#41  
Old 02-25-2020, 03:35 PM
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Originally Posted by ponyakr View Post
Main advantage the 428 had was that it had more compression than the '71-up 455's.

I think that 390hp 428 may have been a little overrated, or the 360hp GTO 455 engine was underrated.

But, some do like the compromise 4" stroke of the 428. Something for everybody.

One of those #64 head 455's, with no change except an 041 clone cam/Rhoads lifters, ran 12.40's in my '68 Bird bracket car. The Bird had 3.55 gears & a stock 13" converter. I think the 455 had around 75-80K miles when I got it. Had never been apart. A lifter had come apart. Owner thought engine was about to blow. So, he paid me to replace it with a junkyard 400, & he gave me the 455. Got a real good deal on that one. Ran it in 3 different bracket cars. We won lots of races with it. Never ran a 428 on the strip. 455's were much easier to come by, back then. LOTS of early '70's big Pontiacs came with one.
Check out Post 182 of this thread. A 428 setup like this would possibly make even more power with a 744 or ra iv cam.

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Old 02-25-2020, 05:01 PM
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Originally Posted by geeteeohguy View Post
There were a lot of Olds powered jet boats in the early 80's
I really wanted to get into jet boats in the mid 70's and likewise, those blue 455 Olds jets seemed to be everywhere.

My friend was really into the W30 455's in those days and had some trouble keeping the rod bearings from spinning.

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Old 02-25-2020, 05:31 PM
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So I'll throw a slightly related but tangential question -why did most of the jet boats in the 70s early 80s use Olds 455s vs Chevy 454, Pontiac , Buick 455s?
Because no one would care if the boats sank

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Old 02-25-2020, 05:31 PM
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If under square was the way to go why did Pontiac use the Olds 403 - 4.351" x 3.385"?

Stan
Simple. 403 came out in 77, replaced applications that used the 455. They needed 400ci +/-, and all small block olds cranks were all 3.385. Only way to get it big enough as a small block was to take the bore out huge. A friend in FL just stuffed an aftermarket 4.00 crank in his 403, its 484" if memory serves. My 350 diesel with 4.00 425 crank and 0.197" overbore ended up 454ci. Still small block.

The olds motor from 1968 to 1976 only had two different combustion chamber sizes, and two different piston dish sizes. They were durable, inexpensive, and did the job. That meant 442s, land barges, jet boats, irrigation pumps, etc. Eight years of production with few changes (besides w-30 specific parts) means that they're quite plentiful, unlike the 455 Pontiac.

I'd love to see two cars of similar weight and gear, one with 428 Poncho and one with 425 Olds, and let them go at it. I'd bet theyd be close.

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Old 02-25-2020, 06:08 PM
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Olds 403 was a decent engine. If your TA came with one they can be built to put a smile on your face.

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Old 02-25-2020, 07:42 PM
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I have 3 455 powered cars; I love the diesel like torque. The TA is just a low mileage, low compression, unopened (sans timing chain) 1971 455 but the torque is unreal. Even the 75 GV I have with a 200 horse smogger will light up the tires anytime.

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Old 02-25-2020, 08:06 PM
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Originally Posted by MarkS57 View Post
I really wanted to get into jet boats in the mid 70's and likewise, those blue 455 Olds jets seemed to be everywhere.

My friend was really into the W30 455's in those days and had some trouble keeping the rod bearings from spinning.
Olds V8s are pretty durable but had a flimsy weak bottom end if you plan on pushing them unless you use the diesel block or girdled it.

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Old 02-25-2020, 09:13 PM
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Originally Posted by PAUL K View Post
Haven't you ever seen an Internet thread road map... It zig zags all over the place. Kinda like one of those spaghetti maps that predict the path of a hurricane

I thought they added stroke to make up for the loss of compression. I also think they did a lot of bad guessing when diving into the emissions part.
Precisely, Paul. The Big Three were already aware that unleaded fuels were coming. The extra displacement was to compensate for the drop in compression ratios that had already been mandated for 1971. Yes, the bureaucrats at EPA really should have left the engineering to the engineers. It's odd: we are coming full circle. In order to conform with more stringent environmental and fuel economy standards we are returning to high compression engines. I read an article a few weeks back that stated that 87 octane unleaded regular will soon disappear because many of the engines powering hybrid vehicles utilize engines with 10:1 or higher compression ratios. The new grades will be 89 octane unleaded regular, 93 octane mid grade and 100 octane premium.

