found my pistons reciept w pics

[66FBCharger]

What is meant by "plunge cut the heads"?
I am very interested with how your Mr. Six pack cam, lifters and springs work out. I ordered a cam package a few years back but have not assembled the engine yet. (life has been chaotic with kids, wife, etc.).

[rt green]

a plunge cut is a straight down cut of about 70-75 degrees in the chambers. kind of takes place of the templates that mopar performance has.

[BSB67]

I don't think it'll run on pump gas with 180 psi unless you back the timing off significantly  

I agree completely.  But he will not know the actual cranking pressure until it is too late.  Please note that I stated that the cylinder pressure as determined with calculator, needs to be less than 180 psi.  My data shows fairly consistent high calculated numbers relative to actual.  So if the calculator gives a 180 psi, actual will be about 170 psi, or a little less (opposite true for solid cams). My experience is an actual 170 psi is on the edge with cast iron heads when everything else is right.

[rt green]

geez. maybe I should just use the .040 head gasket.

[Ghoste]

But if you want to get the most from it...

[rt green]

I still have to buy pump gas for it. if I have to retard the sh*t out of the timing to run pump gas, it'll take away what I gained with compression. am I right? maybe I could make up the lost power somewhere else. I see a lot of older cars around here that look good, but run like ass. I've straightened out a few at work also. so, maybe what I have already properly tuned will run out pretty good and stomp some GM's. I still have a Plymouth I can get nuts with. thanks guys. when I get the heads back from the machine shop and figure out how to post pics, i'll put a few on here.

[BSB67]

I still have to buy pump gas for it. if I have to retard the sh*t out of the timing to run pump gas, it'll take away what I gained with compression. am I right? maybe I could make up the lost power somewhere else. I see a lot of older cars around here that look good, but run like ass. I've straightened out a few at work also. so, maybe what I have already properly tuned will run out pretty good and stomp some GM's. I still have a Plymouth I can get nuts with. thanks guys. when I get the heads back from the machine shop and figure out how to post pics, i'll put a few on here.

If you do the prescribed measurements and math, your answer might become clear, and if not, certainly more clear on what direction to go.  If you don't want to do the measurements and math, and you don't want to risk having to pull the heads, and you want to make the decision with only the information that you have now, then I think you go with the 0.040" gasket.

Reducing total timing can offset some or possibly all of the potential gain from the CR increase.  And I would not recommend that.  What I did recommend that you might do, as a last resort, is to change the timing curve.  If you have a significant ping issue, changing the timing curve will not be enough.  However, if you are on the edge with your combination, ping will first show up under lower rpm high load, like accelerating out of a turn or up a hill in higher gear and then go away.   In that case, you could have success by slowing the timing curve down.  This will have little or no measurable impact on WOT performance, as the motor will spend no time under 3400 rpm, except in 1st gear from a stop.  And that does not normally matter either because you will already have a traction problem.  The negative on a slower timing curve will be the part throttle response while cruising wont be as sharp.  If you are watching gas mileage, you might see it there too.

[rt green]

maybe I'll go to a vet supply store and get a  syringe large enough to hold 100 cc;s. it would be fun to measure anyway. for the hell of it, I priced out mopar per head gaskets, and the .20 was about 25-30 bucks a pair. however the .025 was over 150 bucks!  what a difference. cash broke engine building at its finest.   

[rt green]

It'll be interesting to see what the cranking compression numbers look like when this build goes back together. I don't think it'll run on pump gas with 180 psi unless you back the timing off significantly  

Open chamber iron heads, no quench and high cylinder pressure won't work with pump gas. If this build had a closed chamber aluminum head with .040 quench it would work fine on pump swill with 35* total timing all in by 2500 rpm on a quick curve.  

I spoke with one guy who runs the Mr 6-pack cam and his build is a true 10:1 iron head build with open chamber 906's and his cranking compression was 185psi....and he needs to spike the fuel with race gas when he takes it to the track or pound on it while street driving....or it will ping/detonate. In his car the engine pulls 19-20* of vacuum. The car runs fantastic but it's not pump gas friendly....

The rumour is that Bob K uses Engle and their fast lobe hydraulic grinds for his custom stick. I'd bet that there is a wide LSA and large split duration with short seat to seat timing to achieve the results he does with an OEM iron head casting.  



Ron

yes, Bob K does run Engle cams. looks like I have grind #3 mr6pk   114 degree

[b5blue]

? http://www.mopartsracing.com/parts/Sidewinder.html

[BSB67]

It'll be interesting to see what the cranking compression numbers look like when this build goes back together. I don't think it'll run on pump gas with 180 psi unless you back the timing off significantly  

Open chamber iron heads, no quench and high cylinder pressure won't work with pump gas. If this build had a closed chamber aluminum head with .040 quench it would work fine on pump swill with 35* total timing all in by 2500 rpm on a quick curve.  

