I have a 1986 Chevy C10 pickup that I want to put an LM7 into. Currently the truck has a carbed 4.3L V6 backed by a 700R4, and 3.08:1 gears. The truck is used strictly as a low RPM cruiser/DD. The truck itself is in great shape, but the engine is getting tired, leaks from every gasket and seal, and the valve guides are completely shot. I have a 5.3L on the stand pulled from an '01 truck with about 170k on it. I figure the cost of rebuilding the 4.3L would be about the same as buying the swap parts to drop the 5.3L in, but I could double my current HP and still get the same mileage.

I want to keep basically the same setup I have now, so I want to make the 5.3L carbed, bolt it to the existing 700R4, and hopefully use the truck accessories. This is not a streetrod (very easy driven), so I'm confident the 700R4 will survive for a good while. No soup-ups on the engine other then maybe a mild cam and possibly headers if stock manifolds won't clear. The truck has no A/C so no worries there.

I have done some research and haven't found too many build threads for the C10's, or 73-87 trucks in general. I have a few questions before I dive into this.

1. What motor mounts do I need to physically drop the motor in place keeping the transmission in the stock location? I figure the stock clamshell mounts would be good, so will the generic eBay LS swap plates be the ticket here? Do I need +/- 1" or anything like that?

2. I know I need a crank spacer to mount up to the 700R4, but will I also need spacers for bolting the torque converter to the flexplate, or will that sit flush?

3. Do any of the factory exhaust manifolds work in the 2WD frame? I have two sets of truck ones. If those don't work, will any of the F-body, corvette, Cadillac, etc ones work, or will I need headers?

4. What lines will I need to make the truck power steering pump work with my 86 steering box?

5. Will either my truck oil pan or GMPP oil pan clear everything in the frame? I will most likely use the GMPP pan just because the truck is lowered slightly.

6. Anything else I should know to look out for?

 

Answered in red.

 

Thanks for the reply! A couple of things:

1. The 4.3L has spacers that set the mounts back about 5". They will be removed and the motor mounts placed back to the correct position for a regular SBC. So imagine I'm working with a 350 instead of a V6.

2. Not sure what you mean in the first part? The LM7 will be carbed, no throttle body needed.

4. That's what I was hoping. Good to know.

5. I already have both style oil pans. I thought the GMPP was shallower than the truck pan though?

 

The pan's alittle shallow like an inch or so look in the oil pan thread. Missed the carb part.

 

After doing a bit more research, it seems I will be good with using my 5.3L flexplate and just getting a crank spacer and bolts.

Any more input on the motor mounts?

 

Just get the Hughes bushing as it will be cheaper you won't need the longer bolts. Its only $43 vs $60 for the GM spacer and bolts. Saves you 20 bucks.

For the mounts if they are SBC mount just mock up the motor and make adapter plates like I said be cheaper than $100 bucks for flat piece of steel/AL.

 

Do you have a link to the Hughes bushing?

This project will have to be completed in a single weekend as it is a daily driver, so I will have to just buy what I need, no time for test fits and mount fabrication on this one.

 

Thought it was in the link in my sig I added the link in there as well. But here it is.
http://www.summitracing.com/parts/HUP-HP3795/

You might have to do some more searching on the right mount adapter's well since you don't have time to fab them.

 

Well it seems the 1" setbacks put the bellhousing in the stock position, but I need to watch out for the head clearance against the firewall. Are there any C10 owners here that have done this?

I think I will go with the GM crank spacer as well, I'd trust a bolt on part long before one that just sits there.

 

There's no were for it to go!! The hub of the verter rides in it and the bushing rids on the crank and its all held together buy the verter and crank itself. Save your $20 bucks on something else.

 

What I'd really like to know is if the engine will fit using the 1" setback plates without hitting the firewall? I've found many build threads, but nobody states or shows what mounts they use!

 

Start PM people or asking in the thread. Eventually some will chime in. If not do you have a welder? You could pre make the plates then slide motor in tack them leave motor hanging and finish wled paint and install done. Take hour at most if plates are all ready made.

 

Ordered the Edelbrock carb intake and MSD controller today. Going to order either the DirtyDingo truck mounts or billet aluminum mounts, I'll decide once I call in and ask a couple questions. I already have a Holley double pumper carb laying around off a sprint car, which I may rejet and use.

 

dirty dingo 2wd truck bolt on adjustable mounts for the win.

i have a set and in the most forward position the 5.3 with truck pan still clears the crossmember.

i was able to slide my whole setup back just about 1.25" or so over stock position and hade to flatten the trany dip stick tube just a tweek to clear the fireway perfectly. see my big hand even fits in pan to cross member gap with it slid back.

also search my stupid easy exaust mod thread i posted pics in to get truck manifolds and down pipes to fit. https://ls1tech.com/forums/conversio...xaust-mod.html

 

Ended up going with the DD truck mounts. I'm going to try different exhaust manifolds (I've heard one truck and one F-body will clear) as I am not going to notch the frame at all.

 

like my pics show in link posted no major notch needed.

pass side needs a notch no bigger than my thumb nail. just open up the factory relef a tiny bit more.

otherwise its all drop in truck manifolds from 03 4x4 yukon and down pipes cut just before cat's.

and just drop in motor and then bolt up the driverside manifold and then mod the down pipe like i did and its all good. the driverside truck manifold fits between the C section of the frame rail just fine. pic's show tight but its not that bad at all. try it .

but do what you wana do .

 

This truck is an original survivor, so there will be no modifying the frame. I'm building this to go back to all original if I decide to. The current engine is just worn out and needs to be gone through. I'll source the correct exhaust manifolds needed to clear without notching. Going to run dual exhaust anyway.

 

this made me laugh....its a V6.....

put it in perspective. would you rather have a 30s era vehicle with the stock power plant and drivetrain, or one with a modified lsx powertrain?....which vehicle goes for more money at the auctions?.......

different strokes for different folks i guess.

 

It's only original once! It always makes me cringe when people do things like cut their frame, bash their firewall, etc on an otherwise awesome build, especially when a simple part would avoid having to do that. If I was looking at a vehicle for sale somebody else had already built, and saw that they had done something like that, I'd walk away. I also like having the option of going back to completely original at any time without absolutely any hint of past modifications. I know some people just don't care about little things like that when it comes to their cars, but I care when it comes to mine.

As for a 30's car? Stock without a question! Just makes them that much more fun to drive IMO.

 

Well, it's been a while since my job held me up, but now we're starting to see some progress!

The '86 C10 it's going into. Sorry about it being dirty, didn't get a chance to wash it before winter, too cold to clean right now:



5.3L engine, stripped down to the good stuff and cleaned up. The salvage yard listed it as a 170,000 mile motor, but there is a warranty tag on the block, so I'm guessing this was a warranty replacement at one point and may have less miles.



I picked up a carb intake from SK Speed. The cat decided to help out as soon as it was opened!



And bolted on. Perfect match!