has anyone seen a 7040251 quad Jet on a 70 w30 auto car. looks like a R1
then under that 0700. these are beside the 7040251
friend of mine has a w30 auto car , all original with this carb. looking at different sites...some say yes, while some say no.
My performance guide dated back to early 70's says list this one of three numbers on the auto car.

what say anyone??

Thanks

 

7040251 was sort of the generic quadrajet for 1970, sort of the base model that ended up on more engines than any other. But not the W-30s.


How does the carb's date code compare with the car's build date? 0700 is the 70th day of 1970, so right around March 11.

 

1968 and up, '251 = std issue RWD Auto Trans BB number

while many things are possible, putting the correct carb on a W30 would be something the factory would be a firm on.

 

the car built day was april 70

 

here is the article i found that suggest they were on some W30's equipped with them. it was published by Oldsmobile in spring of 1970. Which incidentally I have a copy of that I bought back in 1974. So when I looked it up for him this is what I found.

so I'm confused once again. Not doubting anyone word or anything. So???
I would have to do some more reseach but Iseen it somewhere else also.
car is all original, 46000 miles second owner the original owner lived two doors down from him- so he knows nothing has every been change and it is all original.
SUPER-TUNING AND BLUEPRINTING SPECIFICATIONS
FOR 1969 & 1970 OLDSMOBILE 350 AND 455 CU. IN. ENGINES
AND "W-MACHINE" OPTIONS
Published by Oldsmobile - Spring, 1970

