I need Clarification on the 1970 455 cams for the 442. I have been told conflicting information. I have been told that the 1970 442 455/370 cam with automatic transmission is the same cam as the 1970 455/365 engine providing the transmission is automatic. Others say the cams are different. Please clarify. Thanks,Twilightblue28A

 

All AT 442s in 1970 (W-30s included) got the same 285/287 cam. How the AT W-30 made more HP is still a mystery of the marketing department. Of course, the 370 HP rating is probably accurate for that motor. The MT W-30, with the 328/328 cam, was proven to put out closer to 440 HP.

 

Joe,


If the cams are the same for the 1970 automatic 455/365 and W-30, is it possible the 'F' heads on the W-30 accounted for the higher horsepower and faster elapsed times? Or, was the 455/365 and W-30 automatic sorry to say badging and stripes? An act of deception?


Harry

 

Well, the published HP numbers were only 5 HP different (365 vs. 370), so one could argue that the heads, carb calibration, and timing differences, along with the select-fit pistons, would give you 5HP. Frankly, manufacturing tolerances in otherwise identical motors would account for a 5 HP difference. Consider that this was the same cam that came in the W-34 Toro, which was given a 400 HP rating with more restrictive intake and exhaust manifolds and E heads. Kinda makes one wonder why the factory bothered to develop F heads if the E-head Toro motor allegedly made more HP. Frankly, it's been proven time and again that the factory HP numbers prior to 1971 were pretty much unrelated to reality.

In any case, I think the bigger deception was the actual 440 HP vs. the 370 advertised for the MT motor.

 

Do you know what RPM the 440hp number was found at compared to the 370hp AT version? Any articles or sources? Very interesting stuff.

 

In the early 1970s, automotive journalist Roger Huntington published an article comparing advertised and actual HP of a number of musclecar engines. Here's the list:



You might want to check out this thread.

Bottom line is that GM had a 10 lb/horsepower limit on the A-body cars. The 1970 442 curb weight was 3700 lbs. Magically, the max HP you could get in that car was 370.

Coincidence? I think not.

 

Here you go 80 Rocket -
http://gearheads.org/the-true-hp-of-...muscle-cars/9/
I did not see the actual source but - 370 hp @ 5300 rpm, at 5600 rpm was closer to 440 horsepower.

 

If the boss says this engine better not exceed 370 HP then I can tune it accordingly and produce a dyno run that has the desired result.

Hey, you know, tuning skills vary, so, maybe some clever hot rodder after he gets his new W30, he manages to eek a few more lb-ft of torque out of it. These things happen. 370 HP it is then.....

 

Regular 442 had 10.25:1 comp and W-30 had 10.5:1 comp. Basically it was all a numbers game to fit within the parameters handed down from the GM brass.

 

Thanks for the source and link!

 

Actually, it made more HP all around. The 5300 number would be higher than 370 if it made 440 @ 5600.

 

Comparing the E vs F heads they seem identical, I believe they have different casting numbers/letters is because the F head only uses 1 exhaust port for crossover heat. The E head uses 2 exhaust ports for crossover heat. I imagine the purpose was to not overheat the aluminum intake heat crossover. I don't know if Oldsmobile continued this practice for the '71 & '72 W-30's, but it makes sense. I don't believe there is any advantage to running a W-30 head, but I could be wrong. Good post, great forum.

 

The single exhaust crossover started with the D heads, before there was any aluminum intake available. I read an article where Olds claimed a horsepower increase from only one exhaust port feeding the crossover. The other advantage is that if you block the crossover with plates at the intake, the exhuast ports were already divided.

I'd be curious to see how Olds determined the 10.25 vs 10.5 compression ratios. All the BBO heads had virtually the same combustion chamber (other than D's).

 

I believe it was the same deal in 71 between the large valve G head and the H head, just the blocking off one crossover on the H. They must have given up in 72 as all 455s including the W30 had Ga heads.

 

LOL. Keyword; reality.

Here's a classic case of the mentioned magic.




.

 

Joe, I think Roger's list was estimated horsepower, not as-tested on a dyno. So not definitive.

In fact, I know a member here who has a hp chart straight from engineering and it shows the actual hp rating of the W-30 AT vs MT. I can't recall the MT number other than it wasn't 440 hp.

 

That wouldn't surprise me, given the logistics of dyno testing that many motors. I have been trying to find a copy of the original article, without success.

 

I remember the article and might still have it in my pile of old magazines. You are right, no dyno testing, just some calculating based on dragstrip results.

 

There is a relationship between HP and drag strip times.

http://www.ajdesigner.com/fl_horsepo...apsed_time.php

Using that formula, a 3700 lb W-30 with mid-12 sec ETs would need about 365 HP at the wheels, which is roughly 425 HP at the flywheel. Yes, there are very large error bars on these numbers.