L31MaxExpress
I'm Awesome
You don't need dual 3, but it doesn't hurt anything either. Thats how alot of the Express vans came from GM. Dual 2.5 to the muffler is what I am using on the L31 I built for the 87 G20 van.
Advice on 5.7 rebuild and performance upgrades
- Thread starter Dk47
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
Way Cool Jr (link to the build in my signature) is built similarly to what you're looking for. The cam is about as big as I would want to go with unported Vortec heads. Using the Vortec heads, keeping the cam mild, and reusing stock valvetrain stuff kept it cheap.
350 4-bolt main TBI block, honed, but no overbore
Factory Vortec heads, 062 castings, no porting, no machining
Factory crankshaft
Speed Pro H345DCP flat-top hypereutectic pistons - 9.5:1 compression ratio
Speedway Motors 5140 steel I-beam rods, 5.7", bushed pin
Lunati 20080720, duration @ .050" 211/219, lift .507/.515, 112 LSA
Factory roller lifters, dog bones, and spider assembly
Chevrolet Performance 12499224 LS2/LS6 valvesprings
Comp Cams 787-16 steel valve spring retainers
Comp Cams 648-16 race valve locks
I have some cheap Proform rockers, but if I were to build it again I'd stick with the stock rockers to save money for something that actually matters. My truck was a TBI, so I went with a Summit 4-barrel manifold and a Holley Sniper, but when I originally built the engine I stabbed it into my '99 Suburban and the factory injection handled it fine. It would have needed a re-tune, but it had a ticking noise so I pulled it back out. A .020" hole in the oil galley plug behind the timing chain fixed the tick. All this, gaskets, bearings, block plugs, oil pump, water pump, vatting, and magnafluxing was a little under $2000 about six years ago.
350 4-bolt main TBI block, honed, but no overbore
Factory Vortec heads, 062 castings, no porting, no machining
Factory crankshaft
Speed Pro H345DCP flat-top hypereutectic pistons - 9.5:1 compression ratio
Speedway Motors 5140 steel I-beam rods, 5.7", bushed pin
Lunati 20080720, duration @ .050" 211/219, lift .507/.515, 112 LSA
Factory roller lifters, dog bones, and spider assembly
Chevrolet Performance 12499224 LS2/LS6 valvesprings
Comp Cams 787-16 steel valve spring retainers
Comp Cams 648-16 race valve locks
I have some cheap Proform rockers, but if I were to build it again I'd stick with the stock rockers to save money for something that actually matters. My truck was a TBI, so I went with a Summit 4-barrel manifold and a Holley Sniper, but when I originally built the engine I stabbed it into my '99 Suburban and the factory injection handled it fine. It would have needed a re-tune, but it had a ticking noise so I pulled it back out. A .020" hole in the oil galley plug behind the timing chain fixed the tick. All this, gaskets, bearings, block plugs, oil pump, water pump, vatting, and magnafluxing was a little under $2000 about six years ago.
L31MaxExpress
I'm Awesome
Both lifter gallery end plugs were factory drilled from GM on the last few I have pulled apart. The replacement plugs are a all over the place. I prefer to have a small hole in both lifter plugs. Not only does it lubricate the chain and sprokets better, it purges air that would make the lifters noisier.
The rockers are where we differ, stamped steel for the trash can and 1.6 full roller is what I generally use. I gained power using them even on a TBI with stock cam and heads and the engine is noticeably smoother to me.
Dk47
Newbie
T
Thanks, I probably looked all over it, but I can't find the link to the build you did. If you can post it for me I'd appreciate it, that sounds like what I'm looking for.
https://www.gmt400.com/threads/89-stepside-way-cool-jr.46961/
The build thread is for the truck, though, not the engine. I built the engine before I joined the forum.
Edit: I just realized you're browsing on a phone. If you turn it sideways it'll show peoples' signatures, or at least mine does.
The build thread is for the truck, though, not the engine. I built the engine before I joined the forum.
Edit: I just realized you're browsing on a phone. If you turn it sideways it'll show peoples' signatures, or at least mine does.
The oil gallery plugs are not all the same size on SBC. Newer engines tend to have larger galleries and therefore larger-diameter plugs.
Be sure to buy the correct soft-plug kit for the block in question.
For the record, Melling sells "vented" plugs including the size needed for the 880 casting I most-recently worked with. This MIGHT be the correct size for the oil galleries:
www.summitracing.com/parts/mel-mpc-54v
Melling MPC-54V Melling Freeze Plugs | Summit Racing
Free Shipping - Melling Freeze Plugs with qualifying orders of $99. Shop Engine Expansion Plugs at Summit Racing.
However, it's simple and easy to use a pin vice and drill your own soft plugs. Some pin vices come with a small assortment of drill bits; something along the lines of .032 works well for this. Amazon has about a zillion different pin-vices listed.
Of course, there's the big push to tap those gallery holes and install pipe-thread plugs. Can't say I'm a big fan of that, but everyone else on Earth seems to think it's the right way to do things. The pipe-thread plugs can get drilled most of the way through with a normal drill and conveninetly-sized bit, then finished-off with the pin vice and a ~.032 bit prior to screwing them into the block.
Dk47
Newbie
I see where you changed valve springs and retainers, did you replace the pressed studs for screw in?
Nope. The LS2 springs are only about 10% stiffer than stock. I would have preferred to swap them to screw in, but it was my first SBC build and I was watching my budget.
What brand headers and mufflers are you using for your truck?
Drunkcanuk
I'm Awesome
They are Hedman headers, didn't have O² bung so had Midas weld one in, not sure what brand of mufflers, just generic Turbos from Midas. This was 20yrs ago
