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Mild 390 build advice

  #46  
Old 12-08-2018, 07:49 PM
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Originally Posted by MIKES 68 F100 View Post
460 jared shoot me all the specs of your build , I'll run it on Desktop Dyno 5 to ball park what numbers for HP/TQ
thanks a bunch for running those numbersand sharing your exhaust clip. Very kind of you to take the time to do that. Maybe itís just me but I hear some lope at idle, sounds good. Iím surprised the basic operating range for the 256/262 cam is 1000-5300, but my peak horsepower was coming in at 4000.
 
  #47  
Old 12-08-2018, 10:59 PM
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Originally Posted by the_hetz View Post
I edited my post above to say *aftermarket* instead of *forged* which is what I actually meant. Thanks for pointing that out. The point I was trying to make is that there are many decisions where "a little more money spent is good insurance" and that it can add up to a cost that is no longer marginal over the course of a project.

My math is solid and not made up; I'm not sure what you have against it. Let me explain: I showed rough ranges for both a 10 cc piston with a 68 cc to 72 cc head (approx 9.7 to 10.1) and similar ranges for a 19 cc piston with a 68 cc to 72 cc head (approx 9 to 9.4). The 4 cc of head difference is neither insignificant, nor is it "only 1/10 of a point of compression" in either case. It could be enough to make or break the build. You may have had chambers at the high end or even above the 'spec' while his may be at the low end. Without measuring, play safe. In a mild build, play safe.

By the way, a 4 cc difference in head volume actually WILL affect the compression more significantly with a 10 cc piston than a 20 cc piston, but not much. This is not a point that I was trying to make before as it doesn't really become significant within reasonable bounds, but you seem to have brought it up. Change in cc is not a linear relationship with compression ratio.

Please be specific about my spelling errors and I can correct them. I do what I can to proofread, but there is a diminishing return on time spent trying to catch every single thing, especially on a cellphone. I did not "chastise" you; I questioned whether you did the math because the "1/10 of a point" claim was solid evidence that you had not.

Regarding the cams: NO, I have not run either, nor have I claimed to. I did not say the 272 was a big cam, I only pointed out that it was slightly wider than what he has chosen and is therefore a step in the right direction. This, combined with other variables (such as actual head volume) may be enough to make or break things. That is the point I'm trying to make. A 290 cam will allow a LOT more pressure to bleed off on the compression stroke which again could make the build work. Dropping this down to a 256 or even 262 is HUGE difference and makes it an apples/oranges comparison.

What did you use for intakes? How aggressive were the ramps on that 290 cam? A 290 cam with similar .050" specs to the ones at hand would be a pretty sluggish ramp/old design/not efficient. If it had big .050" specs then it is no longer mild (I noticed that you didn't claim the 290 to be 'smooth as silk'). All of these things affect cylinder filling and therefore pressure and therefore detonation characteristics.

What did your timing end up being through the RPM range and was it optimized for an old school, slow burn head?
The 290 cam had the same lope the 272 did. And the variance you claim well "make or break a build" certainly will do no such thing. It will simply behave slightly differently. You keep quoting exact specs and make assumptions from that, and that these slight differences somehow "kill" the performance (make or break ) They do nothing of the sort. You would have to do extensive dyno runs on all these variances to find the difference, you wouldn't feel them. If you want to run a lo-po, low compression engine, go ahead. That's what you'll get with low compression and small cams, sure you can pep them up some with a wider LSA cam, but the HP/TQ numbers will suffer vs using more compression and a larger cam better suited to a larger engine. As for the 4 cc difference, again, you forget that is the normal casting variance the the factory cylinder heads here, and if what you claim is true, then why did the factories allow this is performance suffered from it ? Once again, this variance is something where only extensive dyno sessions would reveal the true difference. You're good here at posting lengthly "facts" in trying to make yourself look smarter than others here. I see something different in why you're doing this. I'm posting real world experience here, you're constantly putting it down with specs you've never applied to an engine. There are thousands of possible combinations of parts you can use that do actually work in the real world. There are only a few that produce duds.
 
