jmadison

is there a way to take the pistons out while the engine is still in the car? the only way i know of i going from underneath engine to do it....is there a way to do it from the top?
jim

InfernalVortex

iTrader: (4)

Unless it's smoking when you give it gas, I would leave the pistons, rings, crank etc in there and leave it alone. Unless there's something wrong with the bottom end, just leave it alone, that's your best bet.

No. No. No. Even at .060 over, that's only 10 extra cubic inches. 10 cubic inches is almost NOTHING when it comes to your final hp/tq numbers. Camshaft, heads, intake, etc all make a HUGE difference, 10 cubic inches makes almost no difference in comparison. You bore over a block to get the cylinder bores back round again. More cylinder wall thickness is BETTER. You do not sacrifice cylinder wall thickness for an extra 2, 5, or 10 cubic inches. A well packaged 350 will make around 1 tq per cubic inch. Do you think you can feel an extra 5 or 10 torques? Cams, heads, intake, etc have a MUCH greater impact. If you want more cubic inches you use a special crankshaft with a 3.75 inch stroke and you make the stroke longer. You do not make the bore bigger. A 383 is a full 33 cubic inches more than a 350, this makes a reasonably worthwhile difference.

A 350 has a 3.48 inch stroke and a 4 inch bore.
A 383 has a 3.75 inch stroke and a 4.030 inch bore
A 388 has a 3.75 inch stroke and a 4.060 inch bore.

But if you'll notice, most people build 383's, not 388's, because cylinder wall thickness is much more important than 5 more cubic inches.

If you want more inches, stroke it.

InfernalVortex

iTrader: (4)

I was referring to static, al ot easier to talk about static ratios since that's what people most commonly use, and he doesnt have a cam picked out yet anyway, so it's kind of hard to determine the DCR at this point. If you put your SCR in a reasonable range, the DCR will usually end up where it needs to be unless you make some big mistakes with parts selection.

mr.350

thank a lot let me know how you come out with your block

1gary

The pictures really don't mean much Jim.Hot tanked the block,mag'ed,and a measurement of the bores in multi places in the bores with a dial bore gauge is going to be the final determination of what to do next. You'll find that in many,many,cases these over bores are more the fact of where the bores clean up from the either oval condition or possibly scoring in the bores. Short of stroking,that the difference in c.i's isn't significant enough to really effect the power output. That the SCR/DCR's are effected,but there again it isn't enough for your seat of the pants dyno to detect.

I want to confirm that the rough surface of Vortec intake runners is what makes them Vortecs. To smooth port them destroys what makes them Vortecs.Well really in the intake runner side.To port the exhaust side might help some.But I am big in the CNC programed 5 position porting over the early caveman die-grinder have at it and in most cases the caveman approach aren't not even supported by the very basic home built flow bench and again the OEM ports are limited to what can be done with them before you have cracking/water issues.There are "P" parts small intake runner GM Vortec heads at 180cc sizes for a moderate cam that is the perfect size already.

I am going to go back to what you asked.A 375 to 400 hp 350 should be a walk in the park and easy to get. This .060 bore size and questions about the condition of this engine is complicating that question more than it should be.

1gary

Mind reader.........now that's scary!!!!. LOL.Just kidding.

tylercamaro

iTrader: (1)

those look like lower compression piston heads, am i correct?

1gary

I once bought at a auction yrs ago the 58cc Vett aluminum heads. They really didn't have much of a combustion chamber. They where darn near flat. The pistons that go with that I think I remember where very deep dish 18 cc's.Even at that where very high SCR's. Their down fall is they don't flow very well. We got them for the sole purpose of resale and sold them two wks later at a profit.

InfernalVortex

iTrader: (4)

Yeah I think the iron L98 heads are supposed to flow slightly better? But they're still way better than the 70s smogger heads people try to pass off as performance heads these days.

