found my pistons reciept w pics

[rt green]

found my machine shop receipt .  was wondering what compression they really are with stock 906 heads.  sealed power  piston and ring set   fkh 147cp030. I hope they aren't the 8 to 1 slugs, but I bet they are. they were billed as  9.5 to one. help?  

[Challenger340]

found my machine shop receipt .  was wondering what compression they really are with stock 906 heads.  sealed power  piston and ring set   fkh 147cp030. I hope they aren't the 8 to 1 slugs, but I bet they are. they were billed as  9.5 to one. help?   

About 9.3 or 9.4 with a "composition" style Head Gasket(.040 thick), and 88 CC 906 Heads, which is a fairly common size after rebuild.

[rt green]

so youre saying its not the low comp pistons that everyone is getting stuck with. if thats the case, thank god. can i get a thinner head gasket? 

[Dino]

Yes you can get a 0.020 steel shim gasket.

[Challenger340]

so youre saying its not the low comp pistons that everyone is getting stuck with. if thats the case, thank god. can i get a thinner head gasket? 

Nope, your Pistons are OK !
finally a builder without mush for brains ! 

[rt green]

i built  the 440 about 5 yrs ago, but life got into the way. I haven't fired it up yet.  I installed a mopar stock replacement cam in it, and then put a six pack on it. found Mr sixpack and gave him a call. he sold me a cam and told me to replace the valve springs and do a plunge cut on the heads. I took the engine to work and was going to pull the heads anyway, and couldn't remember what pistons he ordered. thank you for helping me on the piston numbers.

[rt green]

oh, and also I never had a spec on ring gap. they charged me for a balance and I have the sixpack rods and a 10 and a half flywheel. I see no weights welded on or grind marks anywhere. I always thought the flywheel was an internal balance one.

[rt green]

tore the engine down to where i needed to check some stuff. i see signs that he balanced it!!  checked all the bottom end tourques and seem to be correct. built this thing in 2005 anf was drinking a lot of beer at the time. now, i have to take the heads in to get a plunge cut and have the new valve springs installed. looked at the piston to deck distance and it looks like close to zero. thank god. i am in a good mood. now to get it machined and i can install my new cam and sit back and be happy.        bruce

[Ghoste]

What is turning you away from the Kakshian cam?

[BSB67]

looked at the piston to deck distance and it looks like close to zero.       bruce

You don't know anything for sure until you measure it.  You're this close, measure it.

[b5blue]

looked at the piston to deck distance and it looks like close to zero.       bruce

You don't know anything for sure until you measure it.  You're this close, measure it.

100% Agree! Know exactly, check both sides of the block. Degree the cam and cc the heads so you know later! Write it all down and save pics of everything.

[rt green]

What is turning you away from the Kakshian cam?

that's the cam i'm running. and i'll measure the height today.  wish I could degree the cam-he doesn't give out the specs. for 3.23 gears he says to put it straight up. a sheet of paper came with it and says to put it straight up or advance it 2 degrees depending on what gears you have. it is what it is. the specs must be a secret or something.

[rt green]

checked both sides (piston hieght)  came up with 0.20. i'll have to make up somthing to ck the heads for cc's. i see they have been trued up though.       

[BSB67]

You don't need a cam card to degree the cam.  I don't have the energy to type out the details, but at a high level, it goes like this: 1) stuff the cam in the block and install the wheel/pointer. 2) find the intake and exhaust centerline on #1, 3) do the math to determine the LSA, 4) Install cam at your desired intake centerline.  If this is not clear to you, read up on how to centerline a cam, and use that technique to do #2 above to determine both the intake and exhaust CLs and add the BTDC° number (exhaust) and the ATDC° number (intake) and divide by 2.  That gives to LSA..  Advancing the cam 2° is simply LSA minus the 2°

I don't know what the BobK cam LSA is, and it probably has changed over time anyways.  But you probably would be in the 114° LSA area.  Probably install at 112° with a tall gear/tight converter/heavy car.  Probably 116° with a 3.91+ gear/4 speed.

[rt green]

thanks BSB67, I really value your opinion. next, I have to figure out what cc's my heads are. they have been machined square, but I don't know how much have been taken off.  i'll have to rig something up to measure that. maybe then I can figure out what thickness of head gasket to use and then have a clue what compression will be.  bruce- 

[BSB67]

The unmachined factory head will usually measure close to 1.000" at the lower bolt hole pads on the head.  Measure there and see what you have.  You can estimate what was milled off.

