Author Topic: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general  (Read 1569 times)

0 Members and 1 Guest are viewing this topic.

Offline dave brode

  • Site Supporter
  • Full Member
  • *****
  • Posts: 161

With regard to: Cams with mid to upper 24X intake duration, 100 to 105* LSA

All,
 
I read opinion that the MVA exh port is too big. Assuming so, does that mean that these heads like no duration bias? Fwiw, Bob Wood preaches on the sin of extra exh duration, says that the early opening gives up low end.

I will note that I am going to use a small primary fatcat. No extra exh duration = stronger pulse to blow it through the pipe and create the wave? Extra duration = more time for the pulse to get through? Am I splitting hairs?

On LSA, I'm a car guy, and admit to being a Vizard groupie on LSA/valve dia vs compression ratio. It's about the correct amount of overlap to evacuate the chamber. A 2.120" is still small in a 60 cube cylinder. So, go tighter. Then again, the heads flow well, which means go a little wider.

I see big engines with mildish cams from 100 to 108* LSA that work well. The 120R and 120ST cams are both wide, but talking overlap, they are quite different [tells me that the 259E is too wide to be ideal].

I see this as a crap shoot, unless one is copying a known combo...

Cams aside, any head porters care to tell me what not to do to these, I'll surely appreciate it.

Thanks for any insight.
Dave


Offline dave brode

  • Site Supporter
  • Full Member
  • *****
  • Posts: 161
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #1 on: January 10, 2019, 02:02:51 PM »
RE: 120R style engine, flat tops, 10.4-1, maybe 10.5-1.


Edit: ***The thread's purpose is to help me understand theory/opinion shared on the MVA heads' exhaust port, and how it effects cam choices.  Opinion of how the three grinds would compare is welcome, as is opinion on how the 4* advance and 1.72s might do. ***

I have these in my collection, along with S&S 1.72-1 rollers. I ASSume that the MVAs would like the extra lift, at least on the intake.
[no need to mention geometry here]

I am not above buying something different, but I have issues with secret specs.....

I also have a +4 sprocket.....
I would be inclined on the Wood, for 96/104, and maybe the Crane for 99/109 [+5 is about my max]
Not with the Arsenal, they are already +4.

Bob Wood 888.
246/246, .575" [.610 ish at 1.72-1]
100/100 centers
.205"/.205" TDC
23/43 - 43/23 

Arsenal Racecraft [by Andrews]
248/252 - .610" [.645 at 1.72*]
101/109 centers
.213"/.178" TDC
23/45 - 55/17

Edel 1748 [Crane 296-2]
103/105 centers, .188" .193" TDC
246 254 - .619" [they use 1.65-1, so .645" at 1.72-1]
20/46 -  52/22
« Last Edit: January 10, 2019, 02:31:21 PM by dave brode »

Offline kd

  • Site Supporter
  • Full Member
  • *****
  • Posts: 6505
  • Country: ca
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #2 on: January 10, 2019, 02:49:46 PM »
When I spoke with Dan Baisley about mt MVA's (used with 660sm cams at 11.3:1) he told me that in his opinion they were pretty fine as is. I explained the engine would see plenty of high rpm (like every day  :hyst: ) but I wanted to be able to tour 2 up and loaded.  He said MVA's had poor exhaust ports (evo like) and he would be touching them up.  When I got them back with the spec sheet I found out he also changed the intakes for a different tulip profile and up sized the exhaust. My sheet (120 RGU) is in the dyno section and is an all around performer.

Here it is with 2 pipes.  I agree the cams are very different.  The Burns pipe is still in development to pick up the early torque.  Hope this helps.

  http://harleytechtalk.com/htt/index.php?topic=99409.0
KD

Offline HD Street Performance

  • Premium Vendor
  • Full Member
  • *****
  • Posts: 8990
  • Country: 00
    • HD Street Performance
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #3 on: January 10, 2019, 03:15:59 PM »
The exhaust port shape leaves a lot to be desired. There is a 152hp 117 in the dyno section. That port was welded. Have also upsized the valves to 1.65 or 1.7 depending on the compression,  motor size and pipe sizing.