I spoke with one guy who runs the Mr 6-pack cam and his build is a true 10:1 iron head build with open chamber 906's and his cranking compression was 185psi....and he needs to spike the fuel with race gas when he takes it to the track or pound on it while street driving....or it will ping/detonate. In his car the engine pulls 19-20* of vacuum. The car runs fantastic but it's not pump gas friendly....

The rumour is that Bob K uses Engle and their fast lobe hydraulic grinds for his custom stick. I'd bet that there is a wide LSA and large split duration with short seat to seat timing to achieve the results he does with an OEM iron head casting.  

Ron

yes, Bob K does run Engle cams. looks like I have grind #3 mr6pk   114 degree

........you probably would be in the 114° LSA area.  Probably install at 112° with a tall gear/tight converter/heavy car....

[rt green]

installed the cam last nite. the paper inside says the cam is ground 2-3 degrees built in. it says for 4 10 gears- straight up, 391-advance to 112- 355 or 323-advance 110-111 degrees. I put it on the 4 degrees slot on the bottom gear. I will measure with a degree wheel of course. I used a cloyes timing set. it says to shim rocker shafts to proper preload. spring height to 1.835 to 1.850.  I have the manley 22406-16 valve springs.    it also says use a very efficient exhaust system.  the only mufflers I have around here are are flowmaster 40's.  2 1\2 's.  I have a 4-speed  trans.

[BSB67]

installed the cam last nite. the paper inside says the cam is ground 2-3 degrees built in. it says for 4 10 gears- straight up, 391-advance to 112- 355 or 323-advance 110-111 degrees. I put it on the 4 degrees slot on the bottom gear. I will measure with a degree wheel of course. I used a cloyes timing set. it says to shim rocker shafts to proper preload. spring height to 1.835 to 1.850.  I have the manley 22406-16 valve springs.    it also says use a very efficient exhaust system.  the only mufflers I have around here are are flowmaster 40's.  2 1\2 's.  I have a 4-speed  trans.

So if everything is right, you installed your cam 6° - 7° advanced, or 107° - 108° ICL.  I would not change anything though until you degree it.

[rt green]

yesterday Bob K returned my call. I asked him about the cam advance, and he advised me to put the cam in straight up. interesting.   i'll do that and then check on the degree wheel. so far, its been fun blowing off the dust on these old parts and finally doing something with them. I was very pleased to see the lifters that Bob K sold me were Jonson's. I have to wait till next week to do anything to anything. can't wait to see what the heads look like with the plunge cut.

[BSB67]

yesterday Bob K returned my call. I asked him about the cam advance, and he advised me to put the cam in straight up. interesting.   i'll do that and then check on the degree wheel. so far, its been fun blowing off the dust on these old parts and finally doing something with them. I was very pleased to see the lifters that Bob K sold me were Jonson's. I have to wait till next week to do anything to anything. can't wait to see what the heads look like with the plunge cut.

Do you know what straight up is?  Not trying be smart azz, but some people don't know.

[b5blue]

Isn't there a difference between optimizing cam/crank orientation to rear gear ratio and trying to avoid pre detonation?      

[rt green]

yesterday Bob K returned my call. I asked him about the cam advance, and he advised me to put the cam in straight up. interesting.   i'll do that and then check on the degree wheel. so far, its been fun blowing off the dust on these old parts and finally doing something with them. I was very pleased to see the lifters that Bob K sold me were Jonson's. I have to wait till next week to do anything to anything. can't wait to see what the heads look like with the plunge cut.

Do you know what straight up is?  Not trying be smart azz, but some people don't know.

yep. I do. have been a professional mechanic for almost 30 yrs now.

[BSB67]

yesterday Bob K returned my call. I asked him about the cam advance, and he advised me to put the cam in straight up. interesting.   i'll do that and then check on the degree wheel. so far, its been fun blowing off the dust on these old parts and finally doing something with them. I was very pleased to see the lifters that Bob K sold me were Jonson's. I have to wait till next week to do anything to anything. can't wait to see what the heads look like with the plunge cut.

Do you know what straight up is?  Not trying be smart azz, but some people don't know.

yep. I do. have been a professional mechanic for almost 30 yrs now.

No offense, but you did not know how to centerline a cam without a cam card, and you installed the cam at 107° - 108° when the card said 110° to 111° before you talked to Bob.   

