5.2/3.9 Mag. Deck Clearance and OEM Head Gasket Specs (Quench Height Calculations) - DodgeTalk : Dodge Car Forums, Dodge Truck Forums and Ram Forums
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OldMans3.9
 
  5.2/3.9 Mag. Deck Clearance and OEM Head Gasket Specs (Quench Height Calculations) - Posted: 03-16-2005, 06:50 PM
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Post #1

For those that are thinking 'deck wha?', deck clearance is the gap between the piston top and the block deck when a piston is @ top dead center (TDC).

I can't seem to find specs for the 5.2 and 3.9 Magnum engines. I've heard guesses of .025-.050( ) in the hole, but no one I know has actually measured it. OEM head gasket specs are also unknown. For compressed thickness, .047 comes to mind, but I'm not certain. I've heard that gasket bore is 4.060, but again, uncertain. I'd like to get either chrysler's book specs, or some independant measurements. If anyone has them, or knows where they can be found, please, enlighten me. I'd certainly appreciate it.

I posted this in the 'engine tech' forum as well, but hits there are far and few between.
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OldMans3.9
 
 Posted: 03-17-2005, 03:45 PM
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Post #2

ttt
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OldMans3.9
 
 Posted: 03-18-2005, 12:06 AM
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Post #3

I've now read a couple stating the pistons were .050" in the hole. With a .047" gasket, that's a .097" quench height (which would explain why these engines have terrible economy and knock so blasted much). But, I have some contradicting info...

With block deck height: 9.058-9.060, stroke: 3.31, rod length: 6.123, and piston compression height: 1.81, I come up with -.006-.008 deck clearance. The piston tops would be .006-.008" out of the hole @ TDC. With a .047 gasket, that would leave .039-.041" deck clearance, which is about where it should be. What am I missing here?
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Last edited by OldMans3.9 : 03-18-2005 at 12:35 AM.
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HankL
 
 Posted: 03-18-2005, 02:34 PM
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Post #4

Here's some of the harder-to-find 5.2 specs, with my present day
corrections from the original July 2000 post above:

Deck height from centerline of block bore at crankshaft to bottom of head
gasket is 9.585 inches according to Hot Rod Magazine 'Magnum Manifesto' Aug
1998 but I suspect this is only what they measured on that particular Magnum
360 crate engine....old pre-Magnum LA engine spec was 9.599 inches.

In Mopar Performance News magazine MP Engineer Larry Shepard recently wrote
the deck height from the factory was 9.580 inches on Magnums.

Jon Smith reports that on his 1995 5.2 Magnum the piston tops were nearly
flush with the top of the block.

The reason the deck height measure is needed is to calculate the
'Quench Clearance' between the piston and cyl head.
It is calculated this way:

+9.580 deck ht
+0.047 gasket thickness
-6.123 rod length
-1.755 piston compression ht
-1.655 half of stroke of 3.31 inches
--------
0.094 inch Quench Clearance (should be 0.040 or less for good quench)

Combustion Chamber size...nominal 65 cc according to Hot Rod in 'Magnum
Manifesto' article in Aug 1998...62 cc according to Marlan Davis in 'High Perf
Mopar Engines' ISBN 1884089518 ....62cc as measured by Ray Barton Engines on
Dakota owner's 1995 5.2V8. Larry Shepard writes in MPN that the Magnum chamber
is "about 60cc".

Cylinder head intake port volume 153cc according to Mopar Performance.
Cylinder head exhaust port volume - unknown

Sealed Power replacement pistons H814P for a 1995 5.2V8 list a 1.755
compression height flat top piston.

Sealed Power H655CP replacement pistons for the 5.9 list a 1.612 inch
compression height, and minus 11.23 cc rectangular dish volume in the piston
crown.

The Engine Analyser 3.0 software predicts the 5.2 piston compression height to
be about 1.759 inches if the compression ratio is a true 9.10. This would put
the pistons down from the very top of the bores about 0.043 inches at top dead
center.

If anyone has a stock 5.2 Magnum piston they could measure please post it.
Measure from top of pin hole to top of piston, then add half of pin diameter
to get compression height.

