Decisions Decisions!

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dartfreak75

dartfreak75

Restore it, Dont part it!
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So I'm kinda stuck on deciding my next move with my engine. I have called and called and ordered and ordered everyone I can find that "carries" h116cp+60 pistons no one has them apparently they are all shipped directly from the manufacturer even summit! So I called the sealed power and they dont even know when they will have them. I don't want to wait another 6 months or a year to get my engine done so I gotta decide between the h405cp or the kb107
The 405s with my cam and elevation will put me at 7.0 drc the kb107s will put me at 8.1 without elevation it is 7.5 and 8.6 drc.
I dont want to put all this time and money and work into it and then. I be satisfied with the performance of it but at the same time I dont want to put all the time and money and have a picky engine I cant get to tune or run right on pump gas either. It's a shame because the h116cp came out perfectly I was gonna be 7.5 with elevation and 8 without. 8 is my target I have read alot about drc and that is the target for performance on pump gas. I actually have considered going with the kb107s and going one step more aggressive with my cam that will put my drc back in line with the h116 pistons. But I hate to spend an additional 200 on another cam. Plus more springs etc etc. When you change one thing you have to change everything lol tell me what you think.
 
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If you can't decide which woman to marry, pick the one with the biggest boobs... :D :D
 
dartfreak75 said:
So I'm kinda stuck on deciding my next move with my engine. I have called and called and ordered and ordered everyone I can find that "carries" h116cp+60 pistons no one has them apparently they are all shipped directly from the manufacturer even summit! So I called the sealed power and they dont even know when they will have them. I don't want to wait another 6 months or a year to get my engine done so I gotta decide between the h405cp or the kb107
The 405s with my cam and elevation will put me at 7.0 drc the kb107s will put me at 8.1 without elevation it is 7.5 and 8.6 drc.
I dont want to put all this time and money and work into it and then. I be satisfied with the performance of it but at the same time I dont want to put all the time and money and have a picky engine I cant get to tune or run right on pump gas either. It's a shame because the h116cp came out perfectly I was gonna be 7.5 with elevation and 8 without. 8 is my target I have read alot about drc and that is the target for performance on pump gas. I actually have considered going with the kb107s and going one step more aggressive with my cam that will put my drc back in line with the h116 pistons. But I hate to spend an additional 200 on another cam. Plus more springs etc etc. When you change one thing you have to change everything lol tell me what you think.
Click to expand...

KB107 while it's still in stock, then measure and calculate the actual compression ratio. If your compression and DCR end up a tiny bit higher than expected, unshroud the intake valve in the cylinder head a little bit and that will get you back toward the DCR you want. That is how I would do it with your stipulations in place.
 
I would try to go with the cp116's, they sit nice and high in the bore...

We're building a 360 that's .030" over and with the piston at TDC, we're getting 11 cc volume above the piston...

With a set of 340/360 heads we will be in the low 9's for compression...
 
I prefer sealed power over KB because the sealed power pistons have a thicker skirt... I had a skirt break off a KB 107 just handling it... Not sure if some one dropped it before we got it, but I didn't like how easily it cracked and broke off...
 
krazykuda said:
I would try to go with the cp116's, they sit nice and high in the bore...

We're building a 360 that's .030" over and with the piston at TDC, we're getting 11 cc volume above the piston...

With a set of 340/360 heads we will be in the low 9's for compression...
Click to expand...
That's what I want to go with but I cant find them in the plus 60 flavor. The kb107 sets slightly higher iv already milled my heads and everything to get exactly 9.5 scr with the h116cp but now I cant find them sold out and unavailable or backordered everywhere
 
krazykuda said:
I prefer sealed power over KB because the sealed power pistons have a thicker skirt... I had a skirt break off a KB 107 just handling it... Not sure if some one dropped it before we got it, but I didn't like how easily it cracked and broke off...
Click to expand...
My machinist does too! But the only choice I have with the speed pros is is 405 low compression pistons I can find them in the plus 60 and they are cheap.
 
