F heads, other than the fact they came on a 70 w30..everything I read says they have same cc chamber, same flow rate as other heads..are the valves bigger? Do they flow better? What prompted the engineers to use these on w30 over standard 70 442 heads?

 

Divided ports. Matched up better with the exhaust manifolds to better mimic individual center exhaust ports. Although the mating surface for the dividers still didn't go all the way to the end of the port. D heads were the same way.

Plus, the only way you could get them from the factory was on a W-30. Like the intake, nothing special except it was aluminum and had a cool embossing cast into it. Same ports as a cast iron deal. But only way to get it was....W30.

 

Andy - I found this article on Old's heads written by Bill Trovato, and I think I would trust his expertise over anyone else. I found his evaluation of BBO heads to be very interesting!
https://www.cartechbooks.com/blogs/t...kcylinderheads

 

Thanks,after reading it the article really does not define anything on F or D heads, other than rarity doesn't talk about the divided port previously mentioned etc.Interesting using big block heads on a small block tho..

 

To me, this was my biggest and most interesting takeaway, "Of all the factory iron heads I have played with, I have found the “A” heads to be the best in stock form." He attributed this statement as being due to the volume of the runners and port size of the "A" heads. Maybe, and I am just guessing here, but maybe the key words in the quote I just mentioned are "in stock form". Maybe there are other specifications of F and/or D heads that make them easier to professionally port them to increase flow rates? In any case, the good news is for any of our brethren out there that are thinking of building a nice Street Machine, it sounds like any of the BBO heads, with the exceptions of the J's and E's, should provide good performance regardless of which set of heads you put on it.

 

Is there a problem with the 70 E heads?

 

This statement was in the article by Bill Trovato that I posted the hotlink to above.

"In years past, I measured intake runner volume in a bunch of different-lettered iron cylinder heads, and found that the “E” castings were second in line to the “J” heads in small runner size. The “E” castings are smaller than the others, but only by a few cubic centimeters."

 

As preiviously posted the F heads were assembly line only units. If you needed one new back in the day and went to the dealer for one you got a K head. The K's were found on boat engines.

 

So outside of the divided exhaust port on the F head the valve size and runners/cc etc are the same as most other letter heads other than J and E?

 

All Olds BB heads had the center divider 69 and up. None of them had the diveder that came flush with the mating surface. The manifolds 69 and up had the center divider that was flush with the mating surface. You either had the weld the center divider or machine the head to get them to have the complete seperate runners.

 

Keep in mind that the overview of this article is about using the BBO heads on a SBO. I think the E's were very comparable to the F's. Why would the factory put a hugely inferior head on a standard 442 ? Think about it. The J's do have considerably smaller ports.

 

yes

 

You have to remember that the casting # and the letter used for the ID is only denoting a different casting. The slightest change got a different casting #/letter. In 1966 the B heads had a casting revision that added a -1 to the casting #. That revision was sometime around May and all BB heads had that additional -1 @ the end of the casting #. Because the W-30's were built during the first three weeks of June they had the -1 heads. I've had plenty of discussions about the W-30 heads were the only -1 used. They only had the -1 because all BB engines used them. If truth be told all of the BB heads were pretty equal except for the J heads. Joe Mondello was of the opinion that the C heads were the better of them,could it be it was because there were a hell of a lot more of them?

 

As stated, the outer divider was there but not quite reaching the end of the ports. The BACKSIDE of that divider is closed off on one of the center exhaust ports that would normally "siamese" the two center exhaust ports for the crossover on the F and D, and also the H heads having this setup too which I forgot to mention before. Some say the early D heads on 68 W-30 were not split on the center exhaust, but I've never seen a shred of evidence of that.

That's what I was talking about when I said "divided". Only one port is available to the heat crossover. Other heads had both center exhaust ports open to each other and to the exhaust crossover through the intake.

 

Actually, that's not entirely true. This is from the January 1972 parts book. Note that the part numbers for the head assemblies in this parts book for 1970 W30 MT (405588), 1970 W30 AT (406741), and 1971 W30 (409392) match those called out in the Engine Assembly Manual parts lists for the 1970 (top) and 1971 (bottom) W30 engines (TS and TT codes). K heads didn't exist in 1972 when this was printed.




