Question for the engine builders

[longblue72]

I recently bought a truck knowing it had a knocking noise (halfway made the deal) and had some questions on if this idea works, but first here is as much as I know about it:

its a 350 with flat top pistons, has 1.6 ratio roller rockers in a set of brodix heads, and has a Howards cam with 580 lift.

The seller claimed that its a wrist pin knock.. however I spoke with a machinist who said that's wishful thinking.

This build doesn't appear to be all that old. If I find that a rod bearing, main bearing, or wrist pin is bad but all other rotational parts are okay, after using my better judgment, could i throw a set of correct bearings in place and rebuild the engine?

Thanks for the insight

Chuckie

[longblue72]

So we can get a little closer to the engine, here's a pic of the engine bay.

[hamjet]

The correct thing to do is strip it down, clean it up and build it with all fresh rings, bearings and gaskets. with all the high performance parts on it, it's been beat, run hard. you'll most likely regret doing bare minimum to the engine. it could come back and bite you in the kiester if any filings or crud contaminated the rest of the engine. but it's your engine....edit.. short cuts always get me anyway..

[Ziegelsteinfaust]

Originally Posted by hamjet

The correct thing to do is strip it down, clean it up and build it with all fresh rings, bearings and gaskets. with all the high performance parts on it, it's been beat, run hard. you'll most likely regret doing bare minimum to the engine. it could come back and bite you in the kiester if any filings or crud contaminated the rest of the engine. but it's your engine....edit.. short cuts always get me anyway..

This, I have had to do it a couple of times because my DD developed major motor issues, and I was stuck. It's honestly hurts worse to redo it again then to spend the money. Pulling motors is a all day affair.

[randy500]

Originally Posted by hamjet

The correct thing to do is strip it down, clean it up and build it with all fresh rings, bearings and gaskets. with all the high performance parts on it, it's been beat, run hard. you'll most likely regret doing bare minimum to the engine. it could come back and bite you in the kiester if any filings or crud contaminated the rest of the engine. but it's your engine....

Everybody has this standard answer.....

Let the flack fly.

If your doing the work yourself and you dont need to drive it a few thousand miles a month without issues then just repair what is not working properly.

Your Hot rod engine probably got run hard and either spun a bearing or had detonation and a wrist pin got stuck.

If its a rod bearing you should have the crank turned and replace the bearings.

If its a wrist pin the bore is likely messed up. If not too bad
You can replace one piston if thats all thats in your budget.

Whats best, what works and what-works-and-lasts have overlapping areas.

I have patched up engines in all sorts of manners even using used bearings, used pistons and used rings. They all ran great when fixed and served the intended purpose.

[special-K]

I'd go all the way down with it. Whatever part failed left particles. The safe thing to do is go all the way. Only one part makes a bad engine. It's all the labor and hopefully very little parts or machining.

[randy500]

I will ad this doing a full rebuild at this time is probably foolish unless you are prepare to do that to every system on the truck.
Unless you were able to fully road test it you don't know what all the issues may be.
Prob best to patch it up and see what all it needs before committing to a full engine rebuild.

Could have so many issues you would be better off with a different truck, fixing only whats wrong sometimes makes sense.

[longblue72]

Originally Posted by randy500

I will ad this doing a full rebuild at this time is probably foolish unless you are prepare to do that to every system on the truck.
Unless you were able to fully road test it you don't know what all the issues may be.
Prob best to patch it up and see what all it needs before committing to a full engine rebuild.

Could have so many issues you would be better off with a different truck, fixing only whats wrong sometimes makes sense.

Thanks for your reply! im just trying to figure the best way to go about it financially. I can find a decent sbc for 800 bucks to just drive the it for now and pay attenion to the hot rod motor later, and still sell the sbc after for probably the same. The truck is worth it. practically rust free from Georgia. Ran and drove great on test drive. ill post pictures in this thread

[toolboxchev]

Ahhh go ahead and rebuild it. Go through every little thing on it, from distributor shims to the oil pump.

You will be happier in the end with your work, I know even my stocker motor better than any mechanic that ever set foot in a shop.

How well do you know her? It's a hobby, be an enthusiast, get the enjoyment out of it. Its something we do for ourselves.

[truckster]

I've patched up junk motors and driven them thousands of miles. I've also had a rod go through a block in three places. If you just want to get it on the road, patch it up and drive it. If you want peace of mind, rebuild it properly.

[HO455]

Everything posted here is good advice. You need to make the decision that works for you. That being said I would spend the time to figure out what exactly is causing the noise. It could be a bad flex plate, bent push rod, or other less serious type of repair. Here is a link to what my abnormal engine noise turned out to be. Not that yours would be the same.

http://67-72chevytrucks.com/vboard/s...ighlight=ho455

[halfstep]

What else did the machinist say - and did he hear the engine running or did you just you tell him the symptoms? If he didn't hear the actual engine running and the "knock" I'd start there. You should find a lot online about diagnosing sbc engine knocks. A couple suggestions you probably already know FWIW:

1. "Stethoscope" the engine with a couple of socket extensions (or suitable alternative) all around the engine. In short order you should be able to distinguish the various sounds and zero in on what isn't normal and where it is. Have someone cycle engine speed while you're listening.

2. Drain the oil and see if you see significant metal - if not, hook a baby finger or something and try get a reading off the bottom of the pan. May also cut open the oil filter and look there. Replace drain plug with a magnetic one.