  #48  
Old 12-09-2018, 07:44 AM
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Originally Posted by baddad457 View Post
The 290 cam had the same lope the 272 did. And the variance you claim well "make or break a build" certainly will do no such thing. It will simply behave slightly differently. You keep quoting exact specs and make assumptions from that, and that these slight differences somehow "kill" the performance (make or break ) They do nothing of the sort. You would have to do extensive dyno runs on all these variances to find the difference, you wouldn't feel them. If you want to run a lo-po, low compression engine, go ahead. That's what you'll get with low compression and small cams, sure you can pep them up some with a wider LSA cam, but the HP/TQ numbers will suffer vs using more compression and a larger cam better suited to a larger engine. As for the 4 cc difference, again, you forget that is the normal casting variance the the factory cylinder heads here, and if what you claim is true, then why did the factories allow this is performance suffered from it ? Once again, this variance is something where only extensive dyno sessions would reveal the true difference. You're good here at posting lengthly "facts" in trying to make yourself look smarter than others here. I see something different in why you're doing this. I'm posting real world experience here, you're constantly putting it down with specs you've never applied to an engine. There are thousands of possible combinations of parts you can use that do actually work in the real world. There are only a few that produce duds.
I'm raising concern about using a tiny cam with 10:1+ compression, not "trying to look smart." You just said yourself to use higher compression AND a larger cam suited to a higher engine. The lunati cam "chosen" is not large by any stretch of the imagination. IIRC it's the second smallest in that line.

A 9:1 to 9.5:1 engine is not a low comp turd, especially with old head designs and a heavy vehicle which we want to run on pump gas reliably.

You also just said that the variances will "make it behave differently" but also that you'd "have to use a dyno to find out." I'm talking about detonation risk, not some tangible performance change. 10:1+ with a very small cam puts you at unnecessary risk for what the extra compression will give you on gains. That is great that it has worked for you and others, but I do not agree that it is sound advice for someone less experienced.

For crying out loud, you can watch dozens upon dozens of Survival dyno videos with the compression and cam specs posted. Don't you think that if this combination were such a good idea, the pros would be doing it?

You have spelling errors, btw.

Edit:

The factory allows tolerance because they have cars to build. You can throw things together pretty sloppily at what figures out to about 7.8:1 compression.

A wide LSA does not give you more pep. Pep comes from a tight LSA and torque peak. Wide LSA gives you a nice idle, wider curve, and tends to mitigate detonation risk when installed at the common +4* spec.

They say the tight LSA tends to give you more advantage the bigger the engines needs grow in comparison to head flow, as I recall. This makes logical sense to me.
 
  #49  
Old 12-09-2018, 12:39 PM
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you are welcome
I built my engine before Getting DD5 . I was bouncing back and forth between the 256/262 & 262/268 .
be sure to post what you end up with and if you have it Dynoed please post results , I like to see how accurate DD5 is to the real thing .
 
  #50  
Old 12-09-2018, 12:48 PM
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Originally Posted by the_hetz View Post


I'm raising concern about using a tiny cam with 10:1+ compression, not "trying to look smart." You just said yourself to use higher compression AND a larger cam suited to a higher engine. The lunati cam "chosen" is not large by any stretch of the imagination. IIRC it's the second smallest in that line.

A 9:1 to 9.5:1 engine is not a low comp turd, especially with old head designs and a heavy vehicle which we want to run on pump gas reliably.
Here you go again, spouting BS about "old head designs" Those designs are still used successfully today.
You also just said that the variances will "make it behave differently" but also that you'd "have to use a dyno to find out." I'm talking about detonation risk, not some tangible performance change. 10:1+ with a very small cam puts you at unnecessary risk for what the extra compression will give you on gains. That is great that it has worked for you and others, but I do not agree that it is sound advice for someone less experienced.
I never recommended using a small cam on a 10 to 1 motor. You made that assumption.
For crying out loud, you can watch dozens upon dozens of Survival dyno videos with the compression and cam specs posted. Don't you think that if this combination were such a good idea, the pros would be doing it?
I don't have time to watch Boob Tube all day.
You have spelling errors, btw.
Congrats on spotting them.
Edit:

The factory allows tolerance because they have cars to build. You can throw things together pretty sloppily at what figures out to about 7.8:1 compression.
Who recommended an engine with those specs here ?
A wide LSA does not give you more pep. Pep comes from a tight LSA and torque peak. Wide LSA gives you a nice idle, wider curve, and tends to mitigate detonation risk when installed at the common +4* spec.
Once again, you don't know squat here. A wide LSA in a cam profile has less overlap. You don't understand what LSA is. You're 180* off here.
They say the tight LSA tends to give you more advantage the bigger the engines needs grow in comparison to head flow, as I recall. This makes logical sense to me.
They say ? Who's "they" ?
 
