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Old 01-24-2008, 07:04 AM
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Chamber, cam & compression on L05?

In my '34 Ford I have an 1992 model L05 Chevy 350 motor from a Buick Roadmaster. It's a 2 bolt factory roller block.
I've removed the TBI stuff an put on an Airgap intake (not bought a carb yet) It has only 88K miles on it, so I'm planning to keep it and add some performance heads & cam on it later.

I have decoded the engine and the heads block casting No 14093638. Head casting No 14102193 ("High swirl port heads"), but can not find chamber size, piston top-type and compression.

I've searched some other forums but the information vary a lot. For example some says 8,7:1 in compression, while other say 9,5:1.

All of this is important information when I later on start searching for performance heads and cam.

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Last edited by staleg; 01-24-2008 at 10:20 AM.
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Old 01-24-2008, 01:16 PM
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Quote:
Originally Posted by staleg
In my '34 Ford I have an 1992 model L05 Chevy 350 motor from a Buick Roadmaster. It's a 2 bolt factory roller block.
I've removed the TBI stuff an put on an Airgap intake (not bought a carb yet) It has only 88K miles on it, so I'm planning to keep it and add some performance heads & cam on it later.

I have decoded the engine and the heads block casting No 14093638. Head casting No 14102193 ("High swirl port heads"), but can not find chamber size, piston top-type and compression.

I've searched some other forums but the information vary a lot. For example some says 8,7:1 in compression, while other say 9,5:1.

All of this is important information when I later on start searching for performance heads and cam.
LO5 was basically a truck motor that showed up in some auto production. For compression think 8.7 on a good day; figure that something less than 8 is more realistic. The heads have a fairly small chamber at or around 65 ccs with a chamber shape close to the L-98s of the same period, this looks a little like the Vortec chamber but the wall doesn't crowd the ex valve from the plug around the ex valve and the quench side does not have the beak between the valves. The pistons will have large and deep circular dishes in them, which along with head gasket thickness selection, controls the compression ratio. The intake ports feature a backward angled wing in the pocket extending from the guide to the inside wall. This is intended to induce considerable swirl to the mixture. This lets them get away with running the engine at low RPMs in a heavy vehicle using conventional wet mixtures thru the intake manifold without the engine bucking and surging. Port injection provides a significantly better mixture to the cylinder which is why TPI engines don't use swirl port heads and TBI engines do.

The cam is next to useless with durations around 170 degrees and lift less than .4 inch. Considerable improvement can be made here.

If you're running a carb with an OD transmission and a high ratio rear end, you might want to retain these heads and simply improve the cam. The compression could be improved thru the use of a D dish piston. The D dish puts the dish under the valves and a flat surface against the squish/quench deck of the head. This results in a much improved burn and higher innate knock resistance for a given octane fuel.

Bogie
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Old 01-24-2008, 01:44 PM
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What I have in mind is to leave the long block & pistons as is and change to a pair of Vortec heads modified for higher lift, together with a more aggressive cam. Like around ,490 in lift.

But first I want to find out what the Vortecs will do to the compression.
I've heard lots about that the swirl port heads very quickly will loose their breath with a higher lift cam.

The car will weight app 1300kg / 2800lbs. The transmission is a 6 speed manual T56 with 0,5 overdrive on 6th gear and the rear axle ratio is 3,54:1. Rear weel dimension is pretty large diameter tires 295/50-16.

Should probably had 4:1 or even lower in the rear axle, but the 3,54:1 must do from the start.
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Old 01-24-2008, 02:38 PM
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Vortec heads have a 64cc chamber just as the swirl port heads do. The swirl port heads quickly run out of breath at 3500 rpm, but they do make excellant torque. Vortec heads would likely not cost you any torque loss, but you would have much better upper rpm power. Bogie is correct in the things hes told you, and you are correct in saying no matter how much cam you give it with swirl port heads, it won't help power above 3500 RPM.
My truck has a 4.3 V6, I installed a bigger cam, a edelbrock intake, ported TBI unit, I also bowl ported the swirl port heads and added necked down ferrea valves, the power still dies off at 3800 RPM, but it has stump pulling low end torque and tachs fast as lightning, so I'm okay with it. I have a set of vortec heads off a 99 model 4.3 chevy truck, and I could swap it over, but I decided its not worth the hassle right now, as I would need a dyno with a lap top to tune it back in to compensate for the increased flow, and I would rather not go backwards to a carb.
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Old 01-24-2008, 04:24 PM
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Quote:
Originally Posted by staleg
What I have in mind is to leave the long block & pistons as is and change to a pair of Vortec heads modified for higher lift, together with a more aggressive cam. Like around ,490 in lift.

But first I want to find out what the Vortecs will do to the compression.
I've heard lots about that the swirl port heads very quickly will loose their breath with a higher lift cam.

The car will weight app 1300kg / 2800lbs. The transmission is a 6 speed manual T56 with 0,5 overdrive on 6th gear and the rear axle ratio is 3,54:1. Rear weel dimension is pretty large diameter tires 295/50-16.

