Hypothetical cam question...how would it run?

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travis
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Hypothetical cam question...how would it run?

Post by travis » Thu May 10, 2018 10:40 am

Totally hypothetical build at this point, but something I am very curious about.

Basic 8.5-1 smog era 350-ish size engine, smog heads with nothing more that a little port cleanup and a good valve job, basic stock iron or performer type dual plane, small tube full length headers with a decent exhaust system.

I’ve built a million engines like this...mild daily driver or utilitarian use vehicle stuff, using mostly comp cams 252-268 high energy (or similar from other companies), depending on gearing. For a 3.40 geared pickup I would normally use the 268. The result is always predictable, and they will run on cat pee if needed, even with an aggressive spark curve. DCR is in the very low 7’s. They run decent with little maintenance.

Now, change the 268 cam (218@.050, 110 lsa, 106 ica), with a custom ground 256@.006 cam, on a 104 lsa/100 ica...how does the characteristics change? Fuel economy, idle quality, power range, off idle throttle response, etc. Overlap at .006” is still 48*, but the ivc point happens 12* sooner (48 vs 60). Shorter, but harder hitting low end torque? Falls on its face at 4000 rpms? DCR increases to 7.5-7.6 range, so still should be no issues with pump fuel. What about idle vacuum?

I’m thinking an application like my buddies early 80’s ford van with a 351w and 2.75 gears could benefit from something like this, but then again this is well outside of any normal cam specs, so I dunno. If it was something magical then someone would offer something similar off the shelf.

Thoughts?

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Re: Hypothetical cam question...how would it run?

Post by mag2555 » Thu May 10, 2018 12:22 pm

You always ask these hypothetical questions, for Gods sakes buy a Cam stuff it in a motor and find out, Jez!!
Lol!

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Re: Hypothetical cam question...how would it run?

Post by travis » Thu May 10, 2018 1:21 pm

Actually...that is the plan :D The big question is...who can grind something like this? I’ve read that a 104 lsa is hard to grind without cutting thru the hardened area

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Re: Hypothetical cam question...how would it run?

Post by n2xlr8n » Thu May 10, 2018 1:25 pm

travis wrote:
Thu May 10, 2018 1:21 pm
Actually...that is the plan :D The big question is...who can grind something like this? I’ve read that a 104 lsa is hard to grind without cutting thru the hardened area
I'd start with CamKing.
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Re: Hypothetical cam question...how would it run?

Post by groberts101 » Thu May 10, 2018 8:05 pm

travis wrote:
Thu May 10, 2018 10:40 am
Totally hypothetical build at this point, but something I am very curious about.

Basic 8.5-1 smog era 350-ish size engine, smog heads with nothing more that a little port cleanup and a good valve job, basic stock iron or performer type dual plane, small tube full length headers with a decent exhaust system.

I’ve built a million engines like this...mild daily driver or utilitarian use vehicle stuff, using mostly comp cams 252-268 high energy (or similar from other companies), depending on gearing. For a 3.40 geared pickup I would normally use the 268. The result is always predictable, and they will run on cat pee if needed, even with an aggressive spark curve. DCR is in the very low 7’s. They run decent with little maintenance.

Now, change the 268 cam (218@.050, 110 lsa, 106 ica), with a custom ground 256@.006 cam, on a 104 lsa/100 ica...how does the characteristics change? Fuel economy, idle quality, power range, off idle throttle response, etc. Overlap at .006” is still 48*, but the ivc point happens 12* sooner (48 vs 60). Shorter, but harder hitting low end torque? Falls on its face at 4000 rpms? DCR increases to 7.5-7.6 range, so still should be no issues with pump fuel. What about idle vacuum?

I’m thinking an application like my buddies early 80’s ford van with a 351w and 2.75 gears could benefit from something like this, but then again this is well outside of any normal cam specs, so I dunno. If it was something magical then someone would offer something similar off the shelf.

Thoughts?
My thoughts are that you answered your own questions before even finishing them. :D

Higher idle vac.. very narrow but higher low rpm torque output due to lsa/icl.. make sure the collector is no larger than 2.5"(prime candidate for 2" collector choke).. yada yada yada.

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Re: Hypothetical cam question...how would it run?

Post by tresi » Thu May 10, 2018 11:17 pm

travis wrote:
Thu May 10, 2018 1:21 pm
Actually...that is the plan :D The big question is...who can grind something like this? I’ve read that a 104 lsa is hard to grind without cutting thru the hardened area
Really, I've seen 102 lsa white box cams for not a dime more. Not doubting this just want to know if anybody can confirm this.

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Re: Hypothetical cam question...how would it run?

Post by Geoff2 » Fri May 11, 2018 5:38 am

And the hypothetical answer is.....buy the cam & try it!! That is what engine builders DO.

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Re: Hypothetical cam question...how would it run?

Post by CamKing » Fri May 11, 2018 10:40 am

n2xlr8n wrote:
Thu May 10, 2018 1:25 pm
travis wrote:
Thu May 10, 2018 1:21 pm
Actually...that is the plan :D The big question is...who can grind something like this? I’ve read that a 104 lsa is hard to grind without cutting thru the hardened area
I'd start with CamKing.
We grind 104 LSA flat tappet cams, all the time for 2bbl circle track classes.
We used to grins a bunch of 104 LSA cams for the lower NASCAR classes, back when they ran 9:1 compression.
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jonescams@bellsouth.net
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(704)489-2449

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Re: Hypothetical cam question...how would it run?

