72 K20 been parked for 31 years!!

[DeadheadNM]

I don't know anything helpful as relates the motor but this is turning into a motivational build thread for me. I've got a K20 motor w 54k miles caked in a hard shell of west Texas greasy dirt. Keep going!

[Vintage Windmills]

Originally Posted by mrein3

That NP205 is a heavy little hunk of iron isn't it.

Buddy and I lifted the whole assembly and it wasn't unbearable but it wasn't light Is the np205 by itself heavier than a TH400? I can handle those by myself. Also how heavy is the bare 350 engine block by the way?

Originally Posted by mrein3

What did you end up deciding on the engine? 350 when you're done or are you going to stroke it?

Looks like I need to put money in the crank so will probably go with the 383, and stock heads. Biggest question is rollerizing the valve train, lots of debate on the interweb about that.

Originally Posted by mrein3

How about that th350? If I could set the way back machine to the day before I brought my th350 to the rebuilder I'd bring him a 700r4 with the Advanced Adapters output shaft instead of my th350.

I'd like to keep the original trans in there. Would like to put a gearvendors on in the future.

[Vintage Windmills]

Originally Posted by DeadheadNM

I don't know anything helpful as relates the motor but this is turning into a motivational build thread for me. I've got a K20 motor w 54k miles caked in a hard shell of west Texas greasy dirt. Keep going!

Thanks! This is the first chevy engine I'v rebuilt so I'm definitely having to take it slow and ask questions

[SS Tim]

Gear Vendors O/D, now that is a good idea.

[DeadheadNM]

Originally Posted by SS Tim

Gear Vendors O/D, now that is a good idea.

I'm not familiar with these and am trying to decide whether or not to keep the non-original TH350 in my K20 OR go with a built 700R4. Any benefit to going with the Gear Vendors O/D other than preserving an original type tranny and not relocating motor mounts?

[Vintage Windmills]

Originally Posted by DeadheadNM

I'm not familiar with these and am trying to decide whether or not to keep the non-original TH350 in my K20 OR go with a built 700R4. Any benefit to going with the Gear Vendors O/D other than preserving an original type tranny and not relocating motor mounts?

Absolutely there are benefits. It splits gears, meaning your Th350 truck becomes a 6 speed (with overdrive). this means you accelerate faster and keep your engine in peak torque range all the time. On a 4x4 their stock their kit only works in 2wd. I see they make a race version that goes between tcase and tranny though you have to remount your tcase. For more info see http://www.gearvendors.com/index.html

[DeadheadNM]

Great to know! These look pricey but attractive. I bookmarked their website.

So, if I go with a 700R4 AND the OD that gives me an 8 speed and I'll be turning low 2k's at 200 mph with the 411s in my HO52 while towing a flat bed trailer Sweet.

[SS Tim]

Originally Posted by DeadheadNM

Great to know! These look pricey but attractive. I bookmarked their website.

So, if I go with a 700R4 AND the OD that gives me an 8 speed and I'll be turning low 2k's at 200 mph with the 411s in my HO52 while towing a flat bed trailer Sweet.

Might not be the best idea, but it is doable. High drag or heavy vehicles have trouble with double overdrive gears. You did the numbers and saw a big RPM drop. But with that comes a drop in HP and TQ. Add in the fact that the vehicle needs more power to go fast and the increased driveline friction, well available power much less economy disappear fast. My '99 Camaro SS w/T56 has two O/D gears in a slippery chassis, but roll on isn't really too good in 6th. However it cruises nice at 70 @1700 getting 22+MPG. 5th gear gets used a lot in traffic and on the long hills. If you are running hard 5-6 is about 110.
Spending the money for an O/D is good in only few ways. The biggest is reduced RPM and a likely MPG increase when properly geared. Also splitting gears to reduce RPM drop is great when pulling a load and even better on a grade. You get better performance and sometimes better overall MPG numbers as a result.
Last thing to consider is driveline speed. The faster the shafts and gears rotate the more vibration and wear can be expected. Truck drivelines don't like spinning 6K.