Bobzilla said:
KB107 while it's still in stock, then measure and calculate the actual compression ratio. If your compression and DCR end up a tiny bit higher than expected, unshroud the intake valve in the cylinder head a little bit and that will get you back toward the DCR you want. That is how I would do it with your stipulations in place.
Click to expand...
I technically could go with a thicker headgasket too to bring it down if needed too. Right now I have the felpro 8335 gaskets they are .041 thick I'm not sure who makes one thicker than that
 
dartfreak75 said:
I technically could go with a thicker headgasket too to bring it down if needed too. Right now I have the felpro 8335 gaskets they are .041 thick I'm not sure who makes one thicker than that
Click to expand...


Fel pro has a head gasket that is about .062" - .065" thick, it comes in all of the tear down kits... They are 12.4 cc volume...

The only way to get .040" thick fel pro gaskets is to buy them separately...
 
krazykuda said:
Fel pro has a head gasket that is about .065" thick, it comes in all of the tear down kits... They are 12.4 cc volume...

The only way to get .040" thick fel pro gaskets is to buy them separately...
Click to expand...
Hmm that's interesting the ones that came in my kit are the 8335 they are like .050 noncompressed their website has them listed at .039-.041 compressed. I will have look into that that may help me out thats an extra .011 that I didnt account for that's right. How much do they compress when torqued down I figured it was at least .01-.02.
 
dartfreak75 said:
Hmm that's interesting the ones that came in my kit are the 8335 they are like .050 noncompressed their website has them listed at .039-.041 compressed. I will have look into that that may help me out thats an extra .011 that I didnt account for that's right. How much do they compress when torqued down I figured it was at least .01-.02.
Click to expand...

They end up around .062" compressed...

Yeah, I was putting a 318 together with stock pistons, then put a set of 920 heads on it and had to order the .040" head gaskets separately because they didn't come in the kits... That way I got my compression up to 8.5 on that engine...
 
krazykuda said:
They end up around .062" compressed...

Yeah, I was putting a 318 together with stock pistons, then put a set of 920 heads on it and had to order the .040" head gaskets separately because they didn't come in the kits... That way I got my compression up to 8.5 on that engine...
Click to expand...
If that's the case that will work out perfectly! That will put me at 9.8 scr and 7.7 dcr at my elevation and 8.15 dcr without elevation. So I could drive it to the beach or whatever and not where about the elevation change. Thanks for the help I think I will go ahead and order the kbs today
 
Those kb107s come with coated skirts now, but they leave the mic. point uncoated , which I like. I just hung a set on some magnum rods.
 
I've had KB107'S in my la 360 for 15 years and have run flawlessly. Just with KB's you need to be careful with top ring gap. If you do use them be sure to follow gap instructions and they will survive like any other piston type/brand.
 
You're severely over thinking this. You're talking about "maybe" 20 HP difference between 7 and 8 DCR. Just pick one.
 
Diamond makes a nice flat top .
since you're overthinking things, why not ?
 
FYI... Never buy the recommended Edelbrock gasket as it's just a repackaged Fel-Pro 8553 for almost twice the money...
 
I just want to add, I balanced a setup last week with kb107s and they were heavier than their website listed. The lightest was 540 grams and pins were 132 grams average. With an external balance damper and b&m external balance flexplate I had to correct (remove) 28 grams from the rear and 15 grams from the front.

This 360 used magnum rods which are a few grams lighter on the small end. Quick and easy balance job. The Magnum rods are much closer than the LA rods as far as end to end weights.

IMG_1294.jpg
 
The 8553 I've measure after running them..were .046 . Im sure There is a variance of maybe .004

The the 519sd or maybe it was 518, but its measured compressed at .054
Both were for quench motors, set .029-.035 q distance so it was pretty important to get accurate readings
Your results may vary due to manufacturing tolerances. Always check.
 
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