3. If you are comfortable driving - go to more than one machine shop and try to include a "performance" oriented one - you'll probably see a difference. Rarely go wrong getting a second opinion.

4. If you are leaning to the $800 engine, you'll be pulling the engine anyway, so I'd spend a few dollars and have your's checked by the machine shop BEFORE you buy the other. Not uncommon for shops to have stuff they've already checked out or semi built so you may be able work some kind of arrangement for a short block etc. They know they are losing money to crate engines and craigslist, so you may be surprised.

[Molino]

Originally Posted by halfstep

What else did the machinist say - and did he hear the engine running or did you just you tell him the symptoms? If he didn't hear the actual engine running and the "knock" I'd start there. You should find a lot online about diagnosing sbc engine knocks. A couple suggestions you probably already know FWIW:

1. "Stethoscope" the engine with a couple of socket extensions (or suitable alternative) all around the engine. In short order you should be able to distinguish the various sounds and zero in on what isn't normal and where it is. Have someone cycle engine speed while you're listening.

One thing I would add is , while the engine is running at idle, one at a time unplug a spark plug wire. Usually when you get to the Cylinder with the noisy bearing/wrist pin you will hear the noise change. That way you have a better idea of where to look for the noisy pieces.
I too have had very reliable service from only replacing the “bad” parts and buttoning things back up. It all depends on how the rest of the innards look when you crack it open.

[67C10Step]

If I remember correctly, this is the truck you looked long and hard to find. With that said, what are your short term plans? If it is to get the truck on the road to drive and enjoy, I'd pull that engine apart, diagnose the issue, and then build it to what you want or replace it entirely. If you are just going to tinker with the truck for the next year or so and never really drive it any distance a patch job on the existing engine may be in order.

Although, depending upon how "hot rod" the engine is you may not really want to patch it up if it's going to be something that requires attention all the time to keep running correctly. Some love to tinker with engines, many prefer to hit the key and go. All depends upon your preferences.

[SwitchbladeII]

I would consider buying a crate short block. Machine work can get very expensive. One of my projects a few years back was a 69 SS Chevelle with a tired 396 BB. The block and heads were numbers and date correct so I rebuilt it. By the time I was done I spent more then a complete new crate motor would of cost. You could buy a short block with a performance cam use your heads and other parts to complete the motor. IMHO it would cost less and probably less down time.

[kwmech]

Some knocking noise turn out to be an exhaust leak

[longblue72]

Ideally the less down time the better. I really just want to get in and drive the truck because its a driving truck right now. While drive line was out, i wanted to blast and epoxy prime the bottomside of it all so the the mid atlantic rust doesnt take off on it, correct the engine noise along with new seals in it and the transmission, then cruise while no one is out on the road.

Id love to give a machine shop some work, but not if its something i dont need to pay an arm and leg for. From some more looks st the block itself, it looks like it may have been an older block built up.

So essentially like everyone has been saying, once i crack the can ill see if whats worth doing. Shortblock sounds right if the wrist pin has gauged the cylinder on a once before overhauled block. Ill keep you guys posted on what i found. Hope to pull engine this week sometime. Weather permitting

[truckster]

KWmech brings up a really good point. An exhaust leak can sound a lot like a rod knock under the right circumstances. You need to try to pinpoint the source of the noise before you pull the engine out. It might even be worth paying a professional for a diagnosis...

[special-K]

My reply was to go all the way down, but that's assuming you cancel out any external possibilities, Flexplate bolts, cracked flexplate, other thinks can create a nasty sound that seems fatal. Many a vehicle has been sold as "blown up" for cheap where the owner only had to take care of a flexplate issue. And that's just one possibility. But if it's an internal issue you need to get in there and see. I seriously doubt you'll be rebuilding it. You will be patching up what broke after a 100% cleaning and "only" what machining is required to correct the problem spot. It's all the labor with minimal parts and machining.

So you can start driving it, maybe that used engine deal would be good to toss in there while you enjoy "playing" with that performance motor.

[longblue72]

Originally Posted by special-K

My reply was to go all the way down, but that's assuming you cancel out any external possibilities, Flexplate bolts, cracked flexplate, other thinks can create a nasty sound that seems fatal. Many a vehicle has been sold as "blown up" for cheap where the owner only had to take care of a flexplate issue. And that's just one possibility. But if it's an internal issue you need to get in there and see. I seriously doubt you'll be rebuilding it. You will be patching up what broke after a 100% cleaning and "only" what machining is required to correct the problem spot. It's all the labor with minimal parts and machining.

So you can start driving it, maybe that used engine deal would be good to toss in there while you enjoy "playing" with that performance motor.

That may be the way I go. Its got a Saginaw car 4 speed in it so whomever built the truck had fun in mind, which I'm eager to get into!

The noise is definitely internal, my ears aren't quite as seasoned as some, but I've fixed exhaust leaks and some other ticks to definitely see this being inside the heart of the beast.

[GASoline71]

That much lift and 1.6 rockers... heck it could be the valves hitting the tops of the pistons, or valve spring bind. .580 lift in a small block is quite a bit, and adding 1.6 ratio arms just adds more lift to the equasion. What heads are on it?

Gary

[longblue72]

Originally Posted by GASoline71

That much lift and 1.6 rockers... heck it could be the valves hitting the tops of the pistons, or valve spring bind. .580 lift in a small block is quite a bit, and adding 1.6 ratio arms just adds more lift to the equasion. What heads are on it?

Gary

Im not exactly sure what part number, but they are Brodix heads