LS Powered '47 3600 with stock suspension - 2 Questions

I'm hoping someone can help with 2 questions...

First, a little background; My truck is a 1947 3600 (Grandpa's truck), originally a 216 4-speed truck.
Last year I upgraded it to a late 50's 235 and a 1993 (WC) S10 T5 (required switching to a custom 1 piece driveshaft).

I'm now putting together a 2000 GMC 5.3L v8 and a 4L60e automatic transmission. Still with the straight front axle, and original steering (and drum brakes/8-bolt wheels - for now).

So, my 2 questions;

1. Steering box clearance; any good options other than moving the box to the outside of the frame by 1 1/2" or offsetting the engine to passenger side? (as well as using 'block hugger' headers)
2. I have the 'Classic Parts' v8 cross-member, and transmission cross-member - has anyone put an LS style engine in while still retaining the solid front axle ? Any clearance problems?, other than cutting or removing the original trans cross-member?

Thanks - and sorry if these have been answered before, I've been searching the forums but haven't been able to find specifics.

-Arin

 

Arin, I will try to answer your questions, however, my experience is with an "LS" engine, and complete front end replacement.
1. You will have to move the original steering at least 1 1/2". possibly more. I really don't think moving an engine offset is going to work with the Vortec/"LS", engine. The reason I say that is headers or exhaust manifold clearance is a big problem with these engines. Even block huggers.
2. I don't think your original front axle will cause you any clearance problems, although I would check the tie rod to oil pan clearance. There are many different oil pans availiable for these engines, something will surely fit.
3. You may need to fabricate a trans. tunnel for that 4L60E. (I did)
4. I have no experience with the "Classic Parts" V8 cross-member. I believe it is an old design, suited to older small block engines. I used their trans. cross-member for my swap. pretty basic, cut to fit.
5. You will almost surely have to move your brake master cylinder, brake pedal assm. to a firewall mounted one. Our host here sells the kit for this.
I'm sure you are aware these things are NEVER, "yank it out-slap it in" type operations.
One thing to consider, you will have probably at least 4 times the original horsepower, and massive responsiveness being steered down the road on ancient steering/susp. technology...

Hope this helps a little.
By the way...where are you?

Steve.

 

We have done several of these conversions but like Steve, an IFS was also installed. A couple more tips is to have a nipple soldered in your top radiator tank for the steam tube on the LS and replace that *!@% lower water neck with a straight ahead one. Since most use engine mount adapters on the LS block (to put them in the same place as the small block mount) you can get creative and position them to help with header clearance. No rule says the mounts have to be straight across or at the same height or at least GM didn't think so on the 292 I6. If your pocket book can stand it the 4wd Toyota p/s box solves a lot of problems both in clearance and steering stability as you can increase caster by quite a bit. Increased caster makes a straight axle drive straight down the road with no wander. Be sure to have all new bushings, king pins, tie rod ends, drag link---anything that moves in the front suspension because as Steve said, the LS will give the old girl a ride like she's never experienced and YOU will be part of that ride.

 

Thanks guys, my block hugger headers haven't arrived yet - but after another test fit with the engine/trans last night I've decided to move the steering box out to gain some more space. Hopefully the 1 1/2" move that I've seen other guys do will be enough. Also after my test fit last night the axle and tie rod both seem to have decent clearance around the oil pan, so I think that should be good.

Side note; I am doing the kingpins today, tie rods look good, but I'll inspect them closer when I'm in there doing the kingpins today. I also did order a power brake/master cylinder kit, but will be waiting on discs due to budget/time... At that point, I may end up opting for an IFS/Rack & Pinion setup... (but again, that's down the road).

I do have a new 4-core aluminum radiator coming, but I had been looking at the ugly angle of the lower water neck/thermostat housing - so I'll look into a straight one.

Thanks for the tips... I'll update on my progress / fit as I progress.

Oh and Steve - I'm in Minnesota... planning to have this running in time for the MSRA "Back to the 50's" car show on June 17th in St. Paul!

 

Who does disk kits for 3/4 ton trucks?

 

A company called "Classic Performance Products" (CPP) out of California... The kit is supposed to fit 3/4 ton spindles and has a standard 5 bolt GM pattern. I found them while doing an eBay search for parts... I haven't tried it so I can't speak to the quality or fit of the kit.

 

I just looked at their web site and could not find any kits for 3/4 Ton trucks. What CPP part number are you referring to?

 

Bill, I just went to look again and couldn't find it... it's possible I misread the "3/4" from the "5 x 4 3/4" description in that it wrapped onto the next line of my screen.

After some brief searching, I didn't find any 5-bolt disc kits for 3600/3800's - only kits for 3100's and most people seem to put a 3100 axle on their 3600 to make the kit work.

If you want to keep 8-lug wheels with discs, the hollister road company makes a kit that lets you use modern 2500HD rotors/calipers on the stock spindles.

 

I did end up moving the steering box over by about 1 1/2" and that sure seemed to open the engine bay up. Headers should be here tomorrow, so I'll find out if I can keep the engine centered or not.

 

I have a GMC 150 (like a Chevy 3600) that came to me with 5 lug front disk brakes. A hot rod shop about 20 miles north of me put them on, but had to do machine work to get the parts to fit. I went by the shop 3 years after the work was done and no one remembers what they did to the truck. The brackets appear to be from CPP and the rotors and bearings match what CPP uses in their 1/2 ton 5 bolt kit.

 

I am in MN too. Sadly my truck will not be ready for BTT50s.

 

Bill, I believe the larger/odd sized spindles are the reason the 1/2 ton kits don't fit - so I would guess they ground the spindles or customized the bearings to make the rotors fit.

As I side note I also have a '54 GMC 150 that's next on the "to do" list.

 

Try contacting Scarebird to check on a possible brake kit for a 3/4 ton. They make a lot of off beat disc brake brackets.

 

So... The short answer to: move the steering box or offset the engine to the pass side is... YES.

I found doing both necessary for header clearance, even with "block huggers"...

But the engine and transmission are bolted in, and ready for all the "extras" like exhaust, fuel systems and wiring!

I'll try post some pics when I get it a bit further along.

 

Just remembered a dirt tracker trick I saw used to mount disc brake calipers. One guy positioned the caliper on the rotor while a second guy sat in the car and stomped the brake pedal. With the caliper now perfectly positioned a plate was fabbed up with bolt holes for the caliper and the other end welded to the axle (or axle housing). They told me it worked perfect and cost them about twenty bucks for the mount kit.

 

Well... My wiring harness and ECM won't make it here by tomorrow, so the '47 won't make it to BTT50's this year...

But, I'm still shooting to have it completed for a family reunion in ND the following weekend... I'll try post some pics of the progress so far over the weekend.

 

Just fits... by Arin posted Jun 15, 2016 at 10:39 PM

Just fits...

 

Wiring harness and computer finally arrived today! Hoping to finish the truck this week.

Just about done with the exhaust now - needed the harness back to make sure I got my O2 Sensor bungs within reach of the plugs.

Still have the fuel system and all of the wiring to finish up.

 

For those of you that might be interested, an "under the floor power booster / master cylinder" WILL fit with the engine slightly offset. Not sure if there would still be clearance if the engine wasn't moved over.

 

Well... Slow and steady... Busy life has slowed the truck progress, but I did get the wiring harness routed, and 70% hooked up. I was also able to fab up some new fuel tank brackets and got the gas tank mounted and fuel sender hooked up today - so it's coming together.

Oh, and almost forgot - got the O2 sensors installed... Still feels funny putting O2 sensors in Grandpa's old '47 !