[rt green]

I didn't quite understand the sheet of paper that came with the cam. it said intake lobe center 110-111 degrees. then further down it says all cams are ground with 2-3 built into them. this threw me a little and, no I didn't know how to degree a cam without a card or something to say where it is spose to be. but after talking with you on here and when I finally opened the box and saw something to go off of, I was on my way. I admit I was a little confused on a starting point. didn't want to ruffle any feathers or anything. just am very thankful for the advice and help. and yes I can be an idiot at times. I never claimed to be any good at hot rodding an engine.

[firefighter3931]

It would be nice if the seller of that cam was less ambiguous with his instructions. 

If it has 2-3* of advance built in then you should be shooting for 111-112* installed centerline. Why confuse the matter by saying anything about the built-in advance ? 

Anyone who takes the time to degree in a cam will know that a potential problem can exist with the timing set and/or the cam itself. Seen it more than once on a cam degree check.... on a buddies car running the MP 284 cam. The timing set was off by one tooth resulting in a 12* retard on the cam timing. That was just one example. 

It sounds like you used the 4* advance setting and with the built in advance ground into the cam the result was more than what is recommended. Not an uncommon mistake...but easily correctable. 




Ron

[BSB67]

Why confuse the matter by saying anything about the built-in advance ? 

This is where people get confused.

To the OP - Bob is telling you to put it in at 114°.

[rt green]

Why confuse the matter by saying anything about the built-in advance ? 

This is where people get confused.

To the OP - Bob is telling you to put it in at 114°.

that's another thing, he says put it straight up and he also said put it at 110. I think i'll just put it straight up and check it on the degree wheel and adjust to 110 from there. I just have it installed on there hand tight so adjusting will be easy.  thank you guys for the help.

[firefighter3931]

To the OP - Bob is telling you to put it in at 114°.

That's not the way I read it....and therein lies the confusion. Straight Up on the timing set with 2-3* of advance built in would be an ICL of 111-112* assuming the timing set is dead nuts accurate.

The instructions should say : If using the degree method set the ICL to xx degrees or if simply installing without degreeing... line the dots up.

Every cam I've purchased has come with a cam card that gives you all the related timing events so there's no confusion as to what you've got or where to install it. I would never purchase or install a cam that didn't have that information available. 


Ron

[BSB67]

To the OP - Bob is telling you to put it in at 114°.

That's not the way I read it....and therein lies the confusion. Straight Up on the timing set with 2-3* of advance built in would be an ICL of 111-112* assuming the timing set is dead nuts accurate.

The instructions should say : If using the degree method set the ICL to xx degrees or if simply installing without degreeing... line the dots up.

Every cam I've purchased has come with a cam card that gives you all the related timing events so there's no confusion as to what you've got or where to install it. I would never purchase or install a cam that didn't have that information available. 


Ron

Right, but that is not straight up.  That is the manufacturers recommended installation.  The term straight up means the relationship between the cam and the crank, and specifically, that the centerline of both the intake lobe and the exhaust lobe are the same distance (degrees) from TDC.  So straight-up, by definition, for a 114° LSA (cam degrees), is when the intake centerline is 114° (crank degrees) ATDC, and the exhaust is 114° BTDC.  This is straight up, or "zero" degrees, the cam is neither advanced, nor retarded.  So, when a cam is installed straight up, the ICL = LSA,  Of course, one is in cam degrees, the other is crank degrees, but the number is the same.

So when a cam manufacturer says that there is 4° advance "ground in", that means that if everything else is perfect (crank key, sprockets...) the cam will be 4° advanced from straight up when installed.  The 4° advanced ground in is not straight up.  The manufacture will grind in advance, as they believe that this is the best timing for the cam for the typical application of that cam.

It is common for people to call installing the cam per the manufactures specification as "straight up" even though there is advance ground in.  This is incorrect. What should be said is that the cam is installed advanced per the manufacturers specification.  Other believe that lining up the dot is "straight up" which of course means nothing relative to the cam being retarded, straight-up or advanced.

[Challenger340]

In my experience only, and I guess I've lived a sheltered life ? 
But I wouldn't even think about installing a Camshaft that at the very least.... did not come supplied with a PRINTED intake centerline spec recommendation(Full Cam card is best).

I mean everybody may have their "007... top secret... ancient chinese... blah, blah" Camshaft, but the fact remains, if you can't supply anything past "straight up", or "line up the dots"....  as YOUR Cam directions.... with YOUR OWN specialty Camshaft ? then IMO, that just seems hillbilly to me.

The customer would be getting a very nice Invoice for V-Block plotting of the Cam events(making up a Cam card).... and then we would install it whereever the fawk he wants.