Yes. It was rebuilt at some point with flat tops. There is a lot to doing this right you know.

 

Yuup! That is why I spend hours on here talking to all my new buddies!!

 

This is the motor I mothballed my numbers with. I'm happy with it over all but will be changing heads, cam and intake in the future. Over all it's a great bang for the buck

http://www.jegs.com/i/Chevrolet+Perf...67353/10002/-1

 

when money is the issue, and numbers matching doesn't matter... yes, it may be cheaper to box up your motor and get another one.... scrap? no as you could probably get a dollar or two hundred selling the stuff you wouldn't use.

Here's my bet - the crank is forged; which has decent value.

 

You can rebuild the motor. No doubt in my mind, you ask questions which is a positive thing. However, anyone who's rebuilt a motor has had a motor which wasn't right after the rebuild (I've been here, lots of times)... forget the oil plug above the rear main is a favorite of mine; or, and I'm still headscratching as to why - but a machine shop put in a too small oil plug in the back of a 350... which fell out and destroyed the motor (2nd rule, never loan your freshly rebuilt car to an idiot)

 

That does make sense! I appreciate you input as always. The engine is not a matching engine as it is. I only wanted to rebuild myself for 2 reasons. 1 I am enjoying learning the process and thought it would be cool to know I had touched every part on this car when finished. 2 I could do it a little slower by buying parts as I go instead of laying out a bunch all at once.
I hav seen some performance rebuilts on CL for pretty good pricing. What are your thoughts there? I have some music Equiptment I was going to sell to help expenses but was hoping to save that for the paint.

 

Sorry for the typos! Fat fingers and typing on my phone not working so good.

 

Don't go nuts buying hop up parts until you have carefully thought out what you want this engine to do, and what parts you can actually salvage from this engine. With the flat-top pistons (assuming they can be re-used) and depending on what sort of heads you can find a good deal on, it might end up making sense to go with a bigger cam than the one I gave you. If this turns out to be the case, I would appreciate it if you send it back, I'll find a use for it sooner or later. So, do your homework on matching engine components for a good combination, and keep in mind that your diff gear and torque converter stall speed will also effect these decisions.

I sent you that cam thinking we were just going to install it in a stock L48 type engine, which is a good application for it, but don't make the mistake of designing the engine around the cam, just because you have it. Cams are relatively cheap. Don't get me wrong, if it turns out that the cam makes sense, use it and enjoy it! If you stay with 76cc chamber heads, it might make sense to use that cam, but if you decide to go with, say, some 64cc chamber heads, it might make too much compression for that small of a cam. Don't worry, the forum will be here to help you make that decision when the time comes, my main point is to carefully think out what you want from this engine, take into consideration what you have available to work with, and then make decisions regarding purchases. And, if you want to stick to a budget, it is important to make a plan, and stick to the plan! Most projects that go over budget do so because the plan got changed in the middle somewhere.

Edit: Apparently, your engine has been bored .030" over, so it's obviously been to a machine shop. The block may have been decked. The heads look like they have had some work done to them, too, and they may have been shaved. This all means that you can't count on just using the stock specs to do the necessary math involved in figuring out your compression ratio, you're going to have to do some measuring. If you think you'll be able to re-use those pistons, measure the piston-to-deck clearance before you disassemble the bottom end, you'll need this number later. If you're going to re-use those heads, I would take the time to measure the combustion chamber volumes, too.

Good luck, and I am subscribing to this thread, so keep us updated!


Keep the shiny side up!
Scott

 

Hey brother! Happy Thanksgiving! I will certainly get the cam back to you if that is the case. I really still just wanted to rebuild a stock type engine. I was hoping to pull it out hone it clean it up, new rings and bearings, paint and back together. With that being said I don't want to make a huge mistake.

 

I completely agree with you, Scott; but I'm going to disagree with you to give some landscape.

A cam determines how a motor reacts to a given situation. If you're drag racing, you want to motor to perform in a specific fashion that won't, necessarily, be anything you'd like to drive on the street (heaven knows, I've tried)... When you buy the car of your dreams, it has attributes, and deficiencies which come with the car. Fundamentally, hot rodding is making a car work for your specific purpose given the car's qualities.

So do buy the cam first. Here's why, to buy a cam, the manufacture will ask you questions like: gearing, weight, use, transmission type, etc. When you know those things, he (or she) can make a cam recommendation for what you want to do. The rest of the motor is easy, but the cam is the brains of the organization, and anyone who has experienced the Peter principle knows that a bad brain = a bad organization.

What do you want your car to do? once you go there, then you can figure whether you need a BBC or a SBC and in either case, what displacement. I've had a 12.5:1 327 'vette that spanked LOTS of cars, and that car was a BB, 4 speed car prior... it seriously would eat a BB lunch (on the track).... stoplight battles, not so much.

The time to build a motor comes later - and is always best done on an esoteric block; such as a Studebaker, Buick, Olds, etc... there you're far less likely to find what you want in the aftermarket.... however, with a SBC (or even a LS), there are so many parts and possibilities that it costs less to buy a finished motor than it does to buy parts to rebuild yours... seriously.

And in that vein, don't limit your view; if you want get your chops challenged and have something pretty cool in the end.... buy a 5.3, put a cam in it with some LS3 heads and go eat some BB lunch.

I just priced a 5.3 from a wrecking yard.... $500. Conversion parts with cam and heads are roughly $1000. It's an easy 400 hp with awesome mpg and stone cold reliable; especially if you keep the fuel injection....

