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Stock bore higher compression pistons for a 403 available anywhere?
Does anybody know of a simple stock bore 403 piston that is available anywhere that has anything better than the silly 18.5cc ultra low compression dish? I have found plenty of higher compression replacement pistons, but none for a stock bore. I suppose the aftermarket assumes that there is no need for a stock bore improved piston for the poor ol' wheezer 403's? Seems odd that I couldn't find a better than stock piston in the stock bore size. I know it is a demand driven market, and there is apparently just no demand. And no, I'm not spending big money on a custom set of pistons for this temporary engine - just doesn't make sense. Maybe it would help the resale value on the engine though? Dunno, can't see putting heavy money into a set of custom pistons for this 403...
Let me know if anybody by chance may have a vintage set of higher compression 403 pistons. I see they were once available eons ago... or has any knowledge as to possible availability anywhere.
I took a general look around Craigslist Florida areas for the Racetec 403 pistons but didn't turn up anything. I don't have / do Facebook, so I can't look around that way... I was talking to another guy in the Olds industry today and he gave me the heads up to contact Racetec, so I sent them a message requesting info on the possibility of them being able to supply a stock bore 403 piston with something better than the silly +18.5cc low compression dish.
Fingers crossed! Maybe they will get back with me with something I can run with. Hearing from you and the other guy that these do indeed exist gives me hope. It may be a rare elusive animal, but I will track it down anyway I can
Thank you kindly!
Paul
Last edited by Clark455; April 4th, 2022 at 08:57 PM.
I would join FB or find someone with an account. I don't like it either but there is good stuff there. For example, someone is selling a set of standard bore pistons like you need and exactly described (auto tech forged Pistons and rings $400) Brand new in the box.
If you are going to take pistons out anyway, maybe go 20 over since those are easier to get and freshen up the engine?
Absolutely wonderful dealings with Racetec Pistons today!
I called Racetec Pistons today and had a wonderful experience dealing with Tim over there. He is custom building a set of two eyebrow ultra-light 4032 alloy forged pistons for me (matching the weight of the factory cast pistons so that I don't have any balance issues), along with also providing the modern plasma moly ring set to match. I was expecting him to say 2-3 months, but fell out of my chair when he said two, maybe three weeks max (that's lightning speed these days for anything custom!). As mentioned before, you can get all kinds of pistons for the 403 in an overbore sizing, but you will not find pistons for use in a stock bore (other than the stock replacement dismal 7.9:1 dished pistons). I guess the aftermarket doesn't see a demand for a stock bore 403 these days. Since these blocks are just so darned thin in the cylinder walls, I happen to be fortunate to have a low mileage 403 that has almost mint cylinder bores - you can still see the factory cross hatch in some areas. Since I am installing Speedmaster big block heads milled down to provide a 69cc chamber, installing a healthy cam, feeding it E85, all that good stuff, I only need to hone the bores slightly to clean them right up. The forged replacement pistons will benefit from the slightly extra clearance of honing the cylinders - don't want them running to tight (getting hot and pissy). I am SO against boring such a thin cylinder wall that I have moved heaven and earth to prevent boring this engine so that I can keep some strength and rigidity in the cylinder walls - I am going to lean on it some here and there after all.
Here is what I'm going to end up with:
Moving from 7.9:1 to almost 10.5:1 will wake this rascal up. With the big block Speedmaster heads on it, along with a good valvetrain, I am projecting about 350, maybe 375 horse out of it. The fun part is going to be the torque. Even though these weezers only had 180 horse from the factory, they had some pretty good torque. Pumping up the compression and letting it breathe ought to run pretty darn good. I used to build bunches of 403's 25 years ago upgrading customers 350 Rockets to "sneaky 403's" (almost sounds funny 25 years later), so I have direct knowledge of what they can do when you massage them just right. I know I can't lean on it too hard, or else I'll pop the bottom end, but it will keep me at least rolling this summer while my other big block projects eventually come to completion - hoping for spring of '23 (wow, that sounds so far off!).
