I'm Going To Build A 650 HP 496 With 781 GM Oval Port Heads

Mark Jones · Feb 26, 2021

My plan is to build this: A BBC with a 4.310 bore and a 4.250 stroke, 9.8 compression,

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ported 781 GM oval port heads 1.880/2.190 valves, 238/248/578/608/110 hyd roller cam, performer RPM air gap intake, 850 Holley carb. Some pictures.

Mark Jones · Feb 26, 2021

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Turbo4whl · Feb 26, 2021

Even the valves look pretty! I'm going to watch this thread.

bucket · Feb 27, 2021

I'm in for the read.

hirschdalechevy · Feb 27, 2021

I am in as well. Do we get to see a dyno sheet after your build is done?

Mark Jones · Feb 27, 2021

Of course, and a video as well.

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Mark Jones · Feb 27, 2021

More pictures

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Paladin · Feb 27, 2021

What block are you using as in Mark IV, Gen 5, Gen 6, Gen 40?? And pistons??

82sbshortbed · Feb 27, 2021

That sucker is clean. I'll watch.

bucket · Feb 27, 2021

Paladin said:
What block are you using as in Mark IV, Gen 5, Gen 6, Gen 40?? And pistons??

It's a mark IV

BigDaddy72 · Feb 27, 2021

Nice looking work as usual Mark, can’t wait to see it done, I love engine build threads!

Got a question for ya. The closest to me (engine dyno) dyno shop has broken the last 4 engines they have dynoed.

I would love to dyno the afr headed 496 I just finished for my wife’s truck, but this “rumor” has me extremely gun shy.

What or could would cause engine damage like that on the dyno.

Me personally I have never engine dynoed anything for fear of the horror stories I’ve heard.

What is your opinion or advice?

Sorry I guess this is off topic I don’t want to clog up your thread but I gotta know?

Mark Jones · Feb 27, 2021

I guess my advice would be to stay away from that dyno shop? Maybe find another dyno shop. More pictures.

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bucket · Feb 27, 2021

Did the block need clearance grinding for the crank?

Mark Jones · Feb 28, 2021

Yes, the picture above shows the clearencing.

Mark Jones · Mar 1, 2021

More pictures

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I'm Going To Build A 650 HP 496 With 781 GM Oval Port Heads

Mark Jones

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Turbo4whl

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bucket

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82sbshortbed

Fuckemall!!

bucket

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