Now, these original W30 heads were superseded by K heads in the mid-70s. This is from a November 1979 printing of the parts book. Note that every performance application calls for head P/N 231473, which are the KA heads.

 

I remember this being discussed before and I've confirmed this on both D and F heads. Quote from another member on an old thread:

The biggest difference between D and C heads is that the D heads have the exhaust crossover cast differently so only one of the center exhaust ports feeds the intake per head, instead of two. I believe the F and H heads do this as well, but I can't confirm that.

I don't know if this is enough to really reduce the heat going through the intake crossover. But Olds went to enough trouble to cast them this way so somebody thought it was a good idea.

 

I never looked them up but was always under the impression that K's were the replacement heads for W-30's. I stand corrected.

 

It had little to nothing to do with amount of heat reaching the intake. The bigger issue was that it helped reduce the lack of scavenging among all the center cylinders. Now cyls 4 and 5 were the only ones open, and consequently further apart in the firing order. I do this same thing if I’m doing a set of heads where the hot air choke is still being used.

 

Andy. Thanks for bringing this up to begin with. You always dig up truth.


I grew up in the sixties seventies eighties. My factory stock 1970 442 whopped some ***. I didn't know or care about head letters. My car ran like a some bitch. I did nothing to it. To see that in reality E heads could run fine with F heads makes total sense.
Can I ask a question because I don't know. What heads were on my 1970 SX? The car is long gone but damn did it pull.

 

My understanding is that regardless of whether it was an L-31, L-33 or a W-32, it would have had E heads although apparently some L-33s came through with smaller intake valves.

BTW, which was it?

 

This is correct. For 1970 the W32 was just the 365 HP base 442 motor in the Supreme body - E heads, iron intake, 285/287 cam.

 

The 2bbl 455 in the SX used the 2" dia. intake valves from what I recall.

 

Great conversation..thanks for all the info..Merry Christmas guys

 

If it makes any difference the 1970 GT Toro W34 was stock 400 hp with E heads, so Olds engineers musta had something figured out.

 

Yeah, they had figured out how to play by the rules that were laid down by upper management. The consensus is the advertised horsepower was a fictitious number based on the edict of no more than 10 horsepower per 100 pounds of vehicle weight.

1970 W-30 = 3700 pound car rated at 370 horsepower.
1970 Toro = 4000 pound car rated at 400 horsepower.

Do you really think a W-30 with a 328* camshaft / radical idle had less horsepower than a Toronado with a smaller camshaft and smooth idling engine?

 

Yeah, they figured out that GM had a 10 lb/hp limit on the A-body cars, so the 3700 lb W30 couldn't officially make more than 370 HP.

 

Interesting assumption. I wonder why Olds didn't do this to all heads big or small block if it was an improvement on scavaging.

 

I believe the CCs on the F head were 69 as compare to 80 for non W30 engines.

 

Incorrect.

 

They were typically about 82-84 cc from the factory. The NHRA blueprint spec on those heads is 69.75 cc. Don't confuse the NHRA spec with how the heads came from the factory. There's a reason why you blueprint an engine.

 

Then why was a 1970 LS6 Chevelle “A’ body rated at 450hp?

 

Excellent question

 

Apparently Chevy didn't know how to lie. As I've said many times here before, the MT and AT versions of the 1970 W30 motors obviously couldn't both make the same HP, given the huge differences in cam, carb, and distributor specs. Roger Huntington demonstrated that the MT version of the W30 was making a lot closer to 440 HP than the rated 370.

 

It seemsthe other GM branches underrated their top Dog engines. The Buick Stage 1 was 360 HP and the Pontiac RAIV was 370. Torque ratings seemed to be on par.

 

And you think it's coincidence that all of them were exactly at 10 lb/HP?

 

Chevy pretty much dictated whatever they wanted to do. They got the multiple carburetion banned in 67 on anything other than the Corvette. That's pretty strong influence.

 

Yes, but was that Chevy's influence or GM brass's influence?

 

Doesn't matter it was done. Chevy was the top selling GM brand and they fed the beast.

 

Exactly. Sales volume and profitability rule.

 

Do you think that 440 from the factory is legit?