Maybe I missed out on some mystical Facebook deal somewhere. I wasn't in the mood to go chasing maybe something / maybe nothing, instead nailing the objective towards getting where I need to be. Ever since my 488 stroker destroyed the Art Carr 200R4 three years ago, allowing it to go into free rev before I could respond fast enough, I haven't been able to drive my 442 since then, as the engine is in a painstakingly LONG process of receiving a set of billet main caps, a full 5 cap pan rail girdle, along with a bunch of "round two" rework. With a little bit of luck, I should be able to have this 403 back on the test stand to break it in just right in about 4 weeks. I just had it on the test stand running last night - sounded tough with the headers and Flowmaster 40 series mufflers, but even yanking the secondaries wide open on the stand showed it's general unwillingness to respond past 4 grand.
Soooo..... after running it on the test stand to break in the new cam, and then for a few hot / cold cycles, along with some spirited romps on the throttle, if all is well, we drop it into the 442 and start getting everything else set up so that it can move down the road under its own power for the first time in three long years - FINGERS CROSSED! I can't believe I am "settling" for this little 403, but hey, it will make plenty of tire smoke on demand LOL
Does anybody know of a simple stock bore 403 piston that is available anywhere that has anything better than the silly 18.5cc ultra low compression dish? I have found plenty of higher compression replacement pistons, but none for a stock bore. I suppose the aftermarket assumes that there is no need for a stock bore improved piston for the poor ol' wheezer 403's? Seems odd that I couldn't find a better than stock piston in the stock bore size. I know it is a demand driven market, and there is apparently just no demand. And no, I'm not spending big money on a custom set of pistons for this temporary engine - just doesn't make sense. Maybe it would help the resale value on the engine though? Dunno, can't see putting heavy money into a set of custom pistons for this 403...
Let me know if anybody by chance may have a vintage set of higher compression 403 pistons. I see they were once available eons ago... or has any knowledge as to possible availability anywhere.
if you put hood rods and custom lighter pistons, N or 330 crank with a 5 main halo it’ll be tough as nails. With the right cam and big block heads, 490hp/500 tq is easy
I can't imagine why anyone would put a new set of custom pistons in a block and not at least hone it .005-.010 to get a fresh surface and a straight cylinder bore.
Who said anything about NOT honing - what do you think I am, stupid? inexperienced? just some jackass? I have built over 75 Olds street / strip performance engines in my lifetime, never mind all of the other countless brand engines in addition... You ever built any 426 HEMI's? I used to own Unlimited Racing in Detroit 25 years ago building street / strip cars from head to toe, am a GM STG certified master tech, ASE master tech, and the damn owner / master engineer of Hydratech Braking Systems 22 years running now. What is your pedigree? I am the one that is producing the custom camshaft thrust plates for the Olds engines now, so with all due respect, shut the hell up chadman. The honing is not only to clean the (mint) bores up in general for the new rings to seat properly, but also to make sure the clearances are opened up just a hair more to accommodate the forged pistons... (just in case anybody reading doesn't know that is necessary).
Racetec was truly wonderful to deal with. I am looking forward to receiving my pistons. If I like the 403 pistons he is doing for me, I will have him do about 4 more custom sets for my other builds. It wasn't cheap though, $915 delivered, but this also includes a top of the line plasma moly ring set in addition to the pistons. My pistons are not going to have valve pockets as deep as Olds403 has shown, as I opted for the 4cc smaller eyebrows as I am not running a particularly high lift / duration cam. I am still going to install some checking springs and clay test to make sure I don't run the valves anywhere near touching the pistons.
Just some knucklehead in the woods and hills of Tennessee - oh, and I am Ukrainian...
Who said anything about NOT honing - what do you think I am, stupid? maybe? inexperienced? yes just some jackass? no comment I have built over 75 Olds street / strip performance engines in my lifetime doesn't seem likely from the novice questions you ask , never mind all of the other countless brand engines in addition... You ever built any 426 HEMI's? nope, I only build Oldsmobiles, your point? I used to own Unlimited Racing in Detroit 25 years ago building street / strip cars from head to toe, am a GM STG certified master tech, ASE master tech, and the damn owner / master engineer of Hydratech Braking Systems 22 years running now. should I be impressed?What is your pedigree? I am the one that is producing the custom camshaft thrust plates for the Olds engines now, so with all due respect, shut the hell up chadman. The honing is not only to clean the (mint) bores up in general for the new rings to seat properly, but also to make sure the clearances are opened up just a hair more to accommodate the forged pistons... (just in case anybody reading doesn't know that is necessary). If you think those 40 yr old "mint bores" are going to be straight and round after you kiss hone them for your stock bore pistons well you just don't know what you don't know.
