Possible Setup: 383, TH350, 4.11 Rear, 32.3" tires

[Jahloha]

Team:

1970 C20, 2WD, stock everything

I am taking my engine to the shop today and have been thinking a lot about my build and the components I would like it to have in the end. My question is based on my lack of knowledge, but need to develop a budget and good DD in the end.

I have been reading a lot about 383s and know I would enjoy some additional torque for towing and smiles.

I have also been reading a lot about swapping a 700R4 into the truck for its OD and mpg improvements. But also know that a well maintained TH350 is an iron lung, and simply shows up to work everyday.

Lastly, I have 4.11 gears in back and plan on running 32.2" tires on all four corners.

All that being said, would the 383, th350, 4.11 rear, and 32.2" tires be a decent setup for reliability and daily driving?

I am by no means an expert, but can follow logic and most engine/drivetrain talk. So please share any insight and knowledge because I appreciate the learning experience.

Mahalo!

[Fatherof3]

How much freeway driving do you plan to do a year?

The 700R4 is a great upgrade but I would way it against your usage and how long to you plan to keep the truck if money is an issue.

[Jahloha]

Originally Posted by Fatherof3

How much freeway driving do you plan to do a year?

The 700R4 is a great upgrade but I would way it against your usage and how long to you plan to keep the truck if money is an issue.

I plan on keeping the truck until my kids can inherit it. And I drive about 20 miles a day, almost all highway miles. I probably put about 12K onto my vehicles each year, and this truck will be my DD.

[bbcmudtruck]

I'd think that your tire size and gear ratio would be perfect. Since you already have the lower carrier, you could always just swap out to some 3:73's if the motor comes out stronger than you expected. I'd roll with the th350 and not worry about it. Especially since your driving 20 miles a day. I run a fairly hot 350/350 currently with 3:73's and 29" tires. My rpms at 70 are around 2000 to 2200. What are your plans for the motor build? IE heads, cam, crank, rods, pistons, intake, carb etc. Are you wanting a torque beast or something you can wind up?

[Jahloha]

Originally Posted by bbcmudtruck

I'd think that your tire size and gear ratio would be perfect. Since you already have the lower carrier, you could always just swap out to some 3:73's if the motor comes out stronger than you expected. I'd roll with the th350 and not worry about it. Especially since your driving 20 miles a day. I run a fairly hot 350/350 currently with 3:73's and 29" tires. My rpms at 70 are around 2000 to 2200. What are your plans for the motor build? IE heads, cam, crank, rods, pistons, intake, carb etc. Are you wanting a torque beast or something you can wind up?

Yeah, I am guaranteed to drive 20 miles a day, but I am driving about 320 miles every 10 days or so.

Also, I am concerned with mpg, but have been doing my reading on getting a 383 to be a decent DD and MPG engine. I know it is said all over this forum, but I want a solid engine that can tow without stress (tow about 4000lbs one a month), but cruise (70 mph) without screaming down the highway.

[Stocker]

Originally Posted by Jahloha

Yeah, I am guaranteed to drive 20 miles a day, but I am driving about 320 miles every 10 days or so.

Also, I am concerned with mpg, but have been doing my reading on getting a 383 to be a decent DD and MPG engine. I know it is said all over this forum, but I want a solid engine that can tow without stress (tow about 4000lbs one a month), but cruise (70 mph) without screaming down the highway.

My K20 has a basically stock 350, TH350, 4:10 gears, and 33/12.50-16.5 BFG ATKOs. It's not too bad at 55 mph on secondary roads, but 65 to 70 mph gets a bit tiring. It rarely sees freeways though, and it's been a long time but I think 70 mph is around 3500 rpm.

For the driving you describe, I'd either drop in an OD trans or swap the diff gears.

[Jahloha]

Originally Posted by Stocker

My K20 has a basically stock 350, TH350, 4:10 gears, and 33/12.50-16.5 BFG ATKOs. It's not too bad at 55 mph on secondary roads, but 65 to 70 mph gets a bit tiring. It rarely sees freeways though, and it's been a long time but I think 70 mph is around 3500 rpm.

For the driving you describe, I'd either drop in an OD trans or swap the diff gears.

Stocker. Thanks for the insight. That is what I am thinking with the OD, seeing as most my driving is on freeways. My tires being an inch shorter wouldnt make a huge difference either.

[Fatherof3]

Originally Posted by Jahloha

Yeah, I am guaranteed to drive 20 miles a day, but I am driving about 320 miles every 10 days or so.

Also, I am concerned with mpg, but have been doing my reading on getting a 383 to be a decent DD and MPG engine. I know it is said all over this forum, but I want a solid engine that can tow without stress (tow about 4000lbs one a month), but cruise (70 mph) without screaming down the highway.

I agree with the 3:73s. Way cheaper than doing an overdrive. If spending a couple grand is not a problem then 700R4 would give you the best of both

[Jahloha]

Originally Posted by Fatherof3

I agree with the 3:73s. Way cheaper than doing an overdrive. If spending a couple grand is not a problem then 700R4 would give you the best of both

But from my understanding, I cant keep the 8 lugs and switch to 3.73s Parts are too hard to find.

[Stocker]

Originally Posted by Jahloha

But from my understanding, I cant keep the 8 lugs and switch to 3.73s Parts are too hard to find.

Depends on which differential you have. That's true if you have an Eaton, not necessarily true for others.

[bbcmudtruck]

The bigger the motor you build, the happier you'll be! If your hell bent on building a small block, the 383 will be excellent.

