360 compression issues. pick a piston??

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I read somewhere that even the 63cc ede's measure closer to 65cc.
 
moparmat2000 said:
The flat top with valve reliefs then
Click to expand...
If they are the HC116CP flat tops, you won't get a good quench gap.
Rod length 6.123
1/2 stroke 1.79
Comp height 1.660
-------------------
Piston height 9.573 from crank centerline

Stock deck height from crank centerline 9.599

Piston deck height = -0.026" (in the hole)

Felpro 1008 gaskets 0.039" compressed height

Quench gap = .026+.039 = 0.065 " ====> too big for effective quench. Maybe it'll be .060" with a simple decking job, but still too wide. Static CR will be 11.2

Did you read my post on the KB232's? Dish with raised quench pad; in this case, it would work out to a .045 quench height with an 18 cc dished top and the static CR will be 9.7.

Just as a side note..... all the above goes out the window if something is true.... which you need to doublecheck. You are using 65 cc Edelbrock clones? The Edlebrock 65 cc's are not closed chamber. They are like the open chamber SBM heads, with an open area at the top of the combustion chamber. See here for how the Edelbrocks look; scroll to the pix of the bottom and look at the circular area milled on the underside; that is about .060" deep and changes all the quench and CR calculations. Now your Speed Pro flat tops have a quench gap of over .110", or no quench at all. Static CR will be below 9.

http://www.amazon.com/dp/B00063012I/?tag=fabo03-20

I see the pix of the Speedmaster and they do look closed, but I'd make sure.

The spring pressures are on the high side too if you are running .500 lift or less.
 
nm9stheham said:
If they are the HC116CP flat tops, you won't get a good quench gap.
Rod length 6.123
1/2 stroke 1.79
Comp height 1.660
-------------------
Piston height 9.573 from crank centerline

Stock deck height from crank centerline 9.599

Piston deck height = -0.026" (in the hole)

Felpro 1008 gaskets 0.039" compressed height

Quench gap = .026+.039 = 0.065 " ====> too big for effective quench. Maybe it'll be .060" with a simple decking job, but still too wide. Static CR will be 11.2

Did you read my post on the KB232's? Dish with raised quench pad; in this case, it would work out to a .045 quench height with an 18 cc dished top and the static CR will be 9.7.

Just as a side note..... all the above goes out the window if something is true.... which you need to double check. You are using 65 cc Edelbrock clones? The Edlebrock 65 cc's are not closed chamber. They are like the open chamber SBM heads, with an open area at the top of the combustion chamber. See here for how the Edelbrocks look; scroll to the pix of the bottom and look at the circular area milled on the underside; that is about .060" deep and changes all the quench and CR calculations. Now your Speed Pro flat tops have a quench gap of over .110", or no quench at all. Static CR will be below 9.

http://www.amazon.com/dp/B00063012I/?tag=fabo03-20

I see the pix of the Speedmaster and they do look closed, but I'd make sure.

The spring pressures are on the high side too if you are running .500 lift or less.
Click to expand...


Arrrghhhh..................
 
If you are going to have the block decked, just have the shop bolt on their blok tru and measure your decks . Then you can decide on pistons, and they can mill the block for zero deck. By the way, a lot of 360s are taller than the stock spec.
 
Mopar Sam said:
If you are going to have the block decked, just have the shop bolt on their blok tru and measure your decks . Then you can decide on pistons, and they can mill the block for zero deck.
Click to expand...

^^^ Agreed!!,more $$ for competency,machine work & tooling, agreed none the less.

Mopar Sam said:
By the way, a lot of 360s are taller than the stock spec.
Click to expand...

Lol, spoken for truth, not limited to the 360's...
 
