[unruhjonny]

I agree this was interesting;
I picked up the block yesterday from the machine shop and was surprised to see the markings - I had never seen them before, but knew exactly what they were.
I have more pictures, but figured those two would be sufficient for anyone interested.

[johnta1]

Kind of related:

[johnta1]

My 70 Judge had the marks and seems my 74 SD block had them. (stampings)

Most other blocks never looked that close.

Also have a Service News on 1971. (couldn't find any 70 codes)

[Held for Ransom]

It was probably in a Technical Service Manual or Service News (1970-1 period).

[Held for Ransom]

Was out in the storage area and looked at the YZ engine. Stampings are...
S P P S
2 4 6 8
1 3 5 7
S T S T

[SD455DJ]

Cool! Another group of stamps...pretty tight tolerances on your YZ Mike.

It's funny that Oldsmobile's 1970 performance brochure talked about "select-fit" pistons for 'factory blueprinting" their "W" engines, when this was standard practice in the industry. Maybe they held the tolerances a bit tighter(?)...I don't know.

Dennis

[SD455DJ]

The YZ block, main caps, crank, and heads all checked out fine – no cracks. The crank was in such great shape that it only needed polishing and can use std./std. bearings. I got Eagle H-beam rods at the Butler Performance tent at Norwalk last weekend, so saved on paying state sales tax and shipping. It was all delivered to APEX Performance where the heads are now being fitted with Ferrea 1-pc. stainless steel valves, new bronze guides, and new springs. I’m planning on reusing the original factory installed 068 cam and lifters since they’re in great shape as well. Once the heads are done and we can determine the actual chamber volume, we can then order pistons. I’m thinking we may need to get at least a 14cc dish to keep the static compression down to a tolerable 10.2 to 1. We should know soon.

Interesting to see the double VIN stamp on the block.

Dennis

[Formulajones]

I don't remember if I mentioned it Dan but that sounds close. I'm pretty sure I dished mine 13cc, I have 10.13:1 compression.

[Ramairnacho]

In California we only have 91 oactaine. Would lowering compression to 9.5 to 1 be more practical? But will that come with a cost ? At present moment I have #13 heads that have been rebuilt new everything with slightly bigger values if I remember correctly and hardened seats. Got me wondering about compression ratio's. I do have a good set of #12 cores too.

[Formulajones]

That's what we have here in Arizona too. 10.13:1 works fine on it as long as everything else with the car is right.

[SD455DJ]

Originally Posted by Formulajones

That's what we have here in Arizona too. 10.13:1 works fine on it as long as everything else with the car is right.

FJ, what is your elevation? We're around 800 ft average in west and mid-Michigan. We're still waiting on the heads to be able to cc the chambers and see what we need to order for the piston dish size.

Dennis

[Formulajones]

Originally Posted by SD455DJ

FJ, what is your elevation? We're around 800 ft average in west and mid-Michigan. We're still waiting on the heads to be able to cc the chambers and see what we need to order for the piston dish size.

Dennis

It varies drastically depending on where I'm driving. I drive the car regularly from 5000 feet to 1000 feet. Sometimes as high as 7000 feet or more on occasion. 20-30 miles in any direction changes like that. Phoenix is around 1000 feet which is also where the dragstrip is located. Unfortunately they don't offer higher octane at the lower elevations either, we are just stuck with 91 everywhere so that's what I'm forced to use. But it's been happy for the last 20 years on it. I just have to make sure the cam is degreed properly, the fuel system is up to par with a safe fuel curve, and the timing is dialed in. It dyno'd best at 34 degrees total on that gas down near sea level and of course at the track, trying to move timing around I also found it ran best times with 34 degrees so the dyno wasn't lying to me, lol. Less timing the car slowed down a tick, and when I tried 36 it runs the same so I see no sense in running 36 when 34 gives the same result so that's where it stays. I keep the curve mild, all coming in at 2800 rpm.

[SD455DJ]

Originally Posted by Formulajones

It varies drastically depending on where I'm driving. I drive the car regularly from 5000 feet to 1000 feet. Sometimes as high as 7000 feet or more on occasion. 20-30 miles in any direction changes like that. Phoenix is around 1000 feet which is also where the dragstrip is located. Unfortunately they don't offer higher octane at the lower elevations either, we are just stuck with 91 everywhere so that's what I'm forced to use. But it's been happy for the last 20 years on it. I just have to make sure the cam is degreed properly, the fuel system is up to par with a safe fuel curve, and the timing is dialed in. It dyno'd best at 34 degrees total on that gas down near sea level and of course at the track, trying to move timing around I also found it ran best times with 34 degrees so the dyno wasn't lying to me, lol. Less timing the car slowed down a tick, and when I tried 36 it runs the same so I see no sense in running 36 when 34 gives the same result so that's where it stays. I keep the curve mild, all coming in at 2800 rpm.

