We have done the "freshen the 632 every 200 run deal", usually 150 runs later it implodes. What do you replace and what do you leave. Thousands of dollars to "freshen" yet no idea what goes next.
Now we build with the best parts we can, check valve springs, do Used Oil Analysis every oil change and until something shows up, we keep running it. Going to start on season 6 with the 565, mostly 1/8th mile, pre-start oil heater. We are thinking its cheaper to run it until it won't run or gets inconsistent than dropping $3000-$5000 for a "freshen" that still leaves 500 run used parts inside. If you spin a bearing or break a rod....buy a new shortblock with zero runs for about $7000 and no "freshening expenses".

Not for everyone but after our experience, why take something apart that is running great. Valve springs and locks are something to watch in our opinion.

My 406" small block is never going to come apart until it "disassembles itself". Its a $5000 engine, why spend $2000-2500 to see it last another 250 runs, maybe?

I know that NEW always seems better but after sawing a couple 632s in half, I changed my mind.

Jok

quote:

Looking for some input on how many runs I can expect out of this motor before I put in a new short block and take this one out to freshen.

468 in 3000 lb car. Leave at 3400, shift at 6800. 670 lift cam. Ohio Crank, Lunati Rods, JE pistons. 2 bolt main GM block

I run similar stuff and keep stretching out the freshen up time every time I open one up lol. Current 460" in the Firebird has a good set of heads and makes about 750hp, currently have over 600 runs with nothing but oil changes but the springs seemed to have lost some pressure so to be safe were gonna replace the springs and lifters and the plan is to go 1000 runs. This engine had new Molnar crank and rods and new Mahle pistons and fresh .030 454 block. This engines see's 7300 every 1/4 mile pass too

My old Nova that I sold a few years ago and has been passed around to a few different owners was just torn down for a freshen up. We estimate the run total to be anywhere between 800-900 and the engine looked Unbelievable !!! Scat crank and Manley rods with old heavy Manley pistons. That crank has a few thousand runs on it easy as I bought it new back in 2001 and was perfectly straight, like perfect !! Bearings looked great and could be reused, valve job was showing some wear but still decent, heads were bought new back in 2001 also so they are old.

Like already said I believe it's all about the combination and attention to detail.

Valve springs
Locks
Rod bolts

Best was 860+ runs on a 598 dry sump engine. 74-7600 rom, mid 1050 hp
Rebuilt lifters at 350 or so runs, valve springs 400 or so.
Back then 15/40 rotella and probably 40 runs on a change, depending on fuel contamination smell.
Leak was always good after a race usually no more than 10-12%
Rod bolt broke, but all the bearings looked great

Good info, nice to know. I realized I should be more on top of valve train maintenance and replace my springs and lifters last season. I should have looked closer at the locks. What kind of wear should I be looking for?

more and more serious bracket racers who's engines cost between $20k and $35K and built by the biggest names in professional sportsman race engines are now of the opinion that freshening their engine every other season at $8-$10K is costly and stupid. Many now say that they will either run it till it blows up, aside from regular maintenance...oil changes, valve lash, valve springs, rocker are rebuilds, maybe lifters or sell it after season two and build new.

quote:

Originally posted by 1320racer:
more and more serious bracket racers who's engines cost between $20k and $35K and built by the biggest names in professional sportsman race engines are now of the opinion that freshening their engine every other season at $8-$10K is costly and stupid. Many now say that they will either run it till it blows up, aside from regular maintenance...oil changes, valve lash, valve springs, rocker are rebuilds, maybe lifters or sell it after season two and build new.

Seems like an odd decision for a few reasons but, admittedly from a clueless window licking, has been wannabe.
-Cost wise, with the cost of a new machined block and top quality rotating assembly, plus hours of labor, run till failure is way more expensive then an off season or when due if you have a spare.
-A blown up engine at a big race, no matter who you are, is zero fun, can be dangerous and significantly hurts your odds of winning.
-In an industrial world, few expensive machines are run to failure, even with redundancy. Only time I’ve seen it done was when the end product sell price was hugely above market norms.

Just my opinion

Paul, I'm not there yet but over the past few years, this conversation has come up with numerous "big money" bracket racers.

