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Old 01-25-2012, 09:24 AM
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measuring the head cc size & CR

So I got a 1 cup measuring cup from target that has milliliters by 10ml incriments on the cup. I filled the cup with the published head combustion chamber size and put in a plug and poured the water into the head. I know I'm a ml or so off probably but I wanted to see the general size class of the combustion chamber. Hopefully the cup is reasonably accurate.

Did I do this correctly? If I did the size is 75ish cc/ml.

It's a 1987 k5 blazer 350 head (14102193). I've seen two different figures for the combustion chamber size: 64/65ish mostly and one 76cc from a machine shop guy who looked it up. I called chevy and they didn't know. (kinda disappointed on that one...)

A 1987 chevy brochure scanned and online shows the CR for the 350 (LO5) at 9.3:1. I have the pistons from the engine. They are dished 4 valve relief pistons. I think the block number showed it to probably be the original factory engine. So after using a calculator on the net, I'm wondering how chevy got 9.3:1 from this head at 75/76 cc? The 64cc size seems to gel more with these pistons and CR it would seem. But I'm new to this stuff so I need some help. The suburban did offer a 8.6:1 LO5 350 with 195hp in '87.


http://coloradok5.com/brochures/1987/
choose blazer8.jpg for engine specs (burb8.jpg for the suburban specs)

I'd like to use them for a truck engine for normal eveyday driving but I'd like to get close to a 9:1 CR. These are thin wall castings ( I hope that's the right term) and maybe a they could be shaved some to reduce the combustion chamber to bump up CR closer to 9:1. I haven't gotten my pistions yet but the block is cleaned & ready to bore and I need to get this settled. I'll be using flat top pistions. I have a qjet intake to fit both the pre 86 and post 86 center bolt heads. I was hoping to do a 327 but could still do a 350 at this point. Yea... I just want a 327 and I know a 350 is better/cheaper. It might happen. The reason I want to use them is they have a swirl intake (not vortec) and are a good low end torque head...so probably a good daily driver. I'm not interested in big horsepower and I already have them to use.

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Old 01-25-2012, 01:42 PM
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Quote:
Originally Posted by red82c10
The reason I want to use them is they have a swirl intake (not vortec) and are a good low end torque head...so probably a good daily driver. I'm not interested in big horsepower and I already have them to use.
Excellent application for the intended purpose. Flat-top pistons with a 7cc relief will yield ~9.0:1 when used with 76cc chambers. Check the chart on the left of this 350 piston page.....
http://www.kb-silvolite.com/kb_car/p...tails&P_id=157

I might use a cam such as this one that closes the intake valve @21 degrees ABDC, for a dynamic compression ratio of 8.45:1. Mated with a good, tight squish of 0.035" to 0.045", this should make an excellent street motor in my opinion.
http://www.cranecams.com/product/car...detail&p=23788

This would be the same type piston for a 327. The static compression is less due to the decreased volume of the cylinder in a 327, as opposed to a 350 motor...
http://www.kb-silvolite.com/kb_car/p...etails&P_id=44
It will yield a SCR of ~8.4:1 with 76cc chambers.

The 327, being a smaller engine with less static compression ratio, will want a smaller cam. A stick such as this one, that closes the intake at 16 degrees ABDC would be close to what I might choose for a street runner that will operate on cat-piss pump gas.
http://www.cranecams.com/product/car...detail&p=23787
It yields a DCR of 8.01:1.

I'm not saying to use either of these cams, I'm just trying to get you in the ballpark of where you need to be. Use anyone's cam that you want to, just pay attention to basics and match the cam to the other equipment you will use.

Last edited by techinspector1; 01-25-2012 at 01:51 PM.
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Old 01-25-2012, 01:51 PM
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Edit- those are swirl port heads, the info I removed was about 76cc smog heads.

You might want to look into the L31 Vortec head and a matching intake for this engine. It flows a LOT better. Has the same 64 cc nominal chamber volume as the SP heads. If you don't have to tow or the truck doesn't weigh 5500 lbs, that is.

A note on measuring the chamber volume- you have to use a cover on the chamber to prevent errors from the surface tension of the water. You can use an old CD w/the plating scraped off (drag a razor blade backwards across the plated side and the plating will jump off it), or use a piece of plexiglass w/a couple holes drilled in it, one to add fluid through the other to let air escape.

You'll have an easier time using rubbing alcohol/water 50/50 w/food coloring added. The alcohol breaks the surface tension and the food coloring gives contrast. The head needs to be level and the plastic sealed to the head w/vaseline or grease. Chasing the bubbles out is the hardest part but if you're careful and take your time you can get it all out.

If doing this at home, you can use a 10cc syringe from the pharmacy, they should have no problem selling you one w/o a needle attached. It's not illegal or anything. A vet is another place to get one. The syringe will give a much more accurate measurement than eyeballing a measuring cup- and measuring cups are not to be trusted to be accurate anyway.

Last edited by cobalt327; 01-25-2012 at 01:56 PM.
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Old 01-26-2012, 07:37 AM
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measuring head cc size & CR

Thanks cobalt327. I did notice some surface tension and wasn't thinking i had the number exactly right by any means. Just looking to see if i was in the 76cc or 64cc ball park. What source do you have that says a 1987 #193 head has a 64 cc chamber? Chevy doesn't seem to care about people using their stuff if it's not a performance part. They're missing a large market of people who can't just throw money at a project, IMO. I'll try the cd trick.

techinspector1- thanks for the advice
I did find a set of Keith Black KB157 dome pistons with a -.5cc value that could keep the 327 idea alive but they're $260. But they would yield about 9:1 CR instead of a 8.3-5 with flat tops and a 76cc. As far as cam I was leaning towards using the same basic specs as the GM 350 crate 250 hp motor. Which is closely matched by the melling ccs-2 or summit 1101 if I followed the right information and part numbers (#14060650 -> #14060651 -> #14088839) (194/202 @ .050, 112 centerline, .385"/.404", 268/273 duration) The melling cam and lifter kit cl-ccs-2 is $95 at autozone. The summit #1100 cam looks to be very close to the crane 2010 you selected. Moving up to a 350 would you keep the 2010 or select a different grind?

