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-   -   Muncie 4spd to NP440 conversion 66 GMG 3/4 ton (https://6066gmcclub.com/showthread.php?t=49817)

Dazzoman December 31st, 2016 05:25 PM

Muncie 4spd to NP440 conversion 66 GMG 3/4 ton
 
5 Attachment(s)
FYI : this conversion was the best thing I ever did for my 66 GMC 3/4 ton w/ 292 6 cly !
I had to make 2 straps ,1 spacer for the left side bolts , have the driveshaft modified , turn the release bearing housing - but my gas mileage increased as well as shifting 1 thru 4 is amazing !
Even the (now lengthened summit) speedo cable gear gear ratio is perfect as before the 465 was way off with the 356 rear end ( was hoping that would cure the gas prob years ago) .
Heres a few pics . I also had to modify the floor pan shift hole but this truck is my regular driver now . Im going to sell the 292 and pop in a 350 because this setup LOVES torque .
You have to opt for either the aluminum or the iron that these come in made from early to mid 80s , I went with the iron (not pictured , this was when I had the aluminum with the wrong shifter ) .If you opt aluminum go ahead and put in an shaft steel sleeve so it won't break . It'll be lighter and very tough .
I was able to use my original 66 bell housing - so I could not worry about cross mounts plus save the old 3 ear cast starter bolt pattern , plus its stronger than the alum bell they offered for the MY6 NP440 NP833 , not to mention the clutch boot stuff .
MAKE SURE you get the truck shifter with it, they are rare and don't get the 1982 van shifter , it positions too far back .

TJ's GMC January 11th, 2017 02:06 AM

Re: Muncie 4spd to NP440 conversion 66 GMG 3/4 ton
 
350 is Far from being a torque monster. lol It's just an over glorified small block. You want Torque get a 351 - 478 V6. That is torque my friend. lol Or if you have to have a v8 the good ol 366. haha

Dazzoman January 11th, 2017 02:42 AM

Re: Muncie 4spd to NP440 conversion 66 GMG 3/4 ton
 
I need something usable and reasonable on gas . Originally I had the 305E in this truck circa 1980 and it never missed a gas station altho it was a great running and fun to drive .
At least GMC offered the 292 and so I put that in , in 1987 .
Now that Holley has an new EFI Sniper it looks like with this tranny its gonna be a win win .The 292 is a nice motor and mine runs great but it will cost the same to fix the head gasket small oil leak , replace the header , switch to 4 bl carb , cam etc . than to pop in a 350 .Probly get better milage .

TJ's GMC January 11th, 2017 02:53 AM

Re: Muncie 4spd to NP440 conversion 66 GMG 3/4 ton
 
Quote:

Originally Posted by Dazzoman (Post 65893)
I need something usable and reasonable on gas . Originally I had the 305E in this truck circa 1980 and it never missed a gas station altho it was a great running and fun to drive .
At least GMC offered the 292 and so I put that in , in 1987 .
Now that Holley has an new EFI Sniper it looks like with this tranny its gonna be a win win .The 292 is a nice motor and mine runs great but it will cost the same to fix the head gasket small oil leak , replace the header , switch to 4 bl carb , cam etc . than to pop in a 350 .Probly get better milage .

V6's and I6's are usable and can be reasonable on gas, just depends on how you tune them up and how you drive then. Always towing? Doesn't matter what engine you have...it's gonna hog gas. Unless you throw a cummins in there. lol
My 64 GMC with a 305E that has a 4 barrel, HEI, and dual exhaust gets 9.9 in the city and 13 on the highway. Not bad for being 4.11 geared and carrying a 4500 pound 3/4 ton truck around.
I know a guy who had a 292 with a quadrajet, headers, and HEI in a 66 chevy truck that got 20 MPG with a 5 speed.
Carbed 350 will get bad mileage as well, Gearing and Tire size makes for some of the biggest differences. All you'll get is some extra horses.

But you said that setup liked Torque and I was clarifying the 350 is far from a torque monster. lol It is a glorified engine, decent power, but sucks just as much fuel when towing and doesn't do much better either.