Post by Headguy » Fri May 11, 2018 11:12 am

tresi wrote:
Thu May 10, 2018 11:17 pm
travis wrote:
Thu May 10, 2018 1:21 pm
Actually...that is the plan :D The big question is...who can grind something like this? I’ve read that a 104 lsa is hard to grind without cutting thru the hardened area
Really, I've seen 102 lsa white box cams for not a dime more. Not doubting this just want to know if anybody can confirm this.
I've used 101,102,103,104 lobe centers flat tappet and roller, with 95-97 intake centerlines. never heard it couldn't be done. But then again I wouldn't even try to run a cam under 220 that tight. Sounds like trouble.

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Re: Hypothetical cam question...how would it run?

Post by Walter R. Malik » Fri May 11, 2018 11:36 am

Headguy wrote:
Fri May 11, 2018 11:12 am

I've used 101,102,103,104 lobe centers flat tappet and roller, with 95-97 intake centerlines. never heard it couldn't be done. But then again I wouldn't even try to run a cam under 220 that tight. Sounds like trouble.
Bill Metzger at Lazer Cams, when he was still alive, offered what he called a "Street Rod" camshaft series for those enthusiasts not really interested in getting near max power but, wanted something different altogether; like bigger cam sound at idle which would smooth-out at part throttle, going down the highway.

I used many hydraulic flat tappet cams of his which were 210/215 @.050" ground on a 104 degree separation.

They did exactly what they were supposed to do.
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Re: Hypothetical cam question...how would it run?

Post by Headguy » Fri May 11, 2018 12:11 pm

Walter R. Malik wrote:
Fri May 11, 2018 11:36 am
Headguy wrote:
Fri May 11, 2018 11:12 am

I've used 101,102,103,104 lobe centers flat tappet and roller, with 95-97 intake centerlines. never heard it couldn't be done. But then again I wouldn't even try to run a cam under 220 that tight. Sounds like trouble.
Bill Metzger at Lazer Cams, when he was still alive, offered what he called a "Street Rod" camshaft series for those enthusiasts not really interested in getting near max power but, wanted something different altogether; like bigger cam sound at idle which would smooth-out at part throttle, going down the highway.

I used many hydraulic flat tappet cams of his which were 210/215 @.050" ground on a 104 degree separation.

They did exactly what they were supposed to do.
Run like an on/off switch? Lol

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Re: Hypothetical cam question...how would it run?

Post by GARY C » Fri May 11, 2018 1:24 pm

Walter R. Malik wrote:
Fri May 11, 2018 11:36 am
Headguy wrote:
Fri May 11, 2018 11:12 am

I've used 101,102,103,104 lobe centers flat tappet and roller, with 95-97 intake centerlines. never heard it couldn't be done. But then again I wouldn't even try to run a cam under 220 that tight. Sounds like trouble.
Bill Metzger at Lazer Cams, when he was still alive, offered what he called a "Street Rod" camshaft series for those enthusiasts not really interested in getting near max power but, wanted something different altogether; like bigger cam sound at idle which would smooth-out at part throttle, going down the highway.

I used many hydraulic flat tappet cams of his which were 210/215 @.050" ground on a 104 degree separation.

They did exactly what they were supposed to do.
Didn'y Jon run a 100 or less lsa 400m SBF in EMC... Won the deal if I remember correctly.

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Re: Hypothetical cam question...how would it run?

Post by RevTheory » Fri May 11, 2018 1:51 pm

Yeah, I think EMC has blown a hole in the on/off switch, "peaky" deal over the years. 98 LSA, 92 ICL. Maybe even 91 ICL: I'm too lazy to look :D

I like your idea, Travis, I'd just be concerned about a 48* ATDC IVC.

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Re: Hypothetical cam question...how would it run?

Post by GARY C » Fri May 11, 2018 1:57 pm

RevTheory wrote:
Fri May 11, 2018 1:51 pm
Yeah, I think EMC has blown a hole in the on/off switch, "peaky" deal over the years. 98 LSA, 92 ICL. Maybe even 91 ICL: I'm too lazy to look :D
I thought it was something like that I guess once you reach the rpm you need thats all that matters, in some forms of racing you may need it to hold on a little longer, sometimes that just takes a few more degrees of exhaust.

4000 rpm power band is not exactly peaky is it. :D

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Re: Hypothetical cam question...how would it run?

Post by Headguy » Fri May 11, 2018 2:08 pm

GARY C wrote:
Fri May 11, 2018 1:57 pm
RevTheory wrote:
Fri May 11, 2018 1:51 pm
Yeah, I think EMC has blown a hole in the on/off switch, "peaky" deal over the years. 98 LSA, 92 ICL. Maybe even 91 ICL: I'm too lazy to look :D
I thought it was something like that I guess once you reach the rpm you need thats all that matters, in some forms of racing you may need it to hold on a little longer, sometimes that just takes a few more degrees of exhaust.

4000 rpm power band is not exactly peaky is it. :D
EMC cams also weren't 210@.050

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