400 or 351m????
Elder User
Joined: Dec 2004
Posts: 742
Likes: 2
From: Eastern Iowa
I think both the 351 and the 400M's were pigs. But if it's what you have to choose between, definitly go for the 400. These emissions strangled,low compression HUGE chunks of iron need all the cubes they can possibly get.
Senior User
Joined: Nov 2004
Posts: 225
Likes: 2
From: Richland, MO
Originally Posted by masterbeavis
Click on the pic in post #6.
Thinkin I might take mine to the scrapyard. Scrap's bring decent money right now.
Hotshot
Joined: Feb 2004
Posts: 10,860
Likes: 2,621
From: The Shenandoah Valley
Originally Posted by northerndave
... etc ...
Now I've got the 351 in a 77 & your comments on balance really mean something to me. I swear to god when I start that engine cold I can watch that damn crank shakin in the journals!! as it warms up it smooths out but I worry about the froont crank bearings.
power is way below my old 400, mileage seems no better with the 351.
I'm thinkin I'll look for a 400 cank, flex plate & H-balancer... See I have a spare 351 in a stand in the shop, might as well turn it into a 400. do I need the 400 rods or do they use the same rods?
Now I've got the 351 in a 77 & your comments on balance really mean something to me. I swear to god when I start that engine cold I can watch that damn crank shakin in the journals!! as it warms up it smooths out but I worry about the froont crank bearings.
power is way below my old 400, mileage seems no better with the 351.
I'm thinkin I'll look for a 400 cank, flex plate & H-balancer... See I have a spare 351 in a stand in the shop, might as well turn it into a 400. do I need the 400 rods or do they use the same rods?
The 351m and 400 use the same rods, pistons are same diameter but the wrist pin is higher up on the 400 pistons like I said, to accomodate the extra stroke at TDC.
I have a 400 HB to go with my 400 on the stand, but I wasn't aware they used different flexplates? Is it true, are the flexplates different ???? I never gave the HB much thought as I got one with the 400 and am going to use it.
If your '77 is a 4x4, changing out rod and main bearings with the motor in the truck really isn't hard. Need oil pan gasket set, maybe a oil pump if goingto replace it, and the correct bearings. Jack it up with front axle hanging, frame on good jackstands, and drop track rod from frame side and you'll have plenty room. Work from front back, one at a time, use an old shell to push upper half out tang side, place new one on crank and slide it back in on same tang side. Rods likewise are a snap, just use a socket to rotate crank as needed.
Elder User
Joined: Dec 2007
Posts: 813
Likes: 6
From: Up Nort Minnesota
i'm not absolutely sure on the flexplates, it just seems to me for some reason, I guess I can't remember. I know I was buying a lot of them one year after I busted the bellhousing on a C6 & had it welded. after it was welded my flexplates wouldn't last. They would crack all around the crank & eventually break. I was at the salvage yard several times that year before I finally put a new transmission in.
dang if I can remember what worked though... I guess now that I think more about it I think they are the same.
I may have been thinking about building small block stroker chevy's (400 crank in a 350 to make the 383) in that case I'm almost certain the flex plate/flywheel is different from the 350-400 & you have to be sure to have the balancer, & the flexplate to go with the 400 crank....
dang if I can remember what worked though... I guess now that I think more about it I think they are the same.
I may have been thinking about building small block stroker chevy's (400 crank in a 350 to make the 383) in that case I'm almost certain the flex plate/flywheel is different from the 350-400 & you have to be sure to have the balancer, & the flexplate to go with the 400 crank....
Senior User
Joined: Nov 2004
Posts: 225
Likes: 2
From: Richland, MO
Originally Posted by fastfarmer
You could put one in a chebby pickup. Would be an improvement over what was there.
Seriously though, I am going to list these engines in the swap meet section. Both are out of '78s. One 2WD, one 4WD. The 4WD tranny and T-case are already listed. They need a good home. Just not mine.
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Post Fiend
Joined: Mar 2005
Posts: 8,542
Likes: 5
From: Louisiana
Originally Posted by northerndave
typo.. you know what I meant...
Senior User
Joined: Dec 2007
Posts: 255
Likes: 0
I havent yet opened my 351M but the oil pressure sucks. It is normal when the oil is cold and is first cranked then it drops to the starting of the normal line. I reckon its the main bearing from what you guys say. It burns some oil also but no knocking.
Senior User
Joined: Nov 2004
Posts: 225
Likes: 2
From: Richland, MO
I've gotta correct myself. I stated I had (2) 400s earlier. I have since learned, after actually looking at my valve cover on my 2WD, it has a 351m in it. Not that it makes a bit of difference...
Postmaster
Joined: Aug 2000
Posts: 3,312
Likes: 1
From: Eldorado Ca. USA
Originally Posted by 78Ranger_GARedNeck
I havent yet opened my 351M but the oil pressure sucks. It is normal when the oil is cold and is first cranked then it drops to the starting of the normal line. I reckon its the main bearing from what you guys say. It burns some oil also but no knocking.