detailed parts list for direct swap of old GM Vortec heads onto a '78 Gen 1 400 block

[Dan Timberlake]

I've been surfing this subject for a year or 2 now and am surprised I have not been able to find enough information yet.

I know about steam holes, and checking for accessory mount holes on the heads, and that a new intake is needed.

Head bolts are one question. I sheepishly admit I have not explored the ARP site too deep about that.

What concerns me is valve train. Probably going to use a peppy street hydraulic flat tappet.
So the cam grinder's lifters to fit the Gen 1 block is probably the answer there.

The rockers, pivots, studs etc need to be OEM Vortec, or OEM style.

Pushrods are the big obvious question.
Are different ends needed? Are there some production parts that are reasonably close lengths, with the correct ends?

What other parts have I overlooked completely ?

thanks,

Dan T

[travis]

It is really pretty simple. If using OEM type Vortec heads with pressed in studs then you need a later style guided rocker...I’ve used the stock Vortec guided rockers many times with no problems and they are cheap directly from GM. Pushrods are the the same as the earlier engines. You’ll need center bolt valve covers and a Vortec specific intake manifold and intake gaskets. Head bolts are the same. The stock Vortec valve springs will need to be changed. I’ve always used the comp 981-16’s with flat tappet cams with no clearance issues but others have reported clearance issues with .480”+ valve lifts. Comp makes a few beehive springs that drop right in with clearances up to high .500’s lift cams with no machining required. Of course there is the steam holes that need added, and you need to watch compression as it can easily get out of hand on a 400.

With screw in studs and guide plates, which are a good idea anyway, you have many more choices in rocker arms.

[PackardV8]

you need to watch compression as it can easily get out of hand on a 400.

My SBC guru says there's no such thing as too much compression, just not enough cam. ;>)

[rfoll]

I did this a while back as an experiment and the results were so outstanding I put it my truck in place of the 402 I had in there. You didn't say what you were going to use for a piston, but the advice is correct in that your compression ratio can get out of pump gas range really quick. What I did was use a stock short block that had a good bore and pistons, essentially a ring and bearing job. The stock deck with the factory piston is 32 CCs at .025" in the hole. With a .040 gasket and the 64 cc Vortec heads, compression came out to 8.8:1. My heads had been modified removing the need for guided rockers. I used a Comp XE268 cam and a Performer RPM intake. I initially put it in my Impala with a 3.42 rear gear. It had a nice nasty sounding idle, but it worked fine with a stock converter. A tap of the gas pedal resulted in instant tire smoke. Speed Pro has pistons with a 12 cc dish, compression comes out to 10:1. Flat tops will get you close to 11:1. 400 blocks almost always need a cleanup cut on the deck, and every .010" removed will raise compression by nearly 1/4 point. Vortec heads have no provision for carb heat, making driving In cold weather a problem. The easiest solution is the RPM Vortec manifold because it has a passage under the plenum to plumb with the heater circuit to keep things warm in the winter. Vortec heads on a 400 sbc is the easiest and cheapest horsepower you will ever find.

[PackardV8]

I did this a while back as an experiment and the results were so outstanding . . . . Vortec heads on a 400 sbc is the easiest and cheapest horsepower you will ever find.

Agree completely. All those yearning for the good old days of "high-winding 283"/302"/327"s" will spend more money and always lose the race to your Vortec 400" combination.

[travis]

you need to watch compression as it can easily get out of hand on a 400.

My SBC guru says there's no such thing as too much compression, just not enough cam. ;>)

Yeah, sometimes I forget that this is SpeedTalk

[Dan Timberlake]

The owner put some thought into compression for the street, and bought some KB pistons with a useful volume of dish ( according to the catalog ).

thanks for all the help.

Dan T