[mcbassin]

Looks like someone needs to go ahead and start a build thread
Very nice piece of history! That was a beast in it's time. Can't wait to see you get it back on the road. BTW, I have a home for those slots if you get tired of them......

[mrein3]

Originally Posted by Vintage Windmills

Buddy and I lifted the whole assembly and it wasn't unbearable but it wasn't light Is the np205 by itself heavier than a TH400? I can handle those by myself. Also how heavy is the bare 350 engine block by the way?



Looks like I need to put money in the crank so will probably go with the 383, and stock heads. Biggest question is rollerizing the valve train, lots of debate on the interweb about that.



I'd like to keep the original trans in there. Would like to put a gearvendors on in the future.

Originally Posted by Vintage Windmills

Absolutely there are benefits. It splits gears, meaning your Th350 truck becomes a 6 speed (with overdrive). this means you accelerate faster and keep your engine in peak torque range all the time. On a 4x4 their stock their kit only works in 2wd. I see they make a race version that goes between tcase and tranny though you have to remount your tcase. For more info see http://www.gearvendors.com/index.html

When I was a younger man I could pick up and carry a th350. I wouldn't even try it now. I bet the t-cases and the transmissions weigh about the same but that 205 was just hard to hang on to. Like the trannys, I wouldn't consider moving one by picking it up now-a-days. For me now it is lift with the cherry picker and move it on that - or cherry picker to wheel barrow if I have to move it to my other garage.

When I was a kid I picked up the bare 350 block that is now in my 72 Chevelle. Like other driveline pieces, the days of me lifting a bare block are behind me.

I know you're after the original look. What I would do is use a 700r4 and just put that original th350 on the shelf. If some day there is a call for all original, numbers matching K20s, you'll have it handy. In the mean time you'll have a better tranny. Like I said before I REALLY wish I could go back to the day I decided to take my th350 to the rebuilder instead of a core 700r4. I made my decision only on fuel savings. Even at $4/gallon you don't save anything for a really long time. However when I have to take my 3.73 gears out on interstate 35 with a 70 mph speed limit, 3300 rpms really sucks. Its loud and it can't be doing my engine and drivetrain any good.

Does gearvendors even make a unit that bolts to the back of your NP205? That is a whole lot of stuff to run through to get to the rear axel. Flywheel -> torque converter -> tranny -> coupler in adapter -> NP205 -> gear vendors -> driveshaft -> rear axel. Maybe they have a little driveshaft behind the 205 to get into the gearvendors unit. That is a whole lot of stuff to go wrong.

[mrein3]

Originally Posted by mrein3

Does gearvendors even make a unit that bolts to the back of your NP205? That is a whole lot of stuff to run through to get to the rear axel. Flywheel -> torque converter -> tranny -> coupler in adapter -> NP205 -> gear vendors -> driveshaft -> rear axel. Maybe they have a little driveshaft behind the 205 to get into the gearvendors unit. That is a whole lot of stuff to go wrong.

Nevermind. I see SS Tim has a photo of a gear splitter behind a 205. So it can be done.

[Vintage Windmills]

Originally Posted by mrein3

I know you're after the original look. What I would do is use a 700r4 and just put that original th350 on the shelf. If some day there is a call for all original, numbers matching K20s, you'll have it handy. In the mean time you'll have a better tranny. Like I said before I REALLY wish I could go back to the day I decided to take my th350 to the rebuilder instead of a core 700r4. I made my decision only on fuel savings. Even at $4/gallon you don't save anything for a really long time. However when I have to take my 3.73 gears out on interstate 35 with a 70 mph speed limit, 3300 rpms really sucks. Its loud and it can't be doing my engine and drivetrain any good.

What tire size are you running? Did you replace the HO52 with a Dana to get the 3.73's? My truck has 4.1 ratio so I would need overdrive even more than you unless your tires are smaller than I'm planning. Is the 700r4 a direct swap or do you have to modify mounts?