Ed my beef was in general not suggesting my view was for anyone. reading it and reflecting on my stuff, I had to share my view. Cheers!

quote:

Originally posted by 1320racer:
Paul, I'm not there yet but over the past few years, this conversation has come up with numerous "big money" bracket racers.

I think a lot of the big money guys are too busy spending money chasing it, and a lot of times at the end of the year they're like oh s*** I forgot I have to have a running car to be able to race next season!

I ran my 640 hp 415 SBC for 13 years before we opened it up. Everything looked great. We replaced roller lifters, rings, bearings, valve springs, valves and did a valve job. I still feel guilty about not replacing the rods. I estimate it had about 1,000+ runs in that time period. I didn't race a lot for several of those years.

About 8 years in I found a couple small pieces on the drain plug and it was coming from the timing chain! Lucky! I replaced the chain and checked the oil pump. Put it back together.

I think it depends on a lot of factors. Run an air filter! Don't over rev it. Change the oil regularly. My valve springs tested good after every year and I keep a very close watch on the valve lash. I think it also depends on how detailed the builder is on bearing clearances.

This is a very mild combo and I take very good care of it.

Big SBC with 23 degree heads are nice because they don't turn rpm but still make decent power.

So many factors. A PhD thesis could be written on just one component of a race engine. I would love to see what type of analysis some of the manufacturers have done.
It gets very deep very fast. I think you are spot on reducing RPM is exponential in its affect on engine life. If you can stay far enough under the endurance limit you can last A LONG time. Fatigue is a science all to itself. Lot of good discussion.
Timing chain is a perfect example. One component is all it takes......the question is which one.

quote:

It gets very deep very fast. I think you are spot on reducing RPM is exponential in its affect on engine life. If you can stay far enough under the endurance limit you can last A LONG time. Fatigue is a science all to itself.

Totally agree .......I'm also a firm believer in a good warm up/heat soak at the beginning of the day, not killing it in the burnout box, not sitting on the 2 step for 10 minutes. Bouncing off the rev limiter in the burnout box cant be good for longevity ........

it's all relative to your budget and intended usage.

The typical door car bracket guy doesn't have a $20k engine under his hood and therefore his engine makes less power, turns less RPM and has less expensive parts in it. So these lower HP engines turning less rpm, can typically log more runs than the typical $25k BBC engine in a dragster running say 7.50s/4.80s no mind the engines in fast bracket dragsters costing $30-$40K

There are a lot of good technical papers on metal fatigue online that goes into the mechanical and metallurgical science of this. Sometimes I wish I would have been a metallurgist. There are some good failure analysis papers on this as well. Oxygen rich inclusions, hydrogen embrittlement, cyclic loading limit failure graphs. Pretty technical but interesting.

I guess when the rods or crank breaks nobody give a chit about any of that just that their car is broke and now they have to fix it. I do think the different approaches are interesting. Run it till it breaks......change this but not that....check this check that put it back together. Good cost analysis problem. Maybe there is a NDT market for bracket engines I should explore....UT, Mag particle, etc.....lol.

Even the best parts break, new parts break. I guess those parts didn't read those technical papers on metal fatigue.

Further, even when parts are checked aka magnafluxed they too can and do brake.

100% agreed. No doubt!!!

Manufacturing defects occur.

Magnetic particle (magnaflux)and eddy current can detect near surface indications. Eddy current can do more but is very surface condition sensitive. Ultrasonic testing can detect internal indications and grain structure issues. UT is much more expensive than mag particle. There are multiple types of each method. Probably not cost effective for what we do as a preventive measure after a teardown, I am sure with some high dollar components it may be, I don't know.

quote:

Originally posted by Brktracer:
I ran my 640 hp 415 SBC for 13 years before we opened it up.
Big SBC with 23 degree heads are nice because they don't turn rpm but still make decent power.

Curios, what block manufacture, what size heads and what lashed lift intake/ exhaust values , what max rpm ??

Heard a young lady tell her friend I had "rebuilt" her engine, while she was picking it up from a tune up and valve cover gasket.
$240 job...."rebuilt"
I had to whoa her up on that idea....people are ignorant.

So, back on topic, I freshen one up when I drive over the crankshaft, it all ends up the same $$$ anyway.

Drive over the crankshaft. Gotta remember that one!