Reshaping chamber help

[NJ John]

I’ve had these years for a while. Stock bore, ported nicely, but fly cut a bunch. I want to add some cc’s to the chambers. I think I checked them once and it was in the low 30’s. I kinda want to use them for a 1600 turbo project or the next step for the turbo, machine in forged 88’s. Any input on chamber shape would be great. They have 7 fins.

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1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[Pruneman99]

What CC will you need for the target compression ratio? For a turbo engine, I doubt you're going to get there with those.

[Ebel]

You won’t be taking 20ccs out of those heads easily. The compression would be around 14:1 with 30 cc and a turbo it won’t last long. Maybe if you run e85 it would be possible to use those heads and a turbo. I don’t know how much a hemi would gain. But stock chambers are a lot bigger then 30 cc.

[clonebug]

For 88mm P/C's you will need at least 52cc's to get around 8.0:1.

I have .062" deck on a stock untouched case using .010" shims under the barrels and 52cc heads. That gives me a 7.8:1 compression ratio.
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[FreeBug]

How many ccs do you need? If it was me, I'd concentrate on getting the ccs by removing material where it would help unshroud the upper side of the intake (leave the non-plug side alone) to increase flow there, as most of it goes through the bottom.

By going to 88s, you will get a bit more side clearance to enlargen the chamber, and you could unshroud the intake even more, getting the walls as concentric as you can. I use drill bits of increasing sizes to check around the perimeter of the valve for concentricity.

Looks like there is hardly any room to semi-hemi it, but maybe you could create an approximation of the non-plug side of the se-he, I don't see why it should work any less than on a full se-he. Maybe better because you could keep some squish?

Just throwing ideas out, others know more.

[earthquake]

You could have them "Hemi" cut if any body still does it.

Casey
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[nsracing]

For the turbo - just get a different set of heads and save those tight ones for street engines.

If you already removed fins, means it is too tight already. 20cc is a lot. That is half of the chamber you got now. Where are you gonna cut that out from?

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[NJ John]

Thanks for the inputs. I thought it was a lost cause. I’ll save them for a n/a situation. There’s so many major fly cut heads out there.
_________________
1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[BFB]

these were 42cc chambers that i opened up to 60 cc to get an 8:1 2276 , turbo.
funny thing was after i did this a buddy pointed out to me that some of the guys building boosted ls engines have been doing this to the heads. i was just being cheap and wanted to see if i could make it work

[MURZI]

Nothing wrong with running a ton of deck on a turbo engine either
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2276
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[FreeBug]

[Alstrup]

Also, IF you decide to go that route, deck height suddenly doesnt matter anymore because its all part of the chamber.
The downside is that you will loose A LOT of torque compared to normal wedge chambers, like 8%.

[Pruneman99]

I'd be afraid of leaving too much space between the top of the piston and the top of the barrel. Especially in a turbo engine. Even if your running heads with no quench area. If your running hemi heads I'd set the "deck" at zero and keep the boom in the heads, and less in the cylinder.

[mark tucker]

[Clatter]

Maybe work up some dished pistons?
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[NJ John]

I’ll probably not try to use them in a turbo application. The 1600 turbo will be the experimental and my first turbo. So my current heads will do.
I had a n/a 1641 with similar heads that ran 14’s in the quarter. But I hate having all these combos I my head and only half of the correct parts for each one of them.
_________________
1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[sled]

I've heard and read guys say that quench and tight deck do not matter for a turbo. Not disputing this (as I've never built a turbo acvw) but how could it not matter when off-boost? a turbo street car spends the vast majority of its time off boost and wouldn't it be better for performance if it had tight deck/squish? as long as the compression is low enough to handle the extra boost...

at WOT and full boost I imagine its not as much of a factor, but up UNTIL that point it would be nice to have a snappy efficient engine as well?
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