If you really, really, want the most bang for the buck, then pick the cam first, and don't change your mind. Then set the Dcr(Dynamic compression ratio) to run it on your local Premium, and at your altitude.
If you pick a compression ratio to deal with bad gas, you will not get the best bang for the buck. The way to deal with bad gas is either run it out at part throttle, when the chambers only require a much lower octane gas, or drain it out, and burn it in your lawn n garden equipment.Bad gas is not a big deal.
The intake closing angle, and the Dcr, and the gas,and the altitude,are just about married, if you want the most bang for the buck. Until you pick a cam, Scr means very little.It's easily possible to run 11.5 Scr on 91E10 with aluminum heads and the right cam. Running that same cam on 9.8 Scr would make it a big disappointment at lower rpms, and you would be band-aiding it with race gears and hi-stall TCs, and it would be no where near the best bang for the buck.
On the street with a lot of stop n go driving and lots of cruising, a conservative cam will be the most fun. But there's a tremendous difference among cam suppliers who provide similar ICAs but their cams will perform quite differently. This usually boils down to the ramps. Again, for most bang for the buck, you will want a cam with the highest lift and the most .050 duration, that still has the ICA you choose. This means either very careful shopping or a custom cam.
What I'm saying is this; you can easily find several cams from different cam-companies, that all sport the same or similar .050 intake duration numbers.And they might even have similar lifts. In this case they will all make similar power. But, and heres the key, they might all have very different ICAs. A late ICA will put a nice lope in the idle, which is what some guys want. A very early ICA will trap more charge and make low-rpm torque, which another guy might like. But the ICAs could be 5 to 10 degrees apart. If your engine is not set up for an early ICA, it might ping. If it's not set up for the late ICA, it might be soft off the line. Those 5 to 10 degrees could spell the difference of over 1 full point of Dcr! That is from say;8.0Dcr to 9.0Dcr.And that might correspond to close to 2 full points of Scr.Say 9.5 to 11.5.
This Dcr thing is way more important than a lot of guys suspect, and especially so for guys who want the MOST bang for the buck.
So pick the cam to fill your operating range, and get the fastest rate of lift and the highest lift, that the cam guy will sell you.And the springs that are matched to it. Get the ICA from the card. Plug it into the Dcr calculator, to spit out the Scr. Then go build it.
Another option might be to call MRL. Since his shop is spitting out engines with really nice numbers, he must know a thing or two about picking cams.
Or I can just tell you what works for me.......................your results may vary.
 
AJ/FormS said:
If you really, really, want the most bang for the buck, then pick the cam first, and don't change your mind. Then set the Dcr(Dynamic compression ratio) to run it on your local Premium, and at your altitude.
If you pick a compression ratio to deal with bad gas, you will not get the best bang for the buck. The way to deal with bad gas is either run it out at part throttle, when the chambers only require a much lower octane gas, or drain it out, and burn it in your lawn n garden equipment.Bad gas is not a big deal.
The intake closing angle, and the Dcr, and the gas,and the altitude,are just about married, if you want the most bang for the buck. Until you pick a cam, Scr means very little.It's easily possible to run 11.5 Scr on 91E10 with aluminum heads and the right cam. Running that same cam on 9.8 Scr would make it a big disappointment at lower rpms, and you would be band-aiding it with race gears and hi-stall TCs, and it would be no where near the best bang for the buck.
On the street with a lot of stop n go driving and lots of cruising, a conservative cam will be the most fun. But there's a tremendous difference among cam suppliers who provide similar ICAs but their cams will perform quite differently. This usually boils down to the ramps. Again, for most bang for the buck, you will want a cam with the highest lift and the most .050 duration, that still has the ICA you choose. This means either very careful shopping or a custom cam.
What I'm saying is this; you can easily find several cams from different cam-companies, that all sport the same or similar .050 intake duration numbers.And they might even have similar lifts. In this case they will all make similar power. But, and heres the key, they might all have very different ICAs. A late ICA will put a nice lope in the idle, which is what some guys want. A very early ICA will trap more charge and make low-rpm torque, which another guy might like. But the ICAs could be 5 to 10 degrees apart. If your engine is not set up for an early ICA, it might ping. If it's not set up for the late ICA, it might be soft off the line. Those 5 to 10 degrees could spell the difference of over 1 full point of Dcr! That is from say;8.0Dcr to 9.0Dcr.And that might correspond to close to 2 full points of Scr.Say 9.5 to 11.5.
This Dcr thing is way more important than a lot of guys suspect, and especially so for guys who want the MOST bang for the buck.
So pick the cam to fill your operating range, and get the fastest rate of lift and the highest lift, that the cam guy will sell you.And the springs that are matched to it. Get the ICA from the card. Plug it into the Dcr calculator, to spit out the Scr. Then go build it.
Another option might be to call MRL. Since his shop is spitting out engines with really nice numbers, he must know a thing or two about picking cams.
Or I can just tell you what works for me.......................your results may vary.
Click to expand...

Listen and under stand what was just posted.
Camshaft
 
Bad Sport said:
It's leaking out my ears. :D

I "thought" I had mine figured, now ya got me wondering.


Great thread Matt!!!
Click to expand...

