Quick question for you all. My brother has #360 syclone and unfortnately is tearing the motor down as we speak.. main caps... in the process discovered his block is already .30 over. Should he go .40 over or have the cylinder's sleeved or what? Is the Sy/Ty block the same as a normal 4.3, because if it is I think he might as well go .40. Any thoughts??
SY/TY 4.3 Block vs Regular 4.3 Block
- Thread starter vader t
- Start date
the motors are pretty much all the same, with exception to the main caps. If you happen to notice, the ones in that motor should have a "N" cast in them, meaning they are nodular iron instead of the standard 4.3L caps. The pistons are really the only other internal difference.
the blocks are all the same for the most part.
The 1985 and some 1986 blocks have 2 piece rear main seals, so stay away from them.
In 1992, GM started making 4.3's with counter shafts to balance out the vibrations, they are known as "W" motors cause the VIN digit is just that, a W. The GM code for this motor is L35. The SyTy motors as well as the other 1987-1995 engines are "Z" motors, GM code LB4.
Any engine newer than 1996 is a "Vortec" engine. It has a balance shaft and also a weaker crank supposedly. Unfortunately the cylinder heads flow many many times better than the previous years engines, however the intake manifold will not directly bolt to it, so unless you plan on investing some time and money into it the conversion, stay away from the 1996+ engines.
Last but not least, the "W" L35 engines do have the balance shaft, however the L35 heads flow slightly better than the stock SyTy "Z" LB4 heads, so if you have plans to do any port work, I suggest trying to find a part of the L35 heads.
HTH
opps, forgot to mention one thing about the caps, yes, they are better than the normal 4.3L cap, however many people change the center mains over to the Milodon 4-bolt style and if you have access to a mill or even a sawzall, you can cut the outer holes off the "extra" main cap (since the set is for a 350) and you can make a new front cap also. There is only one company who makes an aftermarket rear cap I believe and the price is a little crazy from what I remember.
the blocks are all the same for the most part.
The 1985 and some 1986 blocks have 2 piece rear main seals, so stay away from them.
In 1992, GM started making 4.3's with counter shafts to balance out the vibrations, they are known as "W" motors cause the VIN digit is just that, a W. The GM code for this motor is L35. The SyTy motors as well as the other 1987-1995 engines are "Z" motors, GM code LB4.
Any engine newer than 1996 is a "Vortec" engine. It has a balance shaft and also a weaker crank supposedly. Unfortunately the cylinder heads flow many many times better than the previous years engines, however the intake manifold will not directly bolt to it, so unless you plan on investing some time and money into it the conversion, stay away from the 1996+ engines.
Last but not least, the "W" L35 engines do have the balance shaft, however the L35 heads flow slightly better than the stock SyTy "Z" LB4 heads, so if you have plans to do any port work, I suggest trying to find a part of the L35 heads.
HTH
opps, forgot to mention one thing about the caps, yes, they are better than the normal 4.3L cap, however many people change the center mains over to the Milodon 4-bolt style and if you have access to a mill or even a sawzall, you can cut the outer holes off the "extra" main cap (since the set is for a 350) and you can make a new front cap also. There is only one company who makes an aftermarket rear cap I believe and the price is a little crazy from what I remember.
I've built several really fast syty's using 40 over pistons on stock blocks but thats about as far as I would go on a production 4.3. If it were a bowtie you could go further.
SRP is a good 40 over piston as TRW/federal mogul doesn't sell their blower piston in a 40 over.
SRP is a good 40 over piston as TRW/federal mogul doesn't sell their blower piston in a 40 over.
IMO a stock crank with a four bolt main conversion will go high 11s fairly reliably as long as the oiling system has been upgraded some and you dont detonate it.
FWIW.. Stock cranks have been in the mid tens but they were cryo'ed, properly balanced, and a LOT of attention was paid to proper assembly.
FWIW.. Stock cranks have been in the mid tens but they were cryo'ed, properly balanced, and a LOT of attention was paid to proper assembly.
You can cryo the stocker if you like, it's a nice piece of insurance. I've never done it but from what I gather it's worth it. You definatly don't need a billet piece to run 11's or tens for that matter, but a stock crank will not handle any detonation. Thats where a billet crank would be nice.
Of course you don't want any deto on any motor, but syty's can't take much of it esp in the low 11/10 sec range.
Glad you liked the heads.
Of course you don't want any deto on any motor, but syty's can't take much of it esp in the low 11/10 sec range.
Glad you liked the heads.
Similar threads
