[blazin47]

Need some help from one of you engine guys. A local guy has a SBC for sale, It has Speed Pro HYPER--- .125 dome pistons ( H618P). I don't have access to check but will L31 Vortecs heads have a clearance problem with these pistons. The cam is a XE 284H .507/0510 lift

[johnsongrass1]

They will with a 9" deck.

[T-bucket23]

Unless they have been reworked there not going to like that cam lift either.

[BigDawgsEatFirst]

Im a cam novice but ,furthermore
like stated...
that cam wont take advantage
of the low end torque of the vortec head

[lluciano77]

Taking advantage of the powerband isn't the problem. Coil bind is.

With higher compression you will get more bottom end with a given duration cam. I think it will be fine as long as the heads are machined for it, and the right springs are used.

[blazin47]

I agree with most of the cam replies , but the question is will I have a piston to valve clearance problem. The heads are machined to .625 lift max lift( retainer to guide seal dimension). Will these heads work with .125 domes

[johnsongrass1]

No, the pistons will hit the head. if the chambers aren't machined for the dome. The chambers are designed around a flat top piston. I don't know about the valves. You need to check it no matter what. You might get away with a felpro PN?????? ummmm... The thick one for vortech's.

[56Maynard]

How long is a piece of string?

There is no way anyone here can tell what has been done to the deck height, the head decks, rod length, stroke. or piston pin height. Even if you had included the necessary input with which to base an opinion on, I doubt anyone here would simply throw it togther without the "mock up" to know for sure what the answer is. We could also begin to determine if your compression ratio is going to be reasonable or not.

Even if you provide logical input from which we can determine if it will all fit, you still have to mock it up to determine if your quench is within reason, and if the valves will remain straight. Only then will you know the proper gasket thickness.

[blazin47]

I appreciate all the replies, I asked because I didn't know. I saw an ad for Pro Lightning heads, and it stated flat out "NOT RECOMMENDED FOR DOME PISTONS", so I thought is was a yes or no answer. I know you have to check for valve to piston clearance on all motors, but if the dome of the piston won't fit in the valve chamber, that's definitely a no. There gotta be some off the shelf heads that'll work without machining.

[johnsongrass1]

sometimes with the fastburn type chambers and very small cc chambers running with domes piston upset's the chamber burning characteristic. You can cut a Dart iron ealge 64 cc chamber to 33 cc but you can't cut a 49cc dart less than 45 or so. You'll hit the intake seat first. The 49 cc heads aredesigned to run box stock with flat tops. But it's better to go with the 64 cut to 33 and 1/16 domes flycut to get 16:1 compression. Mahle and JE both can custom a piston for what you want but I would guess that exceeds you budget.

[lanierledford]

Everybody know how long a string is , its from right cheer to over yunder

[jimfulco]

Considering the difference in combustion chamber shapes, there might be a problem with the dome hitting the head itself. The KB piston catalog lists a domed piston (pn KB358) that they say is designed specifically for use with the Vortec head. This would lead me to believe that a standard domed piston might not work.

[acr]

You didn't say what how this engine will be used, but you might also want to check what your compression ratio will be with this combo. To my knowledge,all GM Vortec heads have 64cc chambers & that's assuming their new or haven't been cut. Add dome pistons & you'll need real high octane fuel.

[blazin47]

10.7 to 1 with 64 cc heads ,it'll be a street machine, I figure with .060 head gaskets it'll bring me down to 10.0 to 1 and a little more than 67cc's. may have to sell my .062 vortecs and buy a set of Dart Iron Eagles and eliminate all the questions

[nastynova]

I'm running a set of vortec's with Keith Black KB 180 pistons (.200 dome)... no problems....My Cam lift is .488 though...
be sure to get your quech right...