A. SUPER-TUNING Super-tuning is a term that means bringing every component within the engine up to its peak. Many times off-road operation calls for different settings and adjustments than are proper for street use. A well tuned engine requires proper ignition and carburetor settings, a good performing valve train and non- restrictive air cleaner and exhaust system. Ignition Stock distributors on each of the W-Machines have mechanical advance curves which parallel best spark timing. The mechanical advance curves, vacuum advance curves, and initial timing settings on all models are selected to give best performance with the normal carbon build-up and street equipment. For off-road use in a car where the amount of idle and low speed operation will be held to a minimum, higher timing settings may be used. However, precautions must be taken: 1. Disconnect vacuum advance hose at the distributor and plug the hose. Leave the distributor vacuum connection open. This will preclude road load detonation which must be avoided for long engine life. 2. Use super premium fuels to further avoid detonation. 3. Be conservative. Increase timing in small steps, listening for any detonation ("knock") The important area to watch in changing timing is the advance above 4000 RPM (with vacuum disconnected). For off-road use, timing should be set to give 35 degrees advance BTC above 4000 RPM. Advance beyond 35 degrees should be done in small steps against a timer and in conjunction with changes in carburetor jetting, slight richening until ultimate potential is realized. To set timing accurately above 400 RPM, a new set of scribe marks will have to be added to the balancer, since the normal timing tab stops at 15 degrees BTC. These marks must be made on the balancer below the present mark (clockwise from the front of the car). Timing can then be read using the 0 degree mark on the tab and the new marks on the balancer, while revving the engine to 4000 RPM momentarily. CAUTION: DO NOT LOOSEN THE DISTRIBUTOR HOLD DOWN BOLT AND ADJUST WHILE REVVING THE ENGINE. MOVE THE DISTRIBUTOR A SMALL AMOUNT, TIGHTEN, AND REV TO 4000 FOR 2-3 SECONDS. Scribe the marks clockwise from the present mark per the following chart: Degrees BTC 350 Engines 400 & 455 Engines 30 1 7/8 inches 1 11/15 inches 35 2 3/16 inches 1 31/32 inches 40 2 1/2 inches 2 9/32 inches B. The production method of setting the timing may be used if the mechanical advance curve is known (check curve on a sun machine). The following chart lists the production distributors with settings, along with suggested settings to achieve 35 degrees BTC above 4000 RPM. 1969 --- W30: Distributor Number 1111933 - Production initial setting of 14 degrees BTC at 1250 RPM provides 27 degrees BTC timing above 4000 RPM. - Change to 15 degrees BTC at 500 RPM or less, or 17 degrees BTC at 800 RPM to provide 35 degrees above 4000 RPM. 1969 --- W31: Distributor Number 1111930 - Production initial setting of 12 degrees BTC at 1000 RPM provides 30 degrees BTC timing above 4000 RPM. - Change to 15 degrees BTC at 800 RPM to provide 35 degrees above 4000 RPM. 1969 --- W32: Distributor Number 1111989 - Production initial setting of 14 degrees BTC at 850 RPM provides 37 degrees BTC timing above 3000 RPM. 1970 --- W30 SMT: Distributor Number 1111977 - Production initial setting of 12 degrees BTC at 850 RPM provides 34 degrees BTC timing above 4000 RPM. - Change to 13 degrees BTC at 850 RPM to provide 35 degrees BTC above 4000 RPM. 1970 --- W30 AMT: Distributor Number 1111979 - Production initial setting of 10 degrees BTC at 850 RPM provides 33 degrees BTC timing above 3000 RPM. - Change to 12 degrees BTC at 850 RPM to provide 35 degrees BTC above 3000 RPM. 1970 --- W31: Distributor Number 1111975 - Production initial setting of 14 degrees BTC at 1100 RPM provides 30.5 degrees BTC timing above 4000 RPM. - Change to 15 degrees BTC at 800 RPM to provide 35 degrees BTC above 4000 RPM. 1970 --- F85, 4-BBL (310 hp): Distributor Number: 1111975 - Production initial setting of 10 degrees BTC at 1100 RPM provides 26.5 degrees BTC timing above 4000 RPM. - Change to 15 degrees BTC at 800 RPM to provide 35 degrees BTC above 4000 RPM. 1970 --- 4-4-2 (Except W30): Distributor Number 1111982 - Production initial setting of 12 degrees BTC at 1100 RPM provides 30 degrees BTC timing above 4000 RPM. - Change to 15 degrees BTC at 600 RPM to provide 35 degrees BTC above 4000 RPM. The timing indicator (tab) is marked (in degrees) -4, -2, 0, 2, 4, 6, 8, 10, etc. The top edge of the tab is 14-15 degrees BTC. To insure against point bounce with high RPM usage, double springing of the production point springs may be done. The best method is to use Corvette Delco points No. 1966294. These points are good to 7000 RPM. C. CARBURETION Carburetors are calibrated for best full throttle as best part throttle mixtures and street performance. The best starting point for off-road use is production specifications. However, because of varying climactic conditions and the fact that exhaust headers will be used and part throttle driveability need not be considered, a number of changes may be tried. First, production specifications are as follows: MODEL PART # PRIMARY PRIMARY SECONDARY SECONDARY ROD ON CASTING JET METERING ROD METERING ROD END DIAPHRAGM 1970 W30 7040251 .070 Yes AU .053 7040256 .058 No AU .053 7040258 .070 Yes AU .053 1970 W31 7040255 .057 No AU .053 1970 365hp 7040251 .070 Yes AU .053 7040257 .070 Yes AU .053 7040253 .069 Yes AT .067 1970 310hp 7040250 .070 Yes AT .067 7040253 .069 Yes AT .067 1969 W30 7029254 .075 Yes AU .053 1969 W31 7029255 .074 Yes AU .053 1969 W32 7029251 .070 Yes AU .053

 

Interesting, never read the part on carb's.

 

Reading further down the Olds Document it states the following:
I still looking for the other document....more later...

PARTS IDENTIFICATION - 1970

4-4-2 ENGINE 370 HP 455 cu.in. 365 HP 455 cu.in.
AMT SMT AMT SMT
Cyl. head casting no. 404438 404438 403686 403686
Cyl. head assy. includes 406741 405588 405586 405586
valves and springs
Cyl. head (machined) 230897 230897 230896 230896
Intake valve 403350 403350 403350 403350
Exhaust valve 401762 401762 401762 401762
Valve Spring 404729 404729 397583 397583
Carburetor
Catalog number 7041340 7041326 7041327 7036931
Rochester number 7040251 7040251 7040251 7040253
or 7040258 or 7040256 or 7040257
Camshaft 402569 402569 400165 406768
Piston "A" size 400561 400561 400561 400561
Distributor 1111979 1111977 1111982 1111982

 

here are NHRA limits for the 70 W30
looking more like the 251` carb is one of three that may have been used on the W30 ...

