7.4L Longevity

[Honey Bear]

I was talking to someone the other day and they said that the 454 doesn't last as long as the 350 because of the way they are built. Is that true or do BBs seem to suffer more abuse than their smaller sibling. I have 500 K on my 350 and only 160 on the 454. I do not abuse my engines, no racing or burnouts, IF they ever see 4000 rpm it is a rare thing going up a hill with a load. Waddya think how long will the BB last?

[454cid]

I think it's going to depend on the individual engines and how they are used/abused.

[1998454]

I don't think there are any design differences that would offer an advantage to either the small block or big block. there will be more stories of high mileage 350's because there are more of them. I have also seen more small blocks under 100k blow up. My 454 has 145k and no noises, leaks, or any issues.

[srracer]

There was a guy in the 'long' thread that sold his truck (still running) at ~550K miles. If it's well maintained and not overheated, I think it will last you as long as you want it to. Pay attention to the coolant and intake manifold gaskets and I suspect it will treat you well.

[BigBlockChucky]

Too many factors involved to get a good answer.

[99burban2500]

I cant speak for other owners, but I have just under 150k on mine and its still solid. Ive heard some pretty mixed reviews myself for years. Last I checked compression, numbers were still in the 160psi range about a year ago. Regular maintenance goes a long way. My truck was bought brand new by my father and has only ever seen AC Delco oil filters, Pennzoil 5w30, and Prestone Dexcool 50/50 antifreeze since new. When I replaced the valve cover gaskets and re-painted the valve covers last fall and I could still read factory hand written markings in between one of the valves. Just a light bronze oiled coating on everything inside with no sludge buildup what so ever. Only oil leak that was ever present on the motor too (That also goes against everything Ive heard about Pennzoil). Aside from the poorly designed heater hose fitting on the intake and the occasional thermostat; its still got every piece of the factory cooling system, including the water pump and hoses. Its all about the maintenance....

[someotherguy]

I don't think there are any design differences that would offer an advantage to either the small block or big block. there will be more stories of high mileage 350's because there are more of them. I have also seen more small blocks under 100k blow up. My 454 has 145k and no noises, leaks, or any issues.
I think you'll also see that the majority of big blocks, being in heavier trucks, get worked to death because that's their main role - hauling around heavy loads, doing hard work.

Richard

[Busted Knuckles]

Big blocks have a bit worse rod angle, which can lead to a little more wear on the cylinder walls. Injection helps with this more than anything else since cylinder walls are never washed down with liquid fuel. Flooding and mis-adjusted carburetors really make any engine wear fast.

Canted valves will wear a bit faster in the guides. Not a lot, but some.

I'd say that if engines were simlarly built with similar induction systems, the big block will probably "wear" about 10% - 20% faster than a small block.

[StreetGliderX]

i have 270k on one i work it daily.... uses about a quart per oil changes and i change at 5-7k miles.. i use synthetic..

[kiba]

mine has 255K on it runs fine, driven daily and spent the last 12 years as a plow truck. it dosent burn any oil but it does leak some from leaky oil pan seal

[454cid]

mine has 255K on it runs fine, driven daily and spent the last 12 years as a plow truck. it dosent burn any oil but it does leak some from leaky oil pan seal

I think mine does burn some, as it's always used some oil, but that's always been characteristic of big block Chevys I've heard. I probably loose more through my leaky oil cooler line, and seals someplace...... pan? main seals? somplace any way. I think my valve covers are also leaking now....... those sure last a lot longer than the old steel covers with the cork gaskets! I've got 225-ish on my engine.

[wtd]

I have around 105,500 miles on mine. It did use a little oil until I switched to Pennzoil 5W-30 and that seems to have stopped it. I ran Havoline and Valvoline in it before. My intake may be starting to leak though since I just took about a 150 mile round trip hauling an empty 18 foot flatbed carhauler trailer and my coolant level in the overflow tank went down slightly. I will have to keep an eye on it. I bought this truck used almost five years ago with 94,600 miles on it and it looks like the intake gasket had been replaced before.

My engine does have some startup noise when cold and seems to go away for the most part when warm.

Wayne

[neubauej]

The one in my burb has 236k and runs perfect, no noises smoke or excessive oil use.

The one in the parts suburban has 372k on it and runs fine as well.

I don't think longevity is an issue myself.
;)