Anyone have more information about the 1970 Cutlass S equipped with a 350 w/ M20. There are some articles that indicate that these were produced late in the production run.

Not clear whether these were similar to a W31 or not. Seems to me they were produced in various plants and not just limited to Lansing built cars.

Also not sure where some of the production numbers were taken from. Article said there were 531 of these cars built. To me, seems that the 350 was not much different than the earlier 310hp motored coded, QV. The QB designated that it was a 4 speed. May have also had a hotter cam. Not sure.

Thoughts? Comments?

 

Yes, the 4 speed 4-bbl engines had a slightly larger cam than the auto 4 speed 4-bbl engines, but not anything even close to the W-31 engines, which had a .474" lift, 308º advertised duration cam.

stock 350 cam

Auto
.400"/.400" lift
186°/202° duration @ .050"
250°/264° advertised duration
108° intake centerline
109° LSA

Manual
.440"/.440" lift
206°/218° duration @ .050"
262°/274° advertised duration
108° intake centerline
109° LSA

 

Casey Marks and Brian Wurth are two guys on here with lots of QB 350 knowledge (and QB cars/engines).

Terry

 

The Salesmans Spec booklet shows the L74/M20 combo being available at least as early as January 1st 1970. I have some earlier spec books, but will have to dig them out of storage to check for earlier availability

 

Post #7 in the following older thread is very informative in identifying the differences between the QB and QV code engines:

https://classicoldsmobile.com/forums...50-carb-s.html

 

Thanks! Great information. So the next question I have is... is having QB coded Cutlass S more rare than a Rallye or W31? Not sure where some articles come up with a production number of 531.

I would rather have a W31 but maybe a QB coded Cutlass is just as rare to restore. The project car I am considering has AC. Was it even possible to order a Cutlass S with an 350 QB and M20 with AC? That just doesn’t seem possible. Or is it?

 

That is a nice cam for a cruiser. That with the W25 option and dual exhaust would make noticeably more power than the 310 hp auto and no doubt would have made more power than rated, much like the W31.

 

The only production number I have seen over the years for the QB Cutlass is 531. Based on production numbers less were built than W-31 or Rallye 350 cars in 1970. With the low initial production number not many are still out there. The selected options on the QB's I have seen is interesting. In a couple cases, including my car, the options mirror a W-31, almost as if the dealer or customer wanted the closest car to a W-31, without actually being a W-31.

 

I had a 1970 350 with the manual transmission cam. I recall it was a good performer and a big step up from the AT cam. It had a mild idle because of the 114° LSA.

Karl Sarpolis published a list of Olds cams about 25 years ago in JWO; I've found it to be very accurate. According to his list, these are the only three cams used in the 350 engines for the 1970 model year:
Cam Overlap_Int. Dur._Exh. Dur._Int. Lift_Exh. Lift_______ Application
393859_58°___ 286____ 286____0.472__ 0.472 __350 4BC ex. AT, OAI, high performance
400084_36°___ 250____ 264____0.400__ 0.400 __350 2BC, 4BC AT
402194_82°___ 308____ 308____0.474__ 0.474 __350 W-31 OAI

The Spring, 1970 Supertuning booklet from Olds confirmed these specs for the "1970 310hp Sync. Trans":
P/N: 393859
IO: 30° BTDC
IC: 76° ABDC
EO: 78° BBDC
EC: 28° ATDC
Intake CL: 110°ATDC
Exhaust CL: 118° BTDC
Lobe Separation 114°
Advertised Duration 288°/286°
Overlap: 58°
Valve lift: 0.472/0.472"

Other articles have shown this information on the 393859:
Duration at 0.050": 221°/221°

 

Regarding the difference between QV and QB engines:

The 1970 Engine Assembly Manual calls for
identical parts used throughout these two engines
with the following exceptions:

Cylinder Head Assembly:
QV = 405584 (used on all other 350 exc W-31)
QB = 408187 (unique to QB)
Note that these Head assemblies were "loaded,"
including valves, springs, etc. The only
difference between these two was probably
the springs.

Carburetor:
QV = 7040250 (used on all other 4 bbl 350 exc W-31)
QB = 7040253 (unique to QB among 350s, but also
used on TU 455 (manual-trans 442s))

Camshaft:
QV = 400084 (used on all other 350 exc W-31)
QB = 393859 (unique to QB)

Spark Plugs:
QV = R45S
QB = R44S (unique to QB among 350s)

The 1982 Olds Parts Illustrated Catalog
lists only three differences between the
QV and QB carbs:

Primary Jets:
QV (7040250) = 7031970 "70" (.070")
QB (7040253) = 7031969 "69" (.069")

Primary Rods:
QV (7040250) = 7040701 "52C" (.052" tip)
QB (7040253) = 7040699 "48C" (.048" tip)

Secondary Rods:
QV (7040250) = 7033658 "AT" (.0667" tip)
QB (7040253) = 7033655 "AU" (.0527" tip)

Note that the QB carb is jetted significantly
richer on both the primaries and secondaries.

Regarding the cam for the QB-code engine:
The new 393859 cam is nearly identical to
the 400165 (automatic 442) cam in terms of duration and
overlap. They were also ground on the same
blank. The only significant difference is that the
automatic 442 cam is essentially installed 3 degrees
advanced, while the manual 350 cam is installed 4 degrees
retarded. Makes sense! The 442 is cam'ed more for
low-rpm torque; the 350 more for high-rpm.

Above information was generously researched & supplied by Black Gold.

1970 Camshafts

393859 58 286/286 .472/.472 350 4BC ex. AT, OAI, hi-perf (QB)
400084 36 250/264 .400/.400 350 2BC, 4BC AT (QV)
400117 44 258/272 .435/.435 455 ex. Pol., Toro
400165 57 285/287 .472/.472 4257, 67, 4400 AT, Toro W-34
402486 8 262/274 .440/.440 455 Toro ex. W-34
402569 108 328/328 .475/.475 455 4400 ST (W-30)
406768 68 294/296 .472/.472 455 4400 ST
402194 82 308/308 .474/.474 350 (W-31)

 

One coming for auction in June at Mecum. Nice piece. Iron clad documentation.

 

Great thread, missed it the first time around. Almost missed it the second time around... Glad I came across it. Fascinating and very informative. I will try to add what I can.

Something to keep in mind is that the stick Rallye 350 came QB coded, this is confirmed in original road test back then. So extremely rare, and the quickest 350 powered Olds after the W31. No mystery here, 1968-1970 350s were cream of the crop, so relatively easy to pinpoint peak performance etc. To my knowledge there were 4 different 350 cams offered in those years. The 2 that Fun71 mentioned and the 2 additional VC455 mentioned.

1969 W31 stick QX code, 3650 lbs curb, 97.20 mph in the 1/4 mile, Car & Driver
1970 Rallye stick QB code, unknown curb, 94.33 mph in the 1/4 mile, Car Life (code assumed when compared to Motor Trend test that confirms)
1968 F85 stick QV code, 3330 lbs curb, 93.07 mph in the 1/4 mile, Hot Rod
1970 Rallye auto QP code, 3545 lbs curb, 89 mph in the 1/4 mile, Automobile Catalog (simulation)

P.S. would like to elaborate on some of this info but do not want to take away from your threads original intent. May open a new thread to expound and hopefully fill in some blanks, as well as get some verification.