4-4-2 W-30 SPECIFICATIONS REGISTERED NHRA LIMITS - 1970 455 CU.IN.

Bore and Stroke 4.125 X 4.250
Compression ratio 9.64:1 Nominal
11.148:1 clean
Max. bhp 370 at 5400 rpm
Max. torque ft. lbs. 500 at 3600 rpm
Head gasket thickness, compressed 0.023" - .027"
Head gasket volume 5.32305 cc min.
Deck clearance, min. 0.002" below block
Min. combustion chamber vol. 91.71971 cc min.
Piston type dished
Displacement of dish 1430 cc min.
Cyl. head, part number 230897
casting number 400370
Carburetor, type 4bbl Rochester specially calibrated
Model w/SM trans 4MV
Model w/Auto trans 4MV
Part no. w/SM trans 7040251 or 7040256
Part no. w/Auto trans 7040251 or 7040258
Intake manifold casting no. 406115
Material Aluminum
Camshaft type Hydraulic
Part no. 402570
Assembly no. 402569
Casting no. 389410
Rocker arm ratio 1.6:1
Camshaft timing
Opens, intake & exhaust 56degrees BTC, 96degrees BBC
Closes, intake & exhaust 92degrees ABC, 52degrees ATC
Overlap 108degrees
Duration intake & exhaust 328degrees, 328degrees

 

I tried to reformat the above and put some spaces and carriage returns and tabs to make it readable...

Here at CO.com, tabs do not display properly, nor do spaces reliably locate your text on the screen in columns... but at least broken into paragraph-esque chunks maybe it can be more useful. In Word on my computer screen it is much better.

A couple of obvious typos, errors, and just plain nonsense, but agreed that it appears to show that
_for early 1970 production_
the '0251 carb may have been fitted to W30's - before they developed the '256, '257, and '258 variants.

Some issues with the Supertuning info:

Bless their hearts, the original writers want you to measure and mark the harmonic balancer using stone-age fractional inches. The editor has provided decimal equivalents for the more modern technician.

"listen for detonation" - how does that work for folks whose hearing is not so good? Isn't there a better way?

Under 1969 W32, Distributor 1111989, the "Change to..." part is missing.

Points distributor, heh. Yeah, use TWO SPRINGS. Old racer's trick. Replace the points due to rubbing block wear after every race.

The 1968 RamRod is entirely ignored. Still a secret. To this day.

Cyl. head asm. PART NUMBERS are pretty much useless today. Not going to find one at the "dealer." The Casting number may help get the right-ish part, but there are common E heads and Big Valve E heads. Ditto for carb "catalog numbers."

One may still find NOS valves or springs with a PN on what's left of the box I guess.

Bless their hearts, they list head gasket volume accurate the 1/100,000 cc. Since measurement accuracy is on the order of 0.1mm or so, it is ludicrous to even specify any digits beyond about 0.01 of a cc. According to my math, a measurement error of about 0.001" aka 0.03mm on the head gasket diameter and thickness results in the calculated gasket volume cc varying by about 0.3cc. Therefore your calculated head gasket volume figure is plus or minus 0.5cc or so. This applies if you ascertain a volume by burette also. There is only so much accuracy you can reasonably attain… or that matters.

Ditto for combustion chamber volume [in metric units cc even though all other things are in inches...]
"Min. combustion chamber vol. 91.71971 cc"
Just because your 1970 HP Reverse Polish Notation calculator displays 5 digits after the decimal does not mean that those digits are meaningful or useful...

Obvious error in
"Displacement of dish 1430 cc min."
I could believe 14.30 cc - at least they didnt specify it as 14.3018436572 cc...

They list the heads [from 1969 models] as casting #400370 - but can't be bothered to specify that obvious HUGE letter "D" that is far more prominent.