Compression ratio 9.1 as advertised ....carbon deposits are said to increase
ratio by at least 0.5 in first 10,000 miles of driving.

See this webpage for sample piston picture:

http://www.kb-silvolite.com/page39.htm#SECT2

Throttle body: dual 50mm bores. Chrysler patented 'Progressive Bore' necks
this down to 48 mm at throttle shaft )
Theoretical Throttle Body Flow capacity as measured by Frank at F&B: 560
cfm.....due to restrictive air intake system or 'Progressive Bore choke point,
use about 330 cfm for best match because factory air filter box adds
additional restriction in line with throttle body.

Intake Manifold runner length along centerline: 15.5 inches. Top of runner
17.75 inches and bottom length 12.75 inches.

Intake Manifold runner 'equivalent' diameter 1.59 inches
Intake manifold design type: single plenum with 90% divider (almost a dual
plane)....factory intake manifold seems to be quite restrictive at high cfm
flows.

Cylinder head gasket thickness 0.047 inches

Intake port flow: 208 cfm at 0.450 lift
Exhaust port flow: 173 cfm at 0.450 lift

See this webpage for table of intake/exhaust flow values:
http://www.hughesengines.com/heads/magnum_heads.asp

18 degree inclined valve angle

Intake valve diameter 1.925 inches

Cam design type: mild hydraulic roller
Intake valve timing:
......Lobe centerline 115.5
......Advertised duration 251 degrees
......Opens btdc 10 degrees
......Closes abdc 61
.....maximum lobe lift 0.27 inches
.....rocker arm ratio 1.6
.....gross intake valve lift 0.432
Exhaust Valve diameter 1.625 inches
.....Lobe centerline 109.5
.....Advertised duration 261
.....Opens bbdc 60 degrees
.....closes atdc 21
.....maximum ex lobe lift 0.27
.....rocker arm ratio 1.6
.....gross exhaust valve lift 0.432

{all of the above data can be used to show that the new cam at the factory is
installed 3 degrees retarded, but timing chain wear may change this. The
camshaft specs may have changed a few times since 1992 as the factory tweaked
them a bit, and eliminated EGR in 1997**

Streamlined type cast iron exhaust manifold
.... 2.500 inch outlet in 1992, 2.125 inch outlet afterwards. These 'Magnum'
factory manifold are said by Larry Shepard to be the best flowing smallblock
manifold ever - better than those HP manifolds on the 1970 era 340V8's.

Approximate CFM capacity of factory exhaust system: 200 cfm at 20.4 inches
water. Note that most exhaust companies test at 28 inches water.

Coolant temperature 195 degrees F (180 makes little difference according to
Kenne Bell but helps reduce pinging)

Magnum engine water pump allegedly pumps 100 gpm at 5000 rpm according to
Larry Shepard in 'Magnum Engines' Mopar Perf book.

Air and pressure at dyno:....Society of Auto Engineers standard is 77 F, 40 F
dew pt and 29.6 baro, but.....130 F, 40 dew pt, and 29.92 seems to give better
hp and torque match and is what I measure with actual Scantool on 5.9 engine
in '95 truck.

Notes:
Factory Indy exhaust muffler seems to be about 550 cfm rated
DynoMax/Walker/Tenneco UltraFlow model, resulting in +15 hp increase over
stock 230 HP truck & muffler back in 1996. Exhaust cfm must still be rated
lower than 550 to take into account stock restriction of catalytic converter.
Later year Rams appear to have less restrictive exhaust systems from factory
resulting in increases in HP rating from original 230 to 245, then to 250 HP.
Some of this increase also due to camshaft changes.

According to Larry Shepard, 42 inch long primaries with 1.625 OD dia, with 6
inch collector specs make a good 4 into 1 header specification.

To use this primary length catalytic converter must be moved back behind
factory installed spot. Most aftermarket headers are short (20-26 inch) so
that they can mate to existing Y pipe and cat.