  #51  
Old 12-09-2018, 02:28 PM
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Originally Posted by baddad457 View Post
They say ? Who's "they" ?

Who today is using a non-fast burn, iron head design at today's compression ratios?

Again, the Lunati cam you speak in support of IS A SMALL CAM.

You seem to have time to respond back to these posts, but don't have time to do any actual math or research.

Thanks for the congratulations. Please show me mine and I will share the congratulations.

I didn't recommend an engine with those specs, nor did I claim anyone else did. The factory compression of calculated with the standard "stock" rebuild parts will land <8:1.

Regarding the LSA...I'm not sure I know where to start on that one.

"They"...not sure who they are. Maybe it's all that research I use the internet for...maybe even some books. You know, when I'm not too busy on the boob tube and responding to people on this forum.

Ultimately, I think you have proven the value of your advice. Have a nice day.
 
  #52  
Old 12-09-2018, 02:35 PM
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Originally Posted by the_hetz View Post



Who today is using a non-fast burn, iron head design at today's compression ratios?
Probably 90% of the guys running FE's
Again, the Lunati cam you speak in support of IS A SMALL CAM. I never recommended a Lunati cam here or anywhere else. Get your facts straight.
You seem to have time to respond back to these posts, but don't have time to do any actual math or research.
I don't need to. I'm going on actually experience.
Thanks for the congratulations. Please show me mine and I will share the congratulations.

I didn't recommend an engine with those specs, nor did I claim anyone else did. The factory compression of calculated with the standard "stock" rebuild parts will land <8:1.
You mentioned it in your last post. If you end up with that ratio, you ordered the wrong parts.
Regarding the LSA...I'm not sure I know where to start on that one.
Yea, we know. What is "LSA" anyway ?
"They"...not sure who they are. Maybe it's all that research I use the internet for...maybe even some books. You know, when I'm not too busy on the boob tube and responding to people on this forum.

Ultimately, I think you have proven the value of your advice. Have a nice day.
You know what they say about stuff posted on the net.
 
  #53  
Old 12-09-2018, 03:59 PM
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Originally Posted by baddad457 View Post
You know what they say about stuff posted on the net.
What I meant was, "what manufacturer?" Obviously any one can slap something together with old parts, claim they have 10:1, and start saying it will work without considering that they may be on the lucky side or do not have an optimum time.

I spoke out against a cam that small (the Lunati) with compression that high. You seemed to be speaking in favor of the combination where I am trying to warn that 10:1 is very high for that cam. You did not directly recommend the cam, no, but you did inherently (to me). The original poster "picked" the cam and that is what I am concerned with. I have been trying to say, figuratively, "please do not support this choice of cam and compression without warning that it is on the edge." That is it. Instead, you said "forged pistons are good insurance." I do not necessarily disagree with that but there are smarter, cheaper, more reliable, and more tunable methods to roll with. Among these would be a bigger cam and lower compression. I think it is wise to properly warn someone and/or recommend something much safer when they are investing this kind of money.

So, you have experience. So do I. More so do the pros that show very lucid cam and compression specs regarding their builds which they sell to customers (often with hyper/cast pistons). Having experience is hardly a reason to speak against research; there is always more to learn.

The stock "truck" parts have very low compression. That is how they were built. Are you arguing that fact or telling me that I somehow recommended a build like this by stating the fact?

Wide LSA improves idle and vacuum. Tight LSA gives you a higher torque peak and pulls better within its power band. Wide LSA gives you a wider torque curve/power band. Wider LSA inherently comes with a later intake closing point due to the propensity for cams to have 4-6* standard advance ground in. Tight LSA is good, especially on "under sized heads" but you must of course watch the intake closing point and consider the effective compression and balance these things with idle quality and vacuum. I did not say anything counter to this above and these are facts you can find in many places if you just try.

What do they say about the internet?

Apologies to the original poster. I've tried to respectfully warn and have been stating facts. Apparently this is in favor of me "looking smart" by being able to do math and attempt to spell correctly rather than trying to be helpful.

 
  #54  
Old 12-09-2018, 10:53 PM
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Originally Posted by the_hetz View Post


What I meant was, "what manufacturer?" Obviously any one can slap something together with old parts, claim they have 10:1, and start saying it will work without considering that they may be on the lucky side or do not have an optimum time.

