Will any Chevy 350 bolt to a SM 420 (1 Viewer)

Joined
Jun 2, 2003
Messages
102
Location
Alamosa, CO
Just dreaming of engine upgrades and wondering...I'm running an SM 420 and 3 speed t-case and when my old reliable 2F kicks the bucket I'm thinking 350. I'd love to go with a newer EFI or TBI and if I'm really lucky a Vortec. Will all or any of these bolt up to my SM 420? Thanks,

Scott
78 FJ-40 "Rudy"
 
Joined
Mar 1, 2002
Messages
245
Location
Boise ID
From what I understand the bell houseing that is between the tranny and engine should be the same 4 bolt 90 deg. pattern up till someting like 96' model year. The newer vortecs will not bolt up to older trannys.

Check Advanced Adapters. There forms should tell you exactly what you would need to do a swap like this.
 
Joined
Feb 6, 2002
Messages
15,272
Location
OC, CA
My understanding is that the bellhousing pattern on Chevrolet and GMC engines has remained the same since 1955. There are some differences in the starter mounting and the flywheels. You need any Chev/GMC housing from 1955 to 1967 although passenger cars from 62-67 used aluminum. Later bellhousing have the large diameter bearing retainer hole. Get any cast iron bellhousing on V8s and I6s from up to 67. The I6 version has holes for motor mounts in case you don't want to use the AA rear crossmember.
 

woody

Staff member
Admin
Joined
Jan 15, 2002
Messages
10,332
Location
Toquerville UT
I believe the engine-side bolt pattern is identical until you start hitting the newest 4.7, 5.3 and 6.0 version motors.

My SM465 swapped from my 78 block to the 91 block (TBI) with the only change being the flywheel. IIRC, 96ish is when you need to start double checking bolt patterns.

Medusa is the guru on this stuff...he'll find this later today I bet...
 

woody

Staff member
Admin
Joined
Jan 15, 2002
Messages
10,332
Location
Toquerville UT
420 = 1967-older, 7:1 first gear, 2wd GM trucks only OR rare divorced t-case, 10-spline output

465 = 1968-newer, 6.5:1 first gear, 2wd and 4wd GM trucks, divorced and married t-case, 3 different output shafts (10, 16??, and 23??-spline)
 
Joined
Mar 1, 2002
Messages
245
Location
Boise ID
Main diff is the granny gear ratio. 420 is 7.05 and 465 is 6.55. I have heard that the 465 shifts better and is quieter but not sure, would make sense it is newer. 420 is pre 67 and 465 is 68 and later.
 
Joined
May 2, 2003
Messages
4,925
Location
GSO NC
Woody's right. All the bolt patterns are the same for the bellhousing to the block, however, flywheels are not. When GM changed to a 1 piece rear main seal the bolt pattern on the crank was reduced (1986). The 420 has good strength and is worth keeping. If shopping for crate engines almost all use the old 90 degree bolt pattern but you will want to check closely for which crank they have.

Rice
 
Joined
Jun 2, 2003
Messages
102
Location
Alamosa, CO
Thanks to all for the helpful input. :) It sounds like if my trusty 2 F kicks the bucket, finding a 350 with a bellhousing pattern that bolts to my SM 420 won't be a problem. The issue seems to be getting a 350 with the same crank/flywheel pattern that will fit a 420. I don't even know where to start here? Any suggestions? I'm running a Centerforce Dual Friction Cluth if that helps....

Scott
78 FJ-40 "Rudy"
 
Joined
Feb 6, 2002
Messages
15,272
Location
OC, CA
[quote author=sdgraber link=board=1;threadid=10299;start=msg94506#msg94506 date=1074874821]
Thanks to all for the helpful input. :) It sounds like if my trusty 2 F kicks the bucket, finding a 350 with a bellhousing pattern that bolts to my SM 420 won't be a problem. The issue seems to be getting a 350 with the same crank/flywheel pattern that will fit a 420. I don't even know where to start here? Any suggestions? I'm running a Centerforce Dual Friction Cluth if that helps....

Scott
78 FJ-40 "Rudy"
[/quote]

The flywheel isn't an issue as far as the 420 is concerned. It will work with any of them.
 

woody

Staff member
Admin
Joined
Jan 15, 2002
Messages
10,332
Location
Toquerville UT
exactlee...the flywheel has no bearing on the tranny, clutch, or bellhousing....it's only effect is on the crankshaft and those mounting bolts (6). When you get the motor someday, if it has the flywheel attached, you are stylin. If you need to source one, they are about $100 or so, and you just need to specifiy what year motor you have to ensure it matches the crankshaft size.
 
Joined
Jun 20, 2003
Messages
339
Location
Watertown, NY
Just checked with autoparts shop and I can get a flywheel for my 91 engine for $55 + core, so its better to just swap in a new one.

Chris
 
Joined
Jun 2, 2003
Messages
102
Location
Alamosa, CO
SAAWEET :D

I was a little boggled trying to think why an engine with a bell housing that matches the bolt pattern on my SM 420 wouldn't bolt up due to flywheel issue....perfectly simple...it will bolt up, there is no issue :p Thanks for getting me straight on that. I'm sure the posts will roll in when the time comes to actually drop a 350 in, but for now my mind is at ease. Have a stellar weekend and thanks to those who responded!

Scott
78 FJ-40 "Rudy"
 

Poser

Oh...Durka Durka Durka.
s-Moderator
Supporting Vendor
Joined
Oct 1, 2003
Messages
20,456
Location
MN
The 420 is more desierable also, because of the mainshaft not needing to be drilled and tapped, as it is already, to facilitate holding the Toyota gear on the shaft.

The 465 requires that you use a spud shaft and long adapter, you change out the mainshaft to one that is already modified, which is not that big of a deal if you are going to go through the transmission before install, or as woody suggest, find a machine shop that will work on it installed, and have it drilled and tapped.

-Steve
 

Poser

Oh...Durka Durka Durka.
s-Moderator
Supporting Vendor
Joined
Oct 1, 2003
Messages
20,456
Location
MN
Oh, and about the 'noise' issues with 420vs465..

Land Cruisers are noisy vehicles...period.
 

woody

Staff member
Admin
Joined
Jan 15, 2002
Messages
10,332
Location
Toquerville UT
[quote author=Poser link=board=1;threadid=10299;start=msg94668#msg94668 date=1074899551], or as woody suggest, find a machine shop that will work on it installed, and have it drilled and tapped.[/quote]

Two guys locally have had short fine thread studs tig welded onto the output to hold the t-case input gear in place...there is almost no pressure on the bolt/stud, since the cut of the gear effectively pulls it "towards" the tranny....they've had zero problems with the tig'd stud.

If I were doing it again, that would be my process.
 

Users who are viewing this thread

Top Bottom