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383 piston selection #2310231
05/24/17 10:11 AM
05/24/17 10:11 AM
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70Cuda383 Offline OP
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I'm going to be rebuilding a 383 for a friend. We're still in the planning stages of the build, but based on the rest of the car, this engine needs to be mildly peppy. The car is a 68 road runner 727 car. It's a good 10 footer. Looks good, drives good, but is no show queen, and is no race car. Suspension is very soft and floats over the road, the unibody has a lot of flex in it, and it's a weekend cruiser.

I'm going to try to convince him to go with a stock stroke stealth head build. Stealth heads because they're cheap, light, and enhance performance. The reason for the rebuild is because the #1 intake valve dropped and siezed in the guide, the #1 exhaust is suspect as the pushrod was bent, and to ensure a good rebuild, the heads will need completely reworked. For the money spent on rework, the stealths look like a good option.

But I want to get him some compression...seems there's about 4 options for 383 pistons with stock stroke and they all have 7.8:1 compression with 88cc heads, likely 8.3:1 with the 84cc closed chamber heads.

am I going to be forced to go with custom pistons? I want 9.5-10 compression, but don't really need a full race forged custom piston for $800...unless that's my only choice for stock stroke pistons with compression.


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Re: 383 piston selection [Re: 70Cuda383] #2310278
05/24/17 11:44 AM
05/24/17 11:44 AM
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Originally Posted By 70Cuda383
I'm going to be rebuilding a 383 for a friend. We're still in the planning stages of the build, but based on the rest of the car, this engine needs to be mildly peppy. The car is a 68 road runner 727 car. It's a good 10 footer. Looks good, drives good, but is no show queen, and is no race car. Suspension is very soft and floats over the road, the unibody has a lot of flex in it, and it's a weekend cruiser.

I'm going to try to convince him to go with a stock stroke stealth head build. Stealth heads because they're cheap, light, and enhance performance. The reason for the rebuild is because the #1 intake valve dropped and siezed in the guide, the #1 exhaust is suspect as the pushrod was bent, and to ensure a good rebuild, the heads will need completely reworked. For the money spent on rework, the stealths look like a good option.

But I want to get him some compression...seems there's about 4 options for 383 pistons with stock stroke and they all have 7.8:1 compression with 88cc heads, likely 8.3:1 with the 84cc closed chamber heads.

am I going to be forced to go with custom pistons? I want 9.5-10 compression, but don't really need a full race forged custom piston for $800...unless that's my only choice for stock stroke pistons with compression.



You can build a good running street 383 without going with custom pistons if you are careful with your cam choice. Something like a comp 268XE. Steel shim head gasket,cheap set of headers,maybe a little more stall than stock,more gear if you want but a 3.23 will work. I've got a good running 383 with a setup like that and one not so good with the MP 284-484. Good luck with your build.

Re: 383 piston selection [Re: 70Cuda383] #2310319
05/24/17 12:59 PM
05/24/17 12:59 PM
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Re: 383 piston selection [Re: 70Cuda383] #2310323
05/24/17 01:02 PM
05/24/17 01:02 PM
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https://www.summitracing.com/parts/slp-l2315nf30/overview/make/dodge

Best option for compression distance at 1.920

I ran these for the last 20 years

Measured about .015 in the hole , give or take , on my 71 383 Magnum

Was closer to 9-1 Compression with Fel Pro .038 head gaskets

Was running the 284-484 cam and a set of machined 906 heads with factory size valves

Worked out awesome until I installed a pair of Eddy 75 cc E Street Heads with the larger valves of course and the same Fel Pro Perma Torque .038 head gaskets and tapped #4 piston with an exhaust valve within the first 200 miles wiping out a cam lobe and bent push rod

So my point is without valve reliefs in those pistons your limited on cam selection

Would have never thought a 284-484 cam would have kissed a piston when changing to aluminum heads and everything else the same


1971 Dodge Charger Superbee
2011 Ram Sport 1500 Quad Cab Deep Water Blue Loaded
Siberian Huskies
Re: 383 piston selection [Re: bee1971] #2310338
05/24/17 01:35 PM
05/24/17 01:35 PM
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Originally Posted By bee1971
https://www.summitracing.com/parts/slp-l2315nf30/overview/make/dodge

Best option for compression distance at 1.920

I ran these for the last 20 years

Measured about .015 in the hole , give or take , on my 71 383 Magnum

Was closer to 9-1 Compression with Fel Pro .038 head gaskets

Was running the 284-484 cam and a set of machined 906 heads with factory size valves

Worked out awesome until I installed a pair of Eddy 75 cc E Street Heads with the larger valves of course and the same Fel Pro Perma Torque .038 head gaskets and tapped #4 piston with an exhaust valve within the first 200 miles wiping out a cam lobe and bent push rod

So my point is without valve reliefs in those pistons your limited on cam selection

Would have never thought a 284-484 cam would have kissed a piston when changing to aluminum heads and everything else the same



Seems like you are more limited in head selection. I,m running that cam with 906's and haven't had a problem,other than no bottom end.