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Old 02-25-2020, 09:17 PM
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Originally Posted by Stan Weiss View Post
If that is the case why was the Pontiac 301 so over square?

Stan
A 4" bore and a 3" stroke isn't that over square, Stan. Think about it: the 301 also had an air pump, catalytic converter, altered carburetor jets and ignition timing plus it was designed for unleaded fuel from the get go.

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Old 02-25-2020, 09:21 PM
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Originally Posted by Stan Weiss View Post
If under square was the way to go why did Pontiac use the Olds 403 - 4.351" x 3.385"?

Stan
Stan, you are making this too easy. It was already EPA and CARB certified for CA and high altitude areas. The Pontiac 350 and 400 were NOT. Look at the cam specs, carb jetting and ignition timing of the 403s. Then, consider the 403 had an air pump, catalytic convertor and was designed to burn unleaded fuel.

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Old 02-26-2020, 12:26 AM
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Originally Posted by hurryinhoosier62 View Post
emissions. Under square engines produce few emissions than over square or square engines. The first emissions control protocols were already in effect in CA.
From the perspective of the times, this is true.

Given the decades of additional research, not so much. But also consider, Chevy was cutting bore size and increasing stroke by 1965 compared to the engines designed in the '50s. The 409 "W" Chevy had a much shorter stroke than the 396/402 "Mk IV" Chevy; the 348 W" had a much shorter stroke than the 350 sbc. Even the '66 Buick 401 had a shorter stroke than the '67 Buick 400.

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Originally Posted by PAUL K View Post
I thought they added stroke to make up for the loss of compression. I also think they did a lot of bad guessing when diving into the emissions part.
They were scrambling like mad. They made many bad choices, but I think Management had a hand in that also--by insisting everything be as absolutely cut-rate cheap as possible. It took a couple of decades and on-board computers to even begin to bring power numbers up. If they'd made better choices then about compression ratio, quench distance, in-cylinder turbulence, restrictive pellet-type catalysts instead of monolithic/honeycomb, and a host of other factors, we'd be remembering much nicer cars to drive.

Buick, Olds, Cadillac each built larger engines in the '67--68 time frame, just as the switch-pitch feature was getting deleted from the TH400 and TH425. It was cheaper to enlarge the displacement than to fancy-up the torque converter.

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Originally Posted by steve25 View Post
First and foremost it was the switch to the open chamber heads that got most manufacturers in compliance with the Fed's limits on emissions!

Followed by Bigger motors stroke wise made for increase Torque which allowed less rear gear.
Lower rpm and less emissions go hand in hand!
But open-chamber heads tend to have poor turbulence, slow burn, and need lots of spark advance. They mitigated one problem, but caused two more: Low power and crappy mileage.

"Stroke" doesn't increase torque. Increased displacement increases torque. The Buick 455 was a torque-monster; and it had the shortest stroke of all the GM 454-455s.

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Originally Posted by napster View Post
Think about it. Bunky Knunsen (SP) was at Ford and they had the BOSS 429 and chevy had Delorean and they came out with the 454 LS-6. All Pontiac guys that were gear heads.
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Originally Posted by Formulajones View Post
I tend to believe it was more along the lines of cost. Due to limited bore spacing, the only way Pontiac could increase the CI comparable to other brands was to simply shove a long crank in it, otherwise they would have to spend more money to completely redesign and cast a new block.
The Pontiac block and the Olds block have similar bore-center measurements, along with the FE Ford. I've heard that the same raw forging can be machined into Pontiac, Olds, or FE crankshafts just by altering the way it's machined.

Pontiac "could" have siamesed the cylinders like Olds did with the 403, and had a significantly larger bore (or just gone paper-thin like Ford did with the 427). I wonder if Pontiac management/engineering ever considered that.

