The Stovebolt Site Forums The Shop Area The HiPo Shop 351D-V6 to a ???-V6 can it be done? ?

i would like to swap my 351D-V6 for a big v-6 with more power as i wabt to add an over drive see if i can get it up to 68-72MPH@3,000RPM in stead of 62MPH@3,000RPM...can the 478 be swapped in ? will tha 478 handle 3 grand ? can a 478 even be found ? 351M be a better bet?

I am not an expert, but from what I have read, the 478 would be a difficult swap. The 478 was externally balanced vs. the other GMC V6's that were internally balanced. The 478's only came in the large trucks with the large truck transmission and flywheels. These transmissions and flywheels would not fit in a small truck.

The 351M and 401M would be the ideal swaps. The M designation is for magnum. These engines came with larger intake and exhaust ports. They would be a bolt in swap with your 351D. Check out the following website for the experts. They have an excellent discussion group.

http://6066gmcguy.org/

Regards,
Steve

I just had this idea could get the M head's from a 351 and put them on the 379-V6 mill the head's over size the valve's a bit deck the block. than it would breath better have better compression and still hold 3 grand on the highway ? about all you can rebuild on these engine if you can find the engie's is the head's i've been told there are no hard part's no piston's rod's cam crank's ect. . . bearing's ring's gasket's all i can find. . .

351D:
The magnum heads would be a good upgrade to your 351D, but you would also need the magnum intake and exhaust manifolds to match up to them. They should be a bolt up swap.

I am unsure your source of information for inability to get parts. So far, I haven't had a problem, but it does sometimes take some effort. Some sources you might try are:
www.kanter.com
Mills Supply (Shreveport, LA)
Fliteline Engine Supply (Fort Smith, AR 1-800-
726-1427 ASK FOR BILL)
Napa Auto Parts

Also, check the group I referred you to. They are very helpful.
Regards,
Steve

I just checked with the rebuild shop's around here in wisconsin "midwest engine supply" they said bearing's and gasket's were all they could find. they claim the thing was obsolete I think the lazy Son of A's didn't wanna look for part's ...... i'm tryin to get 175-225HP with about 400FTLB torque...i would like to get 401 432 478 power from a 351 or 379.

I would like a tranny with granny low and over drive but it seem's you only get one or the other. so i was going to go with the richmond 6spd 3.28 first gear .76 6th gear. is why wanted the extra power that i love out puling v-8's with million mile V-6..... But 68mph sound's a whol lot better then runing 62mph over would be nice an extra 6mph don't seem like much it would help out.

If you want granny low and overdrive, take a look at the NV4500 that was used in the late 3/4 an 1 ton GM and Dodge trucks. There's also the 6 speed (Getrag i beleive) that has been used in GM heavy duty pickups the past few years. Contact Advanced Adapters, they make the kits for doing the conversion.
You could also consider using a Gear Venders overdrive, which can be used beind virtually any trans. It's very similar in operation to the old Borg-Warner od that many of us have in our 1/2 tons. I've even seen them put behing NV4500s to get a double overdrive.
One other option,Advaned Adapters also manufactures the Ranger overdrive, which is an auxillary trans that mounts ahead of the main trans. It will move the tranny back about 7". They make them in over, under, and combination over/underdrive.

The NV4500 is a torque loving 5 speed transmission with a granny low (5.61:1 on most models) and a overdrive (0.73:1). There are 2wd applications, and 4wd applications. There are also dodge and gm versions. Both the dodge and gm versions use a 10 spline 1 1/8 inch pilot shaft, so the stock clutch will work. THE 94-97 DODGE 2WD VERSION IS THE EAZIEST TO ADAPT TO AN OLDER GM CHASSIS. The early dodge version had a pilot shaft that is 1 inch longer than the standard gm transmissions. An adapter plate will have to be used to bolt the transmission to the bellhousing. They are available from advance adapters. The early dodge version of the NV4500 is also the only version that can be adapted for a mechanical speedo. That may not be so important if you have a 4wd or an auxilary transmision. There also may be bellhousings available that will bolt an Nv4500 directly on to your motor, but I'm not sure if they will bolt to the frame properly.

NV4500 isn't that the Diesel trans?? for the 5.9/6.7 cummin's?? or the 6.2/6.5/6.6 GM ?

the speedo not that big of deal they offer both style's for the 60-66 in jeg's.
it's a single speed rear end 5.13:1, with 8R19.5's...68mph@3000rpm or less is the goal.
currebtly i'm at 62mph@3,000rpm not bad till you figure the engine comes apart around 3750-4000 rpm.


Adapting that tran's the 351D-V6 is going to be an extreme treat i'm sure. . . but as a wise man once said if you got a torch, a welder and a Drill you can make anything work. . .

so the NV4500 is the tran's i need.
now all i need is to get more grunt out of my engine 175-225hp 380-430tq,i got around to start with like 170hp and 280ish tq, 7.5:1 comp. plenty of room to improve... what about bumping ti to like 8:1 or 8.5:1 should get me about 340ish TQ, idealy i would like it to have 9.8:1 - 10.2:1. if i could get a torque rating of like 415TQ@2250RPM i would be happy. or somthing like 388TQ@1750RPM. . . .maybe the old dynosour just ain't worth time. . . i should be just be happ it's doggy and slow i got less than $2,000 into it and i have gotten almost10 trouble free year's from it tho $115 oil change's suck. . . I'm young yet i'll get over it. :hammering:

The NV4500 was also used in diesel applications. One word of caution, the diesel version has a much larger pilot shaft. It is 10 spline on 1 1/4 inch. I'm not sure what your c40 uses.

What transmission do you have now?

standard issue GM granny 4 spd with reverse by second gear. same tran's you would find behind say a 350 or 400 sbc from as best i can tell. . .

What you have is the SM420, which was used up to '66. Good trans,very strong and has the lowest first gear offered in a light truck at 7.05-1. It should have the standard GM input spline.

i could have told you that much it's an awsome tran's No Over drive bad for truck with low reving engine and 5.13 gear's...

351D-V6,SM420 4spd,5.13 gear's, and 19.5 tire's 7 foot flat bed. . . .it's definatly got the sawed off shot gun affect. i would like it to have the double barrel 10G sawed off shot affect.
:-) !351M-V6 or 379M-V6! (-: i would like 478M power from a 351 or 379. . . 62mph is good but 68mph is better so OD is a must.

the 351M has 190hp and 304tq thats good enough.
a holley 500 2bbl, HEI ignition ,mill the head's for higher compression and shazam...
power house. how you can i get the compression on the 351M 8.5:1 ? it's starting at 7.5:1.

Now all gotta do is fine an engine that hasn't been made in 30year's hope it run's good than fine the NV4500 tran's and hope they match up.

so now how do i go about finding the 351M ? that hopfully won't need a major rebuild cause part's are limited !

You can try Fliteline. They were selling rebuilt 351's on ebay last month. I don't know if they have any left.
Regards,
Steve
Fliteline Engine Supply (Fort Smith, AR 1-800-
726-1427 ASK FOR BILL)

but are they just random 351's or are they labled as 351D 351E and 351M ? cause if i would get sent a 351D it wouldn't do me much good i already have the 351D-V6. . . i need the 351M-v6 GMC. . .