Seriously considering a 88 to 98 Olds powered 4x4 Project Six Liter Slayer

[olds307 and 403]

I really miss an Olds powered truck, they made owning a truck fun. I almost pulled the trigger on a 94 GMC 1500 4x4 a year ago. It had the upgraded 14 bolt front axle. The price was fair, the 4L60E is always an issue with me, it made me think twice and skip it. It is a ticking time bomb, big time in a truck, actually used as a truck. I actually found a 95 GMC 1500 4x4. It is a drive, a trailer is needed due to the blown sbc 350 but being a 1500 strength wise is questionable. I actually have a motor in mind. I have a 403 block sitting and a complete stroker rotating assembly. I will actually have every part except a cam and machine for 424 ci 403 based motor. Build for torque with the Performer and I was thinking of building it, putting the 170cc runner #6 heads once the new SBO Olds heads come out and those go on the 358. Mark is working to convince them for a couple less CC in the chamber and SB sized runners. If that happens they would go on the 424. It will end up around 9.6 to 1. It would be a torque first and if horsepower comes, good. It would probably 400 hp and 500 ft/lbs pretty easy with iron heads, considerably more with the new aluminum. I was thinking of watching out for second gen Trans Am. Finding one that isn't a fortune, is the problem. Not sure I want another car needing every panel. This powerplant would destroy the weak 8.25 aluminum front diff and the 4L60E in a 1500, boom! I will be really looking for a decent body, non rotten 2500 for the strong diffs and a 4L80E. The 36 inch wide rad, the double thick core aluminum plastic rad would cool even a bored .039" oversize 403. Get second gen 403 Trans Am motor mounts, Transdapt adapter, serpentine adapter plates, a 94/95 with a blown 5.7 or 454 TBI would be ideal, best ECM and starting place. I like those years styling wise more than the earlier years. I would crank the fuel pressure to the max, a new high flow in tank pump, use the 454 TBI I have, new TPS and fix the hard throttle movement. The 454 TBI spacer allows antifreeze flow through it, great for winter. I would get the fully programmable ECM to really unlock the motor. The factory ECM would really not like a 220+ duration cam and needs a minimum 10 degrees advanced to even run on an Olds motor. My Dakota has numbered days, the next big issue, I am not fixing it. I may wait till every used isn't solid gold. Yes it would have the graphics in the title on it. Now just to find what I am looking for.

 

[DRIVEN]

So...you're building a 7 liter to slay 6 liters? Solid logic.

 

[olds307 and 403]

Yeah, I want something fun. It shouldn't cost a lot, especially if externally balanced and I put the iron heads on it. Trucks rarely need 4000+ rpms, well real trucks anyways.

 

[DRIVEN]

I'd be interested to see that build. I've said for years that I don't know why GM didn't utilize the 455 Olds in pickups, specifically under the GMC banner. Hell, they did it back in the 50s with Pontiacs, Buick, and Olds in Chevy and GMC pickups and light trucks. Then again with the 5.7 diesel. My brother's GMC motorhome has a fwd 455. The corporate mix-n-match president has already been set so I'm not sure why they didn't go all-in with BBO torque. They managed to keep the 454 emissions compliant so I'm sure they could have done the same with a 455.

Build it.

 

[olds307 and 403]

I will, also have an extra set of Sanderson headers, needed for an Olds in a 4x4. A 403 is perfect for a 5000 max rpm, max torque build. I even have a 1/2" thick CNC 4 main Halo and longer ARP studs. I am not super enthused to used another 403 in a limited radiator and high rpm application. I had this crap for years, time to use it. I would probably either go a factory replacement BB0 pan, little more crank room and a factory baffle, 1/2 quart more or the 6 quart pan deepened factory style pan and pick up. Now, to find a truck, definitely the hardest part. A guy had a 455 in one of these years trucks, a 1500, he blew up the front diff and transfer case, I believe he beefed up the 4L60E and didn't tow much, so it lived. A 3/4 ton eliminates a lot of pitfalls, a former diesel truck isn't out of the question as well. My old boss did that with a 454 in a 93, he had a b*tch of a time getting it to shift right. He even used the Qjet from his 79.

