[Glock 18]

I ran across a remanufactured Vortec 454 long block for sale today and thinking about using it instead of the '86 454 truck engine I have. Does anybody make a high performance carbureted intake for the Vortec engine? Would it be a good engine to build to 500 hp? Thanks.

 

[317millhand]

regular big block oval port intakes will work on the big block vortecs

 

[Schurkey]

But not the 8.1L Vortec.

You'll have to port the L-29 Vortec heads to get to 500 hp.

 

[Glock 18]

I've been told the 454 Vortec engines have real low compression. How would you raise compression ... domed pistons or by another way? Still looking for at least 500HP.

 

[Schurkey]

Most likely a dome piston will require modification (partial removal) of the vane inside the combustion chamber.

 

[Glock 18]

So should I stick with the '86 model 454 for simplicity? And will the L29 Vortec heads bolt right up to the older 454 block? Thanks.

 

[Schurkey]

I had L-29 heads on a '73 Mark IV 454. There is a coolant passage or two in the heads that is JUST BARELY covered by the Mr. Gasket steel shim headgaskets I used.

Other head gaskets might be a better choice.

 

[Glock 18]

OK. Is my '86 454 also the MK IV engine?

 

[Schurkey]

First year of Gen 5 was '90 or '91. An 86 is a Mark IV.

 

[Glock 18]

Did the L29 heads bolt right up to your older 454 or did you have to make modifications? Did you see good performance gains with these heads? Thanks.

 

[Schurkey]

Did the L29 heads bolt right up to your older 454 or did you have to make modifications? Did you see good performance gains with these heads? Thanks.

They bolt right up. You will want to remove the valve spring rotators and replace with solid shims--16 pieces required. There are at least two part numbers for the shims depending on what valve springs you want. Watch the intake valve guides as the machining is not perfect and some spring shims will not clear the poor guide-to-spring pocket fillet without some help from a die grinder.

You will want to remove the rocker studs and either machine the heads for "normal" BBC rocker studs, or purchase the "conversion" studs that screw directly into the net-lash heads. Similarly, you'll want adjustable rocker arms/hardware.

Oversize valves probably won't flow any better than the stock ones due to valve shrouding issues.

The intake port has a ski-jump cast-in to induce swirl. Not the best for performance.

The castings have 7/16 accessory holes; some other castings and accessory brackets use 3/8. I had to sink a drill bit through the brackets bolted to the heads and switch to the larger bolts.

Overall, there's a ton of information on these heads on this web site, use the search function and you'll find porting info and lots of other stuff.

 

[52673tony]

CAN I BOLT VORTEC HEADS AND INTAKE FROM A 1999 GMC 454 TO A 1986 454 BLOCK

 

[68Chevele]

CAN I BOLT VORTEC HEADS AND INTAKE FROM A 1999 GMC 454 TO A 1986 454 BLOCK

This is a really old thread, but yes you can do it but you need to use the conversion head gaskets and may need to drill the Mark IV block not to have cooling issues.

 

[1975TypeS-3]

The 1986 should already have the holes for parallel cooling, they started that in 1980.

 

[Schurkey]

Never mind. Repeated my previous post from over a decade ago.

 

[drayear2323]

Will a 70 454 intake fit on a 94 (before the vortec) 454?

 

[Schurkey]

WHICH '70 intake? Oval port, or rectangular port?

Either one will physically bolt on. The '94 heads probably have round ports, the older intakes will have ports that are much larger.

 

[68Chevele]

Will a 70 454 intake fit on a 94 (before the vortec) 454?

Yes

 

[71350SS]

Will a 70 454 intake fit on a 94 (before the vortec) 454?

Is that a Ford Fairlane in your profile picture ? not that it matters

 

[68Chevele]

Is that a Ford Fairlane in your profile picture ? not that it matters

I think that's an AMC Ambassador in his avatar picture.