[SS Tim]

We did this last week. Short version is mod. the trans. to mimic a T350. Then bolt it up to transfer case and move engine forward about 2". Its not a simple one for one swap.

http://67-72chevytrucks.com/vboard/s...d.php?t=495513

[mrein3]

Originally Posted by Vintage Windmills

What tire size are you running? Did you replace the HO52 with a Dana to get the 3.73's? My truck has 4.1 ratio so I would need overdrive even more than you unless your tires are smaller than I'm planning. Is the 700r4 a direct swap or do you have to modify mounts?

Originally Posted by SS Tim

We did this last week. Short version is mod. the trans. to mimic a T350. Then bolt it up to transfer case and move engine forward about 2". Its not a simple one for one swap.

http://67-72chevytrucks.com/vboard/s...d.php?t=495513

My truck is a 1/2 ton. I believe stock 1/2 ton K trucks were 3.73s unless you ordered a 3.08 gear. I run stock tires which are approximately 28" tall. Since a 4.11 gear would have to spin faster at 70 mph, yes you do need OD worse than I do. I never did count teeth on my ring and pinion but the axel tube did decode to 3.73 and running down the road, writing down the tach reading for the mph reading and computing with a spread sheet - when you take into account the slip in the torque converter the 3.73 makes sense and does tach around 3300 when screaming down the slab with all the other maniacs who drive around our fine twin cities.

If you follow the link inside the link SS tim posted, you'll find a more detailed post I created about this swap.

Long story short, the 700r4 is not a direct swap but with the advanced adapters output shaft it is sort of a direct swap. You have to move your engine forward close to 2" but since a stock 4x4 V8 sits back about 2" compared to a stock 2wd V8, there is enough room. And you can make it look totally stock with a different GM fan shroud. I haven't done this swap yet but I would start with a 2wd shroud if you're planning on going stock.

Since the transmission crossmember on a 4x4 is actually a transfer case adapter cross member, and since the tail-less business end of a 700r4 looks just like the back of a 4x4 th350, you put in that AA output shaft in the tranny, bolt the transmission in place of the th350, move the engine cross member up a bit, test fit with engine installed - to mark holes, get the V8 out of the way, make your holes, then bolt it all together.

Since the speedo output is on the transfercase you don't have to worry about that. If your speedo was correct before it will be correct now. All you need to do is get the cable for the 700r4 and use it instead of the stock TV cable that tells the th350 when you want a downshift.

[SS Tim]

Originally Posted by mrein3

Nevermind. I see SS Tim has a photo of a gear splitter behind a 205. So it can be done.

Just a thought sitting here. The picture is a '70 K20 CST 350/4spd. that I was looking at. The SPID dosen't show an alternate ratio just a NoSpin. Anyway it was sold to Nomad74 up in NorCal. He had some engine issues but should be able to give some real world comparative numbers for you.

http://67-72chevytrucks.com/vboard/member.php?u=96601

[Ozark Tim]

I am sooooo jealous! I want one like this for my place in the country but all I ever find is 2wd.
Are you going to restore or mod or keep it just like it is?
Congrats

[Vintage Windmills]

Originally Posted by mrein3

My truck is a 1/2 ton. I believe stock 1/2 ton K trucks were 3.73s unless you ordered a 3.08 gear. I run stock tires which are approximately 28" tall. Since a 4.11 gear would have to spin faster at 70 mph, yes you do need OD worse than I do. I never did count teeth on my ring and pinion but the axel tube did decode to 3.73 and running down the road, writing down the tach reading for the mph reading and computing with a spread sheet - when you take into account the slip in the torque converter the 3.73 makes sense and does tach around 3300 when screaming down the slab with all the other maniacs who drive around our fine twin cities.

Good info- I need to do something. I even think my 01 turns too fast with OD however it has 4.10's as well. Don't get me wrong its not bad but cruising empty it could gain mpg from another gear. Yes there are plenty of maniacs in the cities here. When riding with friends sometimes I get criticized for NOT speeding around and cutting people off!