But, that is only one of the two variables.  You'll still need to measure the volume of the chamber.

[rt green]

that'll have to wait for Monday when i'm back at work. thank you very much for the info. you.ve been a great help. i'll measure that and get back to you. thanks.          bruce

[rt green]

You don't need a cam card to degree the cam.  I don't have the energy to type out the details, but at a high level, it goes like this: 1) stuff the cam in the block and install the wheel/pointer. 2) find the intake and exhaust centerline on #1, 3) do the math to determine the LSA, 4) Install cam at your desired intake centerline.  If this is not clear to you, read up on how to centerline a cam, and use that technique to do #2 above to determine both the intake and exhaust CLs and add the BTDC° number (exhaust) and the ATDC° number (intake) and divide by 2.  That gives to LSA..  Advancing the cam 2° is simply LSA minus the 2°

I don't know what the BobK cam LSA is, and it probably has changed over time anyways.  But you probably would be in the 114° LSA area.  Probably install at 112° with a tall gear/tight converter/heavy car.  Probably 116° with a 3.91+ gear/4 speed.

1969 charger 23 spline 4 speed mr sixpack cam  3.23 gears 295\50r15 tires. newer mopar dist, (want to change that) sixpack intake with the center machined out. {cant afford to get a new one} center carb is a '69 outer carbs are '71's. 906 heads w/no lead seats. hooker headers 1 7/8 I think. any other specs you need, i'll try to answer. car is to be driven on the street. would like some punch though. boss and all his buddys are all gm guys.

[rt green]

looks like they took maybe 10 thousands off the heads. trying to figure out what head gasket to get. .020 .025 or stick with the .040.

[firefighter3931]

That Mr 6-pack cam builds a lot of cylinder pressure from what I've been told. That being said I'd run the .040 head gasket and keep the compression as close to the mid 9's as possible. If pump gas is the goal...that is 


Ron

[rt green]

 a lot of cylinder pressure and 10 to one not cool on todays fuel?

[BSB67]

The Bob K cam will generate less cylinder pressure than most similar sized cams, i.e. other 268° intake lobe cams.  But it is still a fairly small cam.  We could get into the weeds on exactly what your compression ratio is to help decide if you can go up in CR.  But it is not black and white.  If you don't want to leave any power on the table, and don't mind possibly pulling the heads again, go with the 0.020" gasket.  Otherwise, probably go with the 0.040"

[rt green]

The Bob K cam will generate less cylinder pressure than most similar sized cams, i.e. other 268° intake lobe cams.  But it is still a fairly small cam.  We could get into the weeds on exactly what your compression ratio is to help decide if you can go up in CR.  But it is not black and white.  If you don't want to leave any power on the table, and don't mind possibly pulling the heads again, go with the 0.020" gasket.  Otherwise, probably go with the 0.040"

if this was your car, I have to ask, what would you do?

[BSB67]

The Bob K cam will generate less cylinder pressure than most similar sized cams, i.e. other 268° intake lobe cams.  But it is still a fairly small cam.  We could get into the weeds on exactly what your compression ratio is to help decide if you can go up in CR.  But it is not black and white.  If you don't want to leave any power on the table, and don't mind possibly pulling the heads again, go with the 0.020" gasket.  Otherwise, probably go with the 0.040"

if this was your car, I have to ask, what would you do?

I would measure the compression distance of every piston and record.  CC every combustion chamber and record. Get the valve relief volume, Do the math to see what the compression ratio is for every cylinder, with each head on both sides of the block with a 0.020" gasket. (i.e. 16 different CRs) (If you do this, you'll see why I chuckle when people report CR numbers to the second decimal point).  Take the highest number and do a dynamic CR/cylinder pressure calc.  If you are around sea level, the CR is 9.5 or less, and the pressure calc is 180 or less, I would probably go with the 0.20" gasket, but will also plan to pull the head and replace gasket if it pings.  It's a one day job, maybe two if you take your time.  Higher than that, go with 0.040"

Plan to run the highest octane pump gas available (93 at least), a good cooling system, 160° thermostat, cooler spark plug, blocked exhaust cross over, insulated carb spacer, and possibly slow timing curve to all in at 3000.

[firefighter3931]

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