Thanks FJ! Where do you encounter 5000' of altitude? Driving into the mountains? Fortunately, we have E10 93 octane fuel everywhere, and it has been decent to run on. We have upgraded all the old rubber hoses, accelerator pumps with ethanol compliant replacements, so haven't had any degradation problems there. When we race, we'll add 4-5 gallons of race fuel (110/112 unleaded) to be safe and keep our timing curves conservative (34-36 degrees all in by 3000 rpm, or slightly lower, at the track, and higher (3500 rpm) for street service). We're probably leaving a little hp on the table off the line but need to back-pedal anyway to keep the tires planted.

Dennis

[Formulajones]

Originally Posted by SD455DJ

Thanks FJ! Where do you encounter 5000' of altitude? Driving into the mountains? Fortunately, we have E10 93 octane fuel everywhere, and it has been decent to run on. We have upgraded all the old rubber hoses, accelerator pumps with ethanol compliant replacements, so haven't had any degradation problems there. When we race, we'll add 4-5 gallons of race fuel (110/112 unleaded) to be safe and keep our timing curves conservative (34-36 degrees all in by 3000 rpm, or slightly lower, at the track, and higher (3500 rpm) for street service). We're probably leaving a little hp on the table off the line but need to back-pedal anyway to keep the tires planted.

Dennis

Yeah up in the mountains can reach as much as 7000 feet or more depending on where you go. Even though Arizona is viewed as dry hot desert it actually has a bunch of high mountain terrain we call high desert. Still hot and mostly dry, just closer to the sun, lol.

[SD455DJ]

Our youngest son went to UofA in Tucson, moved him out there in 2017 for grad school and his PHD. He got married up on Mt. Lemmon (8000 ft) the end of April 2021 and I recall it snowed and sleeted in the morning prior to their outdoor wedding. It was very pleasant that time of year down in Tucson...only in the 80's and dry. They moved to Durham, NC in 2022 for his post-doc work at the UNC. They went from the oven to the wet sauna, but they love the green and abundance of water!

Dennis

[HWYSTR455]

I'm in an area that varies rapidly in a 500-6000' range, and that can cause issues with carbs, especially if you are tuned on the ragged edge.

During the 2014 Power Tour, with the 442 fairly fresh, running a 670 Holley, going over the Blue Ridge mountains (Hills to some), many cars had issues. Some actually had to stop and do jet swaps to go over the highest points, the 442 included. I had to step up 3 jets sizes.

The Holley trailer stopped for many, and they provided jets to people for free. From previous stops and tours, they knew right away what needed to be done, and how many steps to recommend.

Aaaand, that's why i went efi on the 442. Being my daughter's car, that would be unacceptable for her to stop and swap jets. And some of the reason I went to efi on everything else.


.


.

[SD455DJ]

Originally Posted by HWYSTR455

I'm in an area that varies rapidly in a 500-6000' range, and that can cause issues with carbs, especially if you are tuned on the ragged edge.

During the 2014 Power Tour, with the 442 fairly fresh, running a 670 Holley, going over the Blue Ridge mountains (Hills to some), many cars had issues. Some actually had to stop and do jet swaps to go over the highest points, the 442 included. I had to step up 3 jets sizes.

The Holley trailer stopped for many, and they provided jets to people for free. From previous stops and tours, they knew right away what needed to be done, and how many steps to recommend.

Aaaand, that's why i went efi on the 442. Being my daughter's car, that would be unacceptable for her to stop and swap jets. And some of the reason I went to efi on everything else.


.


.

EFI sure makes sense in that 'hilly' country. It's pretty flat and consistent in Michigan, Ohio, Indiana, and Illinois where we do most of our traveling in our 'old' carb equipped Pontiacs.

Dennis

[HWYSTR455]

In the mid-70s, my dad took the family in a 24' Winnie around the states. It was used but low mileage, and he did almost everything on it before we left, including a new carb. We went south and across, up CA to WA state, and back east on the north side. We have lots of issues in the mountains, and in the low elevations too. I remember he had a pull-choke put on I think it was like in NM, and he would play with that thing in elevated areas, which helped.

I've always driven may cars up and down the east coast, and thru the 'mountains' of the east. I did carry jets with me, but if I knew I was going to be in high elevations I would start out a little rich before I left home, and just 'deal with it' if that wasn't enough. Usually didn't have too many issues, but there were occasions.

I'm pretty happy with my EFI setups, they work good to very good, with a set it and forget it type approach. Once it's right, like anything really, there's not much that needs to be done. The TBi setups are the least requiring 'fiddling'. I doubt I'll ever go back to carbs, but there is a simplicity thing that's attractive.



.

[SD455DJ]

Sometime in the next several years is to check off a bucket-list item to travel Rt-66 to at least New Mexico/Arizona in our old Pontiacs. Being carbureted, we'll be taking our Q-jet jet/metering rod kits for the elevation changes.

Dennis

[Formulajones]

There is a Pontiac chapter out here that gathers and does the route 66 cruise. Usually every year. I've done it with them a couple of times. They come from the other side of the country to join, start in Illinois and go all the way to California. It's a really great time.

Might be the chapter in Tucson, I can't remember, but there are a couple of other Pontiac clubs out here as well and they all participate.