Home » Public Forums » GMCnet » [GMCnet] Cylinder Head Info
| [GMCnet] Cylinder Head Info [message #84750] |
Sat, 15 May 2010 19:14  |
Rosebud
Messages: 132
Registered: September 2006
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Guys,
I have a cylinder head with a "K" embossed on the end, supposedly a 455 marine engine. Can you tell me what this head is, & what are the best heads to use on the GMC 455 motor? Is this possibly a 403 head? Thanks in advance.
Lanny Young
Kingsland, Tx.
'77 E II
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| Re: [GMCnet] Cylinder Head Info [message #84751 is a reply to message #84750] |
Sat, 15 May 2010 19:30  |
roy1
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K heads are used a lot in Jet boats and are in a lot greater demand then our J heads. They have hardened seats also, the only drawback is they have larger valves and would not be as good at low RPM's. You should have no trouble trading them for a set of J heads. They were also used on some W30 engines.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Cylinder Head Info [message #84806 is a reply to message #84756] |
Sun, 16 May 2010 08:37 |
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Matt Colie
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| Rosebud wrote on Sat, 15 May 2010 20:57 |
Thanks, Roy. That's what I wanted to know.
Lanny Young
Kingsland, Tx.
From: roy keen
K heads are used a lot in Jet boats and are in a lot greater demand then our J heads. They have hardened seats also, the only drawback is they have larger valves and would not be as good at low RPM's. You should have no trouble trading them for a set of J heads. They were also used on some W30 engines.
Roy
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Lanny,
Larger valves is NEVER a bad idea.
Air IS Torque, and horsepower is only torque with speed.
Find some of of the Olds engine builders to talk to before you let go of the K heads.
The may be other issues - like port alignment - that might work out well for TZE, but do not let go of them before you know that for a fact.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Cylinder Head Info [message #84823 is a reply to message #84806] |
Sun, 16 May 2010 10:05 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
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Matt,
Agree that bigger is better when it comes to valves, however, as I
understand it that does not hold true with ports?
Too big and you loose velocity which can effect low end performance?
Old wives, er mechanics tale?
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Matt Colie
Sent: Sunday, 16 May 2010 11:38 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Cylinder Head Info
Lanny,
Larger valves is NEVER a bad idea.
Air IS Torque, and horsepower is only torque with speed.
Find some of of the Olds engine builders to talk to before you let go of the
K heads.
The may be other issues - like port alignment - that might work out well for
TZE, but do not let go of them before you know that for a fact.
Matt
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Cylinder Head Info [message #84825 is a reply to message #84823] |
Sun, 16 May 2010 10:45 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
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Typically if a head has bigger valves it has larger ports too. I think larger intake ports would hurt low end torque(just above idle) more then exhaust ports. I would love to have K heads on my Jet boat but I would think they would have a negative result on the motor home climbing a steep hill with the Toyota in tow at low RPM.At higher RPM they would certainly enhance my headers and 3" exhaust system. The low duration cam I installed sure helped in climbing the mountains out here.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Cylinder Head Info [message #84828 is a reply to message #84823] |
Sun, 16 May 2010 11:22 |
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Matt Colie
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| Robert Mueller wrote on Sun, 16 May 2010 11:05 |
Matt,
Agree that bigger is better when it comes to valves, however, as I understand it that does not hold true with ports?
Too big and you loose velocity which can effect low end performance?
Old wives, er mechanics tale?
Regards,
Rob Mueller
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Rob,
That is completely true, but the practical matter is that the ports are limited buy the parts that they have to mate up to. So, if the ports meet the intake and exhaust manifold without a step (real Bozo No-No) then they can't be very much different than stock.
The valves are usually the choke point in most intake/exhaust systems. Even if the mathematical area of the open valve is equal to the port area, the flow is choked by the shape of the valve seat area.
Port design turns out to be much more important than just the size. Ports often want to be smaller even at high velocities, but this gets to be an engine specific design issue. With the 455, we are talking about an engine that is a little short of 1L per cylinder and is not balanced or lubricated to run much over 4KRev. For the ports to be oversize, I would bet that they would have to be big enough to loose a beer can (American) into the hole.
The torque peak is always at the crankshaft speed for best volumetric efficiency (best charge effectiveness). Above that you need all the air flow you can get because the ports are not handling the airflow (Duh, that's why the volumetric efficiency is tanking....).