Leaning more towards the gear vendors since its a bolt up and then I'd have a 6 speed. I just need to make sure they engine rpm will be 2500 or less at 70 in 6th gear. Although assuming I do the stroker, I will have plenty of torque and could maybe swap in a 3.54 Dana 60 and powerlok I have and really cruise!! That would be amazing, I am excited at the thought of that ...low cruise rpm but plenty of gears for towing. I'd conquer at least the northern hemisphere with that kind of equipment

[mrein3]

Originally Posted by Vintage Windmills

Good info- I need to do something. I even think my 01 turns too fast with OD however it has 4.10's as well. Don't get me wrong its not bad but cruising empty it could gain mpg from another gear. Yes there are plenty of maniacs in the cities here. When riding with friends sometimes I get criticized for NOT speeding around and cutting people off!

Leaning more towards the gear vendors since its a bolt up and then I'd have a 6 speed. I just need to make sure they engine rpm will be 2500 or less at 70 in 6th gear. Although assuming I do the stroker, I will have plenty of torque and could maybe swap in a 3.54 Dana 60 and powerlok I have and really cruise!! That would be amazing, I am excited at the thought of that ...low cruise rpm but plenty of gears for towing. I'd conquer at least the northern hemisphere with that kind of equipment

Regarding MN drivers, I was in Europe in October. The Czech Republic to be exact. They get it. Drive right, pass left. If you're passing and somebody is coming behind you faster, speed up and get the heck out of the way! Unlike here where if your cruise is set at 70.1 mph and you get in the left lane to pass and it takes 5 miles and there are 25 cars behind you by the time you decide to move over - thats ok. NO ITS NOT!
OK I feel better now.

Don't forget if you change the rear to 3.54 you have to change the front too if you ever want to use 4wd again.
Another thing about the th350. Heat. With no lock-up converter it is always slipping some. That energy has to go somewhere and that somewhere is heat. Now I have a th350 and and an auxiliary cooler which handles the heat just fine. But as far as I know GM didn't offer stock auxiliary tranny coolers back in 1972 so then you're stuck back with the not stock looking component on a truck you want to look stock. And unlike something like a 700r4 verses a th350 that blends in, that aux cooler will be sticking out there in front of the radiator for everybody to see.

Heat wise I did a test right after I installed my freshly rebuilt th350. I had to pull my boat from Lindstrom to Red Wing to get ready for a tournament. One Saturday I went without the auxiliary cooler. At a stop light down in Stillwater my transmission temp gauge shot up to 240! That is too hot. It cooled down again when I got moving. The following weekend I did the same pull with the same basic outside temps. Right around 70 degrees outside for both trips. At the same light I was running just over 200 and alot lower before and after that light.

700r4 OD is .7:1. So if I'm running 3300 at 70mph, 30% off of that is 2310 rpms. Plus there will be a hundred or two less for the lock-up converter taking the slip out.

4.10 is 10% more gear than my 3.73s. So if your tire is 28" tall assume you'll be running 3630 rpms at 70 mph. Now I'm guessing stock 3/4 ton tires are taller than stock 1/2 ton but I'm not sure. If you get on the google and look for final gear ratio calculators you can do some pretty good guestimating of what you're looking at with no OD and with. I have no clue what the GV unit gives you for an OD reduction but I'm sure somebody here or the google can tell you that number.

[Vintage Windmills]

Originally Posted by mrein3

Another thing about the th350. Heat. With no lock-up converter it is always slipping some. That energy has to go somewhere and that somewhere is heat. Now I have a th350 and and an auxiliary cooler which handles the heat just fine. But as far as I know GM didn't offer stock auxiliary tranny coolers back in 1972 so then you're stuck back with the not stock looking component on a truck you want to look stock. And unlike something like a 700r4 verses a th350 that blends in, that aux cooler will be sticking out there in front of the radiator for everybody to see.

My truck had a tranny cooler and so did a 69 GMC big block I parted. As far as I know they were factory. Maybe was standard on 3/4's?

Originally Posted by mrein3

700r4 OD is .7:1. So if I'm running 3300 at 70mph, 30% off of that is 2310 rpms. Plus there will be a hundred or two less for the lock-up converter taking the slip out.