Re: 383 piston selection [Re: pushbutton] #2310401
05/24/17 03:21 PM
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Campbell lists the 2315s at $620 per set. That's spittin' close to a decent "custom forged" piston.

The Diamonds that are the same as the 2315s except with valve pockets and weigh 100 grams less are $766.

The Keith Black pistons that JohnRR loves to hate because they've got extra huge valve pockets are more like $344, but they also have about stock weight. They'd get you to 9:1.

I think I'd use the KBs and put any savings into a hydraulic roller cam.

R.

Re: 383 piston selection [Re: 70Cuda383] #2310510
05/24/17 06:35 PM
05/24/17 06:35 PM
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Marysville, O-H-I-O
70Cuda383 Offline OP
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I've done one engine with Hypereutectics. but the kid never really drove it as the truck needed a transmission and then he left for the military. As far as I know the truck is mostly sitting somewhere.

What's the current feedback on running hypers for an NA street build? I know to gap the top ring excessively, but beyond that, is the general consensus still that hyper pistons are acceptable for a good street build?


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Re: 383 piston selection [Re: 70Cuda383] #2310539
05/24/17 07:29 PM
05/24/17 07:29 PM
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and is there any gain by going with aftermarket rods? I see Eagle has a 6.358" rod that weighs around 850 grams. Isn't that about what the stock rods weighed? For a stock stroke NA build, the stock rods are plenty strong. Just wondering if another $400 is worth it or not.

Right now I'm leaning towards: stock crank, stock rod, KB400, 440 Source Stealth heads.

Should have a nice long block for around $2000 to include block machine work.


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Re: 383 piston selection [Re: 70Cuda383] #2310547
05/24/17 07:52 PM
05/24/17 07:52 PM
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Quote:
Right now I'm leaning towards: stock crank, stock rod, KB400, 440 Source Stealth heads.


That's basically how I'd do it, except I'd cough up the extra $89 and get E-Street heads.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: 383 piston selection [Re: fast68plymouth] #2310612
05/24/17 09:55 PM
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Re: 383 piston selection [Re: 70Cuda383] #2310700
05/25/17 12:38 AM
05/25/17 12:38 AM
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Id use the 2315, cut the deck to zero deck. Pick the head you like. You'll have quench and a good CR. You'll need to watch cam size. Small to medium size probably okay, or fly cut for valve relief.

Re: 383 piston selection [Re: 70Cuda383] #2310708
05/25/17 01:06 AM
05/25/17 01:06 AM
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I just did/in the process of a build just like this. It's for my daily driver & I did the 1.920 flat top forged pistons, XE274H comp cam, E-Street 75cc heads, 0.039 Fel Pro gasket, stock forged crank, stock '65 rods, ARP Rod bolts, ARP head studs, Stock Rockers, RPM intake.

It ran good, I put 45 miles on it & the block cracked along the water jacket. Replaced the '65 block with a '68 383 & on start up bent the intake valves while hitting the pistons & all the pushrods bent. Checked the block & it's been decked. Still need to check the timing chain to see if maybe I got it off.

I think it's going to be a good set- up with almost 10:1 compression and as soon as I get my heads back im going to check it much better, run a solid lifter & adjustable length pushrod to check my clearances.


1967 Barracuda Formula S 383
1967 Chevy C10 Short Stepper
1980 Macho Power Wagon LWB 318
2021 Toyota Supra
Re: 383 piston selection [Re: grancuda] #2310723
05/25/17 01:48 AM
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Originally Posted By grancuda
I just did/in the process of a build just like this. It's for my daily driver & I did the 1.920 flat top forged pistons, XE274H comp cam, E-Street 75cc heads, 0.039 Fel Pro gasket, stock forged crank, stock '65 rods, ARP Rod bolts, ARP head studs, Stock Rockers, RPM intake.

It ran good, I put 45 miles on it & the block cracked along the water jacket. Replaced the '65 block with a '68 383 & on start up bent the intake valves while hitting the pistons & all the pushrods bent. Checked the block & it's been decked. Still need to check the timing chain to see if maybe I got it off.