1gary

In theory there is diminishing returns where you reach a too small of a head chamber size where your really limiting the air fuel mixture fed into the engine.

jmadison

honestly im really not sure of what pistons they are sorry. and thank you both for the correction. thats what we got yall for so a newbie like me dont tell someone else the wrong info. thanks
jim

tylercamaro

iTrader: (1)

they look like they have valve reliefs and are dished, ive always considered those smogger heads but they may just be for lowered compression. do you know what compression the guy was running in the engine?

1gary

Jim-please excuse this off topic side bar comment.

Tyler-IF your going to learn from us you have to except what we are trying to teach you. It is not a proper terminology to use "Piston Heads". I am here trying to correct you on that and you have been told that once before in this thread. If you where to go on line to any source for parts like Jeg's or say Summit and look up pistons,you would be hard pressed to find them calling them anything but pistons.

Enough said on that.

jmadison

thank you gary. and tyler no i dont have a clue

tylercamaro

iTrader: (1)

yea i know they are pistons, try straying from a word you hear each time you work on something. not that easy enough said. im not trying to do it on purpose.

1gary

Well because you didn't compression test the engine before you took off the top haft,all really you can do is go with it was a good running engine before and use the bottom haft as is. Not the latest or greatness.

InfernalVortex

iTrader: (4)

Well he could throw some generic head gaskets on there and reuse his old headbolts on there and check it real quick if he wanted to, couldnt he? Might be worth doing...

1gary

I think at this point it is decision time for him. I don't think I can help much more until he makes up his mind without repeating myself.

cuisinartvette

^^^^^^^^^with gary

Amen!!
So many foam at the mouth over "its an 010 high nickel block" so what!
It means nothing, just an OLD block.

Those things had more flaws and core shift its not even funny.

rsmith085

iTrader: (1)

I've seen a couple of marine 350's when taken .060 over there would be a few spots with no cylinder wall at all or it'd be so thin you could poke a hole in it with your finger lol. Mind you those were marine blocks and here in FL people take their boats in salt water so the corrosion in the water jackets were pretty heavy. As for heads I'd stay away from the all the factory castings except for the Vortec's and keep in mind with the Vortec head you need a specific Vortec manifold to match. Personally I'd go with the eBay aluminum Pro Comp heads. The Pro Comps can be had for 600 to 650 depending on the spring setup. You'll be at that or more by the time you get factory heads machined and set up for a higher lift cam. Check out http://www.superchevy.com/technical/...d/viewall.html They built a 407hp 350 for a hair over a 1000 and that includes the price of the Pro Comp heads. Only thing I'd do different is use a dual plane intake like a Performer RPM in stead of a single plane especially for the street.

1gary

Just be very weary of magazine builds designed to sell advertizes parts.

1gary

For his purposes the small port versions is what he wants.

http://www.gmpartsdirect.com/performance_parts/2012/

I think is is page 176 part number 25534421. But that is putting the horse well before the cart. He needs to establish he has a good block first and decide if he is going to leave well enough alone using the current bottom end. Whatever the SCR is going to be is that is the way it is going to play out. That is a decision I am not getting involved in advise.

I suggest the small versions Vortec's primarily because it is just about the ideal intake runner size.

jmadison

i have decided that i am going to not pursue anything further with this block. i would rathere find another one thats not bored over at all and bore it 30 over n go that route. thank you all for teaching me this knowledge
jim

1gary

Jim,in that case look for a L31 1996 roller block. You won't regret it.

rsmith085

iTrader: (1)

Yep I second that. Check out your local u pull it. One of the ones here will run a special every so often where a complete truck engine is $200. Might not even need to be bored if there isn't trapper/out roundness just a honing to brake the glaze so new rings will seal. Like it was said here before get your pistons before you get any machine work done. IMO any competent machine shop want touch it without your pistons in hand. 0.0005" can make the difference between a good engine and a pile of parts hanging out your oil pan.

Thomas Dison

say buddy I am building the same thing as you are I been doing this for about 20 years if you would like to talk we can share ideas and suggestions

8Mike9

Hope he built/figured it out by now