Summit has a converter http://www.summitracing.com/parts/HUP-GM11FUEL/ that claims to reduce slippage by 25% so maybe that would be a good product?

Originally Posted by mrein3

4.10 is 10% more gear than my 3.73s. So if your tire is 28" tall assume you'll be running 3630 rpms at 70 mph. Now I'm guessing stock 3/4 ton tires are taller than stock 1/2 ton but I'm not sure. If you get on the google and look for final gear ratio calculators you can do some pretty good guestimating of what you're looking at with no OD and with. I have no clue what the GV unit gives you for an OD reduction but I'm sure somebody here or the google can tell you that number.

Ok, did some reasearch. GV unit final drive (6th gear) is .78 to 1. I will run 285/75/16 or another 33" tire. The web calculators show 2450rpm at 75mph with this tire combo- seems pretty good to me. at 70 mph it would be 2300rpm. This would be with my 4.10 gears and open HO52 setup.

Now if i wanted to swap in a 3.54 Dana 60 I have, I could have Power Lok and less RPM's. Also if I did that, even without the GV unit, I'd be 2700rpm at 75 mph and 2550rpm at 70mph. I do have 4.10's for it also that I'd use if I ran the GV unit.

So on one hand, I'd have the best of all worlds with the GV unit except cost to install, which would be about $3000. On the other, without GV, I'd have to invest nothing but be running 250 higher rpm at cruise speed and have a lot less wheel torque (3.54 vs 4.10 rear) to get loads started when towing.

I will probably tow 1/2 the time with this truck but when I do it will be pulling a 2500lb trailer that will have up to 5000lbs on it (truck or tractor).

Thoughts?? I would probably have to build less of an engine (flat tappet cam) if I go the GV route since I don't have an unlimited budget.

[Vintage Windmills]

Originally Posted by Ozark Tim

I am sooooo jealous! I want one like this for my place in the country but all I ever find is 2wd.
Are you going to restore or mod or keep it just like it is?
Congrats

The ratio of 2wd to 4wd in 1972 was about 10:1 so they are def harder to find. Also, many of the 4x4's you'll find are converted 2x4's. I looked at so many trucks and still had to drive 300miles one way before I found a truck like this, and even it was locked up and not running

[doubleb's69]

If you are going to build a stroker I wouldn't use the "stock" heads that were on the engine you pulled from the truck. They are most likely 882 heads so they are 1.94/1.50 valves and 76 cc chambers. That engine needs to breathe better than that. If you're worried about your stock crank you could ask a local machine shop if it would polish out with out having to grind it. Just my 2 cents. Killer truck and looking forward to seeing it come together.

[Vintage Windmills]

Originally Posted by doubleb's69

If you are going to build a stroker I wouldn't use the "stock" heads that were on the engine you pulled from the truck. They are most likely 882 heads so they are 1.94/1.50 valves and 76 cc chambers. That engine needs to breathe better than that. If you're worried about your stock crank you could ask a local machine shop if it would polish out with out having to grind it. Just my 2 cents. Killer truck and looking forward to seeing it come together.

I have another stock crank now. These heads are 339X and are indeed 76cc. I did some more research and concluded that they will limit performance even in 2000-3000rpm range so I'm looking at a set of Vortech "Performance Improved" heads that allow perimeter valve cover mounting. Supposedly can get 330ft lbs with these, mild flat tappet cam so I'm thinking on doing this and not going 383. I will save money for gearvendors unit by using stock crank and not rollerizing valve train. Buying ZDDP oil isn't that big of a deal but having OD and gearsplitting would be

[mrein3]

Originally Posted by Vintage Windmills

My truck had a tranny cooler and so did a 69 GMC big block I parted. As far as I know they were factory. Maybe was standard on 3/4's?



Summit has a converter http://www.summitracing.com/parts/HUP-GM11FUEL/ that claims to reduce slippage by 25% so maybe that would be a good product?


