raising 460 compression

left one 88 EFI 460/5.4cc dish
right one 87 carbed 22cc dish
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Damn that's a big dish!! I wish my engine didn't have those 21cc puppies in it... maybe when I put my ported heads on this summer I'll have someone tig-weld some aluminum into that crater [img]/phpBB/images/smiles/icon_lol.gif[/img]
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Man, when you go putting them side by side, that is a big f'n dish! That's a sweet picture, but damn it's depressing.[img]/phpBB/images/smiles/icon_cry.gif[/img]
If the pin heights are the same, why the hell couldn't a person use them? Are the rings in the same relative positions? 20 cc's in a late model(70's-80's) 460 = about 1 point higher right? Right in the sweet spot for pump gas.[img]/phpBB/images/smiles/icon_wink.gif[/img]
So the efi pistons have a way smaller dish. Very interesting.......
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My only concern would be valve clearance with a hot cam,but that could be fixed,every now and then you stumble across a combo like this that just looks too easy.

<font size=-1>[ This Message was edited by: frdnut on 4/4/02 10:31am ]</font>

Looks like the skirt is a little smaller on the EFI piston, but that's probably not a big deal. I wonder how the weights compare. What would be the advantage to using the EFI pistons instead of an aftermarket flat-top?
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SO,88 EFI pistons,0 deck and 69 429 heads with 75ish chambers gives me about 11.7 to 1 compression.WHOOOA
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the rings and rist pin are in the same place.The only diff i can see is the skirt is longer on the 87 piston.
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If the pin heights are the same, you'd have the same installed height and the same deck height as the 22 cc pistons. There should be a ton of clearance with stock valves. If you go 2.19I or 2.25I and 1.75E valve it might be wise to check. But I've always heard late model 460's don't usually have clearance issues.
The efi pistons could be considered cast flat tops basically. Definitely good to 5000 rpm and maybe beyond. I wonder what Summit sells them for? If they are cheaper than hypereutetic(HE) then they are definitely the way to go for a low rpm street bruiser! Hell, I had some KB h.e. pistons in my motor that still had a huge dish. The only thing that made them high comp was the pin height. Honestly, I think they are rated at 9.2:1 with 94 cc heads. The small dish efi pistons might yield an honest 9.5:1 and result in a better flame travel/quench. Less chance of predetonation me thinks.
TBolt, that picture has got my gears churning dude!!!!! I love the thought of using economical parts to make real world power! Anybody checked to see what Summit sells late model efi 460 pistons for lately??
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'Er, IMHO, you are aware that early 429/460 blocks had a deck hight of 10.300 and all post '72 blocks are 10.322. This has a MAJOR efect on compression.