To quench or no quench

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PRH said:
No pissing contest.......I’m simply asking if you’d really do all that work for $680.
(Finished, ready to bolt on heads, flowing 250-ish for $1450)

If so, maybe you’ll get a nice influx of work.

I doubt there would be many Mopar savvy shops in the country willing to do it for that price, but I could be wrong.

But to be clear, my position isn’t that I’m not interested in doing the work....... it’s that if someone is looking for some heads that have those kinds of flow numbers...... they’re going to spend more reworking factory heads than if they had started with aftermarket heads....... if they’re shopping with me.
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Port work alone 680? Sounds fair.
 
yellow rose said:
LOL. I refuse to do iron for more than double that. Probably triple that and I'd still turn down any iron work.
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yeah I've known plenty of people to charge an outrageous price just so people will go away . They don't wanna do it.

One thing for sure is i can get to 250 cfm with a 1.94 easier than a 2.02 by less materiel removal. We all know that path.
 
2.02 hurts from 1.88
especially at lower lifts or with short cams
i fought using them in daily driver or motorhome/ truck builds
they took more work with the lower gear bigger cam looser converter builds to make them worthwhile
I'd always rather start with a 1.88 seat head so can get new higher seats
save the 2.02 heads for the resto guys
I had a pallet of 360 heads pt & magged, some with k-lnes and durabond seats
no way to make a profit on them after the al came out
 
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Wyrmrider said:
2.02 hurts from 1.88
especially at lower lifts or with short cams
i fought using them in daily driver or motorhome/ truck builds
they took more work with the lower gear bigger cam looser converter builds to make them worthwhile
I'd always rather start with a 1.88 seat head so can get new higher seats
save the 2.02 heads for the resto guys
I had a pallet of 369 heads pt & magged, some with k-lnes and durabond seats
no way to make a profit on them after the al came out
Click to expand...

That's right.
1.94 works, ported, gives strong .200-.300 in the 130- 190's cfm. Peter out after 250cfm but easily hang on through .550
They saturate after. 550 , not much more air. The 2.02 is the diff of 8-12 cfm down low and 20-25 up top 'over the 1.94' IF you're on a roll/doing the right things. You do the certainties ...then make little changes to creep up on the number.. which is why the head goes back up on the bench so many times per port.
 
I say take the X heads to a head porter and have them flow just one cyl. Then, Maybe have a better valve job or just a good bowl blend done. Then Run Then.
They should give you the low end torque(Velocity in the port) and have all the air, that Cam is requesting.

The CNC SM head can be made to flow a lot better and make more power. But even after you have spent all that money......I think the slipping of the clutch, to get started out in 1st gear, and the light throttle there after.......will still be more impressive with the X heads.

If your racing it and gearing it for racing then the CNC SM FOR THE THE WIN!!!(After reworking of the head/seat)

IF that cam is a just for now thing and he plans for a more race set up down the road then start with CNC SM.
 
Imo, a mild $200-250 bowl job on the factory X heads is all that’s warranted for a mild 340 build like this.

I can easily see the CNC heads making zero extra tq/hp on combo that mild...... especially with both heads at the same CR.

I’ve dynoed a few mild 340’s built very similarly, one even had the same 270H cam.

On the dyno here, with 1-5/8” headers........they end up slightly over 1hp/ci.
 
With what PRH has just described, i feel, the X heads would make more power all around..........The same work done to a Standard SM would show improvement with the same kind a work.(valve job and bowl work) but............
cost for another set of SM heads, time to look over head for flaws in guide, seal and a good valve/ bowl work.
way more cost and if any, vary little extra HP.

You also have to shave piston top or thick head gasket. (that you said you don't like.) with the closed chamber aka SM heads

For what it is intended, a good runner for the least amount of cash(X head + bowl and valve job) wins!
 
For a build this mild....... the current x heads would be fine imo.

“IF”....... you were starting from scratch........ you could have used pistons that would have given you zero deck without having to machine them.
If you didn’t have heads, you could use aftermarket closed chamber heads, and end up with a nice tight quench combo.

IMO, that would be a somewhat better combo than what you’ll have with your current short block and X heads.
But...... not better enough to start over.

It doesn’t appear there are specific enough goals and requirements for the build to warrant making wholesale changes.

Pull it apart, make sure everything is good to go, have the heads bowl blended(or not), put it all back together ...... and let ‘Er rip.
 
Sounds like the combo was good as it was. After all many 340 were built like that and still are built like that. Thanks very much guys for ur input. Kim
 
I thought you were pulling it down just to check everything over since it’s been sitting for so long.

If it was all good....... you’d only have some time and gaskets into it.
 
There was a posting recently showing recently showing iron heads outgrowing SM heads under .5 inch or thereabouts
me I'd use late 360 heads for a base and use kb pistons to get quench
It might be possible to port Edelbrock or SM heads for max flow for a half inch lift scenario
I do know the way we developed open chamber heads for under half inch flow worked better than the standard 2.02 valve and port job
the three new posts written after I wrote the above- open chambers if you have good gas
 
A bit of an update. I picked up a non cnc set but no way no how were they going on. Has about 200 miles on it now. Seems to run pretty good. Kim
 
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