If you want performance below the torque peak, yes, you might try to increase the velocity or at least the inertial in the intake runners (long runner manifolds like Dodge 318 @ 360 cir 1998), but then I have to ask why you don't downshift and run the engine closer to the torque peak where it is more efficient.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Cylinder Head Info [message #84830 is a reply to message #84823] |
Sun, 16 May 2010 11:35 |
powerjon
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Rob,
You are correct, the bigger valves and ports in this case ( a K Head)
are just fine on a motor that sees higher RPM than we typically we run
with. The smaller ports on the J head keep the air velocity up at the
lower rpm. A sightly larger valve would not hurt the J head, but big
ports and big valves really hurt us as we do not run the higher RPM's
(4500 to 5500) to take advantage of the larger runner cross section of
a K head and bigger valves.
J.R.
> Matt,
>
> Agree that bigger is better when it comes to valves, however, as I
> understand it that does not hold true with ports?
>
> Too big and you loose velocity which can effect low end performance?
>
> Old wives, er mechanics tale?
>
> Regards,
> Rob Mueller
> Sydney, Australia
> AUS '75 Avion-The Blue Streak TZE365V100428
> USA '75 Avion-Double Trouble TZE365V100426
>
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: [GMCnet] Cylinder Head Info [message #84833 is a reply to message #84828] |
Sun, 16 May 2010 12:00 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
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Down shifting and running close to the torque curve is in ones best interest which is what I always do. I am just saying this is not always possible heavily loaded in mountain terrain . There are times when it is in ones best interest to have as much air velocity coming into the cylinder as possible when at low RPM mostly coming out of a tight turn or starting from a stop on a steep grade. I can still remember the tough decision I made years ago when I had to decide whether to get the Chevy heads with F.I. valves or the truck heads for my small block "400" engine in my camper. I decided on the small valve truck heads as I was always towing an inboard boat or dirt bikes.Big valves are a good thing to have but in my opinion there are times when small valves are more desirable. If the coach is used mostly on relatively flat land or if one is not towing bigger valves most likely wouldn't hurt a thing.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Cylinder Head Info [message #84834 is a reply to message #84829] |
Sun, 16 May 2010 12:09 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
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Matt;
There is nothing wrong with this cam choice it is a high torque cam I got from Comp cams the lowest RPM range they had. It was the cam Dick Paterson said worked nicely with carburated engines.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Cylinder Head Info [message #84848 is a reply to message #84828] |
Sun, 16 May 2010 15:03 |
Dennis S
Messages: 3046
Registered: November 2005
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[quote
That is completely true, but the practical matter is that the ports are limited buy the parts that they have to mate up to. So, if the ports meet the intake and exhaust manifold without a step (real Bozo No-No) then they can't be very much different than stock.
snip snip
Matt [/quote]
Matt,
Not sure I am reading this correctly -- can you explain any further..
Also, doesn't the lift of the cam have some difference -- higher lift, more volume.
Thanks,
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Cylinder Head Info [message #84860 is a reply to message #84848] |
Sun, 16 May 2010 19:20 |
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Matt Colie
Messages: 8547
Registered: March 2007
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| Dennis Sexton wrote on Sun, 16 May 2010 16:03 |
| Quote: |
That is completely true, but the practical matter is that the ports are limited buy the parts that they have to mate up to. So, if the ports meet the intake and exhaust manifold without a step (real Bozo No-No) then they can't be very much different than stock.
snip snip
Matt
|
Matt,
Not sure I am reading this correctly -- can you explain any further..
Also, doesn't the lift of the cam have some difference -- higher lift, more volume.
Thanks,
Dennis
|
Ok, The explanation was less than complete.
First, in manufacturing automotive engines, there are limits to the useful variation because they need to have similar parts to keep the cost in line. If the K head ports were significantly different than the J, the intake and exhaust manifolds would also have to be different. If they were not, there would be an edge - properly called a port mismatch - that could dramatically reduce the effectiveness of the port. Hence, the ports of a K head can simply not be all that different.
Valves, now that is a different story. . . . You basically want all the valve size and opening both lift and duration that you can get and everything else is part of valve event timing. Problems are evident, Valve diameter is kind of limited by the bore size (you need at least two valves and a sparkplug in there), lift is inhibited by mechanical issues (and the piston being in the way sometimes) and duration can't be much different than the 90* of stroke without becoming counter productive.
Less than maximum lift an duration simply provide less peak power. Offsetting the valve events can take advantage of the inertia of the air flow, or prevent flow reversal issues - both of those are usually crankshaft speed related.
