When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Ok, first off, I'm new to the LS world and this is my first build. I tried searching for the answer, but I must have been searching for the wrong topics.
I built a 408ci LS2 for my boat. The motor is carb'd using the Daytona Sensors Smart Spark LS set up for ignition. So all I am running is a crank sensor, cam sensor and the coil packs. Here is a pic, I think it turned out pretty cool...
Here is my question, The motor had reversion issues, sucking water back through the exhaust into the engine. By the time I got it fixed, i had sucked something into number 8 cylinder and it scored the block. I found a new block local to me, but it is a Gen III iron block. What do I have to do to make my rotating assembly, cam and sensors from the Gen IV LS2 work in the Gen III block? Or can I? Should I just keep looking for a Gen IV block? Any help is greatly appreciated!!!
Folks upgrade the gen III to use the front cam sensor all the time..It bolts on and guess what? You already have one and the correct front cover. I am assuming you are not using the knock sensors which would be another consideration. Outside of that, it should bolt together short of different head studs/bolts.
Cast iron will add about 100lbs. I am not sure what size boat or use cases so I don't know if that 100lb matters to you. Depending on how you have the cooling system set up, you may actually be a little safer with the iron block. If separate cooling system, probably doesn't matter.
Bottom line, off the cuff, other than the 100lbs and the head fastebers(if you didn't buy expensive studs), I think you shouldn't rule out the gen III block. To the rest: am I forgetting something?
Actually, the extra 100lbs might help me. It's a 25ft boat that had a 454 in it, so I cut 540lbs out of the back. So the extra 100lbs will help balance the boat out a little more. As far as cooling goes, I am switching it over to a closed cooling set up, basically a water to water cooling that uses a heat exchanger that is filled with antifreeze.
So the front timing cover that I am using bolts right on and I can use that cam sensor? Do I need a special timing chain or will the one off my LS2 work? I am not using the knock sensors, so that's not an issue. And I am running ARP head studs right now. Why won't they work? Different thread in the block or something?
Thanks for the reply, if I can get away with a Gen 3, it would save me a lot of time.
It is common for folks to cheaply upgrade gen III truck engines with the LS2 timing setup, whether for a better chain, or for a cheap LS2 cam(similar to LS6 but no provision for rear cam sensor). Bolts right on. I am assuming you have a 3-bolt cam. Some early gen III blocks don't have the holes for the timing chain damper. Many run without it and if it matters to you, Trick Flow sells a retrofit bracket for about $50 to give you the provisions to mount it. I think in a boat app where it is mostly constant RPM it is probably not needed as much as in a car where the throttle is constantly snapping open and closed but it's cheap. Just thought of that.
Any block will need to be clearanced for a long-stroke crank of course.
Some of the head studs are the same length between gen III and IV and some are not. I believe the Gen III has 3 different lengths(2 in the block and short/small inboard on the intake side) and the Gen IV went to two different lengths(1 length in block and shorts inboard). The ARP studs sell well even used so you could sell and get the right kit, or even call ARP and replace just the studs that are different. Search online or here for "LS head stud length" or similar and you will find what I am referring to.
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Slideshow: The controversial Ferrari F6 swaps its original flat-12 for a Corvette Z06-derived LT4 V8 and sends power to four rear wheels through a custom-built drivetrain.
7 Most Reliable High-Performance Engines GM Has Ever Built
Slideshow:These GM engines didn't just make huge power, they survived abuse, boost, track days, and six-digit mileage with a reputation for refusing to quit.
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...
LS2 Build question. 
