I just picked up a 427 truck block with oval port heads, pistons, and rods. This is for a "stump pulling" application, I would like to do this build on an extreme budget with new bearings and rings basically. Don't really want to spend the money on different rods so it will stay a 427 crank the 454 crank and different rod length, pistons would blow my budget. I am thinking of a few tricks though- bigger cam and shaving the heads to bump the CR for more low end power. These pistons have an extra ring groove, could I leave one set of rings out for less drag? Also I plan on making or modifying a set of headers myself. For the intake I am undecided, there is a bus FI setup 427 in a local JY or I could just use spacer plates and an alum. intake/carb setup. Would the FI be compatible with a mild cam/ headers/ and the increased CR? Thanks for any info,
Ben

 

You need to spend more money. The tall deck truck block is because the piston is longer for an extra compression ring. These have no performance potential and are very heavy. To use normal automotive 427 pistons, you need con rods that are .400" longer. Pushrods are also .400" longer. You need a tall deck intake or spacer adaptors to use an automotive short deck intake. Not sure if the distributor is longer also but it should be. Because of the taller deck, there are no swap headers that will easily fit so fabricating a custom set is your best choice.

How good the heads are depends on the casting numbers. If it has the peanut oval ports, they're only good for low rpm truck driving and make good boat anchors. You might have 781 casting heads. These can be worked over pretty good and have some large valves installed.

The truck blocks have thick cylinder walls. You can easily bore it out .125" over size. 427 and 454 use the same bore so a 454 crank will easily fit to make a 454. Just need to check clearances.

 

Thanks for the info, how do I tell if I have the 781 castings?
" oval ports open chamber 427,454 " I ran the numbers and that's all it told me. The port size doesn't look very peanut to me tho so I think I have the good ones.

I didn't really want to stick that much money into this engine as far as custom length rods and new pistons. Would stock 454 pistons werk with longer rods? I see stock 454 pistons on fleabay for cheap. I would like to be convinced I need the 454 crank! I might buy those parts if it has to come down to that to make power or search out some used stuff.

Everything I've read says these stock tall deck engines won't rev past 4500rpm, I just have a hard time believing it's the shorter rods and heavier pistons causing all that. Hot rod printed an article in which they made two identical bbc's one with the shortest rod and one with the longest rod they could find, both were identical displacement and were within 5hp of each other (almost the same anyway, not sure the exact number). Rotating weight was close too which would throw their example right out anyway. I will have to do some more research since this is my first venture into bbc's and I dont want to end up dissapointed.

Headers shouldnt be a problem, I'll just find a used set and make them work. Maybe just run them up through the hood monster garage style. I've seen a couple intakes on ebay for tall deck engines, most were giant single planes though so I'll probably end up using spacers and a regular bbc dual plane intake to better match the "power band" i'm looking for.

Edit- yes the distributor shaft is longer, there is some aftrmarket intakes for tall deck that accept stock length tho. I keep searching and found some sites with info on tall decks, I just haven't seen any cheap builds yet! lol

 

Casting number on the heads will be under the rocker cover. The last 3 digits will be what you want. GM didn't really make any "bad" BBC heads but they did produce a lot of different variations of them. The 781 casting is one of the more common and popular castings to use.

454 and 427 pistons are the same diameter but are different because of the stroke and pin location in the piston.

A stock tall deck doesn't rev high because in a medium duty truck, it doesn't have to so it's built for low rpm torque. Tall deck blocks are nice because the extra length of the cylinder can allow for larger displacements using the proper parts.

 

If I were you,I'd either stick it in that Hellcamino as is,or shelf it for a monster cube build down that road.Tall deck,performance,and cheap are words that will not mix together.We used to drop 427 or 366 talldeck motors in our 4x4's,because you could buy them cheap,and the RPM range worked ok for wheeling trails and stuff.But you've heard pretty much right,I'd say even 4500RPM would be pushing it,more like 3500.
You'll also have a tough time "making headers work",as the ones that are made for our cars fit poorly,let alone headers that aren't intended to fit.

 

Okay thanks again for the info guys, I don't like jumping into engine builds blindly. You guessed it too, it's for the EL Meano~ I guess I will have to start collecting parts for a monster motor as I find good deals. It needs more power with the larger more aggressive 36" tires, I could do the lame thing and just regear it that's the wussy way around it though when deep down I know the problem is not enough power and it's already got 4.11's anyways. I'll be sure to post pic's when I start the engine build since many 3rdgen guys might be interested in building a similar tall deck for their fbody.

Customizing headers is no problem, I had to modify the current camaro shortys that are on the truck. Clutch linkage and frame was in the way, I like the idea of finding a used set of standard bbc headers and basically just cut them off past the heads and use them as flanges. The monster garage episode where they made the 4x4 80's 'vette was pretty neat how they just did "zoomie" headers straight out of the hood.