I drive my 64 7 days a week and that 305 never lets me down. :thumbsup:
My 292 never did either, but I decided to restore the truck. And a way hotter 292 is in there now with a tko600. lol

I guess torque to me is a big cam cummins or a 572 chevy that puts out 800 torque or a 478 V6. :upyes:

Dazzoman January 11th, 2017 03:13 AM

Re: Muncie 4spd to NP440 conversion 66 GMG 3/4 ton
 
Yes the 305 E is an fine engine and is very industrial , will pull a cow off the moon or an elephant up a hill or tree w/ no problems . And VERY dependable .

I had an camper on mine for yrs and later the 292 was great altho not really fast but then again it was all stock .
Hopefully the 350 will be a bit more power or at least quicker .
Where in Oregon are you / I have friends up in Newberg and Im supposed to go there for an funeral Jan 28th but the weather threatens like with the salt on the roads is a deal breaker for me . Im in Calif near san fran.

TJ's GMC January 11th, 2017 04:17 AM

Re: Muncie 4spd to NP440 conversion 66 GMG 3/4 ton
 
Quote:

Originally Posted by Dazzoman (Post 65896)
Yes the 305 E is an fine engine and is very industrial , will pull a cow off the moon or an elephant up a hill or tree w/ no problems . And VERY dependable .

I had an camper on mine for yrs and later the 292 was great altho not really fast but then again it was all stock .
Hopefully the 350 will be a bit more power or at least quicker .
Where in Oregon are you / I have friends up in Newberg and Im supposed to go there for an funeral Jan 28th but the weather threatens like with the salt on the roads is a deal breaker for me . Im in Calif near san fran.

Yeah, the 305 is small and slow for it's weight, and that's the main turn off. Though it does a heck of a job for it's size, and a little more fuel and less back pressure seems to wake them up nicely. I went with 3 different carb stages on a 292 and then went with a full hopped up rebuild on another. Love those engines. Most simple and easiest truck engine I have ever worked on.
I am in Cave Junction, I mapped Newberg and I am 4 hours South. You'll be up near the Portland area. You'll pass through Grants Pass on your way if you take the 5 North. I am 36 miles from Grants Pass. If you happen to have time drop in, always wanting to meet more members. :thumbsup: Sorry to hear about the funeral. Will keep you and the family in my prayers.

Dazzoman January 11th, 2017 05:04 AM

Re: Muncie 4spd to NP440 conversion 66 GMG 3/4 ton
 
Yes thank you for that , prayer is always good and needed indeed .
I just now found out they had the funeral yesterday and but the celebratory meet will be on the 28th .
Im in Sunnyvale but im thinking a plane will save the rust factor on my van .
I wouldn't take the 292 GMC because the head gasket leaks little oil (very rare) when ever it wants to and I just did all this cleanup / trans work and then there is the salt thing . I wouldn't take (maybe) an rental thru that altho that might be the answer .
Im loving ( so is the 292 with 150 lbs in every cylinder) the overdrive NP440 1982 trans - its the best thing this truck ( exept for the 305) ever had .
The original SM450 finally went out this summer 200k miles !
I bought it in 1980 up in Snohomish WA .

TJ's GMC January 11th, 2017 05:29 AM

Re: Muncie 4spd to NP440 conversion 66 GMG 3/4 ton
 
Quote:

Originally Posted by Dazzoman (Post 65899)
Yes thank you for that , prayer is always good and needed indeed .
I just now found out they had the funeral yesterday and but the celebratory meet will be on the 28th .
Im in Sunnyvale but im thinking a plane will save the rust factor on my van .
I wouldn't take the 292 GMC because the head gasket leaks little oil (very rare) when ever it wants to and I just did all this cleanup / trans work and then there is the salt thing . I wouldn't take (maybe) an rental thru that altho that might be the answer .
Im loving ( so is the 292 with 150 lbs in every cylinder) the overdrive NP440 1982 trans - its the best thing this truck ( exept for the 305) ever had .
The original SM450 finally went out this summer 200k miles !
I bought it in 1980 up in Snohomish WA .

