Author Topic: Probe srs 12233 -030 piston advice for 493 stroker  (Read 173 times)

Offline cam440

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Probe srs 12233 -030 piston advice for 493 stroker
« on: July 26, 2017 - 07:48:50 am »
Hey everybody need some advice on a discontinued piston are these any good for a stroker combo price is right
Done some googling and not much came up Campbell enterprises has alittle info but that's it do they need special rings etc , not sure what to think is 11.1 with 84 cc rpm heads is that  high for the street and they are not zero deck height so that means more comp if zero decked  or do you need to zero deck on strokers or just run them as they are with close chamber heads looking at cams around mid to high 240 range with 110 lobe centre hi lift 545 sounds ok etc 241 and 247 at 50 , or  maybe a 564 in 493 stroker with stronge midrange for the street not into racing it much , my cuda is a 4 speed with 3.5 rear in it now


« Last Edit: July 26, 2017 - 08:54:50 am by cam440 »




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Re: Probe srs 12233 -030 piston advice for 493 stroker
« Reply #1 on: July 26, 2017 - 11:00:10 am »
Probe makes a quality piston, 11-1 may work depending on your fuel & your altitude... Zero deck is part of achieving Quench & Quench is part of getting 11-1 to work without race fuel....

I would plan on bolting the heads to the bare block & scribe the bore on the heads then open the chambers to match the bore.... A little work with a die grinder can pick up 3-4 cc's plus blending reduces hot spots....

This should explain "Quench"

I like to go tighter than the commonly accepted .040-.045 but it also depends on what you are trying to accomplish. Here's an article from KB pistons Chief Engineer, John Erb. I've read a lot of articles on the subject and this one helped me to understand better what was going on. It's long but worth the read imo.

What is the most, exact precisely defined occurrence in all piston engines? It isnt ignition timing, combustion, crank indexing, or valve events. It is Top Dead Center. You cant build an engine with an error at Top Dead Center because TDC is what everything else is measured from. Spark scatter, crank flex and cam timing can move, but TDC is when the piston is closest to the cylinder head in any one cylinder. The combustion process gets serious at Top Dead Center and about 12 degrees after TDC, most engines want to have maximum cylinder pressure. If maximum cylinder pressure occurs 10 degrees earlier or later, power goes away. Normal ignition timing is adjusted to achieve max cylinder pressure at 12 degrees after TDC. If your timing was set at 36 degrees before TDC that is a 48 degree head start on our 12 degree ATDC target. A lot of things can happen in 48 degrees and since different cylinders burn at different rates and dont even burn at the same rate cycle to cycle, each cylinder would likely benefit from custom timing for each cylinder and each cycle. Special tailored timing is possible but there is an easier wayMagnificent Quench. Take a coffee can full of gasoline burning with slow flicking flame. Strike the can with a baseball bat and you have what I would call a fast burn, much like what we want in the combustion chamber. The fast burn idea helps our performance engine by shortening the overall burn time and the amount of spark lead (negative torque) dialed in with the distributor. If you go from 36 degrees total to 32 degrees total and power increases, you either shortened the burn time or just had too much timing dialed-in in the first place. If you have really shortened the burn time, you wont need so much burning going on before Top Dead Center. Now you can retard timing and increase HP. Did you ever have an engine that didnt seem to care what timing it had? This is not the usual case with a fast burn combustion but an old style engine with big differences in optimum timing cylinder to cylinder will need 40 degrees of timing on some and others only need 26 degrees. If you set the distributor at 34 degrees, it is likely that 4 cylinders will want more timing and 4 cylinders will want less ( V-8). Moving the timing just changes, which cylinders are doing most of the work. Go too far and some cylinders may take a vacation. Now what does quench really do? First, it kicks the burning flame front across and around the cylinder at exactly TDC in all cylinders. Even with spark scatter, the big fire happens as the tight quench blasts the 32 degree old flame around the chamber. Just as with the coffee can, big flame or small flame, hit it with a baseball bat and they are all big instantly. The need for custom cylinder-to-cylinder timing gets minimized with a good quench. The more air activity in a cylinder you have the less ignition timing you are likely to need. When you add extra head gaskets to lower compression you usually lose enough quench that it is like striking the burning coffee can with a pencil. No fire ball here and that .070-.090 quench distance acts like a shock absorber for flame travel by slowing down any naturally occurring chamber activity. A slow burn means you need more timing and you will have more burn variation cycle-to-cycle and cylinder-to-cylinder, result more ping. Our step and step dish pistons are designed not only to maximize quench but to allow the flame to travel to the opposite side of the cylinder at TDC. The further the flame is driven, the faster the burn rate and the less timing is required. The step design also reduces the piston surface area and helps the piston top stay below 600 degree f (necessary to keep out of detonation). All of our forged pistons that are lower compression than a flat-top are step or step dish design. A nice thing about the step design is that it allows us to make a lighter piston. Our hypereutectic AMC, Buick, Chrysler, Ford, Oldsmobile and Pontiac all offer step designs. We cannot design a 302 Chevy step dish piston at 12:1 compression ratio but a lot of engines can use it to generate good pump gas compression ratio. Supercharging with a quench has always been difficult. A step dish is generally friendly to supercharging because you can have increased dish volume while maintaining a quench and cool top land temperatures. You may want to read our new design article for more information. ".

