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I am helping a friend do a ground up on a 77 PW he has a 76 440 we are building. We dont want anything out of this world just raise the compression and he wants a nice thump from the cam.

So I am saking you guys what pistons and cam to use? he is using 452 heads with a lil wrk done to them, 440 source 1.5 roller rockers, holley 750(we know we will probly need a bigger carb)intake is undecided but will be dual plane and a 4 speed.

We are looking at the KB 236 pistons, what is anyones experience with them? Thanks for any input.

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Did you just wake up Mr. van Winkle ?

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I am helping a friend do a ground up on a 77 PW he has a 76 440 we are building. We dont want anything out of this world just raise the compression and he wants a nice thump from the cam.

So I am saking you guys what pistons and cam to use? he is using 452 heads with a lil wrk done to them, 440 source 1.5 roller rockers, holley 750(we know we will probly need a bigger carb)intake is undecided but will be dual plane and a 4 speed.

We are looking at the KB 236 pistons, what is anyones experience with them? Thanks for any input.

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Did you just wake up Mr. van Winkle ?

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The stock compression ratio will have been measured at around 7.4:1, no matter what the books say. The key thing here is he's using stock heads. If using a closed chamber head your pistons will vary.

I worked with a friend several years ago to build his '76 W250's 440. On my suggestion he went to KB 184 pistons which have a "quench dome" that requires machining to fit. That way the machinist can make sure the squish distance is about 0.040". With some careful measuring and machining, including IIRC milling some off the non-dome top side of the pistons, he ended up with 0.040" squish and 9.5:1 measured compression.

The camshaft was a Hughes with 216 degrees intake and I believe 224 exhaust on a 112 LSA. Intake and carb were stock. He used Hedman Elite headers. Distributor was either stock or MP electronic HP, I don't remember.

I was secretly a little worried about that compression in an iron-headed motor with a rather short intake lobe. I was really relieved when he reported the engine ran like a bear and didn't ping on midgrade (87 octane @ 5900 ft elevation) while doubling the previous gas mileage.

He thanked me later for the tech support and said it had exceeded his wildest expectations and the extra $$ he'd had to put into machining was well worth it. The rebuild turned the truck into something he could afford to drive regularly.

Nothing beats squish and compression for getting results!

R.

PS: If at all possible, a set of long-tube headers will fatten up the torque curve below the torque peak and help drivability, power and economy.

PPS: No need to spend more $ on a larger carb, that 750 is good for 450 hp at least, and that's your top until he gets more flow out of the heads. For a 2-plane intake the only decent choice is the Edelbrock Performer RPM. Everything else is in second place.

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I am helping a friend do a ground up on a 77 PW he has a 76 440 we are building. We dont want anything out of this world just raise the compression and he wants a nice thump from the cam.

So I am saking you guys what pistons and cam to use? he is using 452 heads with a lil wrk done to them, 440 source 1.5 roller rockers, holley 750(we know we will probly need a bigger carb)intake is undecided but will be dual plane and a 4 speed.

We are looking at the KB 236 pistons, what is anyones experience with them? Thanks for any input.

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Did you just wake up Mr. van Winkle ?

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Enlighten me John???

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my experience is that if you go any higher than stock with the cam, you'll be throwing pushrods.

over .460 lift on the cam, get adj. rockers or pushrods. worth the money spent.

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What do you guys think about this piston? Seems to have the same specs as the KB184 but is cheaper when u buy the whole rebuild kit.

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If you want to build a flat top open chamber no squish motor I guess you'll do it, and pay the price in detonation. But there is both performance and mileage to be had by doing what I described in my first post.

As far as I know there isn't a single open chamber engine being put in new cars sold in the USA at present. Since horsepower numbers keep going up and the car companies would kill their mothers for an extra 0.1 mpg for the fleet, that says something. The open chamber Mopar head design was a lazy approach to the smog control program starting in 1968. They could vary compression easily by changing the compression height of the piston. No close tolerances to maintain.

I don't know how much the pistons cost in a kit, but by themselves they are both heavy and expensive. $448 for a set will get you really close to some nice lighter forgings or past the KB184s I mentioned earlier.

R.

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