Thank you,

I got limited funds to giterdun so i wanted to get it right the first time. This is why i asked the question. BTW i was using a couple different compression calculators on the net. They were all spot on with the numbers.

Matt
 
Ok heres another way of looking at it and can be somewhat easier.And is what I would do. I would let the engine pick the cam.
I would build a zero deck short block. I would calculate the Scr using the FelPro .039s for a tight quench, and your favorite heads. From the Scr,I would back-calculate to get the ICA from the Dcr that I have previously figured out will work; with the parameters of gas, and altitude. And finally, I would choose the fastest rate of lift cam I could find that will make the numbers I might be after, and that the heads demand, using that ICA as written in stone.

To illustrate this, I'll throw some theoretical numbers at you; lets say your 360 comes in at .040 overbore, and the stroke remains at 3.58, and the rods come in at 6.120. This makes 367 cubes, and a piston swept of 752cc. Lets assume 5cc for eyebrows,8.6 in the gasket and 58cc in the aluminum head. That total chamber volume computes to 71.6cc. So the Scr will be (752 + 71.6)/71.6 = 11.50
Ok now, from the forum talk and by personal experience, I know that 91E10 will support 8.5 to 9.2 Dcr.( I am successfully running 8.6 on 87E10, at 900 ft above sealevel) Since I want the most bang for the buck, Ima gonna push the edge at 9.0. Going to the Dcr calculator with all these numbers,I find an ICA of 63* at sealevel, will do it.Shazzam! (And if you are at other than sealevel(duh), each 1000ft may require a reduction of 2* in the LCA .That makes about 61* at 2000ft.)
So now we shop for a cam that has an installed ICA ,that we have just determined. Call your favorite cam-grinder and tell him you want such, on a fast rate of lift cam. He will ask you a bunch of questions, to arrive at a duration, lift and LDA, that will satisfy your needs.
And if perchance we aimed a little high on the ICA, you still have recourse.You can; 1)go to a higher octane gas, or 2) reduce the intake air temperature,or 3) reduce the combustion chamber temperature,or 4)retard the cam,or 5) retard the timing, or 6)add octane booster,or 7)add water injection,or 8) upsize the cam adding some ICA, or 9) grind a few ccs out of the piston crowns.. Lots of options.You are in no wise stuck. Also, bear in mind the engine needs just enough octane to suppress knock at full load WOT. More helps not a bit. And If you build an engine to require 91 at full load-WOT, then when cruising or on the primaries it may never require more than 87, or 81, or 60...who knows!

As to the actual build;
I would do a minimum of machining. Of course boring is a must.And crank grinding is usually a must as well. But I would check the decks for straightness, and if there was any way possible to not shave them I wouldn't. I would drop in the crank on new bearings and torque it up. If it turns, I'm not letting anyone ever talk me into an align-hone, period. Here are the reasons why; It's way too easy for a shop to wreck a sbm block by an error in setting up for the align-hone. When this happens the rear mainseal may no longer seal. That is a really sad thing to discover, after the engine is in the car.I imagine there are shops that can do a perfect job, I just have not found one. As to the decks; if you cut them, it leads to more machining costs to get the intake ports to line up, and a tremendous chance that things can go wrong.
Instead, what I would do is, get custom fit pistons to put the crowns exactly up at the decks.KB has several options. I'm guessing other suppliers do too.In the end those off the shelf KBs plus fitting, will probably cost you less than having to machine everything in sight,PLUS you will not have fitment issues with the intake.BONUS.
Ok, that's my story and I'm sticking to it.
 
Actually, most in depth engine building articles say to choose the camshaft last, but that's something I have never done myself.

That said, to the OP, you have aluminum heads. In order to take full advantage of them you will need a moderately aggressive cam at the very least. Those two things alone say you can stand over 10:1 compression with no trouble.

My God. Deck the block to zero deck with the KB 107 and go with it. You will be fine. A lot of yall are WAY over thinking this.
 
RustyRatRod said:
Actually, most in depth engine building articles say to choose the camshaft last, but that's something I have never done myself.

That said, to the OP, you have aluminum heads. In order to take full advantage of them you will need a moderately aggressive cam at the very least. Those two things alone say you can stand over 10:1 compression with no trouble.

My God. Deck the block to zero deck with the KB 107 and go with it. You will be fine. A lot of yall are WAY over thinking this.
Click to expand...

AHAHAHAHAHAHA,
You Sir are OFF the Christmas List...
 
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