By John Erb
Chief Engineer
KB Performance Pistons
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Offline cam440

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Re: Probe srs 12233 -030 piston advice for 493 stroker
« Reply #2 on: July 26, 2017 - 04:45:43 pm »
Hi mate thanks for the email , sorry I get alittle confused sometimes when it comes to tech stuff like you posted it was a good read I'll have to read it a few times so it absorbes, I'm a body and paint guy mainly that's my thing , our gas over here is pretty good we have 98 octane , looking at building a real fun streeter with stronge midrange so you think if it's just on the edge I can blend those rpm 84 cc heads I have to help out with pinging , they are a decent piston you say hey I remember them years ago and people seemed to like them ,I can get these and some stock length 440 I beams with a eagle 4.125 crank which I'm told is a 493 is that correct sounds good to me remember I want to run my ported hp manifolds from year one hope they won't choke it up to much not looking for awesome top end just from 2000 to 5500 would do me on the street with a 4 speed would be a blast on polyglas tires lol , I can exchange those 84 heads for 88 open chamber if I want but closed seem to be the ticket with flat top pistons hey
« Last Edit: July 26, 2017 - 04:50:41 pm by cam440 »


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Re: Probe srs 12233 -030 piston advice for 493 stroker
« Reply #3 on: July 26, 2017 - 08:53:03 pm »
Stay closed chamber, if you can get true 98 octane you'll be fine.
JS27N0B 70 Challenger R/T Convertible  FJ5 Sublime, Show Poodle w/90,000 miles since resto
WS27L8G 68 Coronet R/T Convertible  PP1 Bright Red, Project
RM21H9E 69 Road Runner Coupe R4 Performance Red, Sold...
5H21C  65 Falcon 2 dr Wagon... Dog Hauler...

Offline cam440

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Re: Probe srs 12233 -030 piston advice for 493 stroker
« Reply #4 on: July 26, 2017 - 09:53:31 pm »
When they talk about cams that bleed off comp what size are they usually and bigger cube engine don't need deeper gears hey I'm a Pontiac guy my ho transam is a 455 ho and I run 342 and it loved them even tryed 3.08 and it had good aceleration
« Last Edit: July 26, 2017 - 10:01:54 pm by cam440 »

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Re: Probe srs 12233 -030 piston advice for 493 stroker
« Reply #5 on: July 26, 2017 - 10:03:41 pm »
mid 240's @ .050 & larger.....
JS27N0B 70 Challenger R/T Convertible  FJ5 Sublime, Show Poodle w/90,000 miles since resto
WS27L8G 68 Coronet R/T Convertible  PP1 Bright Red, Project
RM21H9E 69 Road Runner Coupe R4 Performance Red, Sold...
5H21C  65 Falcon 2 dr Wagon... Dog Hauler...

Offline cam440

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Re: Probe srs 12233 -030 piston advice for 493 stroker
« Reply #6 on: July 26, 2017 - 11:11:42 pm »
Cool cheers mate

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Re: Probe srs 12233 -030 piston advice for 493 stroker
« Reply #7 on: July 27, 2017 - 12:23:13 am »
 :cheers:
JS27N0B 70 Challenger R/T Convertible  FJ5 Sublime, Show Poodle w/90,000 miles since resto
WS27L8G 68 Coronet R/T Convertible  PP1 Bright Red, Project
RM21H9E 69 Road Runner Coupe R4 Performance Red, Sold...
5H21C  65 Falcon 2 dr Wagon... Dog Hauler...