Ok, did some reasearch. GV unit final drive (6th gear) is .78 to 1. I will run 285/75/16 or another 33" tire. The web calculators show 2450rpm at 75mph with this tire combo- seems pretty good to me. at 70 mph it would be 2300rpm. This would be with my 4.10 gears and open HO52 setup.

Now if i wanted to swap in a 3.54 Dana 60 I have, I could have Power Lok and less RPM's. Also if I did that, even without the GV unit, I'd be 2700rpm at 75 mph and 2550rpm at 70mph. I do have 4.10's for it also that I'd use if I ran the GV unit.

So on one hand, I'd have the best of all worlds with the GV unit except cost to install, which would be about $3000. On the other, without GV, I'd have to invest nothing but be running 250 higher rpm at cruise speed and have a lot less wheel torque (3.54 vs 4.10 rear) to get loads started when towing.

I will probably tow 1/2 the time with this truck but when I do it will be pulling a 2500lb trailer that will have up to 5000lbs on it (truck or tractor).

Thoughts?? I would probably have to build less of an engine (flat tappet cam) if I go the GV route since I don't have an unlimited budget.

I wasn't aware of a factory transmission cooler of this vintage. Either way I'd make sure that whatever auto you end up with I'd have a cooler plumbed BEFORE the radiator tank. On really cold days you can get the transmission fluid too cold if it is plumbed the other way. Up here you want hot transmission fluid to go to the external cooler, then radiator tank then back to the transmission.

Regarding final RPM numbers, does your tire speed calculator take into account slip in the torque converter? There isn't a lot on the highway but it is still there with a th350. If you run a 700r4 you won't be pulling in OD but I believe the torque converter still locks up in 3rd on that transmission.

If you switch your rear, remember you need to switch your front too. They need to be matched (front and rear gears) when you engage 4wd.

I just dug out my log. I can't believe it has been that long already but I did my 3-speed manual to th350 swap on 12/9/01. 10 years ago. He he he - my notes were projecting that if gas ever got over $1.799/gallon it still wouldn't be worth the swap for the amount of miles I drive the truck. I should recalculate for $4/gallon which is what I've been paying for the non-oxy premium lately.

Long story short where I missed the boat is the wear and tear on my truck and my eardrums when running high rpms down the highway.

All that being said I'd still be leaning towards a 700r4, 33" tires, and 4.10 gears.

[Vintage Windmills]

Originally Posted by mrein3

I wasn't aware of a factory transmission cooler of this vintage. Either way I'd make sure that whatever auto you end up with I'd have a cooler plumbed BEFORE the radiator tank. On really cold days you can get the transmission fluid too cold if it is plumbed the other way. Up here you want hot transmission fluid to go to the external cooler, then radiator tank then back to the transmission.

By tranny cooler I meant the one integral to the radiator. I think I could hide an auxilliary one somewhere where it wouldn't be too obvious.

Originally Posted by mrein3

Regarding final RPM numbers, does your tire speed calculator take into account slip in the torque converter? There isn't a lot on the highway but it is still there with a th350. If you run a 700r4 you won't be pulling in OD but I believe the torque converter still locks up in 3rd on that transmission.

No slip accounted for. What do you think of this? http://www.summitracing.com/parts/HUP-GM11FUEL/

Originally Posted by mrein3

If you switch your rear, remember you need to switch your front too. They need to be matched (front and rear gears) when you engage 4wd.

Yep, knew that. I wonder if the 4.11 vs 4.10 (Dana vs Eaton) would make a difference. I was told that the front turned slightly faster in these trucks to help keep them more stable, is that true? maybe that would be lost if I swapped to the Dana? Had a friend who bought a 4x4 without testing 4x4. Needless to say, he was stumped when it snowed and his truck was less stable in 4x4 than 2x4- he had a significantly slower ratio up front.

Thanks for your advice, nice to talk with someone with a similar rig who's been there before.

[Vintage Windmills]

Been rounding up parts, here are some nice original door panels I scored off ebay a few weeks ago: Now if i could find the matching armrests I'd be in better shape.