Building a beast...doing a 391

[EvanZR1]

A few months ago I had a head gasket fail on my 91 Steel Blue that I bought end of last year update: turns out it was way worse.
At some point in its life a hose clamp had been dropped in the intake.
It apparently sat there for years and then one day, the wife says she hasn't ridden in my new Corvette. So I back it out of the garage (starts fine), she gets in and shuts the door and it suddenly stumbles and start running really rough (not that I'm saying this is all her fault ). So instead of just replacing the head gaskets, I decided I might as well have a 391 build with cams done by Pete.

I know, how the heck do I go from needing a head gasket to building a 391?!?! Well, it all starts with the little statement of "while you're in there...". I'd already been planning to have the top end ported, but since the heads were going to come of for gaskets, that turned into let's port those too. Which was quickly followed by: it's not that much more to build a 391. Which of course was followed by, let's talk about cams since the motor is already going to be out.

Pete will also be doing a little other work for me at the same time:
installing OBX long tubes, DRM coilovers and a few other little odds and ends. Should make for an absolute beast of a car once it's done!

[Demps]

Nicely done! You'll love it.

Balance ride height with clearance v stance & put urethane bushings on lower rear shocks (at a minimum).

Ted

[Flyman 27]

Sounds like a real Beast!
Can you keep us updated on progress and rough costs? I know that many of us would be interested.
Do you know what caused the head gasket problem?

[gtcollins@maxnet.co.nz]

Sounds like a cool plan

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[Paul Workman]

Wuz hopin' to do that very thing last winter. BUT! Mr. tax man and a wedding teamed up to put it on hold for another season.

DO let us know how you like it!

[efnfast]

What does it take to turn a 350 into a 391?
What is the expected hp?

[HAWAIIZR-1]

Nice!!! Best wishes with the build.


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[EvanZR1]

Don't know for sure what caused the head gasket failure. Car has 100K miles on it, but it did sit with very few miles put on it for a significant amount of time (5+ years). I drove the car back from Baltimore to Dallas with no issues, but only a few times since getting it home. While I don't abuse my cars, I do drive them fully (all the way to rev limit) and had taken her for a cruise the weekend before the gasket failed and ran her pretty hard. Gasket failed the next weekend about a minute after starting her up (white smoke, low coolant warning, knock sound).

As for questions of what it takes to do a 391 (and cost), best to contact Pete. He has a post here about 391 build. I will say that the cost of a 391 from Pete is way less than any other quoted numbers I've seen.

Expected power for 391 is 575-600HP (including full porting), plus another 25HP for cams. I may go a little more aggressive with cams, so we'll see how it ends up. Would be awesome if we could hit 540RWHP, which is about what stock C6 ZR1s do, but we'll just have to see what she actually does.

[BigJohn]

Originally Posted by efnfast

What does it take to turn a 350 into a 391?
What is the expected hp?

Crank, rods and pistons

And lots of money 💰

[Karl]

Originally Posted by BigJohn

Crank, rods and pistons

And lots of money 💰

Actually just new pistons and a newly sleeved block. Pete's 391 retains the factory rods and crankshaft.

I gotta get another Z soon!