383 piston selection?

Posted By: DusterKrazy

383 piston selection? - 08/04/10 03:15 PM

Is there a piston made for the 383 that will at least get me into the 9.5 range?? (not intrested in mega buck custom pistons)

It is a '64 383 2bbl engine.

Posted By: Banzaiii67

Re: 383 piston selection? - 08/04/10 04:02 PM

http://www.kb-silvolite.com/kb_car/performance.php?action=details&P_id=327

Posted By: StealthWedge67

Re: 383 piston selection? - 08/05/10 05:42 AM

If you're using your orig. older 516 casting closed chamber heads, the KB400 (posted above) will give you roughly 10.25:1. They make a flat-top that will get you closer to 9:1. For a non-performance rebuild, that's where I'd prefer to be.

Posted By: JohnRR

Re: 383 piston selection? - 08/05/10 12:23 PM

Quote:

http://www.kb-silvolite.com/kb_car/performance.php?action=details&P_id=327

This is the ONLY piston that will do it with an open chamber head , with a closed chamber the Speed Pro L2315 F at zero deck , requires cutting the block , will do it. once you add up all the extra machining cost the big buck custom isn't as expensive as you think .

What happened to your stroker idea ?

Posted By: CR8CRSHR

Re: 383 piston selection? - 08/05/10 03:07 PM

You all are forgetting the KB 162's. They won't get you the 10 + compression number you are looking for but with the 516 closed chambered heads and some work to them will get about 9.25 C/R. I have built 383's with that combo and been real happy...

Posted By: Banzaiii67

Re: 383 piston selection? - 08/05/10 04:40 PM

I've got 162's with a steel shim head gasket w/ some 346 heads, and i can run 89 octane with no pinging....I'm sure i'm at 8.5 to 1

Posted By: cptn60

Re: 383 piston selection? - 08/05/10 04:51 PM

Does the block require boring or is it within tolerance? There is a cheap solution with an early block for standard pistons only

Posted By: 68 Roadrunner

Re: 383 piston selection? - 08/05/10 07:08 PM

KB 400 pistons.

Posted By: cptn60

Re: 383 piston selection? - 08/05/10 07:13 PM

Quote:

KB 400 pistons.

Nope, 69 383 rr/magnum pistons. Positive deck(think stock 340) Really wakes up a 383.

Posted By: JohnRR

Re: 383 piston selection? - 08/05/10 07:35 PM

Quote:

You all are forgetting the KB 162's. They won't get you the 10 + compression number you are looking for but with the 516 closed chambered heads and some work to them will get about 9.25 C/R. I have built 383's with that combo and been real happy...

No , I'm not forgetting that piece of crap , KB dropped the ball making that piston.

Posted By: JohnRR

Re: 383 piston selection? - 08/05/10 07:39 PM

Quote:

Quote:

KB 400 pistons.

Nope, 69 383 rr/magnum pistons. Positive deck(think stock 340) Really wakes up a 383.

Nope , that piston has a 1.932 CH which puts it .003 BELOW the deck on a blueprint 9.980 deck height . You have to cut the block .023 or more to get positive deck height on that particular year engine/piston combo, I have two untouched 69 383 HP engines, neither have the piston above the deck. Then for the OP to use a block like that with a closed chamber head he would need a .060 thick head gasket, no reason to cut the block to achieve positive deck , $$$$ machine work, only to run a thick custom head gasket , more $$$.

Posted By: cptn60

Re: 383 piston selection? - 08/06/10 03:17 PM

Quote:

Quote:

Quote:

KB 400 pistons.

Nope, 69 383 rr/magnum pistons. Positive deck(think stock 340) Really wakes up a 383.

Nope , that piston has a 1.932 CH which puts it .003 BELOW the deck on a blueprint 9.980 deck height . You have to cut the block .023 or more to get positive deck height on that particular year engine/piston combo, I have two untouched 69 383 HP engines, neither have the piston above the deck. Then for the OP to use a block like that with a closed chamber head he would need a .060 thick head gasket, no reason to cut the block to achieve positive deck , $$$$ machine work, only to run a thick custom head gasket , more $$$.

No John it really does give a positive deck on a 66 and earlier block. Hemi Harvester built one back in the mid 80's, And used some shaved 906s on it. Ran well. I'm doing one right now for my 66 Net sedan.

Ask Tom Hoover about it; it was in the old DC manual.

Posted By: lokalik

Re: 383 piston selection? - 08/06/10 03:48 PM

oops... did i screw up 3 years ago? why is the 162 a pos?

Posted By: SomeCarGuy

Re: 383 piston selection? - 08/06/10 03:54 PM

Quote:

Quote:

http://www.kb-silvolite.com/kb_car/performance.php?action=details&P_id=327

This is the ONLY piston that will do it with an open chamber head , with a closed chamber the Speed Pro L2315 F at zero deck , requires cutting the block , will do it. once you add up all the extra machining cost the big buck custom isn't as expensive as you think .

What happened to your stroker idea ?

Agree but will add that he needs to get the block checked. Might need deck height corrected anyway, could cut for a zero deck and kill two with one.

Posted By: Banzaiii67

Re: 383 piston selection? - 08/06/10 04:20 PM

Quote:

oops... did i screw up 3 years ago? why is the 162 a pos?

It's not the piston itself, it is the design.

Quote:

that piston has a 1.932 CH which puts it .003 BELOW the deck on a blueprint 9.980 deck height.

In layman's terms if you have a zero deck block and you use the 162 piston it will sit .024 in the hole no matter what you do. If you have open cambered heads like i do you'll end up with no more the 8.8 to 1 compression even with a steel shim head gasket.

