vortec 454 to 8.1 swap

squeeezer · Posted: Mon Jan 07, 2008 10:09 am Post subject:

CYLINDER HEADS:

GM PERFORMANCE PARTS ALUMINUM GEN V/GEN VI (12363409)
PORTED & POLISHED
127 cc COMBUSTION CHAMBER VOLUME
2.25" INTAKE, 1.88" EXHAUST VALVES
CYLINDER HEAD BOLTS, 11mm x 7/16" (WHEEL TO WHEEL)
CYLINDER HEAD GASKETS (#1047) (FELPRO)

i cannot find a listing on these heads anywhere
closest i can find are 408 castings????

squeeezer · Posted: Mon Jan 07, 2008 10:14 am Post subject:

http://www.www.tbyrne.com/trucks/81truckvalvetrain.html

this company sells lots of parts intakes heads cams for the 8100

Big Dave · Posted: Mon Jan 07, 2008 10:38 am Post subject:

dietzster · Newbie Joined: 04 Jan 2008 Posts: 7 375.62 points

I'm still researching myself, it is hard to find good, reliable info on the 8.1. People are all over the place on the info I've found. But I really want this swap to work, so come hell or highwater I will find out if it 100% can or cannot be done and post the results. That coolside 2 truck is the only one I've found so far and can't find any pics of the engine.

8.1stylemaster1947 · Newbie Joined: 06 May 2009 Posts: 3 214.78 points

The 8.1 is a final evolution of the big block...the heads wont interchange but its not reverse cooled...the heads are left/right and wont swap side fpr side. all the external stuff does interchange...water pump,starter headers,and since its internally balanced I think even the balancer will swap with a 396/427 balancer. I have two of them...paid 300 for both Im really wanting to build a carb intake for one and use a regular distributor...I had the stock cam reground but the second motor would probably use a solid roller with a fabbed intake the distributor would clear but modifying the stock intake even with a small old dual point there are clearance problems...the crank is the same as a Gen 5 or 6 except for the trigger wheel on the back of the crank...they have the same bore spacing...in theory a big block gen 4,5, or 6 head could be adapted,but it isnt practical...i'd like to see more development on these motors that isnt super expensive or high tech...big blocks are meant to have carbs or mechanical injectors

8.1stylemaster1947 · Newbie Joined: 06 May 2009 Posts: 3 214.78 points

the 8.1 is really a good peice...i look at it kind of like they did the hemi in the 50s...no one wanted them at first...then people saw their potential...what would be cool would be a short deck 3.76 stroke version of this motor with a sheet metal intake

8.1stylemaster1947 · Newbie Joined: 06 May 2009 Posts: 3 214.78 points

the coolside pickup you mentioned is a 8.1 and it has gen 5 or 6 style heads on it but they had to be modified and from what I hear some of the head bolt holes in the block had to be changed. This is what I hear anyway. the big hangup with these heads is the port layout. theyre symetrical,but most symetrical port heads for big blocks use the short port from a traditional big block that keeps all the ports centered in the head. these use the long port that swings the ports to the end of the heads,making it hard but not impossible to get a good flowing intake runner especially on a single four intake...but the Dart buick heads for the small block chevy were this way and they worked so it can be done

bowtietbucket · Posted: Sun Aug 09, 2009 4:11 am Post subject: 8,1 Vortec

I've aquired several 8.1 engines to play around with. To date I have found that nothing on a previous engine will fit. However the potential is asme. They are 340 HP to start, are awesome in marine form so therefore are strong enough for the street, can be modified to race. A sheetmetal intake is easy and you can run a distributor by just removing the oil pump drive which is in the stock position below the vortec intake. A Gen 5/6 oil pan fits to eliminate the super deep one that comes with the engine. I retaped the exhaust bolt holes to use earlier exhaust headers with no problems. All exhaust manifolds will fit. The block has every engine mount bolt pattern GM used on the block. It is internally balanced, takes the regular clutch housing. Iamb looking to use one in a 4 WD P/U Iamb building. Changing the cam and chips and playing with the computer would probably do some great things, unfortunately this is not something I know about. If anyone does I would be more than happy to share anything I've found with these engines with you. By the way it is NOT a tall deck, a stock intake fits in but cannot be made to match.