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Discussion Starter · #1 ·
Has anyone put a 4bt in a 67-72 chevy 4x4? I am seriously considering putting a 4bt in my 71 chevy longbed 4x4. I have a 700R4 with the front crossmember and motor moved forward to accomidate for the extra length. Anybody able to use any factory motor mounts in a 67-72 chevy? What about clearance between the oil pan and front diff? I hear that when bolting up the 700r4 to the turbo 400 flex plate you have to drill the turbo 400 plate for the 700R4 converter bolt pattern and find something to make up the 1/4" gap. I have also heard from Bowtie overdrives that as long as it isn't more than 1/4" forward from all the way back you can just pull the converter forward to the drilled 400 flexplate and it will still work. How did you hook the TV cable to the throttle linkage? Fuel mileage?..........I have 31X10.50's I beleive the gears to be 3.4-3.73(not sure) this is a street truck that I sometimes need 4X4 for a bad road when hunting or a slick boat ramp(it's not a mudbogger or rock crawler). I am looking at a 4bt with a liquid intercooler. I will add a 3200 rpm GOV spring. I will insulate the engine compartment and cab with 1/4" self adhesive duct insulation. I am hoping to have my truck get 22+MPG without rattling to peices or being too abnoxiously loud in the cab while driving. I've had a diesel isuzu, 2 diesel mercedes, and 1 diesel vw, but htis is my first try at "building" one......................Any advice?
 

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Welcome to the site! Check out the FAQ, lots of good info in there. And remember what Dirty Harry says...


:D
 

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i have

you will need to lift it ! i have a 6in lift on my swb 71 chevy and i am about 8in from the oil pan to the front dif. and you will need to clearence the firewall i set mine up to use the same driveshafts so it is a little close to the firewall . i used the fluid mounts out of a box van,they work fine . also depending on what tranny you use you will have to make a little room for the starter about 1/4 in off the frame . I have a cpl 857,nv4500,np205,14boltff,dana44 . it was alot of money to do but it was worth it i get 24 mpg on 35in tires and it weights 4900 lb and i can tow 8000 5th wheel with little problems. last week it failed do to gear oil from my transfer case getting in to my tranny killing all the scrincos. so fill the tcase with the same stuff that goes in the tranny!
 

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Discussion Starter · #4 ·
I will cut and reweld the oil pan before I lift it. My 400 was moved forward about 2" to accomidate the 700r4 I hope this extra distance will acommidate the downpipe. How close was your downpipe to the firewall? If it won't make the turn I'll cut and reweld the downpipe with a very sharp bend. I might bash the firewall inward with a big hammer, but I dont' want to cut it. I'll sacrifice some exhaust flow before I cut the firewall. It is possible for me to jack the driveline up higher in the front. I remember onetime needing to take the oilpan off the 400 so I unbolted the motor mounts and put a jack under the flywheel and jacked up the motor about 6" so I could get the oil pan off. I'm going to see what it looks like when I get it in...............This truck is not my 4wheel toy. It is a street truck that will be a daily driver that occasionally need 4x4 on a slick boat ramp or a bad dirt road to my deer stand...........I can notch the frame to clear the starter, but what might be interesting to clear the starter and the diff would be to have the motor angled to the left side of the vehicle instead of centered..? I might be able to loosen up the transfer case crossmember mounts enough to make it work.
 

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If you're running the chevy adapter your engine will be tilted 10 degrees to the passenger side, thus moving the oilpan towards the drivers side. Helps with differential clearance. I'm curious though, as to why you moved the whole engine forward to accomodate the 700R4 length - did you just not want to cut driveshafts? Did you have it built with the short shaft for the NP205 or did you use a spacer?
 

