Topic: 4.3 to sm420

[Rocksnail]

Anyone here running a 4.3 with a sm420? Im getting ready to start a new build with that setup and duels. I'm having problems finding info on what clutch to use for this setup. I'm guessing i would just use  all the parts for a v6 with a factory 5speed. Also have any of you set up your sm420 to use a hydro clutch? or you still running a cable? Any info you have on this swap will help  a lot. Thank you

[HDcruiser]

I ran a 5.7 with a sm420...  its a sweet trans, small and a 7.05 first gear. I went with a mechanical linkage on mine. If i remember right (its been several years since i ran the combo) the sm420's came out out 1965- 1968 chevy truck applications. I used a clutch, thow out bearing, and pressure plate out of a 69 chevy truck/blazer. It all bolts up with no issues. Your 420 should bolt right up to your 4.3 without using any adapters. I'll look into the hydralic clutch for you. I have some friends that i havent talked to in a long time that still run this combo and might be able to find some more info for you.

[RABIDYOTA]

the clutch you want is a sach's #k1909-06 or k1909-02  12 in. will bolt to the 4.3 11 in. flywheel using a stock chevy bell housing A.A. makes a slave cylinder for external mounting   realy most all chevy  1in. x 10 spline clutches that will bolt up to your flywheel will work

[HDcruiser]

My buddy told me that there is a hydralic clutch available for the 420's. He said he would try to get me a name of the company, but im not holding my breath for him. If more info come up, i will send it your way.   

[66cobra]

that would be a sweet combo. post a build on it. wish i thought of that when i did my 4,3 conversion

[Rocksnail [OP]]

Thanks guys. Ill be picking up the sm420 this Thursday. I may also be getting a sm456 that already has a adapter on it for toy cases.( pending) anyone know if the 456 will bolt right up to my 4.3 like the 420 will? I know the 420 has a lower first gear, but the 465 has the adapter already on it( will save about $350) I will go with the 420 is the adapter on the 465 will fit the 420. anyone know? Also i will be doing a build on this one. To bad the only toyota part will be the duels. I'm building a s10 blazer with d60 and 14bolt on 4dees. I'm going with the s10 blazer for the fact that its just like a 4runner and already has the 4.3 in it. plus it has r12 a/c oh so cold.

[HDcruiser]

The 465 will bolt up to your4.3 without any apapters. Call advanced adapters to see if your adapter plate is interchangable with the 465 to the 420. I personally don't thing so, but I'm not sure. The body on the 465 is much bigger than a 420.

[HDcruiser]

Just curious, what year is your s-10 blazer?

[Rocksnail [OP]]

To tell you the truth I'm not sure on the year. It's the square body style.  But my paper work on it says 93. I though that a 93 was the rounder style
 it has the vortech in it. It's in my tow yard and I havnt really started to mess with it yet. Havnt even started the engine yet.  And as far as the adapter go.  It's a marlin adapter. I talked to freds40 about it. Just waiting to see what he says.  If it won't work on the 420 then I'm just going to use the 465.  The 420 adapter is $500.   And I'm going to get both trannys for less then that plus an adapter.  Also been tossing around the idea of going to a 203/205 double.  Face it the toy cases will be my weak link.  But the odds
of that are slim. 

[P-DiseToy24]

please if you have the option now do it the right way and DONT run toyota case's. They might work great for a while but they will always end up in pieces. Go with the 203/205 or better yet a 203/300 so you have the option of a lowmax 4.1 and a front dig.
Not that toy cases are bad they just can only be built so strong.

[Rocksnail [OP]]

If I can find a 203.  Might already have a 205.  I will build it. Toy cases are good.  But your right you can only build them so strong.  The 203/300 would be awesome an is a option. 

[yotatough]

cant wait to see this thing come together!

[HDcruiser]

To tell you the truth I'm not sure on the year. It's the square body style.

My buddy has a 91 S-10 and he allready has 44's and the 465 combo. What he has been looking for is the SAS front hanger kit for his. What kit are you going to use?

[Rocksnail [OP]]

The blazer  is a 93 4 door. Planes are to cut the sky hanger off my yota clean it up and use it on the blazer. As far all the rest of the suspension parts needed for the swap, ill just build those at my shop. I havnt checked the wheel base on it yet, but i plan to move my front axle around 4inches forward. Going to try and keep the rig nice and low. my yota is 25inches from lowest part of tcase. witch is 2 inches under my frame. So im shooting for a flat belly of around 23 inches. I posted earlyer that i might do a 203/205 double. That is going to be out of the question. My front D line will be to long and rear to short with that set up. And the low range is only 2.1 in each case. My cases have alot lower of gears and with the 6.5 first gear in the sm465 that im going to pick up. its going to be stupid low. If i have problems with the toy cases .ill just save my cash and  drop the coin on a atles and call it good. all in all i cant wait to start this build. i have so many parts laying around and a full truck to strip and sell parts off of. I have alot of work ahead of me but hoping i can have it ready to go before all the snow is gone. wish me luck

[HDcruiser]

You can also run a KluneV or a lomax for you np205. it wont be as much as a atlas, just a thought... sounds like a awesome build anyways.. im looking forward to your build on this.   

[Rocksnail [OP]]

i looked at the Klunev and lomax, there nice and a cheaper route. An atles would just be so awesome. It wont happen anytime soon. im going to wheel the piss out of my duel before i do anything. I dont use the gas to much when im wheeling. most the time just let the gears do all the work so the duels should last me a good while. Picked up a bell housing, and a 2dr blazer from my buddy for a few parts. Hes going to strip it for parts and scrap the rest. so iim getting a set of doors, fenders, hood , rear glass and tail gate for free! Hope i can get this sm465 here in the next week so i can start on the tranny swap and making this 2wd into a 4x4. Should be starting a build up on here in the next few weeks. will start it off with the tear down of my 1st gen.