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piston to wall clearance:old TRW forgings #1347340 12/07/12 12:18 PM 12/07/12 12:18 PM
Joined: Jan 2003 Posts: 9,679 Lima, Peru domingo OP EL Master
domingo OP EL Master Joined: Jan 2003 Posts: 9,679 Lima, Peru	I have 2 engines I am gonna build and Im gonna use old TRW pistons. One is a 340 and the other is a 440. 340 has TRW L2316 30 over pistons What piston to wall clearance should i run? 440 has TRW L2355 30 over pistons What piston to wall clearance should i run? Thanks!!!!

Re: piston to wall clearance:old TRW forgings [Re: domingo] #1347341 12/07/12 02:16 PM 12/07/12 02:16 PM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH Taking time off to work on my car
BradH Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	My 1996 Federal Mogul Performance Parts catalog says .0015" clearance for both of these pistons, but I have a difficult time w/ the idea of running a forged piston that tight. I always thought "tight" with a forged piston was .004" and only cast pistons could run safely with that little clearance. My $.02 is to hope some people who have used those TRW / Speed-Prod forgings in the same applications can provide some real world input.

Re: piston to wall clearance:old TRW forgings [Re: domingo] #1347342 12/07/12 02:30 PM 12/07/12 02:30 PM
Joined: May 2011 Posts: 4,492 northern,Ohio,USA C Clanton master
Clanton master C Joined: May 2011 Posts: 4,492 northern,Ohio,USA	I used .004 and ran it on the street/track. GOTBOOST!New improved with Victor heads. http://www.enginelabs.com/mopar-big-bloc...t-of-necessity/

Re: piston to wall clearance:old TRW forgings [Re: BradH] #1347343 12/07/12 02:50 PM 12/07/12 02:50 PM
Joined: Jan 2003 Posts: 9,949 Weddington, N.C. Streetwize master
Streetwize master Joined: Jan 2003 Posts: 9,949 Weddington, N.C.	I always ran my old 340 TRW stuff on the loose side, 005-..0055. Them old slugs took a while to get some heat in them but once they did they sealed up really nice. Not sure if the metallurgy of the new forgings is the same though ( been about 22 yrs since I actually used an OEM style forging)...safe bet (to me) is a half-though (.0005) MORE than the TRW spec. Just because the part number is the same doesn't mean the aluminum is exactly the same grade as way back when. Turned those old 340 TRWs up around 7800 with stock shot peened rods way back when, nothing ever went 'free range' on me and they made good power. .004 seems tight for those old slugs to me, especially for a motor your going to wind up tighter than an OEM style build, but that's just my opinion. Heat goes up not only from higher cylinder pressures, but also from higher piston speeds (increased wall friction = increased HEAT) The old six pack slugs we used to flip around backwards (notch to the back) to get rid of the factory pin offset. They'ed slap like all get-out cold but the motor would rev a bunch quicker up top. We used to do the old Dick Landy trick of shortening the 1.09 pressed pins about 1/2-5/8" to save about 50 grams per slug and lighten up the bob weight. Last edited by Streetwize; 12/07/12 02:58 PM. WIZE World's Quickest Diahatsu Rocky (??) 414" Stroker Small block Mopar Powered. 10.84 @ 123...and gettin' quicker! https://www.youtube.com/watch?v=-mWzLma3YGI In Car: https://www.youtube.com/watch?v=PjXcf95e6v0

Re: piston to wall clearance:old TRW forgings [Re: Streetwize] #1347344 12/07/12 03:10 PM 12/07/12 03:10 PM
A Anonymous Unregistered
Anonymous Unregistered A	.005 if you got away with it was amazing! The big block forged TRW's can seize / scuff on a hot day with .005---I would not let one out of the garage with less than .007 on those dogs--no way no how! .005 on a small block would be minimum IMO The ONLY pistons I have ever had scuff were all TRW forged --you let an engine with those get over 220 for a second and they are toast. It boils down to this---all that crud talk about super sealing with tight fit is BS--you can't measure an increase in performance on the street or track --but...you build one that is tight, it scuffs and drags the pistons --then you have a pile of junk--I have never ever seen a HP fall off on the dyno from too loose--ever! Matter of fact they always make better power---If you are in a class and taking a test on it--the answer is yes --run em tight, seal em better but in the real world--that is total Bull IMO unless you are talking a zillion $$$ Nascar unit builtbetter than any Swiss watch ever made and We do not have units like that. So...The "talk" and CW that surrounds very high tech units does not come into play on the ancient iron we play with.