.================================================= ===========
SUPER-TUNING AND BLUEPRINTING SPECIFICATIONS
FOR 1969 & 1970 OLDSMOBILE 350 AND 455 CU. IN. ENGINES
AND "W-MACHINE" OPTIONS
Published by Oldsmobile - Spring, 1970

A. SUPER-TUNING
Super-tuning is a term that means bringing every component within the engine up to its peak. Many times off-road operation calls for different settings and adjustments than are proper for street use. A well tuned engine requires proper ignition and carburetor settings, a good performing valve train and non- restrictive air cleaner and exhaust system. Ignition Stock distributors on each of the W-Machines have mechanical advance curves which parallel best spark timing. The mechanical advance curves, vacuum advance curves, and initial timing settings on all models are selected to give best performance with the normal carbon build-up and street equipment. For off-road use in a car where the amount of idle and low speed operation will be held to a minimum, higher timing settings may be used. However, precautions must be taken:

1. Disconnect vacuum advance hose at the distributor and plug the hose. Leave the distributor vacuum connection open. This will preclude road load detonation which must be avoided for long engine life.

2. Use super premium fuels to minimize the risk of detonation.

3. Be conservative. Increase timing in small steps, listening for any detonation ("knock") The important area to watch in changing timing is the advance above 4000 RPM (with vacuum disconnected). For off-road use, timing should be set to give 35 degrees advance BTC above 4000 RPM. Advance beyond 35 degrees should be done in small steps against a timer and in conjunction with changes in carburetor jetting, slight richening until ultimate potential is realized. To set timing accurately above 4000 RPM, a new set of scribe marks will have to be added to the balancer, since the normal timing tab stops at 15 degrees BTC. These marks must be made on the balancer below the factory zero mark (clockwise on he balancer, as viewed from the front of the car). Timing can then be read using the 0 degree mark on the tab and your new marks on the balancer, while revving the engine to 4000 RPM momentarily. CAUTION: DO NOT LOOSEN THE DISTRIBUTOR HOLD DOWN BOLT AND ADJUST WHILE REVVING THE ENGINE. MOVE THE DISTRIBUTOR A SMALL AMOUNT, TIGHTEN, AND REV TO 4000 FOR 2-3 SECONDS.

Scribe the marks clockwise from the present mark per the following chart:
Degrees BTC 350 Engines 400 & 455 Engines
30° 1 7/8 inches 1 11/16 inches
35° 2 3/16 inches 1 31/32 inches
40° 2 1/2 inches 2 9/32 inches

[Editor - As of 2015, it is assumed that technicians have or can procure a digital or Vernier calipers, and can work in thousandths of an inch - or even in mm - rather than the archaic “wooden wheel” manufacturing techniques using fractions and halves of halves of halves. For your convenience the above fraction idiocy is presented here in figures accurate 0.001” or so. (mm also)
30° 1-7/8 = 1.875 (47.6) 1-11/16 = 1.688 (42.9)
35° 2-3/16 = 2.188 (55.6) 1-31/32 = 1.969 (50.0)
40° 2-1/2 = 2.500 (63.5) 2-9/32 = 2.281 (57.9) ]

B. The production method of setting the timing may be used if the mechanical advance curve is known (check curve on a Sun distributor machine). The following chart lists the production distributors with settings, along with suggested settings to achieve 35° BTC above 4000 RPM.

1969 W30, Distributor 1111933
Production initial setting of 14 degrees BTC at 1250 RPM provides 27 degrees BTC timing above 4000 RPM.
Change to 15 degrees BTC at 500 RPM or less, or 17 degrees BTC at 800 RPM to provide 35 degrees above 4000 RPM.

1969 W31, Distributor 1111930
Production initial setting of 12 degrees BTC at 1000 RPM provides 30 degrees BTC timing above 4000 RPM.
Change to 15 degrees BTC at 800 RPM to provide 35 degrees above 4000 RPM.

1969 W32, Distributor 1111989 - Production initial setting of 14 degrees BTC at 850 RPM provides 37 degrees BTC timing above 3000 RPM.
[“Change to…” text is conspicuously absent]

1970 W30 SMT, Distributor 1111977 - Production initial setting of 12 degrees BTC at 850 RPM provides 34 degrees BTC timing above 4000 RPM.
Change to 13 degrees BTC at 850 RPM to provide 35 degrees BTC above 4000 RPM.

1970 W30 AMT, Distributor 1111979 - Production initial setting of 10 degrees BTC at 850 RPM provides 33 degrees BTC timing above 3000 RPM.
Change to 12 degrees BTC at 850 RPM to provide 35 degrees BTC above 3000 RPM.