It will for sure, luckily here in Oregon they don't use salt. :upyes: I am looking into either a gear splitter or an OD trans for my GMC. Since I am a uniqueness nut, what I REALLY want to do is find a 2 speed rear axle, NP435 4 speed, And do a 2 speed gear splitter. That would make for 16 gears! haha Course the truck would be converted to a dually and I would go with ton and a 1/4 rear suspension. All these plans! haha Gotta get my 66 done 1st though.

Dazzoman January 11th, 2017 07:14 AM

Re: Muncie 4spd to NP440 conversion 66 GMG 3/4 ton
 
OK and yes I except your offer to visit ifI ever go thru S, Oregon .
I was thinking this :
My buddy is a truck driver in Weed CA and an mechanic Chevy nut for 40 yrs .
He swears by ( and I drove in it to see this ) putting an modern rear end (they have more higer gears ) in his 72 chevy half ton with I think an 307 in it and leaving the SM450 in it because you can't break those really and he is into towing . His truck gets up and MOVES I mean that high rear end did something for it (but I gotta see what he gets gas wise maybe you arent into that ).
The 66 Dana Spicer rear end I have only will go up to 356 or something whereas it had the original 411 when I got it . I was into gas milage and the combo of the 292 and the 356 made things nicer for me since I wasnt pulling tree stumps , only an camper .
Now I have no camper and Im still searching for the perfect win win situation where I have the gas mileage and the power IF I NEED IT I can call upon it !

TJ's GMC January 11th, 2017 03:28 PM

Re: Muncie 4spd to NP440 conversion 66 GMG 3/4 ton
 
Quote:

Originally Posted by Dazzoman (Post 65905)
OK and yes I except your offer to visit ifI ever go thru S, Oregon .
I was thinking this :
My buddy is a truck driver in Weed CA and an mechanic Chevy nut for 40 yrs .
He swears by ( and I drove in it to see this ) putting an modern rear end (they have more higer gears ) in his 72 chevy half ton with I think an 307 in it and leaving the SM450 in it because you can't break those really and he is into towing . His truck gets up and MOVES I mean that high rear end did something for it (but I gotta see what he gets gas wise maybe you arent into that ).
The 66 Dana Spicer rear end I have only will go up to 356 or something whereas it had the original 411 when I got it . I was into gas milage and the combo of the 292 and the 356 made things nicer for me since I wasnt pulling tree stumps , only an camper .
Now I have no camper and Im still searching for the perfect win win situation where I have the gas mileage and the power IF I NEED IT I can call upon it !

With a taller rear gearing it'll move better in lower gears because the driveshaft is turning less revolutions per revolution at the tire.
That's another reason why the v6's don't seem so fast, the torque is there, but the gearing is not. Put a 3.73, 3.42, or 3.07 gear behind a GMC v6 and it'll move! I guess GM didn't understand that low gearing and low rpm engines Don't mix. haha
With my 66 c10 I kept the 3.73's and I went with a 30 inch tire and put a TKO600 behind the 292. It'll do 65 at 2500 all day in 5th. :thumbsup: And still have plenty of power to pull 5th if I want to as 2500 rpm is in the torque curve! I built the engine to handle 5000 RPM with ease, and doing so brought the torque curve to the mid-range with the new cam. :upyes:

in my experience, the Best cruise RPM for an engine is to find its peak torque RPM or just below.

With a v6 for instance, bone stock they peak torque at 1600. So finding the gearing to cruise 65 at 2000 RPM would be optimum. You are close to the engines peak torque, RPM's are low, and fuel consumption and engine wear is decreased.

With a v8 350 the torque tends to be more mid-ranged...somewhere's between 2500-3300 as from the crate they are capable of 5000 RPM. So the win win to me would keep the rear gearing fairly low and put in a 5 speed, that way you won't have to down shift all the time.

I think the best win win would be fuel injection. haha


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