I spoke out against a cam that small (the Lunati) with compression that high. You seemed to be speaking in favor of the combination where I am trying to warn that 10:1 is very high for that cam. You did not directly recommend the cam, no, but you did inherently (to me). Never said any such thing. Once again, you're making assumptions here.
So, you have experience. So do I. More so do the pros that show very lucid cam and compression specs regarding their builds which they sell to customers (often with hyper/cast pistons). Having experience is hardly a reason to speak against research; there is always more to learn.

The stock "truck" parts have very low compression. That is how they were built. Are you arguing that fact or telling me that I somehow recommended a build like this by stating the fact?
You're arguing with yourself. You went off on this on your own.
Wide LSA improves idle and vacuum. Tight LSA gives you a higher torque peak and pulls better within its power band. Wide LSA gives you a wider torque curve/power band. Wider LSA inherently comes with a later intake closing point due to the propensity for cams to have 4-6* standard advance ground in. Tight LSA is good, especially on "under sized heads" but you must of course watch the intake closing point and consider the effective compression and balance these things with idle quality and vacuum. I did not say anything counter to this above and these are facts you can find in many places if you just try.
Gee, you do know something about LSA, except for this BS about intake closing points, that seems to be your pet thing everywhere. And you're making another assumption associating wide LSA's and closing points. One narrow LSA cam could have the same closing point as a wide one. They're not all the same. A wider LSA generally has a wider powerband, which is better for overall performance. The cams and compression I recommended also have wide powerbands despite what you assume. And they're quite tame despite what you also assume. I know, I've run them.
What do they say about the internet?

Apologies to the original poster. I've tried to respectfully warn and have been stating facts. Apparently this is in favor of me "looking smart" by being able to do math and attempt to spell correctly rather than trying to be helpful.

You know you're really good at reading things into what other have posted. Nothing you said I recommended happened. If you can't dazzle with brilliance, baffle em with B.S. Seems your favorite thing is intake closing point, with nothing in the real world to back that up. You have no idea what each ad every cam made it ground as far as advance/retard. Only way to truly know that is to have installed and degreed each and every one. Then run them to see the results. Then there's those pesky "undersized heads" FE's were never cursed with those. FT's were, FE's ? No.
 
  #55  
Old Yesterday, 07:24 AM
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Originally Posted by baddad457 View Post
You know you're really good at reading things into what other have posted. Nothing you said I recommended happened. If you can't dazzle with brilliance, baffle em with B.S. Seems your favorite thing is intake closing point, with nothing in the real world to back that up. You have no idea what each ad every cam made it ground as far as advance/retard. Only way to truly know that is to have installed and degreed each and every one. Then run them to see the results. Then there's those pesky "undersized heads" FE's were never cursed with those. FT's were, FE's ? No.
I'm guilty of reading into things and you are not. You can definitely hold yourself to a higher standard than I can myself.

There is nothing in the real world to back up any relevance to intake closing point. I don't even know if it exists...seems to be some mythical dragon.

There is no relevance to the specs the cam manufacturers give you and buying a cam is a total crap shoot because of this.

FE heads are Godsend and will continue to deliver what you need as the build gets hotter and hotter. This must be why they don't make any decent aftermarket heads and nobody would buy them.

There. We are on the same page. You realize I continued to address specific things you say, yet you seem to continue a dance to get further from the point? Are you just trolling? You don't seem to add much value or understand what you are talking about. Are you just trying to look smart? You're not very good at it.

FWIW had more spelling errors.
 
  #56  
Old Yesterday, 08:49 AM
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Since you two are the only ones arguing, take this to PMs or just stop it already. It's serving no purpose to the original poster.
 
  #57  
Old Yesterday, 10:20 AM
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Amen Krewat !
 
  #58  
Old Yesterday, 11:29 AM
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Originally Posted by Krewat View Post
Since you two are the only ones arguing, take this to PMs or just stop it already. It's serving no purpose to the original poster.
I agree with you fully and apologize for delving into such nonsense.
 
  #59  
Old Yesterday, 06:14 PM
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video was on a cold California Morning about 40f
like i said before if I had to do again i would opt for the 262/268 added hp/tq and a little more lope
 
  #60  
Old Yesterday, 06:55 PM
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Originally Posted by MIKES 68 F100 View Post
here's the video I took this Morning .
https://youtu.be/Q49QB5-pkVU
Sounds exactly like both mine with the Crane 272 and that Cam Dynamics 296* cam. Neither of them loped so's you'd notice. Both those had the 10 to 1 flat tops in them. What octane are you running ? Truck looks just like my 70 F100 too.
 


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