Example:
A 1" valve seat has a circular area of about 0.780 square inches.
A 1" valve only needs to open about 0.250" to equal that area.
That is what the math says. That is not the way air flows. If you open a valve more than the theoretical requirement, there will usually be an improvement in the air flow through the port because the has fewer turns to make. To get the charge or exhaust where it needs to be requires ports that work correctly as not all of the hole can actually be used if it is not designed correctly. Examples are bountiful, but I'm tired.
If this did not answer your question, please try and again and I will as well.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Cylinder Head Info [message #84864 is a reply to message #84860] |
Sun, 16 May 2010 19:36 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
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Professor Colie,
How great an effect does port misalignment have on engine performance in a
low revving engine like our GMC's?
How great does the misalignment have to be to effect it.
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Matt Colie
Sent: Monday, 17 May 2010 10:21 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Cylinder Head Info
That is completely true, but the practical matter is that the ports are
limited buy the parts that they have to mate up to. So, if the ports meet
the intake and exhaust manifold without a step (real Bozo No-No) then they
can't be very much different than stock.
Matt
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Cylinder Head Info [message #84868 is a reply to message #84860] |
Sun, 16 May 2010 19:49 |
Dennis S
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Registered: November 2005
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Matt
Thank you!
Great to have your experienced view and explanation of the technical
aspects.
Regards
Dennis Sexton
73 GMC
Germantown, TN
Sent from my iPhone
On May 16, 2010, at 7:20 PM, Matt Colie <mcolie@chartermi.net> wrote:
>
>
> Dennis Sexton wrote on Sun, 16 May 2010 16:03
>> Quote:
>>> That is completely true, but the practical matter is that the
>>> ports are limited buy the parts that they have to mate up to. So,
>>> if the ports meet the intake and exhaust manifold without a step
>>> (real Bozo No-No) then they can't be very much different than stock.
>>> snip snip
>>>
>>> Matt
>>
>>
>> Matt,
>>
>> Not sure I am reading this correctly -- can you explain any further..
>>
>> Also, doesn't the lift of the cam have some difference -- higher
>> lift, more volume.
>>
>> Thanks,
>> Dennis
>
> Ok, The explanation was less than complete.
>
> First, in manufacturing automotive engines, there are limits to the
> useful variation because they need to have similar parts to keep the
> cost in line. If the K head ports were significantly different than
> the J, the intake and exhaust manifolds would also have to be
> different. If they were not, there would be an edge - properly
> called a port mismatch - that could dramatically reduce the
> effectiveness of the port. Hence, the ports of a K head can simply
> not be all that different.
>
> Valves, now that is a different story. . . . You basically want all
> the valve size and opening both lift and duration that you can get
> and everything else is part of valve event timing. Problems are
> evident, Valve diameter is kind of limited by the bore size (you
> need at least two valves and a sparkplug in there), lift is
> inhibited by mechanical issues (and the piston being in the way
> sometimes) and duration can't be much different than the 90* of
> stroke without becoming counter productive.
>
> Less than maximum lift an duration simply provide less peak power.
> Offsetting the valve events can take advantage of the inertia of the
> air flow, or prevent flow reversal issues - both of those are
> usually crankshaft speed related.
>
> Example:
> A 1" valve seat has a circular area of about 0.780 square inches.
> A 1" valve only needs to open about 0.250" to equal that area.
> That is what the math says. That is not the way air flows. If you
> open a valve more than the theoretical requirement, there will
> usually be an improvement in the air flow through the port because
> the has fewer turns to make. To get the charge or exhaust where it
> needs to be requires ports that work correctly as not all of the
> hole can actually be used if it is not designed correctly. Examples
> are bountiful, but I'm tired.
>
> If this did not answer your question, please try and again and I
> will as well.
>
> Matt
>
>
> --
> Matt & Mary Colie
> '73 Glacier 23 Chaumiere (say show-me-air)
> SE Michigan - DTW 3.2/4R
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Cylinder Head Info [message #84885 is a reply to message #84864] |
Sun, 16 May 2010 22:00 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
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| Robert Mueller wrote on Sun, 16 May 2010 20:36 |
Professor Colie,
How great an effect does port misalignment have on engine performance in a low revving engine like our GMC's?
How great does the misalignment have to be to effect it.
Regards,
Rob Mueller
Sydney, Australia
|
Rob,
I would love to give you a solid answer to this, but this is very case/application specific.