Racetec was truly wonderful to deal with. I am looking forward to receiving my pistons. If I like the 403 pistons he is doing for me, I will have him do about 4 more custom sets for my other builds. It wasn't cheap though, $915 delivered That's actually really cheap , but this also includes a top of the line plasma moly ring set in addition to the pistons. My pistons are not going to have valve pockets as deep as Olds403 has shown, as I opted for the 4cc smaller eyebrows as I am not running a particularly high lift / duration cam. I am still going to install some checking springs and clay test to make sure I don't run the valves anywhere near touching the pistons.
Just some knucklehead in the woods and hills of Tennessee - oh, and I am Ukrainian...
Paul
Good luck there with your custom "ultra-lite" yet still stock weight pistons. Lol!
Clark455 I don't know why I'm bothering to attempt to help you at this point but here goes. If you were smart you would do one of two things, either 1) have the block torque plate honed first to see what size it needs to be to get the cylinders round, straight and to the correct surface finish. Then you would have Race-Tec make the pistons for that bore size. or 2) order the pistons oversized and have the block torque plate honed for that size piston.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,721
Originally Posted by chadman
I can't imagine why anyone would put a new set of custom pistons in a block and not at least hone it .005-.010 to get a fresh surface and a straight cylinder bore.
I would have to agree.........010 with the plate.
Last edited by VORTECPRO; April 6th, 2022 at 07:01 PM.
I have been a member of some high end forums since their inception over twenty years ago and enjoyed it. This forum has now gotten under my skin, so, since I don't need this BS from you, I have VASTLY better things to do than to waste my time here in your little click...
Man, go to bed at a decent hour, and miss all the fireworks!
$915 shipped is a smokin' deal!
I have to agree with chadman. This dude is the classic ask-for-advice/post-questions-don't-like-the-answer-and-get-mad type. If you don't want to hear the answer, don't ask the question.
Last edited by fleming442; April 7th, 2022 at 04:55 AM.
Wow, this got interesting.
Some other info;
If you actually get those pistons in 2-3 weeks I’ll be a monkeys uncle. I do a ton with them and I’m waiting 4-5 months even for ones that are just a slight variant of a current design.
You don’t need ANY valve reliefs. If possible just have them put a small dish in it.
And you don’t need to add “extra clearance”. Just give them the finished bore size and the right clearance will be built in. I’ve never had to deviate from their spec.
Wow, this got interesting.
Some other info;
If you actually get those pistons in 2-3 weeks I’ll be a monkeys uncle. I do a ton with them and I’m waiting 4-5 months even for ones that are just a slight variant of a current design.
You don’t need ANY valve reliefs. If possible just have them put a small dish in it.
And you don’t need to add “extra clearance”. Just give them the finished bore size and the right clearance will be built in. I’ve never had to deviate from their spec.
An "experienced" engine builder should know all that, correct?
Clark455 I don't know why I'm bothering to attempt to help you at this point but here goes. If you were smart you would do one of two things, either 1) have the block torque plate honed first to see what size it needs to be to get the cylinders round, straight and to the correct surface finish. Then you would have Race-Tec make the pistons for that bore size. or 2) order the pistons oversized and have the block torque plate honed for that size piston.
Golden heart to still help after that verbal diarrhea.
Last edited by Bernhard; April 7th, 2022 at 06:20 AM.
Clark455 I don't know why I'm bothering to attempt to help you at this point but here goes. If you were smart you would do one of two things, either 1) have the block torque plate honed first to see what size it needs to be to get the cylinders round, straight and to the correct surface finish. Then you would have Race-Tec make the pistons for that bore size. or 2) order the pistons oversized and have the block torque plate honed for that size piston.
Just went through this with my 455 build. I bored and honed with torque plate and sent the bore size to piston manufacturer.
Option #1 is best. My pistons are coming from Diamond and they say 12 weeks + (not holding my breath) and I wish they were only $915.
I have been a member of some high end forums since their inception over twenty years ago and enjoyed it. This forum has now gotten under my skin, so, since I don't need this BS from you, I have VASTLY better things to do than to waste my time here in your little click...
BUH BYE
HAVE A GOOD LIFE
I'M OUT OF HERE
Dude... Don't worry to much about it!