Offline ndmp40

  • Full Member
  • Posts: 1002
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #4 on: January 10, 2019, 04:50:38 PM »
Those heads like a wider LSA, little to no bias on the exhaust duration, and lower overlap.  They can make excellent power, the ports and valves are no way too big for a 120 " engine.

Offline dave brode

  • Site Supporter
  • Full Member
  • *****
  • Posts: 161
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #5 on: January 10, 2019, 08:39:48 PM »
Thanks, Gents,

Don [HDSP],
I've seen several opinions that the exh port needs welded, ain't going there.  I'll read at the dyno runs forum. [I have not]

KD,
Danged impressive! I wonder how much of a cut it took Dan to get to 89cc? A quick look at my trusty Moroso slide chart says 10cc more would be a hair over 10.3-1 [at your .030" quench distance that I like!]. I'll look to see if I can find out how your 660SMs compare to the current 660s.

ndmp40,
 Thanks for the insight, that is what I was looking for.

Dave

Offline kd

  • Site Supporter
  • Full Member
  • *****
  • Posts: 6505
  • Country: ca
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #6 on: January 10, 2019, 09:29:53 PM »
Thanks, Gents,

Don [HDSP],
I've seen several opinions that the exh port needs welded, ain't going there.  I'll read at the dyno runs forum. [I have not]

KD,
Danged impressive! I wonder how much of a cut it took Dan to get to 89cc? A quick look at my trusty Moroso slide chart says 10cc more would be a hair over 10.3-1 [at your .030" quench distance that I like!]. I'll look to see if I can find out how your 660SMs compare to the current 660s.

ndmp40,
 Thanks for the insight, that is what I was looking for.

Dave



Dave, I looked at the sheet and they were 89cc  with the front cut @ .051 and rear @ .046.  The pistons were both .003 out of the hole with .020 base gaskets.  I wafered another .003  of Vellum cotton (rag) paper with aviation sealant to give zero deck.  Compression was set at 11.13
KD

Offline dave brode

  • Site Supporter
  • Full Member
  • *****
  • Posts: 161
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #7 on: January 10, 2019, 10:01:56 PM »
Thanks, KD

I would have bet that it would have taken a way bigger cut. I would guess 7-8 thou per cc? Yours must have been mid 90s. Maybe mine will be as small?
Dave
 


Offline HD Street Performance

  • Premium Vendor
  • Full Member
  • *****
  • Posts: 8990
  • Country: 00
    • HD Street Performance
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #8 on: January 11, 2019, 05:27:28 AM »
They are 95cc nominal before chamber or valve work. Cut .025 from the factory

Offline kd

  • Site Supporter
  • Full Member
  • *****
  • Posts: 6505
  • Country: ca
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #9 on: January 11, 2019, 06:54:09 AM »
Don, are you saying the MVA's are already cut .025 from the comparable 110 OEM format head? 

FWIW the .046 to .051 cut to my heads meant I had to sand off about .010 to .020 from the manifold for a comfortable fit.  I may not have needed to do it but I felt it gave me security it knowing there was at least some air gap for the seal to compress into. The manifold did actually still make it into position without the massage.
KD

Offline HD Street Performance

  • Premium Vendor
  • Full Member
  • *****
  • Posts: 8990
  • Country: 00
    • HD Street Performance
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #10 on: January 11, 2019, 07:31:13 AM »
Yes they are. 3.725" height out of the box last set I had here. So are the 110+ head which is the origin casting for the MVA

Offline dave brode

  • Site Supporter
  • Full Member
  • *****
  • Posts: 161
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #11 on: January 11, 2019, 07:44:43 AM »
Don,

I have read that the MVAs often a few over 95cc. I'll check mine out in the coming week. Understood on the -.025". I remember the old bathtub SEs were -.050". Plays hell on piston to valve at the outside....

kd,

I had to do the same intake fitting on the G intake on my 117" dyna years ago. I welded and re-drilled the flanges' upper hole shut and rolled them uphill to allow taking the extra mat'l [1.800", iirc] out of the roof on the bathtub SE heads. 2.02"/1.60", blah blah blah....   