 

[olds307 and 403]

There have been a few possible candidates, reasonable amount of rust and shiny paint for acceptable money. The used truck market has also softened a bit. I may wait till it is limp as possible. Honestly, unless I start the Dakota and put a rock on the gas pedal and walk away or it naturally breaks, not impossible with a Dodge, I'm in no rush. Unless the perfect truck, right close by for the right price happens, don't hold your breath. After project runaway budget Olds 358, I plan on spending only 2K on the motor, if it happens. About 95% of that would be machine work. It would be externally balanced. Being a 6.9L, a good workhorse displacement, it will be a mild truck engine, lower horsepower but big torque at a low rpm. I would go 9.25 to 1 max compression with the 204/214 .448/.472 on a 114 LSA Edelbrock cam, stock push rods and rocker arms. All used in good shape. I also have a good used double roller timing set with minimal slop. The #6 heads have 2.07"/1.56" valves, positive seals, upgraded springs with the bowls opened and air bumps removed, not all that many miles since they were completely built. The intake runners are about 170cc factory, I believe. They maybe flow 215/165 from similar SB Olds heads done. I would polish the 62 to 64cc chambers to reach my compression goals. Basically, getting the main caps getting cut for the 4 main Halo is only extra cost for machine work but my crank being already offset ground should offset it's cost, so $1500 or darn close. I have very recent bill's to prove that number. I have the used custom factory sized 21cc dish 2618 forged .043" top ring 4.390" bore Venoila 550 gram .927 pin stroker pistons, rings, new cam and main bearings, only need standard small journal sbc rod bearings for the Scat 6" long, 2" journal sbc rods. It would get my good used balancer, flex plate, a new stock volume oil pump, pick up and probably a replacement 455 pan. Bigger hump for crank clearance and a factory baffle, less than $100 new. I have the used small runner Performer intake. I need the factory 1" tall aluminum Qjet 454 to TBI adapter. There are multiple used ones on Ebay. The nice part it has heated lines on it. My last one had a mangled fitting, couldn't use them. I would run heated coolant through in the Winter. I would have shut of valves for the Summer. I have 454 TBI 2" bores TBI base. I would just need higher flow injectors, pod, new TPS, maybe IAC and adapter harnesses, also available for cheap. I would also use an adjustable regulator and new in tank fuel pump. Also would need a used CCC 307 distributor. Eventually it would get a custom tune. I need one Felpro 403 head gasket, neoprene rear main and a cheap conversion gasket set, I have all the rest of the gaskets. I also have the used Sanderson shorty headers. I would also run the serpentine conversion brackets, $200 US, my good used or maybe a Flowkooler water pump and get the double thick replacement single core 36" wide aluminum/plastic rad with a 195 Robert Shaw thermostat. Where trucks actually need power, idle to 4000 rpm, bye bye LS 6L/6.2. Over 4000 rpm, absolutely not but who cares, it will be a truck engine. Now, I just need the Dakota to let me down one more time or the perfect truck to fall in my lap. I have a lot of times on my hands to think, sitting all day in the Hospital, Wife sleeps a lot and nights alone. I wonder which one will come first, this motor build or the right truck for the right price? More likely the Dodge will die first in a major way🏆.

 

[L92 OLDS]

Those “weak aluminum” front differentials you mentioned aren’t all that weak in the OBS and GMT800 platform. We’ve been beating ours for years with a 750 hp LSA and have yet to do any damage. I can’t remember seeing anyone break one yet. I would be more worried about the crappy 8.5” in the rear that GM put in most K1500’s

 

[olds307 and 403]

Yeah, the Gov lock especially if equipped is on borrowed time. I thought Steve O put a mild Olds 455 in a 95 1500, put it in low range and blew the front diff but it might have been the transfer case. Supposedly Eaton developed a lunch box Locker for the 8.25" aluminum front diff. Off road, they broke a bunch and it was never made. I really like the 1500 trucks but honestly between both diffs and the 4L60E, high torque is the pin for multiple grenades. A 2500 will take everything I plan on throwing at it. Now the race between my Dodge Dakota, really gets full size mileage while still being 1/2 a truck breaking big again or finding a nice, non rotten clapped out GM/Chev in the 88 to 95 range for a reasonable price. Gentlemen, start your engines! Can someone boost the Dodge🤣.

 

[DRIVEN]

Seems like a 1500 wouldn't even be a consideration then. Focusing on a 2500 now?

 

[olds307 and 403]

A 2500 always was the plan, for the above reasons. It would have to be a really nice shape 1500 with a fresh 4L60E with the important upgrades. I thinking 250 to 275 hp and 450+ ft/lbs of torque, so a beefed up 4L60E should probably survive.