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Discussion Starter · #6 ·
The 700R4 was about 3" longer than the turbo 350 it replaced. So I could either move the transfer case back or the motor forward. The crossmember under the transfer case is much bigger with more bolts than the one under the engine. Also if you move the transfer case you then have to alter 2 driveshafts. It was much easier to move the engine forward......Very simple: Unbolt the crossmember from the frame and use a "come-a-long" to attached between the crossmember under the engine and the front of the frame(engine still in truck). Pull the engine forward about 4". Put in tranny and bolt to transfer case. Now attach the come-a-long between front crossmember and the crossmember under the transfer case. Pull the engine/crossmember back to the tranny. Once it's bolted up you can either drill and put new bolts through the frame and crossmember, or you can do what I did and weld it in place which is easier. There was no issue with hoses or wires as they had enough slack for the 3" move. Exhaust was hooked up by pulling a few inches out of the flex pipe that was curved over the rear axle. The power steering pump was about 1" too close to the plastic radiator shroud. It "self clearanced" a notch in the fan shroud when I cranked it up..........For some reason even when I explain how easy this is some people still would rather cut and lengthen driveshafts. The most bizarre reason I've heard for not moving the engine 3" is that "the weight shift would adversly affect handling"???
 

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This is how i hooked up my 700r4, it bolts up fine and works well too. I'm at about 800 miles on the combo, hopin to put on a few hundred more this weekend, we will see.



 

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The 700R4 was about 3" longer than the turbo 350 it replaced. So I could either move the transfer case back or the motor forward. The crossmember under the transfer case is much bigger with more bolts than the one under the engine. Also if you move the transfer case you then have to alter 2 driveshafts. It was much easier to move the engine forward......Very simple: Unbolt the crossmember from the frame and use a "come-a-long" to attached between the crossmember under the engine and the front of the frame(engine still in truck). Pull the engine forward about 4". Put in tranny and bolt to transfer case. Now attach the come-a-long between front crossmember and the crossmember under the transfer case. Pull the engine/crossmember back to the tranny. Once it's bolted up you can either drill and put new bolts through the frame and crossmember, or you can do what I did and weld it in place which is easier. There was no issue with hoses or wires as they had enough slack for the 3" move. Exhaust was hooked up by pulling a few inches out of the flex pipe that was curved over the rear axle. The power steering pump was about 1" too close to the plastic radiator shroud. It "self clearanced" a notch in the fan shroud when I cranked it up..........For some reason even when I explain how easy this is some people still would rather cut and lengthen driveshafts. The most bizarre reason I've heard for not moving the engine 3" is that "the weight shift would adversly affect handling"???

Yeah mounting the thing further to the front will affect handling. Those 67-72's had a lot of underhood clearance and I Believe the V8's were mounted further back. There were two sets of mounting points for the I6 and V8 models. I built two of these trucks several years ago. I would figure a rig that old (if it had the stock driveshafts) would need to be rebuilt so cutting wouldn't be an issue.

Also - you never said: Did you put a spacer between the 700R4 and the adapter or did you have the short 4wd shaft installed for the 700R4? Also consider you'll need some internal changes when switching to the diesel (governor, 13 vane pump if you haven't already upgraded, Torque converter)


Here's a few pics of my old trucks like your model.

1972 Chevy Cheyenne Super 350/TH350 air/ps/pb/tilt/tach


1970 Chevy All original (except the seat cover), 2nd owner. 95k miles when purchased in 1995. Repainted & Restored.

 

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Discussion Starter · #10 ·
I had the tranny built with a tailshaft needed to bolt to the transfer case. Tranny is supposed to have been built for "high performance" by bowtie overdrives. Hopefully the pump has been upgraded as you mentioned. I got the springs and weights on the governor changed to lower the shift points for a diesel yesterday. Last night a welded together a unusual bracket for TV and throttle cable that allows me to adjust the cable pull travel as well as the tension for the TV cable, but it doesn't look as nice and simple as what was posted in the pic above. Maybe I'll redo it again. Nice looking adapter ring for the converter. I plan on using a simpler method used by the guy I got the engine from. I will post pics after I am sure it works, or it breaks..........Handling in my 4x4?? well, I must admit I never took it to the drag strip, never took it on a timed road course, and I never took it on a skidpad. If I had I probably would have seen a time difference. I noticed no difference in my daily driving. Having 2 friends in the cab, gas tank full or empty, or a ATV in the bed makes a much bigger difference. Thanks all for the advice and keep it coming.
 

