[Formulajones]

Originally Posted by 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

That's cool. I think I'm done with the humid Eastern side of the country. My allergies were so bad out there I had to get off the prescription medication somehow or my kidneys wouldn't take it. The dry desert air is a huge relief. So that was a big reason for the move. Haven't had allergy medication in 20 years.

Mt. Lemmon is beautiful up there and the views are fantastic.

[Formulajones]

I typically don't have issues with the elevation and carbs. I've lived out here long enough that I've found a happy medium with fueling that works well at elevation yet doesn't get too lean near sea level. Usually that means letting it be a little rich up high and still safe down low and the plugs still stay clean enough. Each car is different and takes quite a bit of time to get it dialed in.
I did go EFI on the Chevelle a few years ago, primarily to experiment. It's nice to let closed loop comp make the necessary changes on the fly while driving from the mountains down to sea level and back. Dad did the same on the GTO and it's worked well on both cars.

[SD455DJ]

We got the machined engine block, heads, and rotating assembly back a couple weeks ago and yesterday Dan & I (more Dan than I) got busy and assembled the YZ short block with the dished (14cc) Icon forged pistons (+.030” over) and Eagle H-beam rods. The rods bearings have .0023” clearance and the mains are at .0026”. The cam bearings went in without a hitch and the original 068 cam spun easily without any tight spots or having to mess with the bearings.

You may have noticed that there are 2-bolt mains where there should be 4-bolt mains. When the engine was getting cleaned and magged, the shop discovered an interesting factory “issue” with the #4 main thrust cap. It appears the factory used a bad casting that had to machined further on one side eliminating the inset the thrust bearing shoulders sit in. The factory “repaired” it by spray welding (or some other process of building up metal) around the saddle so the thrust bearing still would fit and sit correctly. The engine has never been apart until now for this rebuild, so this main cap is from the factory. Why the factory didn’t replace the cap, or a new set of caps, is a mystery. It must have been cheaper to ‘fix’ it this way than to re-line hone the block for new caps (?).

The machinist was surprised to see a different material (metal) that appeared was welded to the cap face and had never seen anything like it before. He did scrap/blast some off with a bit of difficulty, so it adhered pretty well after all the years. After debating whether to reuse the caps, or just replace the ‘weird’ one, we went with neither and substituted a set of 2-bolt main caps we had on hand for the original 4-bolt caps and line-honed the mains for them. We have no fear of using 2-bolt mains as they are more than strong enough for the 3” main blocks. The original 4-bolt mains will stay with the car.

The pistons are an average of .013” in-the-hole after the decks were squared up, so we’ll be using a set of .027” Cometic head gaskets to achieve .040” quench depth. Dan will be cc’ing the heads soon to see where we end up with the static compression.

Dennis

[Held for Ransom]

Wow. You would think being the thrust cap, that should have never been used. Factory got lucky with no warranty being issued.

[Transamric]

That is totally bizarre!
So now at shows when someone askes if it have 4 bolt mains, your answer will be "Well yes,......and no".

[SD455DJ]

Dan cc’d the #12 heads yesterday and after a minimal resurface cut and new 1-pc SS Ferrea valves installed, the chambers measured 71.25 cc’s average. With deck height at -.013”, .027” head gasket thickness, 14 cc piston dish, 2 cc’s above the top ring, with 4.15” bore an 3.75” stroke, the calculated static compression ratio is 9.65 to 1. It should run fine on 93 premium fuel and make good power with the original born-with 068 cam & lifters.

Dennis

[SD455DJ]

Dan installed the heads & the .027 Cometic head gaskets today along with the original 068 cam & valvetrain (lifters, rocker arms & pivot balls, pushrods), original 60 lb. oil pump and hardened drive shaft, front cover (new) with the original rebuilt water pump, and the original windage tray and oil pan. It’ll be ready to run on the test stand after the holidays and then on to the dyno.

Dennis

[Norwood]

Watching this build closely. It probably looks like this under those nice heads. Lol

[SD455DJ]

Originally Posted by Norwood

Watching this build closely. It probably looks like this under those nice heads. Lol

That does look mighty familiar...lol!

