv and left bank 6 deg retarded which means the actual lifter bores are 3 deg different per side

 

You know what that does to a running motor? It makes it into a 300hp paint mixer. If you make that mistake you'll know it immediately when you start it.

 

If I were boring the the lifter bores, I would indicate the lifter bore square to the boring head/tool, either by aligning the machining head to the bore or tilting the block on the machine, until the indicator reads "zero" for some of the bores length. Can't assume it's exactly the angle given, a 1/4 degree out is approx. .004 per inch, enough to move the lifter out of proper position with the cam shaft In industry we use sine plates and bars to set up angular boring and milling. Bubble levels are for building house's.

 

It would be interesting to find out what was discovered.

 

I talked to somebody that I know pretty well at one of the cam companies. They told me that the actual GM spec is 39 degrees and it is measured from the vertical but . . . . he said that over the years it seemed like something happened and the blocks drifted out more to around 42 like this one is. He said that they actually have been grinding theirs closer to 42.

I know for sure that the next "39" degree block I get in here I will definitely try to measure it

 

Was this all "GM" or just Oldsmobile ? I find it hard to believe that someone didn't notice the change.

 

I would think only Olds. You never know and unless you could find somebody with an actual original Oldsmobile engineering drawing for the blocks we probably will never know. When you work on this stuff day after day for 35 years you tend to find out that factory machining from back in those days simply was not very good. And its not just GM believe me. I have seen so many things machined wrong over the years that I just laugh when I see some of the comments on the interweb. The funny thing is all of those engines ran just fine for hundreds of thousands of total miles with no real issues in their stock applications.

Just one recent example was a late 80's 350 Chevy block I had about a week ago that I had to mill almost .020" off the decks just to get them parallel to the crankshaft. That engine was out of a truck that had close to 250k miles on it. Should somebody have noticed that or did GM just figure it was good enough ? Same with the lifter bores. And in a 455 put into an old "boat" Delta 88 station wagon nobody would ever know the difference.

 

Bill, I find it hard to believe that a degree or two error wouldn't have been noticed and corrected. Without a doubt, the factory cams used gentle opening/closing ramps for the valvetrain, and no appreciable flow started until the valve was .050" off the seat (Harvey Crane). A "few degrees" probably wouldn't have affected performance.
With the "new technology", faster opening/closing ramps, degreeing the cams and dyno's, discrepancies have showed up.

That 350 Chevy block is whats considered "seasoned" engine block. All the residual stresses are out of the block. It will remain as it was just machined.

 

Ralph,
You need to go work in a machine shop for a year. You will quickly change your mind Plus none of us know what the tolerance on the drawings was.

 

The level of machining from yesteryear never ceases to amaze me.
I’ve posted this before, this is why ALL the engines I build are machined this way. The bores are always off, as much as .040.

In addition I’m about 3 weeks away from doing my own halos as well. And guess what, virtually every block we’ve patterned them after is different. Unbelievable.

 

When building my 400, I found the deck surface on the passenger side to have .003 less deck height at the bottom side of the deck than at the top.
The driver side was .010 taller at the rear than the front.

Also when getting the block line bored, they found the center main cap was not vertical on the block.
You could see the resulting uneven wear on the thrust bearing as it was not parallel to the crank.

...but it lived for 70K miles before I took it apart.

 

the 39 comes from the 6 deg at the crank difference. Cams are always spec’s in crank deg.

the difference between the 45 deg block and so called “39” is 6 crank deg… which is what you get

Thats 3 deg at the lifter = 42deg

I’ve never heard of the blocks drifting over time.

I’ve found no different from the first blocks made after going away from the 45 till the last ones in the 80’s.

 

Do you have an online catalogue or any other place where someone can find all the parts you have available and the price list?

I checked your website but didn’t see anything there

 

Once everything is ready to ship I’ll be redoing/updating my website. Thanks.