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Does your gas-tank have baffles? That 1970 model didn't, it sloshed ALOT. The 72 wasn't as bad, but still noticable. Having the gas tank behind the seat is almost as bad as those old army jeeps where they were right under the seat:eek:

Here's my fix for the torque converter:

 

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I had a '72 C20 Custom Camper with a 350/350 and for whatever reason, the engine was installed from the factory set forward about 3". I have seen a few others this way. They seem to handle fine with the extra weight forward.
 

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Does your gas-tank have baffles? That 1970 model didn't, it sloshed ALOT. The 72 wasn't as bad, but still noticable. Having the gas tank behind the seat is almost as bad as those old army jeeps where they were right under the seat:eek:


'67-'72 Suburban fuel tanks bolt right in. You just need to move your fuel filler and spare tire to the inside of the bed. I did the swap in a '70 SWB I had.
 

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I had a '72 C20 Custom Camper with a 350/350 and for whatever reason, the engine was installed from the factory set forward about 3". I have seen a few others this way. They seem to handle fine with the extra weight forward.
It was moved if it was in the front holes. If I remember correctly there were 3 bolt holes per in the top of the frame, and 2 in the lower crossmember per side. 6cyl's mounted in the front set, V8's in the rear. This was for a 2wd Truck. The 4wd trucks probably had only one mounting point, in the front holes, due to a different front crossmember.
 

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Yes there are different mounting holes in the frame rails. I removed a 250 6 cylinder in my '70 and installed a 468 big block, using the forward mounting holes so I didn't have to beat on the firewall to get it to fit.
 

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Here are the drivers side frames in 2WD and 4WD with the mounting brackets set up for a V8:
 

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I knew the 67-72 crossmember was different from the 73-87, but dang, i'm getting old trying to remember stuff I did in 1995 :( .

I have seen the later model 73-87 mounts used on the 2wd frame pretty easily and it eliminates that bastard type mount with the single bolt @ bolt hole. Much easier using the long-bolt type mount of the 73-87.
 

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Discussion Starter · #18 ·
I test fit the 4bt tonight. It fits Ok, but I have to pull it out fix some problems.

I didn't check the bolt holes on the engine adapter plate before I put it in. It is aluminum and the threads on 2 of the holes are weak. I could helicoil them, but I think I will drill all the way through and use a nut and bolt as this will be stronger. The small block chevy is cast iron and the short bolts work fine in it. I think the aluminum adapter plate on the cummins needs longer bolts at a minimum.

The oil pan will clear the front differential. During all but the hardest of off roading. (If I bottom the front end metal to metal) it might dent the side of the oil pan in slightly as it makes contact. The starter cleared the frame OK.
I am using the original motor mount brackets from the bread truck on the motor. I will also use the bread truck rubber mounts. I will weld 3/8 plate tabs to the bottom of the frame rails for the mounts to sit on. I will gusset these with 2X1/4" bar stock. I will have a problem with the exhaust downpipe clearing the firewall. I will cut all the straight pipe between the turbo and the bend so it begins to turn down immediately after the turbo. I will try to "clearance" the firewall a bit with a sledge hammer. Hopefully I can make it fit.
Diesel Governor went in the 700r4 today. I think I'll be driving this thing by next weekend.
 

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"I will try to "clearance" the firewall a bit with a sledge hammer. Hopefully I can make it fit."

That pipe gets stinkin' hot just out of the turbo. Try and make room for some heat shielding or air gap of some sort. The quick bend downward is a good starting point...
 
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