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which is the greater evil?

mudbuggy

mudbuggy

1/2 ton status
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I am split on a 350 or a 400, both are virgin blocks, both are rediculous cheap. I understand that the 400 will run 'hotter' because of the siamese heads, but I have a 454 radiator already in the truck. I guess I'm trying to figure out, how much of the 350 will transfer over to the 400 if I go that way? How is the mileage with the 400? Of course (I'm assuming) I won't have to push on the pedal as much to get moving, but what are all of your thoughts.

I know this has been a thrashed topic, but I've search the other discussions and I haven't really found the answers to the questions that are bouncing between my ears!

Here we go-

Thanks for your thoughts
 
400 period. Sell the 350 block or use it for a doorstop...

I've had a lot of 400s, both stock and built. The ONLY one that I ever had any problems with was because it was bored either .040 or .060 over. Was in a truck I bought, so didn't have much choice. The cooling system was all new, still got hot idling or slow moving traffic.

I had one in a Malibu, stock 3 core rad, never got hot. Another in a 90 GMC that was TBI, never got hot. Can't remember how many I've had, but the one mentioned above was the only one that had problems with.

Also gas was better cause had more torque to get the vehicle going.
 
400, unless the 350 is a factory roller motor then its a toss up.............but I'd probally still go with the 400
 
ooo just got interesting

isn't the 509 a 4 bolt roller mid 90s block? Trying to remember...
 
First off whats your goal? If its more horsepower the 400 has the edge. Is it reliability? If so I have to give it to a 350 any day. My approach on engines for 4wd vehicles is like this. If this thing breaks down where you would be using a 4x4 (aka the backwoods or BFE) you dont have the easy accessability of a tow. So even though the 400 is a good engine i rather have the peace of mind and reliability of a 350 that isnt prone or at least known to overheat, or have issues with non compatable parts. (balancer and flexplate) Remember we often like to wheel slow with little airflow and that a recipie for thermal issues. I like crate engines, they have a great warranty and can be had in a number of different configurations. Yes, you could probably build the same power level for cheaper but I have yet to find any small builder that will give the warranty that GM does. Plus the blocks and parts are brand new not refurbished.
 
goal

The purpose is low end torque. Not really hp, but I want that idle 1k grunt. Thought that I might be able to do it with a 383, but all of the power for those don't really show until 1500 to 1800 by then I'm half way to the next gear. I would like to see 450 hp/650ft/pds of torque. Ya know stumpbuster ****. I can't get it economically with a 350, the 400 I can still use the accessories from the current motor. The parts cost for a 400 is dirt cheap compared to the same part for a 350 that produces the same amount of hp. Nowhere near where I want or need for torque.
I really am thinking of long stroking it 434? Don't really know how far to go. Got 3 virgin blocks 509 castings for 200 bucks for all three. Might build a stock block, a 427, and a 434? Don't really know figured I'd see what the collective brotherhood had to say. What transmission can put up with that abuse? I really doubt the factory R4 can deal with it
 
I call BS on the 400 longevity. Of one of the many 400s that I had, one that I had in my 78 Malibu. I got it off a buddy who owns a junkyard. The motor had who knows how many miles, but I needed a pipe wrench to get the lifters out. Motor was a sludge pit on the inside. I put in a new cam, oil pump, timing chain/gears and a rebuilt set of stock heads off a 350 with the steam holes. We were guessing the motor had well over 100k, it was in a 74 Impala IIRC. I drove the car every single day for 6-7 months, put about 70k on it driving back and forth from Ottawa CA to where I live in Binghamton NY. Only issue I had with is it is every now and then I would break a rocker arm. The cam that I used was .480 lift, which is the max for a stock set of valve springs. Only pulled the motor to put in a 454....

All the parts off a 350 will work on the 400. Only external differences is the balancer and flexplate/flywheel.
 
I love my 406... I have no issues keeping it cool with a 4 core radiator. The only issues I've had were around the rocker studs pulling out until I studded them. I'm running heavily modified 305 HO heads (opened up to 2.02 / 1.94 valves and 64 cc's). The engine has quite a few "goodies" added to it...

I'm estimating my hp to be right around 430 at the flywheel @ 6500RPM.
 
"I drove the car every single day for 6-7 months, put about 70k on it driving back and forth from Ottawa CA to where I live in Binghamton NY" Thats highway driving. Totally different than off road driving where you may be 20 miles from civilization going 2mph up a hill or over an obstacle with little to no airflow going through your radiator. Try a 400 then and tell me you don't start to worry about overheating when the gauge creeps up to 220 and doesnt go down but you need the engine to keep going because you can't stop and are commited to the trail. Thats where i am saying a 400 sucks. If you don't do that kind of driving don't worry about it but out here if that happens and you do break down there is no getting a tow out there easy or cheap. This IMHO is where the advantage of a 350 comes into play. I do that kind of wheeling all the time out in calico or gorman, big john etc. I guess it depends what the weather is like in your area and the style of wheelin you do. Had a 400 in my K5 factory but wouldn't do it again especially if it was bored out or i didn't replace every component of the cooling system with bigger HD parts and add a electric fan.
 
The longevity thing with the 400's is caused by the shorter connecting rods, I dont remember the length, but 350's have a stock 5.7" rod.

The shorter rod will push the piston towards the cylinder wall on compression stroke, causing increased wear compared to an engine with longer rods. My understanding was that to keep the wrist pin out of the rings, while keeping the stock deck height with the increased stroke, the engineers had to shorten the connecting rod.
 
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