Re: piston to wall clearance:old TRW forgings [Re: ] #1347345 12/07/12 03:12 PM 12/07/12 03:12 PM
A Anonymous Unregistered
Anonymous Unregistered A	Non Plate honed engines are even worse-- Wise knows what he is talking about, I respect his input always

Re: piston to wall clearance:old TRW forgings [Re: ] #1347346 12/07/12 03:22 PM 12/07/12 03:22 PM
Joined: Jan 2003 Posts: 9,949 Weddington, N.C. Streetwize master
Streetwize master Joined: Jan 2003 Posts: 9,949 Weddington, N.C.	David, The respect is mutual buddy. Like I said + 1/2 thou (.0005) over spec is my old rule of thumb and on boosted and sprayed 440's I used to run .008 P/W with zero sealing issues. Another thing that's not mentioned that also comes into play, way back when the oils were a lot thicker (nearly everybody ran 20w/50 or straight 40W Kendall GT-1) which is like 'Ragu' compared to todays thin oils. Thick oils were good for wicking away heat....provided they could get in all the tight nooks and crannies....too tight a P/W could be an issue for the old oils but maybe not for the light oils of today....all the same scuffing can occur "at the turns" where the slugs 'rock' in the bore at TDC and BDC. And as David said, the deck plate hone does make a difference, you want more clearance if it's not plated for the finish hone because the finished bore distorts when the head gets clamped to it. Last time I saw an old 2355 my buddy had it in his shop....he was using it as an Ashtray!!! Last edited by Streetwize; 12/07/12 03:31 PM. WIZE World's Quickest Diahatsu Rocky (??) 414" Stroker Small block Mopar Powered. 10.84 @ 123...and gettin' quicker! https://www.youtube.com/watch?v=-mWzLma3YGI In Car: https://www.youtube.com/watch?v=PjXcf95e6v0

Re: piston to wall clearance:old TRW forgings [Re: Streetwize] #1347347 12/07/12 03:55 PM 12/07/12 03:55 PM
Joined: Jun 2008 Posts: 3,916 usa L lewtot184 master
lewtot184 master L Joined: Jun 2008 Posts: 3,916 usa	trw clearances depends on if the piston has the slotted oil ring groove or the solid oil ring with drilled oil return holes. the slotted piston can run .004 or a little less. the solid will use .005-.007 as minimum.

Re: piston to wall clearance:old TRW forgings [Re: domingo] #1347348 12/07/12 04:20 PM 12/07/12 04:20 PM
Joined: Jan 2003 Posts: 27,201 Rio Linda, CA John_Kunkel The Erection Connection
John_Kunkel The Erection Connection Joined: Jan 2003 Posts: 27,201 Rio Linda, CA	The piston should have the desired clearance built in; the difference between the actual measured piston diameter and the bore nominal size is the clearance the manufacturer wants it run at. The INTERNET, the MISinformation superhighway

Re: piston to wall clearance:old TRW forgings [Re: John_Kunkel] #1347349 12/07/12 04:31 PM 12/07/12 04:31 PM
A Anonymous Unregistered
Anonymous Unregistered A	They Should ...but on the older TRW's they do Not have enough to keep the regular guy out of the weeds. I am glad to learn the diff in the TRW forgings as to the slots etc--great info but...you will never catch me doing one with TRW's ever again. They are way too heavy and swell up if all is not perfect. That being said I won many a race with a screaming 340 and TRW forged pistons ---and ...one of the best 340's I ever did for a customer had TRW Domes in it--that engine has bracket raced for years , won enough to pay for itself and made me very proud--but I will tell you this--it went out the door with .007 on a 4.070 bore. My main point is to inform unsuspecting builders that TRW forged slugs need a LOT of PTW so that you do not have issues--thats all I am saying. Good Topic--we have all learned something.

Re: piston to wall clearance:old TRW forgings [Re: ] #1347350 12/07/12 04:37 PM 12/07/12 04:37 PM
Joined: Oct 2003 Posts: 7,506 Az Crizila master
Crizila master Joined: Oct 2003 Posts: 7,506 Az	Quote: .005 if you got away with it was amazing! The big block forged TRW's can seize / scuff on a hot day with .005---I would not let one out of the garage with less than .007 on those dogs--no way no how! .005 on a small block would be minimum IMO The ONLY pistons I have ever had scuff were all TRW forged --you let an engine with those get over 220 for a second and they are toast. It boils down to this---all that crud talk about super sealing with tight fit is BS--you can't measure an increase in performance on the street or track --but...you build one that is tight, it scuffs and drags the pistons --then you have a pile of junk--I have never ever seen a HP fall off on the dyno from too loose--ever! Matter of fact they always make better power---If you are in a class and taking a test on it--the answer is yes --run em tight, seal em better but in the real world--that is total Bull IMO unless you are talking a zillion $$$ Nascar unit builtbetter than any Swiss watch ever made and We do not have units like that. So...The "talk" and CW that surrounds very high tech units does not come into play on the ancient iron we play with. TRW's in my old max wedge motor were .008" to .010". Fastest 300

