I have some heads on my engine with casting #3947041, date code of 2/69. Can anyone tell me about these heads. Good, bad, valve size? I have checked Mortec, but no real info other than good HP. What do you all have to say?

Same ports and chambers as the "186" double humps. 99% of 041's were 1.94"/1.5" valves from the factory.
The local oval track guys go nuts for those 041's since the double humps are not allowed in the thunder cars.
Don

Hexafamily, i think if i remember correctly,, the 041's were re-vamped to be a bit thicker in the spring pocket area at the ends of the heads. the 186's are pretty thin and you don't want to go any deeper,, period,, with them. pretty good heads for factory heads if you just want to get some compression on a street setup.
but,, by todays standards,, you can do alot better by the time you machine for and purchase and install the screw in studs and guideplates,, hardened ehaust seats for unleaded fuel,, replace the valves with some bigger stainless ones,, machine the decks,, machine for and install new guides,, etc..... you can get some decent iron heads for about the same price. and they'll flow better out of the box. hope it helps.
andy

I agree with Rat - there are a lot better heads sitting out there at a good price. That's why mine (041's) are sitting in the shed and I'm running Eddy's. BTW, mine are 2.02/1.60 64cc. It's night and day between the new and old.

Aluminum heads will walk all over 041's.
But compariing Stock SBC heads, the 041's rank up there with the 186,291,461,462,492 heads. all the "fuelie" heads.
Its the same port in all those heads.

And, fwiw, they should have bolt-holes on their ends if you need them whereas the short water pump engine heads won't have.

pdq67

I ran a set in my Nova on a 350 they were bone stock with a performer intake 10.1 and a Lantai brack master II cam 515 lift. It would run 12.90's all day with a 3600 converter. They were on the engine when I bought the car but for no more than it had it ran good and would ocasionaly hit 12.80's.

But now I have AFR's and aint looking back!

Matt

New aluminum heads have much better chambers and much better flow pattern. For that matter so do the Iron heads that also come in aluminum. The material has nothing to do with it.

What ever, they are still darn good double-hump heads, imho!!

pdq67