[SD455DJ]

Dan finished the reminder of the long block assembly, got it painted and ready for the last remaining components (carb, distributor, flex plate, exhaust manifolds, and pulleys) to be installed, so it will be ready to put on the engine stand to test run prior to going on the dyno in a few days. The paint on the exhaust ports will be touched up once that dyno session is done in a few weeks. The In-Line Tube ’66-’70 metallic blue paint is a little darker than the original factory color, but it still looks pretty sweet! The desktop Dyno estimated 370 hp at 5000 rpm with 441 lbft. torque at 3500 rpm with the 068 cam and 9.65 to 1 compression.

Dennis

[Held for Ransom]

I like a black heat shroud more...

[SD455DJ]

Actually, I do too Mike. We'll paint it with hi-temp black before it goes back in the engine bay.

Dennis

[Formulabruce]

I humbly recommend a " smoke test" on Any engine that had a " align bore" at rebuild. Raising up the crank where the front and rear seals are " Fixed" can cause oil leaking..

[SD455DJ]

We finally to around to test running the RAIII. It was pretty painless since we reused the original 068 cam & lifters/ rockers and pushrods, so no new cam to break in. No leaks of any fluids and it ran well. Now we're just waiting on the call to get some dyno time.

Dennis

[unruhjonny]

I haven't seen a 'pure stock' dyno of a RAIII since I think it was 'Musclecar Review' did their couple ages ago;
It would be nice to see if you observe variation from their dyno...

[SD455DJ]

Originally Posted by unruhjonny

I haven't seen a 'pure stock' dyno of a RAIII since I think it was 'Musclecar Review' did their couple ages ago;
It would be nice to see if you observe variation from their dyno...

Well, since Dan dyno'd those RAIII & RAIV engines for MuscleCar Review way back in the late 1990's (dang, it seems just like yesterday!), we have a lot of good information to compare with for this RAIII. We were thinking that since my '70 small valve XV code 400 made 380+ hp and 450+ lbft. of torque with log manifolds, 9.95 to 1 compression, and the 2801 cam, this RAIII should be in the same ballpark power-wise. It gives up a little compression (9.65) and slightly less cam but has RA manifolds and large valve heads. It'll be an interesting comparison for sure.

Dennis

[unruhjonny]

I thought that might have been your or your brothers - but like you pointed out, it has been some time.

[SD455DJ]

The dyno session is on for next Tuesday, April 22nd. So, we'll see how a fresh '406' will do with the factory 068 cam & lifters (and pushrods and rocker arms). The DeskTop Dyno predicts 370 hp at 5000 rm and 441 lbft torque at 3500 rpm. I hope we come close to that myself.

Dennis

[SD455DJ]

Today the Desktop Dyno proved to be right on the money with the power calculated (370 hp/441 lb-ft torque) compared to the actual dyno of the ’70 RAIII YZ 400 (+.030” 406, actually). The base pulls were made with total timing at 36 degrees (and left there the entire dyno session) with 93 octane E10 fuel. The original 7040270 carb was not cooperating, so we switched to a dyno proven 7040267 (455HO manual) carb with 42 primary metering rods & 71 jets, “B” hanger, and CC secondary metering rods (0.0300” medium tip). The best base pull made 365.9 hp @ 5200 rpm and 440.2 lb-ft torque @ 3600 rpm without the air cleaner base and through 12’ of 2.5” exhaust pipe dumping onto the sound chamber. AFR’s were 12.8 average through the pull. Changing the exhaust headpipes to dump into 6” diameter sewer pipes reduced the back pressure and helped power output to climb to 370.1 hp @ 5300 rpm and 443.6 lb-ft tq @ 3700 rpm with the AFR at 12.9 average. The best pull of the day came with adding the air cleaner base that smooths out flow into the carb that netted 372.3 hp @ 5200 rpm and 449.2 lb-ft tq @ 3600 rpm. The air cleaner base leaned out the AFR average to 13.2!

We brought the Firebird RAIII air cleaner assembly to see what it would do to power and with the 14x3 #212 paper filter element inside the power dropped to 358.2 hp @5400 rpm and 440.0 lb-ft tq at 3600 rpm…a reduction of 14 hp and 9 lb-ft tq and the AFR leaning out further to 13.6! Adding a coil of 3/8” rubber fuel hose below the air filter raised the breather lid the same amount restored half the power we lost to 364.6 hp @ 5100 rpm and 445.0 lb-ft tq @ 3600 rpm (AFR stayed at 13.6 avg.).

The air/atmospheric conditions were almost perfect with the correction factor at 1.01.

Dennis

[johnta1]

NICE!