Should probably had 4:1 or even lower in the rear axle, but the 3,54:1 must do from the start.
Let me start with some cam to port flow comments. When the port is maxed out, which happens fairly early with the swirl ports, adding lift is inconsequential as the valve's curtain area at this point is not the limiting factor. However, adding duration, which is open time, allows more flow simply because of the more available time even though the port is maxed. So more duration will help a bit with the Swirl Port port where greater lift will not.

The Vortec head is usually good for 20 to 40 or more horsepower depending upon what it's replacing. This is do to a combination of some better upper end flow and certainly the effect of the Ricardo fast-burn combustion chamber. Compression with the Vortec would stay about the same as the chamber volume is pretty close to that of the Swirl Port. Typically Vortecs surrender a little torque on the bottom end but this is 4 or 5 pound feet, which isn't really noticeable.

Chevy High Performance Magazine did an incremental build up on a Mr. GoodWrench Henco-en-Mexico engine some years ago. This engine is actually similar to yours, less the Swirl Ports. I've included some links so you can read the blow-by-blow. It actually did pretty well with pistons similar to yours.

http://www.chevyhiperformance.com/te...320/index.html



http://www.chevyhiperformance.com/te...326/index.html



http://www.chevyhiperformance.com/te...359/index.html



http://www.chevyhiperformance.com/te...364/index.html



http://www.chevyhiperformance.com/te...370/index.html



http://www.chevyhiperformance.com/te...438/index.html



http://www.chevyhiperformance.com/te...461/index.html



http://www.chevyhiperformance.com/te...467/index.html

Bogie
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Old 01-25-2008, 12:29 AM
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Sound very promising!

But I don't get this:
You say that my swirl port heads has app 64 CC chamber size, engine has flat top pistons like the engine in that article and no more than 8:1 in compression.

But the engine in the article has 76 CC chamber size AND 8,4:1 in compression? Schouldn't the compression drop compared to mine if it had bigger chambers?
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Old 01-25-2008, 07:31 AM
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If your compression is a bit low, and if your pistons are down in the hole, you can run a thin head gasket to improve things. GM has a .028" gasket that looks nice. You can get head gaskets all the way down to .015" I think. Try and shoot for between .040" between the top of the piston and the cylinder head (quench distance).

I did a search and it seems people are reporting finding this head in both 76cc and 65cc, but 65cc seems more common. check this link here:
I need head info

The best thing to do would be to pull off the heads and see what you have for piston tops, do you have the time/space to do that?

Last edited by fiscus; 01-25-2008 at 07:39 AM.
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Old 01-25-2008, 07:56 AM
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I would send that intake back and get a regular rpm intake (non-air gap). The air gap intake suffers from very slow carb warm up due to no heat riser under the carb. If you are planning to drive the car on the street when the air temp is under 50F (11C) then it will take 15 minutes of driving before the lean stumble goes away.
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Old 01-25-2008, 09:56 AM
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Quote:
Originally Posted by staleg
Sound very promising!

But I don't get this:
You say that my swirl port heads has app 64 CC chamber size, engine has flat top pistons like the engine in that article and no more than 8:1 in compression.

But the engine in the article has 76 CC chamber size AND 8,4:1 in compression? Schouldn't the compression drop compared to mine if it had bigger chambers?
If Chevy engine's all used flat top pistons that would be true, but, GM uses a circular dish of different depth to manage compression. These will vary from less than 10cc to more than 20. This needs to be added to the chamber volume when calculating compression. Add to that, the actual chamber volumes are almost always larger than the advertised by several cc's.

Bogie
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Old 01-25-2008, 04:28 PM
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Thanks for all your information.

It seems like there are 3 different versions of the L05:
1. Low compression truck version.
2. Police version (availiable on Caprice's only).
3. The version used on all other L05 cars.

Since my engine comes from a Buick Roadmaster, I must have the third version and this is what I've found out about it. Apologize the caps look, but I just copied it down from an internet page:

2 BOLT MAIN 1 PIECE CRANKSHAFT SEAL BLOCK( NO MECHANICAL FUEL PUMP PROVISION)NODULAR IRON CRANKSHAFT
POWDERED METAL CONNECTING RODS
FLAT TOP HYPEREUTECTIC PISTONS
9.6:1 COMPRESSION RATIO
SHORT WINDAGE TRAY
SINGLE ROLLER TIMING CHAIN

HYDRAULIC ROLLER CAMSHAFT
INTAKE LIFT-.359" * EXHAUST LIFT.384" *
INTAKE DURATION @.050-186.5 * EXHAUST DURATION @.050-193.8
LOBE CENTER SEPERATION -110.3
CAMSHAFT MECHANICAL SPECS:
INTAKE VALVE OPENS @ -16.9 BTDC * INTAKE VALVE CLOSES @ 23.4ATDC * INTAKE LOBE CENTERLINE - 110.3 EXHAUST VALVE OPENS @ 25.6BBDC * EXHAUST VALVE CLOSES @ -11.9 ATDC * EXHAUST LOBE CENTERLINE - 110.3
CYLINDER HEADS:
CASTING NUMBER 14102193
SWIRL PORT INTAKE PORT DESIGN
65.3cc COMBUSTION CHAMBER
1.94" INTAKE 1.50" EXHAUST VALVE self-aligning rockers.
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