I've been beat down by some of the members of the so called "click" or as I call them " the engine god's". I don't give a sh**t. Just keep moving forward. I was enjoying your recent threads.
Although I do agree with bore size first and piston to match, the engine god's aren't always right. Some of them think that there way is the only way. Not true !
There is a forum member on here who is obviously a very experienced engine builder. In fact I know some members who have had some pretty awesome engines done by him. I have seen him get abused like no other by the so called click ( mostly by the head " engine God") but he keeps coming back. I don't know how he does it, but I'm glad. I enjoy reading his post's. I have to admit that some of the bickering is entertaining.
The point is.... Keep moving forward and keep us posted on your builds
Dude... Don't worry to much about it!
I've been beat down by some of the members of the so called "click" or as I call them " the engine god's". I don't give a sh**t. Just keep moving forward. I was enjoying your recent threads.
Although I do agree with bore size first and piston to match, the engine god's aren't always right. Some of them think that there way is the only way. Not true !
There is a forum member on here who is obviously a very experienced engine builder. In fact I know some members who have had some pretty awesome engines done by him. I have seen him get abused like no other by the so called click ( mostly by the head " engine God") but he keeps coming back. I don't know how he does it, but I'm glad. I enjoy reading his post's. I have to admit that some of the bickering is entertaining.
The point is.... Keep moving forward and keep us posted on your builds
This ^ ^ ^
I’ve seen people get away with a lot of things on engines and some of them ran really well while holding up admirably. I see all of this as partly entertainment and partly education. I’ve enjoyed following this thread, Clark has shown no deficit of enthusiasm!
BUH BYE...........got to get back to my rebuilds at a high level
Hey, I dingleberried my D block build after the dyno session and I have no regrets.
Yeah, it's funny how the shittiest builds run perfectly, then my builds where I freak out over every detail and am absolutely meticulous on assembly just fails immediately.
It's a great hobby. Keeps me busy.
Hey, I dingleberried my D block build after the dyno session and I have no regrets.
Yeah, it's funny how the shittiest builds run perfectly, then my builds where I freak out over every detail and am absolutely meticulous on assembly just fails immediately.
It's a great hobby. Keeps me busy.
100%!!!!
I traded a running 455 for 2 350s about 15 years ago. That same 455 has done 3 or 4 Power Tour long hauls and 2 Drag Weeks, all with stock cam and valve train. I've dumped an @$$load of money into 2 468 engines in the same time frame, but probably have similar mileage and none of the accomplishments. 😕
100%!!!!
I traded a running 455 for 2 350s about 15 years ago. That same 455 has done 3 or 4 Power Tour long hauls and 2 Drag Weeks, all with stock cam and valve train. I've dumped an @$$load of money into 2 468 engines in the same time frame, but probably have similar mileage and none of the accomplishments. 😕
Well I am not a expert. I do need help sometimes. I do not have any accomplishments . I am not humble sometimes . I do admit when shown wrong I don't like it but I do accept it.😂 Can you expert guru types take it easy on the uninformed? Nah just dish it out it okay. I learn stuff on here all the time. I will go back to my rock now.😂😂😂
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,721
Originally Posted by wr1970
Well I am not a expert. I do need help sometimes. I do not have any accomplishments . I am not humble sometimes . I do admit when shown wrong I don't like it but I do accept it.😂 Can you expert guru types take it easy on the uninformed? Nah just dish it out it okay. I learn stuff on here all the time. I will go back to my rock now.😂😂😂
I don't claim to be an expert; I can't even put my own shjt together. I'm still trying to drive the car to its potential. TnT tomorrow, fingers crossed that I stumble on to something and run a number.
edit: didn't happen. Spun twice and efi took a dump on the 3rd.
Last edited by fleming442; April 10th, 2022 at 12:54 PM.
Does anybody know of a simple stock bore 403 piston that is available anywhere that has anything better than the silly 18.5cc ultra low compression dish? I have found plenty of higher compression replacement pistons, but none for a stock bore. I suppose the aftermarket assumes that there is no need for a stock bore improved piston for the poor ol' wheezer 403's? Seems odd that I couldn't find a better than stock piston in the stock bore size. I know it is a demand driven market, and there is apparently just no demand. And no, I'm not spending big money on a custom set of pistons for this temporary engine - just doesn't make sense. Maybe it would help the resale value on the engine though? Dunno, can't see putting heavy money into a set of custom pistons for this 403...