( CCS-2: 194/202 @ .050, 258/269 duration, .390/.409 lift, 108/116 CL )

The cost of keeping this 327 idea is possibly on the way out and I'll just do a 350 since I've not yet got the pistons. I'll have to get a 350 crank but then it's all good from there. Northern Auto has a 350 master kit for just under $200 before a few tweeks to the parts. But this head chamber size issue will get settled in the next couple days so I know what I'm getting.

Again, thanks for your advice and time giving a response to my rambling.
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Old 01-26-2012, 09:21 AM
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Quote:
Originally Posted by cobalt327
The head needs to be level and the plastic sealed to the head w/vaseline or grease. Chasing the bubbles out is the hardest part but if you're careful and take your time you can get it all out.
Slightly off topic. I tend to not have the head level but make it so that the air bleed hole in my plate is the highest point which is somewhere near an edge of the chamber. I've tried level but I find that the final air bubble generally gets trapped everywhere except where I want it. Not that level is wrong because like anything with engines there's many ways to skin a cat. For me I just have better results putting the bleed hole on the edge of the chamber and tilting the head slightly.
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Old 01-26-2012, 01:05 PM
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Quote:
Originally Posted by red82c10
So I got a 1 cup measuring cup from target that has milliliters by 10ml incriments on the cup. I filled the cup with the published head combustion chamber size and put in a plug and poured the water into the head. I know I'm a ml or so off probably but I wanted to see the general size class of the combustion chamber. Hopefully the cup is reasonably accurate.

Did I do this correctly? If I did the size is 75ish cc/ml.

It's a 1987 k5 blazer 350 head (14102193). I've seen two different figures for the combustion chamber size: 64/65ish mostly and one 76cc from a machine shop guy who looked it up. I called chevy and they didn't know. (kinda disappointed on that one...)

A 1987 chevy brochure scanned and online shows the CR for the 350 (LO5) at 9.3:1. I have the pistons from the engine. They are dished 4 valve relief pistons. I think the block number showed it to probably be the original factory engine. So after using a calculator on the net, I'm wondering how chevy got 9.3:1 from this head at 75/76 cc? The 64cc size seems to gel more with these pistons and CR it would seem. But I'm new to this stuff so I need some help. The suburban did offer a 8.6:1 LO5 350 with 195hp in '87.


http://coloradok5.com/brochures/1987/
choose blazer8.jpg for engine specs (burb8.jpg for the suburban specs)

I'd like to use them for a truck engine for normal eveyday driving but I'd like to get close to a 9:1 CR. These are thin wall castings ( I hope that's the right term) and maybe a they could be shaved some to reduce the combustion chamber to bump up CR closer to 9:1. I haven't gotten my pistions yet but the block is cleaned & ready to bore and I need to get this settled. I'll be using flat top pistions. I have a qjet intake to fit both the pre 86 and post 86 center bolt heads. I was hoping to do a 327 but could still do a 350 at this point. Yea... I just want a 327 and I know a 350 is better/cheaper. It might happen. The reason I want to use them is they have a swirl intake (not vortec) and are a good low end torque head...so probably a good daily driver. I'm not interested in big horsepower and I already have them to use.
The 14102191 and 14102193 heads drive me nuts, GM says the 191 is 76 cc's and is used on the 4 bolt engines going into vehicles over 7200 GVW and that the 193 is 64 cc's and go on vehicles under 7200 lbs GVW. When I measure these things it seems that 191 pretty much stays at 76 but the 193 can vary from head to head between 64 or 76 and that GVW of the vehicle doesn't seem to matter as pistons are changed to get the DCR the engine was qualified for. Maybe it's a west coast thing since we all have to put up with California's specific and different emissions requirements. So I often wonder if west coast aimed production often includes California parts whether needed or not in the surrounding states.

Bogie
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Old 01-26-2012, 02:06 PM
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I have a set of 193, from '92 IIRC. 64 cc chambers.
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Old 01-26-2012, 02:42 PM
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Quote:
Originally Posted by cobalt327
I have a set of 193, from '92 IIRC. 64 cc chambers.
That matches GM published spec.

Bogie
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Old 01-26-2012, 03:22 PM
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Quote:
Originally Posted by red82c10
Thanks cobalt327. I did notice some surface tension and wasn't thinking i had the number exactly right by any means. Just looking to see if i was in the 76cc or 64cc ball park. What source do you have that says a 1987 #193 head has a 64 cc chamber? Chevy doesn't seem to care about people using their stuff if it's not a performance part. They're missing a large market of people who can't just throw money at a project, IMO. I'll try the cd trick.
There's a guy at 3rd. generation that goes by "fast355" who posted a lot of info on the SP heads, some of it is- http://www.thirdgen.org/techboard/tb...ted-193-s.html

Yeah, the surface tension plays havoc w/the exact size but for the purpose of seeing if they're 76 or 64 it really doesn't matter. Buy anyway, I cc'd the ones I have and they're right at 64cc. The heads weren't cleaned, so it could be slightly over that, but you get the idea. Call it 64cc nominal.
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