Quote:
Originally Posted by Skip Fix View Post
So I'll throw a slightly related but tangential question -why did most of the jet boats in the 70s early 80s use Olds 455s vs Chevy 454, Pontiac , Buick 455s?
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Originally Posted by PAUL K View Post
Tons of torque from the long and relatively small intake tract.... IMO
Quote:
Originally Posted by Stan Weiss View Post
Unless I am thinking of something else jet boats were not high RPM.
Far as I can tell, the Olds management made engines available to the Berkeley Jet company cheap. Olds also sold engines to companies producing agricultural irrigation pump systems. Maybe the Olds engine plant(s) had excess capacity and needed a way to dispose of a heap of engines. Every time I saw a jet-powered ski boat with a white painted (Berkeley) jet drive, there was an Olds engine powering it. Every time I saw an Olds engine in a jet-powered ski boat, it had a white Berkeley jet drive. There were other brands of jet drives, but Berkeley was "the" main player in the market I was exposed to.

Ever driven a jet boat? The L-A-S-T thing you need is big bottom-end torque. Low-RPM torque is TOTALLY WASTED. A jet pump is a centrifugal pump. At 2K rpm, they barely move any water. I think a Techumsah lawn-mower engine could spin one at 2000 rpm. It takes ~600 horsepower to spin them 6000 rpm, and probably 400+ horsepower to spin one 5000 rpm. The power absorption of the pump is VERY non-linear. (i.e., it takes much more than double the power to double the RPM.)

So lots of Olds/Berkeley power packs ran 4500--4800 for hours on end, 'cause that was WFO and all the engine could do. The torque curve of the engine intersects with the torque absorption of the jet pump; and that's it for RPM unless the boat hits a wave and the pump sucks air.

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Originally Posted by steve25 View Post
Other then the Olds motor bring lighter then a BBC for use in a Boat I can't see why Edelbrock made the needed water cooled Exh Manifolds for them.

I think Mondello was twisting Vic's Arm a lot to do that!
Edelbrock made marine parts for heaps and piles of different engines. Marine engine mounts, timing covers that could mount a cam-driven marine water pump, and water-cooled aluminum exhausts for Ford small-block, Ford FE, Ford 460, SBC, BBC, Olds, Pontiac, Mopar B-RB-Hemi...Edelbrock made lots of marine stuff. Far as I know, every bit of it was discontinued decades ago.

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Originally Posted by chiphead View Post
Yeah, now we understand the concept of crevice volume and how much unburned hydrocarbons hide there. This is one reason there are precious few modern engines over 4" bore. The unburned HC emisions go up along with bore size. Top ring placement has an impact on crevice volume, so even that affects emissions. They didn't undertand any of that yet in the late 60s.
There was also the idea that large-scale production machine tooling couldn't control tolerances very well. The quench distance was huge. Part of that was the machining engineers telling GM they couldn't hold tight tolerances, and they had to go big because going small could result in things hitting each other. The other part of it was LIES told to the upper management. Example: There was a problem with certain Chevy engines not making advertised horsepower. Engineers grabbed several engines from a warehouse, and measured them. The cylinder blocks were too tall, leading to the piston being way "down in the hole" which lowered compression. Why? It cost less to leave the blocks too tall rather than spend the machining time and tool wear to cut them lower. The plant manager probably got bonuses for increasing production and lowering the wear on the tooling, while at the same time he was sabotaging the power, efficiency, and emissions output of the engines he was making.

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Originally Posted by chiphead View Post
There were no overdrive automatics in 1970s american cars, so the only way to move a heavy car around with freeway gears is to put a larger engine in... ...The emission laws of the early 80s caused a slaughter of engine families, Pontiac, IHC, Caddy, most Olds and Buick, among others ,were discontinued by '82
Yeah, the outright failure of GM and the competition to produce a REAL automatic transmission with additional gear ratios was a stunning mistake. The TH400 and variants was a great trans, but it needed another gear. This happened in '91 or '92, but only in trucks, and only with computer control. They needed it in '73 or earlier, with no electronic controls beyond the kickdown. Same with the TH350. It was sort-of replaced with the 700 a decade or more too late; but the 700 was a piece of crap for the first three or four years, and wasn't really right until...1988? And even then, it was at best a "light-to-medium duty" trans, and at worst it was a hand grenade.