1970 W31, Distributor 1111975 - Production initial setting of 14 degrees BTC at 1100 RPM provides 30.5 degrees BTC timing above 4000 RPM.
Change to 15 degrees BTC at 800 RPM to provide 35 degrees BTC above 4000 RPM.

1970 F85, 4-BBL (310 hp), Distributor 1111975 - Production initial setting of 10 degrees BTC at 1100 RPM provides 26.5 degrees BTC timing above 4000 RPM.
Change to 15 degrees BTC at 800 RPM to provide 35 degrees BTC above 4000 RPM.

1970 4-4-2 (Except W30): Distributor 1111982 - Production initial setting of 12 degrees BTC at 1100 RPM provides 30 degrees BTC timing above 4000 RPM.
Change to 15 degrees BTC at 600 RPM to provide 35 degrees BTC above 4000 RPM. The timing indicator (tab) is marked (in degrees) -4, -2, 0, 2, 4, 6, 8, 10, etc. The top edge of the tab is 14-15 degrees BTC.

POINTS DISTRIBUTOR:
To insure against point bounce with high RPM usage, double springing of the production point springs may be done. The best method is to use Corvette Delco points No. 1966294. These points are good to 7000 RPM.

C. CARBURETION Carburetors are calibrated for best full throttle as best part throttle mixtures and street performance. The best starting point for off-road use is production specifications. However, because of varying climactic conditions and the fact that exhaust headers will be used and part throttle driveability need not be considered, a number of changes may be tried. First, production specifications are as follows:

Car Model
Carb # - Jet Size - [Y/N info is ??] - Secondary Rod ID - Tip Dia.

1970 W30
7040251 .070 Yes AU .053
7040256 .058 No AU .053
7040258 .070 Yes AU .053

1970 W31
7040255 .057 No AU .053

1970 365hp
7040251 .070 Yes AU .053
7040257 .070 Yes AU .053
7040253 .069 Yes AT .067

1970 310hp
7040250 .070 Yes AT .067
7040253 .069 Yes AT .067

1969 W30
7029254 .075 Yes AU .053

1969 W31
7029255 .074 Yes AU .053

1969 W32
7029251 .070 Yes AU .053

 

Here's my take. "Real" 1970 W-30 motors with the 328 deg cam, used in manual trans applications, did not pull enough vacuum to operate the power piston, which is why those applications used carbs without primary metering rods. The "psuedo" 1970 W-30 motors with the 285/287 cam used in AT applications were pretty much W-34 motors and did use carbs with power pistons and primary metering rods.

No, I don't have any proof of this, just logic.

 

Thanks guys, I may have answered this question myself, thanks again

 

I am quite confident that the W-30 engines did not receive the '251 carb from the factory. The engine assembly manual is quite clear on which carb is to be used on each engine.

So why does the Supertuning guide list the '251 carb? Two reasons: First, in this guide and elsewhere Oldsmobile wanted to establish for the NHRA and other racing bodies that the '251 is an acceptable part number for the W-30. They do the same with other components so that the guys running the Stock class aren't stuck having to purchase rare parts. Same thing with the blueprint specs in the guide. Olds published dimensions which allowed the racer to maximize his engine. It doesn't mean the engine was shipped from Lansing with those dimensions.

Second, there were plenty of non-W30 owners reading the Supertuning guide wanting to step up their plain 442. There's no sense misleading them into purchasing another carb when their '251 will work just fine with some tweaking.

Now, having said all that, I'll always be open-minded to the possibility that the factory screwed up and installed the wrong carb once in a while, or perhaps even made a conscious choice to do so if they ran out of the right part. But frankly, I consider it more likely that the carb was replaced at some point in the car's life.

 

Remember they were selling cars, if line stopped because of part shortage there was he11 to pay!

 

Classic, very possible since it was a May 70 built or he might have had it change and forgot...

 

A friends Uncle worked on the line in 69 and 70 building 442's and W cars. He stated there weren't much protocol on the line believe it or not. That is why build sheets are found anywhere they wanted to throw them, and many found their way in the trash can...say he..