datzenmike Posted March 28, 2017 Report Share Posted March 28, 2017 Post #2 is for Rat720 for an '81 720 truck. You are posting in his thread and hence the confusion. For a car application like yours.... I said: A truck oil pan definitely won't fit. A truck oil pan is deep at the back and a car is deep in the middle with room at the back for the steering linkage to pass. IF your L20B is in a car then putting it on a Z series engine should work. The following L series front cases will convert that Z 5 speed for use on your car but the 720 5 speed came it two different lengths. One 26" long will fit the other 31.5" will need the driveshaft shortened. Both will need the transmission cross member modified. 4 or 5 speeds '75-'78 280z '79-'82 280zx non turbo '74-'79 620 '80 2wd 720 not 4x4 810 '81-'84 Maxima Quote Link to comment
CableDroid Posted March 29, 2017 Report Share Posted March 29, 2017 Good info. The Z24/5 speed I am looking to get is out of a '87 D21. Does that make any difference on the 5 speed front case swap? Not sure if they changed any with the body style change. Quote Link to comment
datzenmike Posted March 29, 2017 Report Share Posted March 29, 2017 The length is different again probably around 30" so maybe a driveshaft modification. OK the D21 Hardbody uses a 71C transmission. The 720 and earlier are 71B transmissions. An L series front casefrom a 71B will bolt on but the counter bearing is larger in the 71C. You can simply pull the 62mm one off and us a 56mm from a 71B in place of it and the matching 71B cover plate. The 1st/2nd shift rod is also 16mmon the 71C instead of 14mm on the 71B so the hole for the rod needs to be enlarged and can be done with a Black and Decker hand drill. Now the big problem is the 71C gears are wider and the front counter drive gear will rub the case. Some machining is required by a shop. No way around this. If you go ahead with this I can give you come specifications for the machinist. Quote Link to comment
CableDroid Posted March 29, 2017 Report Share Posted March 29, 2017 Sounds like I need to find a 720 5 speed....lol. If I still lived in Bakersfield I wouldn't bat an eye on still using the D21 5 speed. But I moved to NorCal in a small town 6 months ago and there are no machine shops that will attempt it. I already tried with having an aluminum blower snout I needed turned on a lathe for another project. They all looked at me like I was from Mars. The source for the Z24 is a small tow yard, but I think he might have a '86 720 2wd too. The engine in the '87 has less than 100k, not sure on the 720. Quote Link to comment
datzenmike Posted March 29, 2017 Report Share Posted March 29, 2017 If '85 and newer it will also have the larger 62mm counter bearing. Easiest thing is to replace with a 56mm one. Quote Link to comment
CableDroid Posted March 29, 2017 Report Share Posted March 29, 2017 A bearing I can handle, as long as it doesn't involve a machine shop. Lol Quote Link to comment
banzai510(hainz) Posted March 29, 2017 Report Share Posted March 29, 2017 technoToy Tuning has 5 speed xmembers Quote Link to comment
CableDroid Posted March 29, 2017 Report Share Posted March 29, 2017 For wagons? They are only about a hour from me too. Easy drive to save on shipping.... Quote Link to comment
CableDroid Posted March 29, 2017 Report Share Posted March 29, 2017 Okay, I found a low mileage Z24 and manual transmission in that same tow yard from a '84 2wd 720. Was a 4 speed even offered in '84? I know it's a manual, I can see the stick. I can't tow through the gears because the truck was rolled and the cab roof if caved in. Thanks!! Quote Link to comment
datzenmike Posted March 29, 2017 Report Share Posted March 29, 2017 Negative. No 4 speed was available on the Z24 ... so none after 'Oct/Nov '82 build dates on any gas or diesel engines. Quote Link to comment
CableDroid Posted March 29, 2017 Report Share Posted March 29, 2017 That's good to know. Think it's worth going with a bigger cam with the W58/L20b head on a Z24 short block? Quote Link to comment
datzenmike Posted March 30, 2017 Report Share Posted March 30, 2017 A mild cam. The L20B head alone will be a nice improvement above 4K. Quote Link to comment
CableDroid Posted March 30, 2017 Report Share Posted March 30, 2017 Cool. Been awhile since I bought a cam for a L-Series, who are the better companies to source from these days? Another question, my stock distributor I am running now will work with the Z24 short block, correct? Quote Link to comment
datzenmike Posted March 30, 2017 Report Share Posted March 30, 2017 I believe so yes. On second thought you may need the L20B spindle. Quote Link to comment
CableDroid Posted April 2, 2017 Report Share Posted April 2, 2017 I might just stroke my L20b block with the Z24 crankshaft instead. Quote Link to comment
datzenmike Posted April 2, 2017 Report Share Posted April 2, 2017 The Z24 crank does not fit without cutting the counter weights down and trimming the L block. There's a reason for rod stroke ratios. Short rods on long stroke increase the side loading on the piston near BDC. Quote Link to comment
CableDroid Posted April 2, 2017 Report Share Posted April 2, 2017 I know the crank counterweights have to have about 1/4" trimmed off and the block needs clearance. As far as the rod to stroke ratio, it's no different than a SBC 383 stroker using a 400 crank (3.76") and 350 rods (5.7") and I have literally built 100's for myself, customers, and friends. Still have one I built in 1996 and its still going. Quote Link to comment
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