[ap72]

Originally Posted by cr480r

another tight lash flat tappet was not an option for me. The truck often sits for long periods, and although they work fine for most i didnt want to risk another lobe failure. I feel the dry starts may have been a factor, as well as my springs. And In my new neighborhood a camshaft breakin with 3" exhaust isnt a good idea. I dont wanna name drop the cam company on a open forum. not til after i use it anyways. Initially the rep suggested a 236-240 cam on a 110 lca. staying under .500-525" lift for the vortecs. But when we discussed this being a max effort with my existing parts and usage we decided to change it. After I stressed I had a loose converter, as well as a true 10.7 CR he decided to bump it up one step for pump gas. The LCA was tightened to 108 because i have no vacuum acessories. He felt my previous 106 was too tight for the 5.7 rod length? the cam lobes are .501" with 1.5 rockers and it was the closest lobe master he had in this duration range that would let me keep my 1.6 rockers without the lift going sky high...

For fully ported Vortec heads the rep's initial recommendation was about right. Go figure.

[cr480r]

Originally Posted by F-BIRD'88

My 406 screams with my vortec heads on it.
revs right up to 6700rpm. pulls like a frieght train. well past 6000 rpm.
The vortec heads are ported but not max ported by any means.

The solid roller cam that you have will work really well in the 400 with your vortecs.
re valve lash:
I trust you were not trying to set the lash "hot".

Its a lot easier to set the lash "cold" a lot more pain free.
You won;t hate doing it either.

Set the lash cold about .004" tighter than the hot lash spec.
I'd reconsider using that cam in your 400 w the vortecs. IMHO it is just right for your 400 w vortecs.

Ap72 has no clue.

The Hyd roller you got is just dandy too. Just not my preference.
These cams are just right.

If you liked the vortec heads on your 350, you are going to really like them on a 400SBC.

Use a -18cc dished piston on your 400 for pump gas compatability with 64cc heads.

A flat top piston 400 with vortecs will need about a 100 octane fuel to keep it happy.
A bit much for pump gas.

the old cam was flat tappet and it wiped a lobe. I was lashing cold, but its a pain in this truck while basically sitting on the motor. The old truck had no fenderwells so i could sit on the tire and go through them very easily. I went hydraulic because my springs were too weak for a solid roller, and i read many horror stories of cheap roller lifter failing with street use. pressure fed lifters are alot of money.

with my intake valve closing at 74 on the new cam i figured i could up the compression to 11:1.. i dont remember the intake closing on the old cam but with a 102 installed ICL it was trapping over 200psi with no pump gas issues. I always spiked the fuel before races, but i did plenty of street flogging on pump 91. always had 32* total timing. I always figured the stall speed and tight quench made it more forgiving

[F-BIRD'88]

The mild 32deg timig allowed you to get away with it.

Don't get nuts with the cr.. Don't buy into the dynamic cr BS.
Its is way to simplistic.

keep it under 11:1 and keep "spikeing" the fuel some, as required.

A little too much compression is $$$$$ A LOT TOO MUCH $$$$

[techinspector1]

Originally Posted by F-BIRD'88

Don't buy into the dynamic cr BS.
Its is way to simplistic.

Yeah, I can see where it makes way more sense to just pick a cam out of thin air and hope for the best. Holy Jesus H. Christ !!!!!!!!!!!!!!
You seem intent on calling BS to most everything I write, so I'm gonna start bitin' back. You don't know all the answers and neither do I.

Can't you give some sound engineering reason as to why you don't like DCR or is it just that I happen to champion it and you have to try to call it BS just because I like it.

Let the biting back begin, here and now. I'm tired of you and your punk attitude. Several board members have PM'd me and asked why you are the way you are toward what I write, so it's not just me. Others see your attacks also. So, either lighten up or I'm gonna have something to say about every damned thing you write.

For the rest of you, here's an article written by Pat Kelley that might explain some of the process of choosing components....
http://cochise.uia.net/pkelley2/DynamicCR.html

[F-BIRD'88]

Its real simple. The dynamic compression ratio is based on simplictic intake valve closing point.
When for 1 is very hard to accuratily establish.

2. the RUNNING engine's real in cylinder pressure has nothing to do with the cranking compression.
when its running at speed.

Highest pressure is right at the peak torque output.

Engines do not run a 500 rpm.

In the real world, engines do not operate in a tightly controled environment.
Gas quality changes, operating temps change, air inlet temp changes widely.
The knock tolerance of a engines varies widely based on the actual operating conditions at any one time.

As a general statement engines that operate in the real world with more than 10.5:1cr that are not computer electronic controled will be knock sensitive on even good pump gas reguardless of the cam used.
When things get hot they get hot.

if you build and engine with excessive compression ratio for the fuel and conditions your luck will run out sooner
or later.

rutching a engine by over camming it does not work and builds a crap engine at best.

For every internet guru that claims that you can do this and that there are 4 guy who found out how the real world really works.
You don;t pick a cam based on simple dynamic compression ( theory).

You cannot predict the cranking compression based on published cam specs.
These are not the true running open close specs of a RUNNING engine.

Here is some cold hard truth, based on 40 some years of doing this kind of stuff.

11:1 is real diecy on pump gas in any real world engine operating in the real world on pump gas.
and caming it up more will not change that. ( without real power loss)

You cannot establish or correct an engines fuel octane requirement
by fugging the cam.
Your cam picks are always lame and wrong fo both power and .....

