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Currently running a 360 LA smallblock mopar motor, totally stock junkyard bottom end, making just under 9:1 compression at the very most. My cam was ground to make the most of my heads (RHS LA-X heads) and build power with the low compression. specs are as follows

Hydraulic roller
230/230 at .050" duration
576 int/569" exh lift with a 1.6 rocker
106 LSA
installed at 101 ICL (4 degrees advance ground into the cam)

this current combo has run a best of 12.3 in a 3400lb stickshift car with 4.10 gears on 87 octane pump puke...based on my calculations im currently making about 320hp TOPS at the rear tires

My bottom end has taken a shit on me, and I have been thinking of putting in a good piston to get compression up to about 10.5:1, with good quench to be able to run on pump gas (we get up to 94 around here). With just a piston swap and a cam change to take advantage of the compression (not even sure if that cam swap would be help though?:confused:) how much more power can I expect to make? Was thinking of more cam, but that would probably mean having to rev higher, and this is a street car that buzzes the 2 hour drive to the track at 3,000rpms already, so more rear gear is out of the picture

What do you guys say? Will I notice a different in power, or is it not enough of a CR bump for me to really gain anything?
 

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Assuming those heads have a quench area, shoot for zero deck with enough dish that you hit 9.5:1. You could reuse your current cam, or even step it up another 10 degrees or so. The std transmission is pretty forgiving.
 

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You wont really see anything from the comp bump no more than your going, and the new cam may let out more air than the comp is going to take it up to. Not knowing what the old cam was it would be hard to know.
 

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You wont really see anything from the comp bump no more than your going, and the new cam may let out more air than the comp is going to take it up to. Not knowing what the old cam was it would be hard to know.
the old cam specs i listed in my original post
 

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I thought that was the new one sorry, then without the new one
well then lets take it a step backwards...with a bump in compression, would I even bother changing this cam with everything else in the motor being exactly the same? Would this grind still perform well with a motor that has say 10.5:1 CR with tight quench? Would I want more duration? spread out the LSA?
 

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At the risk of sounding like a broken record, that compression/deck height improvement might net you 3 tenths. You're still boring/balancing/resizing rods/grinding the crank/decking the block. The crank is reasonably cheap from Scat (9000 series) you can reuse your rods, pistons will be the same price. all the other procedures will be the same. (other than possible block and rod clearancing) I think the 408 combo could have you running mid 11's and allow you to go up a couple of inches on the tire (or lower the rear gearing) so your drive to the track doesn't have to be 3000 RPM.
 

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At the risk of sounding like a broken record, that compression/deck height improvement might net you 3 tenths. You're still boring/balancing/resizing rods/grinding the crank/decking the block. The crank is reasonably cheap from Scat (9000 series) you can reuse your rods, pistons will be the same price. all the other procedures will be the same. (other than possible block and rod clearancing) I think the 408 combo could have you running mid 11's and allow you to go up a couple of inches on the tire (or lower the rear gearing) so your drive to the track doesn't have to be 3000 RPM.
hey man, I am more than likely going to a stroker...this was just more for personal knowledge thats all lol I am always looking to learn what kinda changes would affect certain things

I agree that the machine work im going to spend on stock parts would be better spent prepping a stroker rotating assembly and the block for it. I will be running a forged crank, as good as those 9000 series cranks are, just do to the fact that this is a stickshift car and I dont want to take any chances...plus im hoping i can go in there once and not have to go back into the motor again for a while, so i can build a solid foundation

As far as the gearing and tire goes, I will run it as is and see...With the old combo the car would have liked a 4.56 to cross the stripe at 6k i would think (I was doing 5500rpm with the 4.10's and 28" et streets)..So im thinking with the added torque of the stroker the 4.10's and 28's might be perfect if my peak is around the same rpm. Because I don't have the torque multiplication of the converter i unfortunately need steeper gearing to be equivalent to a converter car
 

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pig hunter
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give shady dell a call does very nice mopar work for a good price..
 

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those heads won't support a 4" arm...
How come you say that Jeff?

I don't want to sound like a know it all here, but they do from what I have seen...IMM did a mild 4' arm small block for car craft with these exact heads, and there are quite a few running these same heads on their stroker combos and performing quite well in alot of forum threads I have been reading...i think it will be more of a torque motor with these heads, but thats fine by me

one fella has ran a best of 10.14 with these heads on a 416 stroker in a 3100 pound duster...12.5:1 CR, 4.56 gear, slick, etc. dont know all the details but they definitely work

These heads have proven performance, and this is with untouched ports...Brian offers a porting service to get them just over 300cfm on the intake side (which would obviously take more advantage of the 4" arm)

Edelbrock is coming out with a new victor small block mopar head in the very near future, so I can always upgrade later when and if the time comes:cool:
 

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give shady dell a call does very nice mopar work for a good price..
Brian at IMM will get ALL of my business for anything mopar I ever do in the future...I could not be happier with how my junkyard heap ran with his custom cam for my combo and these heads...he definitely knows his shit!:cool:

3k from carb to pan with a measly 8.5:1 cr, running 87 pump puke with a 4 speed in a 3400lb street car and i was doing 12.3 lifting the front wheels! Everything we talked about when spec'ing the combo was spot on when i got it together and ran it

I have nothing against Shady Dell, but I have had nothing but good luck with Brian at IMM and intend to continue to use him
 

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It will still depend on valve events you have made on the new cam. DCR#s mean things

If they are longer lobes the compression will be down, if the .050 is the same and the .200 number is bigger and more lift, then you will make more power. Get a cam ground for low compression.
 

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pig hunter
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LIFT------IN/EX
.100"----77.6/N/A
.200"--144.9/112.2
.300"--204.3/151.8
.400"--255.3/189.8
.450"--276.0/199.1
.500"--286.0/201.9
.550"--292.2/206.3
.600"--297.4/208.4
.650"--297.4/209.8
.700"--297.4/211.1


eddy HEADS... on my old 408 in my 73 340 duster ran 10.83. [email protected] and .690 lift. on a 108. 11.3 to 1 running pumpgas.. car had full interior and all steel. 4.30 gear with a th400 gm trans..
 

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Discussion Starter #18
It will still depend on valve events you have made on the new cam. DCR#s mean things

If they are longer lobes the compression will be down, if the .050 is the same and the .200 number is bigger and more lift, then you will make more power. Get a cam ground for low compression.

ok
 

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Discussion Starter #19
LIFT------IN/EX
.100"----77.6/N/A
.200"--144.9/112.2
.300"--204.3/151.8
.400"--255.3/189.8
.450"--276.0/199.1
.500"--286.0/201.9
.550"--292.2/206.3
.600"--297.4/208.4
.650"--297.4/209.8
.700"--297.4/211.1


eddy HEADS... on my old 408 in my 73 340 duster ran 10.83. [email protected] and .690 lift. on a 108. 11.3 to 1 running pumpgas.. car had full interior and all steel. 4.30 gear with a th400 gm trans..
Nice combo man! Im assuming your eddy's had the stage 3 port job from Ryan J? Im not looking to set any records, in fact, i dont want to go faster than 11.50's right now as i really don't want to put a cage in my car as it is a street car 99% of the time
 

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pig hunter
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i posted that to show you it can be done. where does the convertor stall to? DON'T BE Afraid to put some convertor behind it.. i had a 8" that hit right at 4900 drove that car to work everyday for 2 yrs and everywhere i went..
 
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