[my67c20]

Well from your build thread it looks like you are embarking on quite the adventure. Living in the snowy north, fortunately offers us 6 quality month of build time. Currently i have a 383 with a 4 speed granny and 3:73 gears. I tow several times a year on the freeway doing 75 and its got plenty of power left, and this is turning between 2500 and 2800 rpm's. If you unable to change from the 4:11's to 3:73's look for a 14 bolt that you can swap in, you will not be disappointed. The whole trick with towing is getting going, and stopping, so having a the th350 vs the 700r might not make too much difference, until you get up to speed. These trucks are like tanks and have horrible aerodynamics, so the cost of the 700r might be more than the gas saving over the life. I have thought about the 700r swap myself but am cautious as i have heard that towing in overdrive is bad without the proper torque converter, or something along that lines. Plus i like to put the pedal on the floor, allot, and do not feel like shelling out the bucks for a built 700r. Chicks dig burnouts and chrome, not some truck flying down the freeway at 75mph.

[Jahloha]

Originally Posted by my67c20

Well from your build thread it looks like you are embarking on quite the adventure. Living in the snowy north, fortunately offers us 6 quality month of build time. Currently i have a 383 with a 4 speed granny and 3:73 gears. I tow several times a year on the freeway doing 75 and its got plenty of power left, and this is turning between 2500 and 2800 rpm's. If you unable to change from the 4:11's to 3:73's look for a 14 bolt that you can swap in, you will not be disappointed. The whole trick with towing is getting going, and stopping, so having a the th350 vs the 700r might not make too much difference, until you get up to speed. These trucks are like tanks and have horrible aerodynamics, so the cost of the 700r might be more than the gas saving over the life. I have thought about the 700r swap myself but am cautious as i have heard that towing in overdrive is bad without the proper torque converter, or something along that lines. Plus i like to put the pedal on the floor, allot, and do not feel like shelling out the bucks for a built 700r. Chicks dig burnouts and chrome, not some truck flying down the freeway at 75mph.

Thanks for the feedback. A few things I have been thinking about, I want to keep the Eaton due to its reputation of being incredibly durable. I have read finding gears to swap into the Eaton are extremely hard to find, so if I want the Eaton, the 4.10 gears stay.

I also have been thinking about my trans and feel that the 700r4 is an upgrade that I can down the road, so I believe I will rebuild the TH350 for less and just keep driving/towing normal, get up to speed, then cruise at 55/60.

Lastly, the engine is a must change, seeing as I want to keep this truck forever, I prefer to start new with the engine. I am almost set of picking up a crate engine this winter.

So long story short, I plan on keeping my current setup (at least for the next few years), minus the engine and throwing in the 32.3" tires to assist my my rear gears.

But then again, half the fun is pondering what swaps/improvements we can make, right? But for now, I want her up and running, looking clean, so Gramps can see it one last time. Any other upgrades/mods, I can do down the road.

[Jahloha]

PS...the winter months are killing me, I am a Utah transplant and still not used to this weather. I have the truck in the garage, with a space heater, so that should get me through the next two months of prepping the chassis, getting trans rebuilt, ordering engine, etc. I want this thing close to completion by end of summer.

[davepl]

I have TKO-600s (overdrive) in a couple of vehicles; in my Pontiac 427 I have 4.11 gears and its fine on the highway, plugs along under 2k rpm at 60 if I recall, so not bad at all.

In my truck, which isn't running yet, I rebuilt the rear end, upgraded to a locker, and went with 4.56:1 gears because I'm running a 200-4R trans and the tires are taller (31" or 32", so close to yours). But if I recall the 200 has a slightly deeper overdrive than the 700.

Which is long way of saying "I have even more gear than you, but haven't driven it yet", which is kind of useless. But the cars with overdrive have been fine.

[Jahloha]

Originally Posted by davepl

I have TKO-600s (overdrive) in a couple of vehicles; in my Pontiac 427 I have 4.11 gears and its fine on the highway, plugs along under 2k rpm at 60 if I recall, so not bad at all.

In my truck, which isn't running yet, I rebuilt the rear end, upgraded to a locker, and went with 4.56:1 gears because I'm running a 200-4R trans and the tires are taller (31" or 32", so close to yours). But if I recall the 200 has a slightly deeper overdrive than the 700.

Which is long way of saying "I have even more gear than you, but haven't driven it yet", which is kind of useless. But the cars with overdrive have been fine.

Good to know, I am interested in seeing how that 2004r turns out. And what size tires were running with the 427?

[litew8]

I considered a 383 build but decided to go with a healthy 355 instead. Plenty of torque and makes a great street truck. A 383 would be TOO much engine for a daily driver, in costs and all IMHO.

[Jahloha]

Originally Posted by litew8

I considered a 383 build but decided to go with a healthy 355 instead. Plenty of torque and makes a great street truck. A 383 would be TOO much engine for a daily driver, in costs and all IMHO.

Lite:

Thanks for the 411. I dont remember seeing your engine build on your project build thread...is it in there? I would be interesting in seeing what components you used.

I also dont know if its advantageous to buy a turn key crate motor or a block then build from that. Suggestions?

PS...your video looked/sounded awesome. Congrats on the first ride!

[litew8]

Thanks for the complement. Yes, my engine build is in there. I didn't provide many details, but it isn't much. I purchased an Edelbrock top end kit, and recently added an Edelbrock carb (I think this is the right link, or could be this one. Sorry, it's been a while and I tend not to remember exactly). I have a roller setup, which would add more $$. The block used was originally a crate engine. The block was good so that's what I used. Depends on your budget mostly. If you're capable (with the help of others etc..) to build it yourself, you'll have more opportunity to pick and choose what you want, vs. a crate engine as is. If your current block is old/original - it should be a nice solid one if no issues.