Your power estimate are always wrong and lame based on over simplistic $20 computer programs and wrong inputs.
Your technical advise is either very generic, inaccurate, based on inaccurate popular internet theory and definately not from real experience.

There is a very good but old saying:

Believe none of what you hear, only half of what you read, (especially on the internet) and all of what you can PROVE.

In short you are full of BS,,,, SIR. have a nice day.


Hey F bird tell us what your really think

[0trbo4myCHEVUICK]

rawr? Dont run him off right when hes about to help me lol.

[techinspector1]

Originally Posted by F-BIRD'88

Its real simple. The dynamic compression ratio is based on simplictic intake valve closing point.
When for 1 is very hard to accuratily establish.

I call BS. The mfg will give you the intake closing point down to minutes and seconds if you ask for it and it's not that difficult for a home garage builder to find 1 degree.

Originally Posted by F-BIRD'88

2. the RUNNING engine's real in cylinder pressure has nothing to do with the cranking compression.
when its running at speed.

I call BS. Show your scientific data to support that statement.

Originally Posted by F-BIRD'88

In the real world, engines do not operate in a tightly controled environment.
Gas quality changes, operating temps change, air inlet temp changes widely.
The knock tolerance of a engines varies widely based on the actual operating conditions at any one time.

I call BS. What are you going to do, reach out into thin air and pick a cam?

Originally Posted by F-BIRD'88

As a general statement engines that operate in the real world with more than 10.5:1cr that are not computer electronic controled will be knock sensitive on even good pump gas reguardless of the cam used.
When things get hot they get hot.

I call BS. What data do you have to back up what you say?

Originally Posted by F-BIRD'88

For every internet guru that claims that you can do this and that there are 4 guy who found out how the real world really works.
You don;t pick a cam based on simple dynamic compression ( theory).

I call BS. Where's your data to prove what you're saying?

Originally Posted by F-BIRD'88

You cannot predict the cranking compression based on published cam specs.
These are not the true running open close specs of a RUNNING engine.

I call BS. Where's your data?

Originally Posted by F-BIRD'88

Your cam picks are always lame and wrong fo both power and .....

I call BS. Sounds like one punk's opinion to me.

[quote=F-BIRD'88;1625176]
Your power estimate are always wrong and lame based on over simplistic $20 computer programs and wrong inputs./[QUOTE]

I call BS. Sounds like one punk's opinion to me.

Originally Posted by F-BIRD'88

In short you are full of BS,,,, SIR. have a nice day.

Again, BS. Just one punk's opinion.

That seems to be all you have is opinions with nothing scientific or mathematical to back them up. I call BS on your entire agenda.

Just for the record, I have PM'd you in the past and tried to make friends. My PM was never answered, leaving me to think that you are just a punk who is devoid of honor and integrity and chocked full of BS opinions.

[F-BIRD'88]

I have enough friends... thanks.... I don't try to be popular.. Just here to help a few, who ask,, based on the real world and
how it really works.

[techinspector1]

Originally Posted by 0trbo4myCHEVUICK

rawr? Dont run him off right when hes about to help me lol.

Nobody is runnin' me off. Stay tuned.

[F-BIRD'88]

Here is some data for your that pretty much matches what happens in the real world.
Daytona Sensors LLC - Tech FAQ Engine Tuning

[techinspector1]

Originally Posted by F-BIRD'88

I have enough friends... thanks.... I don't try to be popular.. Just here to help a few, who ask,, based on the real world and
how it really works.

Then back up what you say with science and math and quit raggin' on my stuff.

[vinniekq2]

I see a lot of new cars with 12:1 CR and mazda uses 14:1 for both gas and diesel economy engines.None of those cars are running lumpy cams? BMW has a lot of 11:1 and higher engines.
Maybe tech is not that far off? He uses friendly and conservative numbers.
I like to debate with him.

[F-BIRD'88]

Originally Posted by techinspector1

Then back up what you say with science and math and quit raggin' on my stuff.

i don;t "rag on your stuff" I don't knock what your say reguarding DCR just cause I don;t like you. and I don't not like you.

But your advise based on this inaccurate over simplistic application of a over simplistic theory

Is what I like to call..... WRONG...

[techinspector1]

Originally Posted by F-BIRD'88

Here is some data for your that pretty much matches what happens in the real world.
Daytona Sensors LLC - Tech FAQ Engine Tuning

Thank you for the article. I read it. While it addresses air fuel ratio and spark timing, it stops short of explaining what camshaft timing needs to be used to complement the max 10.5:1 static compression ratio. Could a guy supposedly use any cam he feels like using? That's what the article suggests. In other words, you could use a cam that closes the intake valve at 20 degrees and have the same results as another cam that closes the intake valve at 60 degrees. I call BS. If that's your "real world", I call double BS with sprinkles.

[techinspector1]

Originally Posted by F-BIRD'88

i don;t "rag on your stuff" I don't knock what your say reguarding DCR just cause I don;t like you. and I don't not like you.

But your advise based on this inaccurate over simplistic application of a over simplistic theory

Is what I like to call..... WRONG...

Not all the experts and engineers that I read call it wrong. You are the only person I see calling it wrong. I call BS. You have no data to support your opinion. Just keep raggin' on my stuff and I'll keep on raggin' on your stuff.
You are about to find me relentless because I'm now pizzed-off.