This is a serious memory test and may be less than completely actuate, but the numbers here are pretty close to the values in the reports I wrote at the time.
On an SB 302 (aka 5.0 HO) we had on test to develop a new intake manifold, the tech had not checked the intake gasket alignment and it hung into the port by about 0.060 (1.5mm) along the inner edge (the narrow edge) and when that gasket was trimmed to the larger casting and the smaller filed to make a better match, torque picked up by 7% and peak HP by ~11%. This report was immediately challenged by the corporate client, and the experiment repeated with two other engines all with new castings and factory production parts. This was particularly annoying because fixing the DFU (design error) got more than the contract target and we had a very hard time getting paid for the work we did do.
Another case was an aftermarket manifold for SB Chevy 305. As the ports in the manifold were larger by about 0.040 (1mm) all around than the production head casting (in production at that time), the performance of the engine after a manifold swap only (we broke it in and did a three WOT pull as stock) was down about 7% from stock(Sorry - I do not recall the specifics of this one). The client came up with another pair of heads that were GM, but not a production part (bow tie maybe). Nearly the same combustion volume and valve size but with ports that matched within 0.010. This got him about a 7% improvement on stock. When we put the stock manifold on the larger port heads we back to sort of low from stock (IIRC a little low from peak torque(~5%), but in the noise low at peak horsepower).
The significance of these two cases is that I remember these out of several decades of independent dyno lab rat years.
Again, as I have said before, I am no expert on the 455 or 500 engines, but I would expect the same level of performance change.
An when you were doing all the Harvey work and trimming the intake gasket edges, I bet someone asked you if that time was well spent - Right?
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Cylinder Head Info [message #84912 is a reply to message #84907] |
Mon, 17 May 2010 08:06 |
Steven Ferguson
Messages: 3447
Registered: May 2006
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Great way to cut your mileage in two.
On Mon, May 17, 2010 at 5:53 AM, Matt Colie <mcolie@chartermi.net> wrote:
>
>
> Gary Casey wrote on Sun, 16 May 2010 15:09
>> There seems to be a lot of people who go to great lengths to get more power out the coach engine. Well.... assuming you are towing a vehicle, why not just get a radio control gizmo for the throttle, leave the engine running in the toad (in drive) and let the towed vehicle do its share. A LOT cheaper than getting another hundred or two hp out of the coach engine. A twin-engine coach - what could be cooler than that?
>> Gary, thinking about carrying my scooter on the back. hmm...
>> '73 23
>
> Sounds like something that railroads have been doing in one form or another for over a century. Doesn't mean it's a bad idea, just not new. Since many people have a towd that is about the same horsepower as the coach, this could be good.
>
> Matt
> --
> Matt & Mary Colie
> '73 Glacier 23 Chaumiere (say show-me-air)
> SE Michigan - DTW 3.2/4R
> _______________________________________________
> GMCnet mailing list
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--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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| Re: [GMCnet] Cylinder Head Info [message #84938 is a reply to message #84750] |
Mon, 17 May 2010 10:38 |
Gary Casey
Messages: 448
Registered: September 2009
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Sorry about the diversion from the thread. But, if the coach gets 9mpg by itself and maybe 10 with the towd engine running, and the towd gets 30 (after all, there will be no aero drag :-), then the combined fuel economy will be about 8. Not bad for having maybe twice the horsepower....
Gary
ubject: Re: [GMCnet] Cylinder Head Info
To: gmclist@temp.gmcnet.org
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<AANLkTill9ukd_8Gtg1EWDdAlSXhyG6jKzrdpkMtOUiKj@mail.gmail.com>
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Great way to cut your mileage in two.
On Mon, May 17, 2010 at 5:53 AM, Matt Colie <mcolie@chartermi.net> wrote:
>
>
> Gary Casey wrote on Sun, 16 May 2010 15:09
>> There seems to be a lot of people who go to great lengths to get more power out the coach engine. ? Well.... assuming you are towing a vehicle, why not just get a radio control gizmo for the throttle, leave the engine running in the toad (in drive) and let the towed vehicle do its share. ?A LOT cheaper than getting another hundred or two hp out of the coach engine. ?A twin-engine coach - what could be cooler than that?
>> Gary, thinking about carrying my scooter on the back. ?hmm...
>> '73 23
>
> Sounds like something that railroads have been doing in one form or another for over a century. ?Doesn't mean it's a bad idea, just not new. ?Since many people have a towd that is about the same horsepower as the coach, this could be good.
>
> Matt
> --
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