301 cam choice

Bonnewagon

Bonnewagon

Geezer
Sep 18, 2009
6,183
113
Queens, NY
After researching on 301Garage.com I settled on the 1979 301 manual trans cam. The engine in my Bonnewagon is a '79 301 w/manual trans so it should be a good fit. It was rebuilt years ago with the automatic cam before I converted to a manual. Melling makes the SPC-9 which they say is the replacement for the factory part. It is a copy of the Pontiac 527471 cam. This cam was also used on all standard 1978 400's. The TA I am working on has this cam and I am impressed with it. It should be somewhat more radical in the smaller 301. The regular 301 I have used 250° adv duration and the W72 used 274° adv. The W72 needed a timing retard module so I assume that duration is at the ragged end of the scale. This SPC-9 cam is right in the middle with 264° adv/189°@.050" and .364" lift. That seems puny by traditional Pontiac V-8 standards but remember the 301 is an economy/emission engine with restrictive intake and exhaust passages. That said I have been very happy with my 301's and 20mpg is a nice thing these days. I wanted something specific for the manual trans and I think I'll get some more mid-range power too. There were a few for sale on Fleabay and I chose the cheapest at $91. As luck would have it they had a 15% off coupon yesterday so the cam only cost me $77 w/free shipping. At that price I can't complain and if it is not what I expected no harm done.
 
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K

Kennybill

Greasemonkey
Mar 17, 2010
160
43
Braceville, Ohio
That's a bargain price. I always said it's better to be under cammed than over. I always thought the same about carburetion also. 301's are very rare now days.
 
Bonnewagon

Bonnewagon

Geezer
Sep 18, 2009
6,183
113
Queens, NY
it's better to be under cammed than over
I agree with that fully. A rear gear change will wake up most motors better than a cam change. I am afraid of over-camming it because I use it as a daily driver and I tow trailers. I have had a lot of great cars with 301 engines mostly Firebirds. I saved this rebuilt '79 301 from a '79 Formula my Daughter crashed. I also have an '80 Turbo engine converted to normally aspirated 4 barrel. I have all the Turbo parts too. Lastly I have a factory replacement 301 short block saved from a defunct Buick dealership. It is still wrapped up with the original Cosmoline treatment.
 
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olds307 and 403

olds307 and 403

Comic Book Super Hero
Oct 14, 2008
4,497
113
Melville,Saskatchewan
There are some cool stroker's being made from 301 Turbo block's. They are a sturdy motor, quite thick mains, putting out about 3.5 times as much hp as stock once 4 bolt mains and real cranks, heads and custom intakes have been put on. The 301 is very similar to the Olds 307 swirl port, both have similarly awful head flow numbers The Olds Vin 9 has similar duration numbers but way more lift, even converting from 1.5 to 1.6. Ironically both put out 170 hp but also had higher output versions that never made it to production, it would have helped their dog reputation.
 
olds307 and 403

olds307 and 403

Comic Book Super Hero
Oct 14, 2008
4,497
113
Melville,Saskatchewan
Of course there is confusion on the lift numbers for the W72 cam but I believe this must be right.

Part # 10003402 (used for all 1978-79 W72 engines)
Advertised Intake Duration 274 Degrees
Intake Duration @ .050 inch 192 Degrees
Open 18 Degrees B.T.D.C
Close 75 Degrees A.B.D.C.
Gross Lift with 1.50: rocker arm ratio .395
Lobe Lift .263
Intake Centerline 118.5 Degrees
Advertised Exhaust Duration 298 Degrees
Exhaust Duration @ .050 inch 210 Degrees
Open 73 Degrees B.B.D.C.
Close 36 Degrees A.T.D.C.
Gross Lift with 1.50: rocker arm ratio .401
Lobe Lift .267
Exhaust Centerline 108.5 Degrees
LSA 113.5 Degrees
Overlap 54 Degrees
That converts to .421/.428 at the Olds 1.6 ratio. Even the Olds swirl port Vin 9 cam had .435/.438 lift. Otherwise besides the Pontiac having a wider LSA, very similar.
Here are the Olds Vin 9 specs
Cam
0.440/0.440 lift 196/208 @0.050 lift 109LSA for 83-85
256/270 109LSA
0.435/0.438 194/210 0.050 lift 109LSA for 86-90
Your SPC-9 seems to be 189/189 264/264 with .364/.364 lift, not sure of the LSA. That converts to .388 with a 1.6 ratio, less than the awful Olds Vin Y 307 cam, even less than the 260 cam. The duration is similar to the exhaust spec on those two Olds cams and actually less than the base 350 and 403 cam on the exhaust side, nearly indentical on the intake side, 2 degrees less on the intake for Olds. Interesting to see how different GM divisions did things a bit different with their unique V8's.
 
Bonnewagon

Bonnewagon

Geezer
Sep 18, 2009
6,183
113
Queens, NY
My data for the W72 cam is the same as yours but remember that was used in a 400 engine. Lift around .400" was used for decades on traditional Pontiac engines. The reason for that is that the Pontiac head used 30° valve seats that flow tremendously at low lift. They adjusted the power band with duration. The 301 W72 used 274° duration but .364" lift because the 301 has very restrictive intake and exhaust ports for emissions/economy reasons so going to a traditional high lift cam is pointless. Duration still affects the power band but I don't need a street engine that has no bottom end grunt. That is why I chose the SPC-9 cam as it used the lift of the 301 W72 but less duration. I think using the '79 301 manual trans cam and carb specs are the way to go. That is what they offered in the '79 Trans Am 301 so it must have been the best they could do considering the 301's limitations.
 
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TURNA

TURNA

Geezer
Jul 24, 2009
7,739
113
Socialist NY
There is a turbo 301 on CL local.....
 
Bonnewagon

Bonnewagon

Geezer
Sep 18, 2009
6,183
113
Queens, NY
I got my $300 Turbo engine on CL from a guy on Shelter Island. He delivered it right to me because he was visiting his Mom in Baldwin anyway. Someone had yanked this Turbo engine out and replaced it with a 400. He was glad to get it out of his way in the shop. I made it a NA 4 barrel and used it for years in my '81 Malibu wagon.
 
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Bonnewagon

Bonnewagon

Geezer
Sep 18, 2009
6,183
113
Queens, NY
So my Melling cam, arrived today. I opened it up to see if it was a new casting or a regrind. It is indeed a regrind of a Pontiac #540233 which was the '61-'62 389 SD mechanical cam. Here's the odd part. When I took the cam out of the 301 Turbo motor it was a TRW regrind of another Pontiac #540233!?! The specs were for a standard 4 barrel 301 which is what the Turbo motor used. I guess there was a big surplus of these cams that made their way to the re-grinders and they became 301 cams.
 
79Lemans

79Lemans

Greasemonkey
Oct 23, 2015
117
18
Michigan
How are those 301s on Mileage and power? Pretty neat engines. I'm buying a 81 4Dr I might keep which has that engine (Sleeper :banana:)
 

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