Let me know if anybody by chance may have a vintage set of higher compression 403 pistons. I see they were once available eons ago... or has any knowledge as to possible availability anywhere.
How does the 403's cylinder walls hold up GENERRALY SPEAKING? Any of you guy want to opine what kind of condition my great running 403's cylinder walls might show, on teardown? It is in my 79 Trans Am, with Turbo 350 AT and 2.73 gears. 105,000 miles.
I cant speak about maintenance history, as I bought it approx. 20 years ago, with approx. 98,000 original miles. Thanks.
Do you need to say hey search I believe in Florida craigslist and Facebook marketplace a guy has a set of standard 403 auto tech distance. But they are dish
Do you need to say hey search I believe in Florida craigslist and Facebook marketplace a guy has a set of standard 403 auto tech distance. But they are dish
I read your suggestion and, originating in Jacksonville FL., I searched ,including all surrounding areas. I found a gut w/ 8, Old's 455 Pistons. I will look some more. Mike
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,721
Originally Posted by chadman
i can't imagine why anyone would put a new set of custom pistons in a block and not at least hone it .005-.010 to get a fresh surface and a straight cylinder bore.
So how about I get a second chance with you guys now that you can actually see one of my builds? YES, the bores were as clean as I had said they were (as per my initial teardown showing a considerable amount of the factory crosshatch still in place, finding only a minor carbon ridge at the tops). They straightened right up setting the Lisle 15000 bar hone at .002 with 280 grit, final finish with 320 grit stones for an overall total of a mere .003 looser than stock - no dingle berry hone like you guys were poking at me. The bore gauge readings turned out perfect for any possible taper and out of round you were insisting I was going to be seeing... I have since also built another stout street / strip 455 "roller motor" that just finished up all of its test stand run time perfectly. That one is going into the 442 next after the 403 is sold. Then after that, my 488 stroker will be the next one going up for sale.
The king daddy I'm currently working on in the background is the 540 Rocket block, with Mark Remmel (cutlassefi here) currently doing a lot of custom CNC porting, valve, and special chamber work to my Speedmaster heads to accommodate the TorqStorm twin supercharger setup that is going to be force feeding it:
Let me know if I can get back in the club here after my little temper tantrum (that I admit I shouldn't have thrown) exactly a year ago. I'm on different meds now LOL.
Thank you kindly - I'm looking forward to getting back into the swing of things with you guys
I moved heaven and earth chasing a true flat top stock bore...
I moved heaven and earth chasing a true flat top stock bore size 403 piston to find that they just do not exist. People had me chasing unicorns all over the place (likely at their amusement), but after exhausting untold amounts of research, the only way I am aware of to get a stock bore 403 flat top piston is to have it custom made. I sourced mine from Racetec. It only took two weeks for me to receive them, despite others saying months of lead time - maybe I just got lucky. At the time, they cost me just shy of a grand including plasma moly piston rings - I'm sure that pricing is long gone now...
Let me know if / how I may be of any further assistance.
I moved heaven and earth chasing a true flat top stock bore size 403 piston to find that they just do not exist. People had me chasing unicorns all over the place (likely at their amusement), but after exhausting untold amounts of research, the only way I am aware of to get a stock bore 403 flat top piston is to have it custom made. I sourced mine from Racetec. It only took two weeks for me to receive them, despite others saying months of lead time - maybe I just got lucky. At the time, they cost me just shy of a grand including plasma moly piston rings - I'm sure that pricing is long gone now...
Let me know if / how I may be of any further assistance.
Paul
Thanks. A grand is a LOT of dough for pistons! One of the two sources I contacted said "when your ready, we can MAKE them for you". When I heard "make" I heard $$$ !
For my 1979 "Bandit" Trans Am, ALL I want , due to SMOG (POSSIBLY) passing and STOCK appearance factors, is
1Flat Top Pistons
2 A MILD cam upgrade. MILD.
3 PORT stock heads (to retain AIR tubing ports).
4 Re-Jet Rochester Quardajet Carb
5 Recurve factory distributor.
April 3rd, 2022, 10:51 PM
Stock bore higher compression pistons for a 403 available anywhere?
I contacted Racetec
Absolutely wonderful dealings with Racetec Pistons today!
It was fun, and it was real, but...
The 403 is now completed, running astoundingly well - check it out :)