 

I've been wanting to do the same for the "fun" and learning, since I have never tore down and rebuilt an automotive engine. Problem is we aren't really gonna save any money over a crate engine and as weekend warriors its easier for us to screw something up or not use optimal combo of parts. For me I think the bigger regret would be trying to do it all myself from the ground up in an effort to learn and "save money" only to have a substandard engine with no warranty, then to plop down the lump sum and get the crate with warranty, etc. But keep us posted. Don't rush

 

I have realized the money saving aspect is out the window!!!! I also already have the while I am her mindset. I may be screwed! Hahaha

 

I added an edit to my last post, so go back and read it again, please.

Ya know, after thinking about it for awhile, I see this as a possible outcome: You may be dealing with an L48 engine that somebody rebuilt, using flat-top pistons, and kept the stock cam. It might be making too much compression for that small cam with it's relatively short duration. That could be why you are experiencing detonation. If you are able to just re-use the existing pistons and crank and rods and heads and such, just freshen it up with new bearings and rings and stuff, that cam may be just what you need, as it's just a little bigger than a stock cam. It's all just speculation at this point, we will find out once we actually see what's inside and make some measurements. As my Granpappy up in Maine is fond of saying "Hard sayin', not knowin'." (try to imagine it with a thick Maine accent!) I suppose it's even possible that your engine already has that exact cam already in it! Wouldn't that be a kick in the a$$?

I think your next step is going to be to remove the balancer, timing cover, oil pan, timing set, and cam, So we'll be finding soon, won't we? Man, I always feel like I'm doing an autopsy when tearing down an engine, don't you? Pay close attention to the pieces as you disassemble it, they can tell you a whole lot about the engine. Make sure you keep all the valvetrain parts in order with the other pieces that they mate with, in case you end up re-using them, especially the lifters and cam. Who knows, the existing cam may be better than your new one, and you may be able to re-use it. An upside to that would be avoiding the dreaded flat-tappet cam break-in procedure, always stressful, even back in the old days. Like I said, we'll find out soon, won't we?


Keep the shiny side up!
Scott

 

suspect that the detonation came from the old heads with too much compression. Any of the 70s heads had lots of sharp edges, terrible quench, and absolutely zero swirl (which makes the detonation wave almost a certainty).

This might help to understand. I had a 350 with a B&M blower on my Skylark (which left to make room for the 'vette), I constantly had issues with detonation. I took the 882 heads off (ported, polished, deburred, 2.02 valves) and put simply aluminum D port heads (1.94 valvues). For those counting, that's 76cc (measured) to 64cc - which effectively raised my static compression from 8.5 to 9.78. Funny thing - the motor made more power AND I lost the detonation issue. In a fit of stupidity, I swapped out the 350 for a 400 that (in theory) a better fit for the car/gearing/etc.... that motor burned to the ground in a fit of detonation from some (grumble) leaky fel-pro intake gaskets.... couldn't figure out how I had a random detonation - now I know, under 7 lbs boost it'd leak, thus lean out the cylinder....

another possiblity... LS your car, practice rebuilding the motor that came out... in the end, maybe you too will be a engine builder

 

everyone who hot rods a car should be required to buy a cam from the bottom of the page and try to make it run.... everyone - that's not a cynical statement; I learned more from doing that than any other thing I ever did. Funny thing, I literally took someone's lunch* who was telling me I was an idiot and I couldn't make it work


*backstory - I know someone that I'll loosely call "a friend" that, for the most part, is easy to get along with.... unless it comes to cam selection. He runs a really nice 427 Mustang (68 fastback).... he told me when I bought thumpr cam that I was a complete baffoon because that motor "would never run right" in my car.... I bet him lunch. It was tasty

 

That's all true, SBG, the point I was trying to make was just that, in a situation like the OP is in, it may not be the best idea to use a certain cam just because you already have it. If you are designing an engine from scratch, it might be a good idea to begin with the cam choice, I don't really know, I've never designed an engine that way (I guess what some people would call the "right" way.) but if dealing with an engine where you're trying to use what you have available, on a budget, a camshaft is pretty cheap, compared to a new set of heads, or pistons, or what have you, so it might make sense, from a financial point of view, to match the cam with what you have available.

My brother keeps telling me the same thing about doing an LS swap, but still, I find the idea intimidating. I am not convinced that it is as easy as some people make it out to be. To hear some people talk about it, you'd think it's just something you could do in an afternoon, no more difficult than replacing brake pads. It may not be as difficult as it once was, but still, It's gotta be a bigger project than removing the small block, and then re-installing it. On the other hand, I really do see the small block chevy starting to go down the same road that the Ford flathead engine went down, back in the '50s. At one time, it was the hotrod engine, but once the Chevy small block came onto the scene, it didn't take long for it to just be an old, obsolete piece of junk. And now, I see the LS engine doing the same thing to the small block chevy, although, I can't help but think that the LS engine's cam-in-block architecture may someday have to give way to an overhead cam design. And that day may come sooner than some people think. Who really knows? It's a mystery....wrapped in a riddle....surrounded by a conundrum....


Keep the shiny side up!
Scott

 

That's too funny to not be true!!!


Keep the shiny side up!
Scott

 

You guys got me all fired up! I am going to get to work here in a few minutes. I will post some pix for you. Let me know if there are any pix that would help you guys help me diagnose. I have to work off some of this dang food!!!

 

Hahahaha! Yummy!

 

Anything here guys? I will have to wait until tomorrow to pull the balancer since I don't have a puller unless there is a way to do it without one.