---------------
RAM MAN
From: Haslett, MI
posted December 28, 2000 10:58 AM
------------------------------------------------------------------------------
--
The engine type is 90 degree V* OHV
Bore and stroke is 99.2 X 84.1mm (or 3.91 X 3.31 in)

Displacement 5.2L (318 cu in)

Compression ratio: 9.1:1

Power (SAE net) 230 bhp @ 4,400 RPMs

Torque 300 lb fts @ 3,200 RPMs

Firing order is 1 8 4 3 6 5 7 2

Lubrication type: Pressure feed - Full flow filtration

Engine oil capacity: 4.7L (5 quarts w/filter)

Cooling system: Liquid cooled - forced circulation

Cylinder block - Cast Iron

Crankshaft - Nodular Iron

Cylinder heads - Cast Iron

Combustion chambers - Wedge-High Swirl Valve Shrouding

Camshaft - Nodular Cast Iron

Pistons - Aluminum Alloy with Strut

Connecting Rods - forged steel
Valves: valve face angle is 43.25 - 43.75 degrees

Head diameter
intake - 48.666mm or 1.916 in
exhaust - 41.250mm or 1.624 in

Length overall:
intake: 124.28 - 125.92 degrees
Exhaust: 124.64 - 125.27 degrees

Lift (zero lash) - 10.973mm (0.432 in)

Stem diameter 7.899 - 7.925mm or 0.311 - 0.312 in

Stem to guide clearance is 0.0254 - 0.0762mm or 0.001 - 0.003 in

TB type is progressive bore

compression pressure is approximately 140 psi on third revolution of crank.

The cam info I have is on the R/T version:
204/208 degrees duration at .050", 458/.467" lift with the 1.6 ratio rockers.
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HankL
 
 Posted: 03-18-2005, 02:35 PM
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Post #5

Here are as many 5.2 V8 Magnum (post 1992)
engine technical specs as I have been able to acquire various places. Please check these dimensions and post any mistakes you find or additional stuff.

Some of this stuff came from PerformanceTalk and I repost it in the hopes it may help someone else - particularly those playing around with Engine analysing computer programs.

I will post 5.9 Magnum measurements later.

Bore 3.91
Stroke 3.31
Connecting Rod length 6.123 inches

Deck height of block 9.585 inches according to Hot Rod Magazine 'Magnum Manifesto' Aug 1998 but I suspect this is incorrect ...may only apply to 1997 MP Crate Engines...old LA spec was 9.599 inches

Distance from piston quench pads to cyl head quench pads approxmately 0.050 with 9.585 deck height or 0.064 with 9.599 dk ht.

18 degree inclined valve angle

Combustion Chamber size...nominal 65 cc according to Hot Rod in 'Magnum Manifesto' article in Aug 1998...62 cc according to Marlan Davis in 'High Perf Mopar Engines' ISBN 1884089518 ....62cc as measured by Ray Barton Engines on Dakota owner's 1995 5.2V8.

Cylinder head intake port volume 162cc
Cylinder head exhaust port volume - unknown (70 cc ?)

Compression height of factory cast aluminum pistons 1.81 inches
Volume of piston valve clearance 'eyelass' cut-outs: 5 cc
Compression ratio 9.1 advertised (8.7 with clean metal chamber....carbon deposits said to increase ratio by at least 0.5 in first 10,000 miles of driving)

See this webpage for piston picture:

http://www.kb-silvolite.com/page39.htm#SECT2

Throttle body: dual 50mm bores. Chrysler patented 'Progressive Bore' necks this down to 48 mm at throttle shaft )
Theoretical Throttle Body Flow capacity: 440 cfm.....due to restrictive air intake system or 'Progressive Bore choke point, use about 400 cfm for best match

Intake Manifold runner length along centerline: 15 inches. Top of runner 17.75 inches and bottom length 12.75 inches.