Timing evens aside, anyone care to give thoughts on .640-.650" lift vs 600-.610" on the MVAs? It seems the HD feels that the MVAs like lift with the SE266s.  Lots of T-man 660and 662s and S&S640s matched to MVAs out there.  Even a Wood 400 or 408 or two [eek].

Increase intake lift only via 1.72-1s? I understand the mechanical effects of the ratio increase. No killer Bob Wood or Lieneweber lobes here.

Dave
p.s. - I welcome any PMs, which will be held in strict confidentiality.   

Offline HD Street Performance

  • Premium Vendor
  • Full Member
  • *****
  • Posts: 8990
  • Country: 00
    • HD Street Performance
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #12 on: January 11, 2019, 09:21:45 AM »
Harley transfers the geometry to the intake flanges when they produced the old SE Performance heads and the Compressor heads. I haven't measured the mva heads flanges but .025 is a non-issue.

Offline HD Street Performance

  • Premium Vendor
  • Full Member
  • *****
  • Posts: 8990
  • Country: 00
    • HD Street Performance
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #13 on: January 11, 2019, 09:25:23 AM »
Not sexy but the se259e would work great with added lift and compression set at 10.8

Offline speedzter

  • Full Member
  • Posts: 605
  • Country: au
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #14 on: January 11, 2019, 04:58:23 PM »
Yes, I ran a TW8 at 10.6:1 in my current 120(110+ head) build.
Worked well from the bottom end right to the top, just too noisy !

Offline dave brode

  • Site Supporter
  • Full Member
  • *****
  • Posts: 161
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #15 on: January 11, 2019, 07:32:29 PM »
Don,
 It seems that some head cleanup, a head cut and tight quench would wake the 120ST right up. I certainly would try them if I had a 120ST and the cams.   I need to study the dyno runs to see if there are any so equipped.

I like the 259s, but it always seemed odd to me that they came out with them, as they are just a tick bigger than, but so similar to the 251s.

LSA, 

speedster,

I had TW8s in a 95", and later TW9Bs in the same bike at 117". I really hate that noise.

Offline HD Street Performance

  • Premium Vendor
  • Full Member
  • *****
  • Posts: 8990
  • Country: 00
    • HD Street Performance
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #16 on: January 12, 2019, 05:25:28 AM »
Let's go back a minute and review for the purpose of focus..
The motor is a 120 cu in, 5/8 stroke, short (5.575) rod, carbureted, compression TBD based on the cam intake close, I assume
Pipe has 1.75 OD primarys and a 2.?? baffle
Heads flow ~315 / ~200
Carburetor and intake TBD

Now that we got that out of the way what is it you expect to get out of this build?
From past experience I can tell you that anywhere from 120-150 horsepower is achievable. Torque is a consideration with a loaded bagger. So is heat and octane. Payload and typical use are factors. The other you touched on is tolerance for valvetrain noise. How long do you expect this build to stay fresh between rebuilds? The top 7% of that horsepower range is expensive to achieve and complicated by a carburetor VS EFI. From 120-135hp the cost will be about the same and you will just be swapping cam size and adding compression. Then there is the wild card, the carb. This one element becomes the constraint albeit I have helped with a few 124" motors that did achieve 150hp, Woods & Williams / CV51, while still retaining streetability. Not your cross country or Sturgis traffic bagger however.

So the thread reads as a "best cam" when it should really be a "the best fit cam to meet my expectations based on using the parts I already bring to the table" My assumption is, again, that you won't be changing a lot of the hardware already acquired. The software out there will get you close and provide comparisons.

Consider what I am proposing rather than a line by line analysis. Tell us where you want to be and I can zero in a little closer. Also consider this is not a good brand VS another study either. I work for some dealers that insist on Harley cams and in some cases they work great. The motor combination meeting the owners expectations including and especially the budget considered.

Thoughts?