'Course, we could see what was happening in '67, when GM killed the switch-pitch TH400 for the '68 model year. They were carving money and utility out of the transmissions even then. The Powerglide was even worse. Had GM spent a little more, a little earlier, they'd have eliminated untold problems in the '73--'90 timeframe; and they'd have pissed-off fewer customers in the process.


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Old 02-26-2020, 02:15 AM
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Reading this post we have different conversations going all over the place, from 428 to Olds power boats.

Let's start with emissions. Thank you, California. Yep, that's where it began. 1961 an administrative organization called the Motor Vehicle Pollution Control Board (MVPCB) was created. Later changed to the State of California Air Resources Board in 1967.

In 1961 the board required all new motor vehicles sold in California to have crankcase emission control devices (namely to control engine blow-by gases) as factory installed equipment aimed at reducing hydrocarbons down from 1.25 pounds per car per day to 1.0 pounds. This changed in 1966 when unburned hydrocarbons had to be limited to 275 part per million (ppm) and the carbon monoxide to a 1.5% concentration by volume dropping the pollution levels to .046 pounds per day per car. The projected number that California was looking to see by 1970 was 0.20 pounds per vehicle per day.

Thus began the introduction of the PCV valve, the closed crankcase system, A.I.R. systems, open chamber heads, thermostats changed from 180 to 200 degrees, reduction of idle port holes/limited idle screw adjustments, retarded timing controls and the double acting vacuum advance can, the catalytic "after burner" (yes, 1968), and the gasoline vapor recovery systems. All thanks to California and mandatory on all cars/engine sold in California and this was all by 1968, and of course more was to come after 1968. In other states, some of these requirements were not required and thus a CA car will have the AIR system while one in New York would not, but still had the AIR heads. The better burning open chamber heads did away with the AIR system......but it did return at a later date along with those charcoal canisters if anyone recalls those.

The use of the Oldsmobile 403CI came about because it was the only comparable engine to the Pontiac 400CI that met California emissions standards. So California cars were fitted with the Olds engine in lieu of a Pontiac 400. The 403 was also an optional engine on the Catalina.

The Olds may have had smaller valves (2.07/1.62) and even flowed less than a Pontiac head, but the use of a longer duration and higher lift did wonders for the W30 option. The 1970 W30 455 was rated at 370HP @ 5200 RPM and 500TQ @ 3600. The cam had a 328 duration on Int/Ex, Lift was .475, and had an overlap of 108 degrees! So do you want to compare it to the 370HP RA IV or the 360HP 455? Oldsmobile had some hot set-ups to include the W31 350 with its 308 duration cam and .474" lift and 82 degree overlap cam. Same HP as the Pontiac 350HO, but my guess is it'll outrun the 350HO.

You can also look to an earlier time when the engine option in 1966 on the 442 could be had with the 400CI, tri power, ram air induction, close ratio 4-speed, and 4.33 gears and would have been the match to Pontiac's 389 XS tri power, ram air option.

I have never owned an Olds 442, but I would say they had a few engine options that may have put a hurting on a Pontiac GTO, or a Tempest/Lemans with the 350HO.

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Old 02-26-2020, 04:09 AM
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Originally Posted by PontiacJim1959 View Post
the catalytic "after burner" (yes, 1968)
No catalyst before model-year 1975. I think you mean "Thermal Reactors".

Essentially after-burning exhaust manifolds fed with fresh air from the AIR pump or the Pulse Air system. The added oxygen allowed the overly-rich mixture to continue to oxidize.

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Old 02-26-2020, 07:10 AM
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Low power and crappy mileage came about due to the drop in compression that just so happened to come along with the open chamber, but it does not have to be that way!

And you have something way the heck wrong, as closed chamber heads require more timing then open chamber heads to make max power, its just that the open chamber heads can be more prone to ping and knock if compression ratios your looking at are are kept equal.

Anyway have we gone off the rails in regards to the OPs original question here, sorry about that!

