L31 Extreme Budget Build

[Erik the Awful]

I need to pickup a nutsert tool sometime and start using them.

Absolutely. I bought one at Northern Tool probably ten years ago for $20, and it's excellent. You don't have to spend a gazillion dollars to get a good one, but be sure and get one with a lot of thread pitches. When you set them, don't try and gorilla them as tight as you can, just crimp them until they're done.

 

[GrimsterGMC]

Absolutely. I bought one at Northern Tool probably ten years ago for $20, and it's excellent. You don't have to spend a gazillion dollars to get a good one, but be sure and get one with a lot of thread pitches. When you set them, don't try and gorilla them as tight as you can, just crimp them until they're done.

I second the nutserts, with the weight of that reservoir acting like a pendulum, it wouldn't take much to pull the sheet metal and come loose but a nutsert has all the extra real threads that you can put Loctite on if you need.

 

[L31MaxExpress]

I second the nutserts, with the weight of that reservoir acting like a pendulum, it wouldn't take much to pull the sheet metal and come loose but a nutsert has all the extra real threads that you can put Loctite on if you need.

Oddly enough that is how both the windshield washer reservoir and power steering reservoir on these vans that came with them were always mounted from GM. Not saying it cannot pull out, but I put the OE G-van reservoir on my 83 nearly 2 decades ago and drove it daily for years and it stayed in place.

Speaking of washer bottle, the OE bottle was cracked, assuming it froze with water based washer fluid in it. I have a solution to relocate the washer reservoir and double the tiny OE reservoirs capacity. What looks to be a quality USA built washer bottle with a built in pump. My tape measure shows, it should just squeeze in next to the radiator under the master cylinder on the front core support.

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[tayto]

Someone is sure to hate my cushion clamps and sheet metal screws securing wiring and hoses in this van in the future. Just the vacuum booster hose in this case, but up off the manifold and away from the belts.

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Express or Astro van power steering reservoir, easiest way to attach it, with sheet metal screws. I need to pickup a nutsert tool sometime and start using them. I used the pump reservoir from the same van on the 87 G20 pump to gain the remote fill location. The OE filler was burried in the engine compartment. If I add hydroboost later, will simply swap that reservoir with one that has the hydroboost return port in it. I have a few of them laying in a bucket of power steering pumps here at the shop.

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i like the late GMT400. accessories, do you think they would work with a TPI intake?

 

[L31MaxExpress]

i like the late GMT400. accessories, do you think they would work with a TPI intake?

I know for a fact they will not without using a smaller idler pulley and relocating the compressor. There was a guy that posted his truck a few years ago but never elaborated on any of the build. IIRC his was a 400 small block with 113 aluminum heads and it was a stump puller but no HP. I ran TPI years ago with aftermarket runners and a ported Edelbrock vortec base. Ran OK, but the Indmar intake I have would run circles around it.

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The Indmar intake will clear using a Fitech 92mm LS 4 bolt throttle body with some slight grinding on the ac bracket for IAC clearence. The Indmar upper I have was designed for a GM 90mm 4 bolt DBW throttle body and only needs some slight rework to match the 92mm opening of the TB. The Indmar intake has a similar torque curve to a Ramjet, runners are about 2" longer on the Indmar.

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[L31MaxExpress]

A couple more pictures from his build and ac relocation. He had to chop up his ac bracket as well for throttle linkage clearence. All that work for ~240 whp from a 400. My stock L31 intake made 272 whp and 330 wtq on the 350. On the 383 it made close to 400 whp and over 400 wtq. Much flatter power curve than a TPI 400.

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This is the torque and hp curves of the Indmar intake on a L31 using the GM 6395 roller cam.

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[L31MaxExpress]

I think this L31 will be healthy with the Proflow 4150 manifold. GM Performance sells the ZZ6 with it included. The ZZ6 is a ZZ4 that has been upgraded from the 113 heads to the Fast Burn heads. The Fast Burn heads dropped the static compression ratio a bit but flow a lot better than the 113s. The ZZ6 makes 420 hp and 408 TQ out of the box from a 9.7:1 350 using the very mild cam dating back to the ZZ2 or ZZ3, a 208/221 @ 0.050 roller cam. Down where a stock torque converter stalls it is already making 350 ft/lbs even with the single plane manifold and 200cc head ports.

19433044 ZZ6 EFI Turn-Key Engine Assembly 420 HP 408 lb.-ft

19433044 ZZ6 EFI Turn-Key Engine Assembly 420 HP 408 lb.-ft

www.crateenginedepot.com

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[L31MaxExpress]

Had some more stuff show up today like the air cleaner spacer, 1/2" PCV hose, 1/2" ID PCV grommet and a 1/2 barb union. I am out of town for a week or so. When I get back I have a day or two of just small finish work before it is ready to run and drive. I need to visit my local muffler shop and have the 02 sensor bung added to the LH exhaust pipe so that the Edelbrock system can enter closed loop as soon as possible and start learning. I have some wiring and plumbing to finish. A universal battery tray to install on the passenger "frame" rail. It will eventually be for the house battery for the lighting and inverter but for now it will be for the engine battery. I will drive it to the muffler shop after I get it up and going and get the exhaust setup done. Then I need to take it over and have the ac hoses made.

I modeled the final engine build on Engine Analyzer. Should be about 375 hp @ 5,500 and 425 tq at 3,400 with the accessories in place. Turned around and modeled that on the Wallace Racing drag racing calculator. They are both very accurate given good information. At 4,800 lbs, TH400 with its ~1,800 rpm stall speed converter, 3.08 gear and 28" tall P275/60R15 tires it should run pretty good. I modeled 300 msec shift time for the TH400 which should be fairly close. FWIW the 6.0L I pulled out modeled at 435 hp @ 5,600 and 430 tq @ 4,800 and the 350 should outrun it with the stock torque converter and limited gearing. Exactly why I pulled the 6.0L out. I will add that putting the power down will probably be the biggest challenge for the 3.08 open differential. My 1983 G20 never managed better than a 2.2s 60' time with an open 3.08 even with a 295 wide rear tire. I have no plans to take it and abuse it at a track, but still interesting comparisons none the less.

Stock L03 305 TBI

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LQ4 6.0L with Lloyd Elliot 862s, mild truck cam, TBSS intake and headers. I think the lack of low-speed power is evident in the 6.0L especially given the marginal improvement compared to the L03 in the 60' time.

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The flat top piston L31, GM 6492 cam, 1.6 rockers, Proflow single plane, and Hooker manifolds. Definitely apparant how much the L31 350s low speed torque helps with the tall gearing and tight converter.

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[L31MaxExpress]

The 6.0L would have done a little better if reved a bit higher ~6,000 but power fell off at about 5,800 and it was just a cruiser. The 6.0L was just gutless down low and it is hard to overcome that initial torque loss without gearing and converter, which both would have made for a lot more RPM on the highway with the non lockup 3spd auto. Best thing GM ever did for the LS was put that 4.03 1st gear 6spd behind them.

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[0xDEADBEEF]

435 sounds pretty low for a heads/cam 6.0.