Posted By: dm69charger

Re: 383 piston selection? - 08/06/10 04:29 PM

Quote:

Quote:

oops... did i screw up 3 years ago? why is the 162 a pos?

It's not the piston itself, it is the design.

Quote:

that piston has a 1.932 CH which puts it .003 BELOW the deck on a blueprint 9.980 deck height.

In layman's terms if you have a zero deck block and you use the 162 piston it will sit .024 in the hole no matter what you do. If you have open cambered heads like i do you'll end up with no more the 8.8 to 1 compression even with a steel shim head gasket.

Mine sit .040 in the hole. Block probably was not decked by previous owner. Terribly Compression ratio. Looking to stroke it since I will have it out and torn down.

Posted By: ademon

Re: 383 piston selection? - 08/06/10 04:44 PM

This may be a dumb question so sorry, but why cant someone just copy the stock 383 hp flat top piston and maybe add very small 2/3ish cc valve pockets, so when you deck the block to clean and say mill your 906 heads 20 or 30thou you will end up with 9.5 + with a flat top. my stock bottom end 383 hp has flat tops that sit at about zero and with 80cc 915's and a .039 gasket CR ended up at 9.8 ??

Posted By: Banzaiii67

Re: 383 piston selection? - 08/06/10 04:56 PM

That sucks man, I bought my motor from a guy who already had motor rebuilt by a reputable shop here locally. Supposedly it was 9:1, at least that is what he told me. I purchased it for $2200. A few weeks later, after doing the research on what i really had, i took the build paperwork to the place that rebuilt it, and asked them about the build, the owner helped him at the counter and looked at the paperwork and the specs. Come to find out that the guy who built it was no longer an employee of the shop and according to the notes, it appeared he also completely overlook the piston comp ht even though it was balanced and blueprinted. The good news even with 8.8 compression it still runs pretty hard, with a Comp XE274 cam and 3.73 gears and i can run 89 octane with no issues. The 440 source alum. heads or even some steel closed chamber heads would solve a lot of issues, just wish i did it before i put the motor in the car.

Posted By: JohnRR

Re: 383 piston selection? - 08/06/10 08:17 PM

Quote:

Quote:

Quote:

Quote:

KB 400 pistons.

Nope, 69 383 rr/magnum pistons. Positive deck(think stock 340) Really wakes up a 383.

Nope , that piston has a 1.932 CH which puts it .003 BELOW the deck on a blueprint 9.980 deck height . You have to cut the block .023 or more to get positive deck height on that particular year engine/piston combo, I have two untouched 69 383 HP engines, neither have the piston above the deck. Then for the OP to use a block like that with a closed chamber head he would need a .060 thick head gasket, no reason to cut the block to achieve positive deck , $$$$ machine work, only to run a thick custom head gasket , more $$$.

No John it really does give a positive deck on a 66 and earlier block. Hemi Harvester built one back in the mid 80's, And used some shaved 906s on it. Ran well. I'm doing one right now for my 66 Net sedan.

Ask Tom Hoover about it; it was in the old DC manual.

Sorry , there is no way that can happen , the numbers don't lie , unless a 66 383 has a shorter deck height than a later 383? The .020 over deck height is the NHRA blueprint spec and you have to build a 68-69 383 to NHRA spec to get the factory advertised 10.0 compression ratio , that's piston .020 above the deck and the head cc at 79.5 , I've yet to cc a 906 under 90 cc .

I'll save you the trouble here is the math.

1.932 CH
6.358 rod
3.375/2= 1.6875 stroke

1.932 + 6.358 + 1.6875 = 9.9775

9.9775 - 9.980 = -0.0025

Ok I was wrong , my 56k mile original 69 383 HP in my original 69 Dart GTS had a piston .003 in the hole so the deck on that block is actually .0005 over stock , I screwed up my math at some point thinking a stock piston was .003 in the hole.

Posted By: JohnRR

Re: 383 piston selection? - 08/06/10 08:23 PM

Quote:

This may be a dumb question so sorry, but why cant someone just copy the stock 383 hp flat top piston and maybe add very small 2/3ish cc valve pockets, so when you deck the block to clean and say mill your 906 heads 20 or 30thou you will end up with 9.5 + with a flat top. my stock bottom end 383 hp has flat tops that sit at about zero and with 80cc 915's and a .039 gasket CR ended up at 9.8 ??

Because the aftermarket thinks that every 383 that exists has already been decked .010 or more , the closest currently available pistons are the speed pro L2315F flat top at 1.920 with no valve reliefs or a Diamond at 1.916 but the Diamond at least has valve reliefs , but you lose compression with the 4cc relief .

I'm currently building a Pure Stock Drags legal 383 using a semi custom Diamond piston , it will have a 1.935ish CH, because my block has already been decked .025 because I zero decked it for speed pros and the shop that did it screwed up and it had to be trimmed more, with no valve reliefs and a set of 906's cut to 80 cc .

Posted By: JohnRR

Re: 383 piston selection? - 08/06/10 08:30 PM

Quote:

oops... did i screw up 3 years ago? why is the 162 a pos?

I screwed up and rebuilt a 383 using them and didn't do the math till it was too late , I never ran the motor , took it apart and another member bought the pistons from me, he didn't seem to mind it, I did.

Why KB decided the piston needed to be .024 in the hoile and have a 6cc valve CAYNON is beyond me, In my opinion they dropped the ball, if they have made a quench dome piston it would have been a better solution.