Offline rigidthumper

  • Administrator
  • Full Member
  • *****
  • Posts: 4869
  • Country: us
  • Buying a scalpel, don't make you a surgeon.
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #17 on: January 12, 2019, 05:51:17 AM »
"I like the 259s, but it always seemed odd to me that they came out with them, as they are just a tick bigger than, but so similar to the 251s. "

Guy from the SE dept told me they were carb vs EFI versions of the same cam, like the 203 (EFI) & 204 (carb). I always thought either the 251 or the 259 were right up there with the W8, as far as being noisy.

Just curious, what are the goals of this build? I did a 120 build with ported 110 heads and a T-Man 662-1 cam, and played with the baffle in the boarzilla when I had it on the drum.
Edit: added sheet
« Last Edit: January 12, 2019, 08:45:54 AM by rigidthumper »

Offline dave brode

  • Site Supporter
  • Full Member
  • *****
  • Posts: 161
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #18 on: January 12, 2019, 06:57:55 AM »
I thank you both.

This thread is not a pick best cam, although me listing my inventory does say that it is. It's a let's talk about the subject so "we" can better understand what the heads like and dislike. I like when the little light bulb goes off. 

On 251 vs 259s and cams in general: I never thought about efi vs carb'd. Makes sense. I'd love to see a back to back on both on either engine. It seems to me that the MoCo moves every grind around to find the best spot. I see everything from -1 to +7* or more on lobe centers.

I wonder how many here have even "degreed" the cams [I admit that I have not]. I recall a thread by Blackhills Ken, in which he stated that he had to move a certain cam 4* to put it in at the specs stated. Then again, one should not forget Doug Coffey's sermon on comparing asymmetrical lobes vs symmetrical. We rode up there and visited him and Jo, I hope that they are well....

Goals: Moderate on cranking psi, 130 square would be great, or a little more to the left side. I am realistic, as the little pipe fatcat will probably hurt the right side. [starts out at 1.625"]

Carb? I doubt that I'll be willing to spend the money on a 51, esp from Bob. He did my 44, but I see the 48 mik as a better value for this. The one that I had on my 117 worked great imo. Kinda like a QJ vs 4150 dp.
Dave
« Last Edit: January 12, 2019, 07:06:28 AM by dave brode »

Offline HD Street Performance

  • Premium Vendor
  • Full Member
  • *****
  • Posts: 8990
  • Country: 00
    • HD Street Performance
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #19 on: January 12, 2019, 07:20:03 AM »
OK now consider the heads CSA and engine demand. Many of the builds that lay flat after 5k are experiencing reversion. Others lack of airflow or combinations of both.
My point is the decision of LSA, LC, and timing needed to meet the goal heavily weighs on the airflow potential and sizing of all the components. The wave tuning you alluded to is nothing more than a nuance. There isn't any going on on the intake side and with the best of pipes a cam with added duration bias will actually create the improper handling of the overlap event.

Offline dave brode

  • Site Supporter
  • Full Member
  • *****
  • Posts: 161
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #20 on: January 12, 2019, 08:44:51 AM »
Veering off on however related to the cam timing issue of reversion:

I see these things as being much more fickle than a V-8. Due to odd firing order? Short shared inlet manifold?

My 117 with TW9Bs did not like a propipe at all. Big peak torque, but huge dip in the middle, peak horse not impressive. Tried various baffles to no avail. KW 2" stock dyna looking 2 into 2s, big fat curve, but like a light switch, stand off 12" out of the carb at 5750. Swapped in higher flowing baffles and cut 1" off of the tapered ends. Next day, no stand-off to 6400. Gained 3 horse, lost 3 lbs, still lovely fat curve. It also liked a boarzilla. Less peak horse  than the KWs, but more T. Kept it.

rigidthumper,

That's a bad mofo you had there. I wonder if treating that big 'zilla muffler like a terminator box might work better than just baffle removal. Bell mouthed inlet, plate at the end, trying various size outlet pipes? http://www.superchevy.com/how-to/exhaust/0505phr-exh/

Dave
 

Offline 1FSTRK

  • Full Member
  • Posts: 8253
  • Country: 00
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #21 on: January 12, 2019, 09:31:35 AM »


My 117 with TW9Bs did not like a propipe at all. Big peak torque, but huge dip in the middle, peak horse not impressive. Tried various baffles to no avail. KW 2" stock dyna looking 2 into 2s, big fat curve, but like a light switch, stand off 12" out of the carb at 5750. Swapped in higher flowing baffles and cut 1" off of the tapered ends. Next day, no stand-off to 6400. Gained 3 horse, lost 3 lbs, still lovely fat curve. It also liked a boarzilla. Less peak horse  than the KWs, but more T. Kept it.

