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#1
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Do you have the 60243 camshaft in hand? I haven't called to check on my order yet, they are showing various dates out a week (Crower website/e-mail) to August(Summit) for availability. I ordered one via Crower's website a couple days ago. I've got a 428 that I'm finally assembling, Icon pistons w/10cc dish. I have '68 #16 heads and compression calculates to about 10.5
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1968 Firebird 400 coupe, Verdoro Green w/black vinyl top 1969 GTO Judge, Carousel Red, 4-speed, numbers matching 1971 Trans Am Cameo White, Auto, numbers matching 1970 Buick Skylark Custom convertible Fire Red 1972 Buick GS 455 Stage 1 Royal Blue |
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#2
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Quote:
Woven - isn’t that compression a bit high for pump gas, or do you have access to AV fuel or race gas to mix? Sent from my iPhone using Tapatalk
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Three times the sound peaks, falls back, peaks again. A throttling back to cruising speed, a dwindling grumble of thunder and...gone. The frogs take up where they left off. |
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#3
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My other engines are 12.0(Pontiac w/RA II heads), 10.2(Pontiac), 9.9(Buick) and a stock '71 455HO engine. No pinging on any of them. I do run 100+ octane in the 12.0. So, this is a little higher but nothing like the 12.0. I do have ready access to 93 here in Texas.
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1968 Firebird 400 coupe, Verdoro Green w/black vinyl top 1969 GTO Judge, Carousel Red, 4-speed, numbers matching 1971 Trans Am Cameo White, Auto, numbers matching 1970 Buick Skylark Custom convertible Fire Red 1972 Buick GS 455 Stage 1 Royal Blue |
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#4
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Someone on this board might know what the volume is on the head of those 428 pistons is so you would not have to cc it. I don’t have them in any of my speedpro or TRW books. Speedpro may have changed them on the later years and made the dish a bigger diameter. Seems like the later production runs had a 8.5 cc dish and 5 cc VR’s and the older pistons like yours are a 5 cc dish with just under 6 cc VR’s. Measure the dish dimensions and see which pistons you have. Then check the deck clearance.
The 6x-4s on that 428 is more of an 87 octane combo with either cam. I am guessing there is just under 2 points difference in octane requirements between the Crower 60243 and the 274XE. I would not consider either cam big enough to be a “crutch”. I would not do Rhoads if you have the Johnsons already. I agree with FJ, figure the compression and pick the cam. |
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#5
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They are flat top pistons originally, with 4 valve reliefs. I can't remember what the CC of the valve reliefs were anymore. The dish you are seeing in my previous picture, I machined in there. In the OP picture someone has done the same thing, although to a lesser degree. Way back when there weren't any off the shelf forged dish pistons for 428's, pickins were slim, so we had to make our own. |
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