Intake Manifold runner 'equivalent' diameter 1.59 inches
Intake manifold design type: single plenum with 90% divider (almost a dual
plane....intake manifold seems to be quite restrictive at high cfm flows**

See this webpage for view of underside of Magnum 'beer barrel' intake manifold

http://home.att.net/~flyboy01/360Dakota.html

Cylinder head gasket thickness 0.047 inches
Intake port flow: 208 cfm at 0.450 lift
Exhaust port flow: 173 cfm at 0.450 lift

See this webpage for table of intake/exhaust flow values:

http://www.hughesengines.com/heads/magnum_heads.asp

Intake valve diameter 1.925 inches
Cam design type: mild hydraulic roller
Intake valve timing:
......Lobe centerline 115.5
......Advertised duration 251 degrees
......Opens btdc 10 degrees
......Closes abdc 61
.....maximum lobe lift 0.27 inches
.....rocker arm ratio 1.6
.....gross intake valve lift 0.432
Exhaust Valve diameter 1.625 inches
.....Lobe centerline 109.5
.....Advertised duration 261
.....Opens bbdc 60 degrees
.....closes atdc 21
.....maximum ex lobe lift 0.27
.....rocker arm ratio 1.6
.....gross exhaust valve lift 0.432

{all of the above data can be used to show that the new cam at the factory is
installed 3 degrees retarded, but timing chain wear might gradually advance
this. The camshaft specs may have changed a few times since 1992 as the
factory tweaked them a bit, and eliminated EGR in 1997**

Streamlined type cast iron exhaust manifold
.... 2.500 inch outlet in 1992, 2.125 inch outlet afterwards

Approximate CFM capacity of factory exhaust system: 184 cfm at 20.4 inches
water. Note that most exhaust companies test at 28 inches water.

Coolant temperature 195 degrees F (180 makes little difference according to Kenne Bell but helps reduce pinging)

Mgnum engine water pump allegedly pumps 100 gpm at 5000 rpm according to Larry Shepard in 'Magnum Engines' Mopar Perf book.

Air and pressure at dyno:
....Society of Auto Engineers standard is 77 F, 40 F dew pt and 29.6 baro,
but...
.....130 F, 40 dew pt, and 29.92 seems to give better hp and torque match and
is what I measure with actual Scantool on 5.9 engine in '95 truck.

Notes:
Factory Dakota RT exhaust seems to be about 550 cfm, resulting in +15 hp
increase.

According to Larry Shepard, 42 inch long primaries with 1.625 dia with 6 inch
collector specs make a good 4 into 1 header specification. To use this primary length catalytic converter must be moved back behind factory installed spot. Most aftermarket headers are very short so that they can mate to existing Y pipe and cat.

Hope this data helps.
Please check and pass along any mistakes spotted.
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#2
Old 07-29-2000, 03:35 AM
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I have received tips by email that:

(1) In the April 2000 issue of Mopar Performance News Larry Shepard writes about the new aluminum Magnum head. In the article he says that the 5.2 and 5.9 use the same cast iron Magnum head, and that head's combustion chamber is 'nominal 60cc.'

Shepard also writes that the aluminum head loses more heat to the coolant, so they upped the compression ratio of the aluminum head by 1 pt of CR to compensate. I guess that makes the Aluminum Magnum head cc about 53 cc. Each cast iron Magnum head is 48 lbs, and the new Aluminum Magnum head is 25 lbs. Aluminum Magnum head is said by Shepard to make 15 HP more 'out of the box.'

(2) In the Nov/Dec 1999 issue of Mopar Performance News there is a tech article about the short block assemblies. In this article they say that the deck height of the old LA blocks was 9.60, the factory Magnum blocks are 9.58, and the used shortblock assemblies from Mopar Performance they call 'seasoned' blocks are milled down to 9.56 prior to re-assembly.
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OldMans3.9
 
 Posted: 03-18-2005, 10:15 PM
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Post #6

I really appreciate the info. Hank. Thanks!

I acquired some more independant measurements today. Dan 'The Fastman' said his couple have been .060-.062 in the hole, and the engine builder at KRCPerformance said theirs have averaged low-mid 70's. I guess Chrysler just didn't care much for keeping tolerances. It's almost hard to believe they very THAT much. At over .060 QH, I imagine it probably wouldn't make much difference what it was. You'd have no 'squish' with such a gap.

I guess I'll be ordering some .005" tin foil and just hope for the best lol...
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