So I'm trying to decide what cylinder heads to go with. I have a set of camel hump heads and a set of power packs sitting in the shop. The double humps are 2.02 - 1.6 and are off of a '69 Z28. The power packs are 1.72 - 1.5 The motor set up I'm planning on using them with is: '67 327 block Forged 283 crank Tunnel Ram intak with 2 600 Edelbrocks I'm not sure of the cam/lifter set up I'm going to run yet.
Go with the newer, they might have hardened valve seats. I always thought 'power pack' heads were one of the camel or double hump heads - they made lots of different ones.
Power pak's have a rectangle with a triangle on top casting mark on the front of them and there are a few variations of them. Mostly chamber size but there are staggered bolt and straight bolt valve cover versions. The 67 327 set are bigger chamber straight bolt. I have a set of "3731539" heads I'm going to use on my 283. They are the heads used on fuel injected engines in 56-57 and are 54 cc chambers with staggered bolt pattern. With a tunnel ram I would think the camel humps would be better for you. Sent from my Droid powered Samsung Galaxy S
Power pac heads used little 1.72" intake valves and your double humps are 2.02s..no brainer for a 4 inch bore engine like yours. The bigger intake valves will give a bunch more power on mid and top end. Neither head has hardened valve seats.
I've run camel hump heads on a 327 and a 350. The camel hump heads would be my choice because of the 2.02" intake valves with 1.60" exhaust valves. These heads also have larger ports.
That's a no brainer...Double hump heads are 62/68 cc with flame harden seats, and will flow better no matter what...All pre unlead gas Chevy heads are flame harden seats. Don't waste your money on new seats unless some yaywho has messed them up....Happy Motoring....
The power pac's are super small and flow like shit. I forgot the valve sizes, but you dont even have to measure them to disqualify them as a choice, just look at them. That being said, I only have them on my '55 for looks. I spent more money on new valve guides, hardened seats and fresh hardware than the cost of a nice set of cast performance heads.
IF the Camel Humps you have are truly 69 Z28, 302 heads, they are worth some real money. You could buy any head you want AND get the benefit of hardened seat, which the power Packs and Camel Humps don't have. I would'nt risk ruining those heads. Sell them to a restorer, and get some Darts. You could get by with the Power Packs by having larger valves installed (1.94/1.60 intakes/exhaust), and have some bowl/port work done with your windfall from the Camel Humps, and still have money left over for other parts and pieces. Just my opinion. Butch/56sedandelivery.
I have power pac heads on my 302 chev. Im not sure what cc's the 69 heads are but the early one (461 and 462) are 64 cc and the power pacs (896 and 520) are 64 cc also.The 302 isnt the most torquie motor and the smaller runner /port and intake valve size of the power pacs will help here. It all comes down to what its in and what you want from it.When i built mine in 83 i looked into all this and decided the power pacs were right for me. JW
They're going in a '41 Plymouth Coupe. Here's the specs on the build: http://www.jalopyjournal.com/forum/showthread.php?t=741479
I would say for flow and breathability go with the camel humps. IMHO dual holleys would look and perform better, even WCFBs or old as cast AFBs. Just tired of looking at monster HEI caps and polished edelbrock performers, not traditional or ol skool.
Be sure you take the head's cc of chamber, cid, and pistontop/deck clearance configuration and their effect on compression ratio into account. You don't want to wind up with something you can't run on today's shitty pump gas. What worked in the 60s and early 70s is gonna be borderline today. A little carbon build up and you'll hate it!
I would go for the 2.02's hands down,I built a 302 the same way you did this cam worked real well with the tunnel ram and had a great sound as well:http://www.summitracing.com/parts/CRO-00244/ be sure and get the matching valve springs.With the smaller cubes of the 302 it is easy to over cam and over carb,you would be better off going with 500 CFM carbs instead of the 600's.The 600's will work well with the 327 if you go that route,with these http://www.ebay.com/itm/Speed-Pro-T...8-/190727398674?forcev4exp=true&forceRpt=true with these you can run 92 octane pump gas and they will give you plenty of clearance with the above cam.
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