I think it's going to be a good set- up with almost 10:1 compression and as soon as I get my heads back im going to check it much better, run a solid lifter & adjustable length pushrod to check my clearances.


Sounds like we both learned the hard way

With the Speed Pro 2315s and no valve reliefs , running the 75cc E Street Heads

Cam selection is pretty limited or tame


1971 Dodge Charger Superbee
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Re: 383 piston selection [Re: 70Cuda383] #2310741
05/25/17 02:58 AM
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I'd probably pass on the Speed-Pro L2315s. A friend in Tampa built one using them and every piston was a slightly different size. They honed the block to match the piston for each hole. Then they had problems with the stock 383 rods. The big ends wouldn't stay round and went through about 60 stock rods to get eight good ones. They ended up buying some use Hale Performance (Manley) rods and rebuilt them. Those are hard to find and Manley won't make any more of them. I think I'd look at the BBC 6.585" rods and a piston with the .990" pin size, or go with a 440 rod and pistons like these.

http://www.manciniracing.com/di94bo3st2.html


Floyd Lippencott IV
Re: 383 piston selection [Re: 70Cuda383] #2310772
05/25/17 07:17 AM
05/25/17 07:17 AM
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So if you go with the 2315's on the std rods the crank balance target would be 100 grams more than stock ie add mallory metal $$$ and just heavy and at a guess, crap compared to ANYTHING else your looking at building

Stock 383 bob weight is approx 2480gr

The diamond piston mentioned above (1.516CH) with a 440 source stock journal size 6.76 rod ($640+500) will net you a target bob weight of only 2205gr and roughly .016 off a 9.98 deck

kb162's 1.908CH matched to some K1 6.385 2.1 Sm Chev journal rods (CH6385ALRB8-A) plus some crank grinding to get them to fit ($440+322+machining) will be looking at 2312gr minus whatever the .275 worth of missing rod journal takes away, .0005 above a 9.98 deck
Cant find a 2.2 Journal size for that length rod for under 600, making the previous option better
http://www.jawzys.com/product.cfm?product=12050
http://www.cnc-motorsports.com/keith-black-kb162-030-hypereutectic-flat-top-pistons-4280-bore.html

I like the diamond/source option, but its not my money smile

edit the diamond piston with stock 440 rods will be roughly 2382gr BW - cheaper if you have good rods kicking around

Last edited by Alchemi; 05/25/17 07:22 AM.
Re: 383 piston selection [Re: Alchemi] #2310839
05/25/17 11:34 AM
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"Keep It Stupid Simple"

Stay out of the weeds here. Using the KB 162s with a 75cc E-Street, and zero decking the block, you will have approximately 9.7:1 CR.

A hydraulic roller would be nice, but a Lunati 10230703 flat tappet, a 1.6 roller rocker, and a RPM manifold makes a nice package. Even with cheap headers and a 750, your up about 100 hp over a factory HP 383. That's more than the soggy chassis will ever be able to use, and for relatively very little dough.

Make sure you follow KBs directions for ring gap, and keep the total timing at 34 or below to start. Proper distributor tuning/curving will make a huge difference in overall performance.

Can't get much simpler than that. Everything else is standard rebuilding procedures with quality parts and machining.


Mike Beachel

I didn't write the rules of math nor create the laws of physics, I am just bound by them.
Re: 383 piston selection [Re: 70Cuda383] #2311037
05/25/17 04:59 PM
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B3RE, you nailed it. 70cuda383, you can call Silvolite, aka, KB, Icon, pistons and they will tell you the same thing. The KB pistons are the best selection for your build. Call Daniel or Glen at sales, tech. and they will help you.

Re: 383 piston selection [Re: 70Cuda383] #2311834
05/27/17 01:07 AM
05/27/17 01:07 AM
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Diamond makes a nice 383 piston using a 440 rod.


Nautilus Racing-
We use Superformance gaskets and Turbo Action converters/products.
Re: 383 piston selection [Re: 70Cuda383] #2312053
05/27/17 05:24 PM
05/27/17 05:24 PM
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Reasons why 383 piston selection is tough:
1. large chamber volume of any B head makes static CR difficult to reach without a dome
2. short stroke + long rod (1.88:1 ratio) means piston motion near TDC is very slow - very tight P/V clearance during overlap (compared to RB)


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Re: 383 piston selection [Re: 70Cuda383] #2312111
05/27/17 07:54 PM
05/27/17 07:54 PM
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Marysville, O-H-I-O
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Isn't piston dwell time more a function of stroke than rod length?


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