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Author
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Topic: TRW L2379F Pistons
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svt522
Journeyman Posts: 64
From: Hampton, Va
Registered: Jul 2001
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posted 07-03-2001 08:12 PM
   
I just tore down my Cleveland after 15 years of terrorizing the streets. The engine developed a bottom end noise, thus the teardown. Cylinders # 3 and 4 had broken skirts and number 6 was cracked. It had .030" over TRW L2379F pistons. The oil returns on these pistons were really large slots, almost the width of the skirt. Has anyone had similar problems and do the new TRWs still have the large oil drain back slots? Thanks! [This message has been edited by svt522 (edited 07-03-2001).]
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kid vishus
Gearhead Posts: 4357
From: middle of NC
Registered: Oct 2000
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posted 07-03-2001 08:26 PM
If they are anything like my domed TRW's, they are extremely tough. Perhaps your taper got to be too much and they were rocking in the bore. [This message has been edited by kid vishus (edited 07-03-2001).]
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svt522
Journeyman Posts: 64
From: Hampton, Va
Registered: Jul 2001
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posted 07-03-2001 08:40 PM
There was amost no cylinder wear...just a really slight ridge. The pistons came out easily. I'm not sure about too much taper. I'll have to check it out. Thanks for the reply.------------------
svt522
1996 SVT Cobra (#522)
1967 F100 351C
1973 "Q" Code Mach1 [This message has been edited by svt522 (edited 07-03-2001).]
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SteveLaRiviere
Administrator Posts: 32961
From: Saco, Maine
Registered: May 99
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posted 07-03-2001 08:53 PM
How much clearance were you running? Welcome to M&M! ------------------
'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC {Wife's car...}
All Fords since 1977
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Gary Ferringer
Journeyman Posts: 59
From: Kennerdell,Pa.
Registered: Feb 2001
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posted 07-03-2001 08:56 PM
I am running these in my Cleveland with no problems, and I am running a high compression ratio with them (12.27:1). This was accomplished with .060" off the heads, and .035" off the block. They have been in use for maybe 10 years or so. They also have the wide slot behind the oil ring like you described. It sounds to me like you might have gotten into some detonation. As a point of reference, I am running about .009" piston to wall clearance with these without collapsing or breaking off the skirts. Not by choice, my block is getting tired,and I certainly don't want to bore it out past .030". I'll live with a little less cylinder sealing to be able to race another day. ------------------
'85 Capri
Cleveland powered
carburetted
6.95 1/8th
@94 1/2 MPH
1.49 60 ft.
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svt522
Journeyman Posts: 64
From: Hampton, Va
Registered: Jul 2001
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posted 07-03-2001 09:05 PM
If I got into detonation that bad...shouldn't there be some evidence on the piston crowns? Also, is .040" over too much on the thin-wall castings? I know everybody says no way...but all the piston manufacturers make them!? The bores look really good for the miles/abuse they've seen! Should I just hone it and throw some new .030" slugs in it? It was balanced with them during the original build. Thanks.FIRST ON RACE DAY! ------------------
svt522
1996 SVT Cobra (#522)
1967 F100 w/351C, C-6, 4.11 Detroit Locker
1973 "Q" Code Mach1, 3/4 Vinyl Top, Fold-Down Rear Seat, A/C [This message has been edited by svt522 (edited 07-03-2001).] [This message has been edited by svt522 (edited 07-03-2001).]
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SteveLaRiviere
Administrator Posts: 32961
From: Saco, Maine
Registered: May 99
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posted 07-03-2001 09:15 PM
I should add that I've used two sets of those pistons over the last 20 years without problems.I would just hone and replace the pistons, myself, after having the bores magged. {thinking of Kid's and Peter's cracking problems} I wouldn't bore a Cleveland more than .030", at least not without having the bores sonic checked first. ------------------
'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC {Wife's car...}
All Fords since 1977
IP: Logged |
Gary Ferringer
Journeyman Posts: 59
From: Kennerdell,Pa.
Registered: Feb 2001
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posted 07-03-2001 09:19 PM
Usually with detonation like that you will see a little bit of aluminum on the insulators on the plugs, or the insulators themselves will actually be cracked. Look very closely at the top of the piston,especially near the valve reliefs, you will also see some pitting as well if you had some detonation,or if you got a little lean for some reason. .040" over isn't that bad depending upon your power level, or you rpm's. In my personal opinion it is a good idea to get the block sonic checked first. Look at some of the problems that kid vishus has had with cylinders cracking,and you will see that it can be a problem. Why don't I go to the next size overbore? Because I am making acceptable power with what I have, although not great, and it doesn't affect my consistency as of yet, and that is the most important thing in bracket racing. One thing that I definitely do is not let the engine much above an idle until it is thoroughly warmed up. If fact that is one thing I wanted to ask you. Are you in the habit of revving the engine up while still cold? this will do it as well. ------------------
'85 Capri
Cleveland powered
carburetted
6.95 1/8th
@94 1/2 MPH
1.49 60 ft.
IP: Logged |
SteveLaRiviere
Administrator Posts: 32961
From: Saco, Maine
Registered: May 99
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posted 07-03-2001 09:26 PM
Another sign of detonation is excessive ring/land clearance. Detonation actually makes your top compression ring flutter, which is the sound you hear. Over time, this widens the clearances, although not as much with a forged piston.------------------
'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC {Wife's car...}
All Fords since 1977
IP: Logged |
kid vishus
Gearhead Posts: 4357
From: middle of NC
Registered: Oct 2000
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posted 07-04-2001 08:56 AM
I would like to add, the first cylinder I cracked this year was .030 and only 10.4-1 compression. But that was with a domed (heavy) TRW piston and it did see 7400 rpm. And with that bad rod to stroke raito, and stock (heavy) rods, the load on the side of the cylinder had to be tremondous. When the shop went to sleeve that hole, they actually broke thru the cylinder wall while boring it out to put the sleeve in. He said that was the first time that had ever happened to him. If thismotor doesnt see much rpm, and the cylinders sonic checked ok, going .040 would probably be fine. I dont have anyone local that can sonic check, so I have yet to have that done.
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svt522
Journeyman Posts: 64
From: Hampton, Va
Registered: Jul 2001
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posted 07-04-2001 09:25 AM
Here's the combination I was running:
.030" L2379F Pistons
D1AE-GA castings with guide plates
Crane F-246 Flat Tappet
.570" Intake .590" Exhaust
282 and 292 at .020"
246 and 256 at .050"
71 degrees of overlap
108 degree LSA
ARP rod bolts
ARP main studs
oil gallery restrictors
Edelbrock Torker
Holley 3310 Carb w/ secondary metering block
generic 1.75" Headers
FMX w/3500 stall
4.11 Detroit Locker
All this is in a 67' short bed F100 that weighs 3600 lbs. I used to turn it to about 6500 rpm. I have a new COMP Cam still in the box with the following specs:
32-644-5 Flat Tappet
.589" Intake .615" Exhaust
294 and 304 at .020"
256 and 266 at .050"
87 degrees of overlap
106 degree LSAAny thoughts? I want this thing to "haul" when it goes back together. It needs to embarass those LS1 Slugmaros! ------------------
svt522
1996 SVT Cobra (#522)
1967 F100 w/351C, C-6, 4.11 Detroit Locker
1973 "Q" Code Mach1, 3/4 Vinyl Top, Fold-Down Rear Seat, A/C
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