Re: piston to wall clearance:old TRW forgings [Re: ] #1347351 12/07/12 04:50 PM 12/07/12 04:50 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	Quote: They Should ...but on the older TRW's they do Not have enough to keep the regular guy out of the weeds. I am glad to learn the diff in the TRW forgings as to the slots etc--great info but...you will never catch me doing one with TRW's ever again. They are way too heavy and swell up if all is not perfect. That being said I won many a race with a screaming 340 and TRW forged pistons ---and ...one of the best 340's I ever did for a customer had TRW Domes in it--that engine has bracket raced for years , won enough to pay for itself and made me very proud--but I will tell you this--it went out the door with .007 on a 4.070 bore. My main point is to inform unsuspecting builders that TRW forged slugs need a LOT of PTW so that you do not have issues--thats all I am saying. Good Topic--we have all learned something. I ran .007 on my old 340 12.5:1 and it did just fine but that was as tight as I would go...... JMO

Re: piston to wall clearance:old TRW forgings [Re: MR_P_BODY] #1347352 12/07/12 05:23 PM 12/07/12 05:23 PM
Joined: Jan 2003 Posts: 2,344 NE Ohio DoubleD top fuel
DoubleD top fuel Joined: Jan 2003 Posts: 2,344 NE Ohio	A minimum of .007 is what I have run � and I have run many of these in the past � the old Aries are even worse - those with the slots in the skirts BradH that .0015 is per inch of bore � that is the old TRW calculation

Re: piston to wall clearance:old TRW forgings [Re: MR_P_BODY] #1347353 12/07/12 05:41 PM 12/07/12 05:41 PM
Joined: Jan 2004 Posts: 8,949 fredericksburg,va C cudaman1969 Itch Nutz
cudaman1969 Itch Nutz C Joined: Jan 2004 Posts: 8,949 fredericksburg,va	Good post, I have .060 BRCs in my hemi with 13 thousands side clearance. After I miked the piston cold I heated it with a propane torch( just top) about what I though it would be running, piston skirt grue 11 thousands, I could almost hold it, that hot. Very supprized with that. Don't know how much the cylinder grows?

Re: piston to wall clearance:old TRW forgings [Re: domingo] #1347354 12/07/12 05:49 PM 12/07/12 05:49 PM
Joined: Nov 2004 Posts: 3,547 Syracuse,NY CompWedgeEngines master
CompWedgeEngines master Joined: Nov 2004 Posts: 3,547 Syracuse,NY	I have always ran those at -.005/.0055 small block, -.007-.008 big block. Yes , depending on engine operating temperatures, including oil temps, they can even scuff at those clearances. You need to know their tendancies. We use to cut the skirts, lighten the inner skirts, groove them,cut the pin bosses, as well as cut extra pockets to get more weight out of them, You could get a TREMENDOUS amount of weight out of them. RIP Monte Smith Your work is a reflection of yourself, autograph it with quality. WD for Diamond Pistons,Sidewinder cylinder heads, Wiseco, K1 rods and cranks,BAM lifters, Morel lifters, Molnar Technologies, Harland Sharp, Pro Gear, Cometic, King Engine Bearings and many others.

Re: piston to wall clearance:old TRW forgings [Re: CompWedgeEngines] #1347355 12/07/12 06:02 PM 12/07/12 06:02 PM
Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey J jamesc master
jamesc master J Joined: Jan 2003 Posts: 5,875 communist bloc of new jersey	correct me if i'm wrong but wasn't the idea of their being that heavy to bring them in line with the weight of stock pistons?

Re: piston to wall clearance:old TRW forgings [Re: jamesc] #1347356 12/07/12 11:11 PM 12/07/12 11:11 PM
Joined: Jan 2003 Posts: 9,949 Weddington, N.C. Streetwize master
Streetwize master Joined: Jan 2003 Posts: 9,949 Weddington, N.C.	Jamesc, Yes that was the idea, upgrade performance without having to spend a ton on rebalancing the bottom end. Aftermarket rods and cranks were only for Rich people back then, strokers were 'exotic' and if you had one you sure never 'tipped your hand' that you did WIZE World's Quickest Diahatsu Rocky (??) 414" Stroker Small block Mopar Powered. 10.84 @ 123...and gettin' quicker! https://www.youtube.com/watch?v=-mWzLma3YGI In Car: https://www.youtube.com/watch?v=PjXcf95e6v0

Re: piston to wall clearance:old TRW forgings [Re: Streetwize] #1347357 12/08/12 07:52 AM 12/08/12 07:52 AM
Joined: Mar 2006 Posts: 9,910 Eighty Four, PA B G Racing master
B G Racing master Joined: Mar 2006 Posts: 9,910 Eighty Four, PA	I is important where you measure the piston skirt for clearence.Most piston manufactures want .0045 to .005 at mid skirt(about 1/2" up) and .0015 to .002 at the bottom.Some of the new style with coating want a little tighter clearence. [IMG]http://i430.photobucket.com/albums/qq21/ajcasini/max_zpsdppwd9km.jpg[/IMG]

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