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Old 02-26-2020, 12:00 PM
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I wide ranging thread with all kinds of emission and good info about the Pontiac 428, 455, and even the Oldsmobile V-8's! It's an interesting look back. To the OP's original question, "why was the 428 discontinued?" I think the advertising and marketing group had more to do with it than engineering. Pontiac simply wasn't going to be left in the "displacement dust", by the 4 other GM divisions. Cadillac was moving toward 500 CU IN. Olds, Buick and Chevy were 454,455. Pontiac stuck at 428 would have been a sales disaster in that time period, no matter the HP. Pontiac had to be equal or larger. The move from 428 to 455 was an easy deal. No clearance issues in the bottom plenty of cylinder wall, same engine package, easy change. BTW, I have owned numerous 421's and ran them as 428's, as well as a few stock 428's. I can't fully explain why, but that was a real sweet spot in cylinder head flow, rod ratio, bore and stroke. They just ran beautifully and had superior power to a 455 from 4000-5500 RPM stock. A very nice engine package. 455 was essentially a smog package big engine with the exception of the high compression 70 455. The 71-72 HO had the better top end to help utilize the displacement and of course we know how that was improved more in the SD-455, allowing higher RPM's with a better bottom end and even more improvements up top. Other than that, a stock 455 is just a big smog engine. At my school, years ago a student brought a really nice Grand Ville in for a run on the chassis dyno. Stock engine, about 80K miles, 455. Ran it several times, sounded pretty good too, Q-jet sucking all the air available. When the dust settled, it had made peak power at the wheels of just under 140 HP!!. The owner was ready to cry. This was the reality of cars from that era.

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Old 02-26-2020, 12:24 PM
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Pontiac 428 is one of the vintage cars I want to add to my collection.

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Old 02-26-2020, 12:32 PM
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"The 409 "W" Chevy had a much shorter stroke than the 396/402 "Mk IV" Chevy" 4.3125 bore X 3.50 stroke. Sam main spacing as a BBC crank just turn down the mains.

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Old 02-26-2020, 12:43 PM
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Quote:
Originally Posted by mgarblik View Post
I wide ranging thread with all kinds of emission and good info about the Pontiac 428, 455, and even the Oldsmobile V-8's! It's an interesting look back. To the OP's original question, "why was the 428 discontinued?" I think the advertising and marketing group had more to do with it than engineering. Pontiac simply wasn't going to be left in the "displacement dust", by the 4 other GM divisions. Cadillac was moving toward 500 CU IN. Olds, Buick and Chevy were 454,455. Pontiac stuck at 428 would have been a sales disaster in that time period, no matter the HP. Pontiac had to be equal or larger. The move from 428 to 455 was an easy deal. No clearance issues in the bottom plenty of cylinder wall, same engine package, easy change. BTW, I have owned numerous 421's and ran them as 428's, as well as a few stock 428's. I can't fully explain why, but that was a real sweet spot in cylinder head flow, rod ratio, bore and stroke. They just ran beautifully and had superior power to a 455 from 4000-5500 RPM stock. A very nice engine package. 455 was essentially a smog package big engine with the exception of the high compression 70 455. The 71-72 HO had the better top end to help utilize the displacement and of course we know how that was improved more in the SD-455, allowing higher RPM's with a better bottom end and even more improvements up top. Other than that, a stock 455 is just a big smog engine. At my school, years ago a student brought a really nice Grand Ville in for a run on the chassis dyno. Stock engine, about 80K miles, 455. Ran it several times, sounded pretty good too, Q-jet sucking all the air available. When the dust settled, it had made peak power at the wheels of just under 140 HP!!. The owner was ready to cry. This was the reality of cars from that era.
The SS GT racers have latched on to the 428, with the legal Edelbrock heads that can be used, for what is essentially some of the reasoning stated above.
Robert Cruzen's Cavalier is super competitive. He never did say who he had build his engine, but is ws a shop that primarily built Chevrolet stuff, even they were impressed with his Pontiac mill...

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Old 02-26-2020, 12:43 PM
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Wanna have some fun? Put a 428 crank in a 455 block with some light pistons and longer rods, good flowing heads and a nice cam and get ready for power out to 7000+ RPM.

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Old 02-26-2020, 12:45 PM
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Bunkie Knudsen left GM to go to Ford. Later, he was fired from Ford.

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No kidding Knudsen went to Ford and got fired. You miss the point, there would not have been a Boss 429 if he was never there. It took a gear head to get the Boss 429 in the first place as opposed to the non gear heads that were division managers after Delorean .

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