Dave

Great post Dave, it is a great example of how these HD's work as apposed to how the "academics" think they will work. You can read and write all day on the internet about engine design and particularly other engines and how their info applies to the  HD's design but most of it means very little when you go into the dyno cell with a running HD engine. There is nothing like the puzzled look of a automotive or 2 stroke expert when their super high performance designed HD prototype comes up short on the dyno.
"Never hang on to a mistake just because you spent time or money making it."

Offline Admiral Akbar

  • Past Poster
  • Full Member
  • Posts: 24093
  • Country: tr
  • Not Admin
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #22 on: January 12, 2019, 10:20:03 AM »


My 117 with TW9Bs did not like a propipe at all. Big peak torque, but huge dip in the middle, peak horse not impressive. Tried various baffles to no avail. KW 2" stock dyna looking 2 into 2s, big fat curve, but like a light switch, stand off 12" out of the carb at 5750. Swapped in higher flowing baffles and cut 1" off of the tapered ends. Next day, no stand-off to 6400. Gained 3 horse, lost 3 lbs, still lovely fat curve. It also liked a boarzilla. Less peak horse  than the KWs, but more T. Kept it.

Dave

Great post Dave, it is a great example of how these HD's work as apposed to how the "academics" think they will work. You can read and write all day on the internet about engine design and particularly other engines and how their info applies to the  HD's design but most of it means very little when you go into the dyno cell with a running HD engine. There is nothing like the puzzled look of a automotive or 2 stroke expert when their super high performance designed HD prototype comes up short on the dyno.

Why do you spout out this ridiculous crap?
24036 useless posts, 1 good one and 28 deleted by admin.

Offline 1FSTRK

  • Full Member
  • Posts: 8253
  • Country: 00
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #23 on: January 12, 2019, 10:39:35 AM »


My 117 with TW9Bs did not like a propipe at all. Big peak torque, but huge dip in the middle, peak horse not impressive. Tried various baffles to no avail. KW 2" stock dyna looking 2 into 2s, big fat curve, but like a light switch, stand off 12" out of the carb at 5750. Swapped in higher flowing baffles and cut 1" off of the tapered ends. Next day, no stand-off to 6400. Gained 3 horse, lost 3 lbs, still lovely fat curve. It also liked a boarzilla. Less peak horse  than the KWs, but more T. Kept it.

Dave

Great post Dave, it is a great example of how these HD's work as apposed to how the "academics" think they will work. You can read and write all day on the internet about engine design and particularly other engines and how their info applies to the  HD's design but most of it means very little when you go into the dyno cell with a running HD engine. There is nothing like the puzzled look of a automotive or 2 stroke expert when their super high performance designed HD prototype comes up short on the dyno.

Why do you spout out this ridiculous crap?

Speak of the devil and he appears.
How ya been?

I do not think Dave's post was crap and I agree with his post of actual findings over a lot of the theoretical posting above it.
« Last Edit: January 12, 2019, 10:43:50 AM by 1FSTRK »
"Never hang on to a mistake just because you spent time or money making it."

Offline dave brode

  • Site Supporter
  • Full Member
  • *****
  • Posts: 161
Re: Cam duration bias and L/Cs for MVA heads on a mild 120 - MVAs in general
« Reply #24 on: January 12, 2019, 10:56:04 AM »

1FSTRK,

I can't disagree with any of the theory/academics above. It's just that these odd machines sometimes defy all logic.

Admiral,

I hope that you and yours are well.

DB
oldguytalkingaboutabikehehad15yrsago