i just stripped my 91's stock 305 and noticed that these pistons look very much like aluminum. are they? also,, when i cleaned all the carbon off and took all the rings off,, i noticed the pistons dont fit super tight in the bore,, i can wiggle them in the bore... is this normal?

no one tell me not to rebuild this 305,, im in highschool, and gas is to pricy. My 434 sbc will be gettin done through winter, so dotn worry about it the 305 is just temporay to make sure my t.p.i still works and whatnot, plus i gotta learn to burn chips.

 

Yes, pistons are made out of aluminum. Some very slight amount of rocking is normal.

 

You're in high school and you have the cash to build a 434 ??
Damn, you must do well.
Wait, don't you have a 355 vortec? Why are you rebuilding the 305 if you have that motor?

Well hey, rebuilding a 305 is good experience, if anything goes wrong it's not that big of a deal. I just wouldn't *WASTE* too much cash on it. Rings and bearings are cool, but if you're dropping $200 on pistons then you've really gotta wonder if that's a smart thing to do.
You got a set of feeler gauges? You can slip them inbetween the piston and the bore to check how much clearance you got. I forget the stock spec, i'm guessing in the .005" ballpark? Check your haynes, they'd list that spec.

 

I agree with my boy Sonix here. The only thing you're going to gain out of this is a great lesson with experience- don't try to carry your 305 into the performance aspect. Take it from a guy who wasted a ton of cash on his 305 around your age

And as far as the gas prices go, there really is no difference between a 305 and a 350 in fuel consumption. It's gonna eat a lot of fuel regardless. I get about 6-8 mpg in the city with my setup. One of the biggest things that cut down my fuel economy was the high stall converter (oh, and the lead shoes didn't help either!)

GOOD LUCK to you though!

Yeah, what about that zz4?

 

I think you've got some tuning issues to be worked out.

 

The stall isent what is killing you. I went from a stock converter to a 3500 converter in a th350 and dident knotice a big diffrence at all. I get about 20 hwy and around 15 city.

 

lol ya ill change it, i had a 350 block and some vortec heads, but that got changed when i aquired a free 400 and heads.

and yes lol, i do very well for a kid in highschool, trying to pay off car, motor, stunting ticket, tires and NO my parents arent my income, in fact i have to loan them money sometimes.

but for the 434 , i will be out of school this year, and still living with parents ill be nothing full of money.

 

I was looking into building a 434, but its a rediculously high price to pay!

 

I may have asked before, but are you in calgary or otherwise?
Do you need to bore out the 305? If it's temporary i'd just hone the bores and stick new rings on and put the stock pistons back in. Was that the plan or were you doing a full on rebuild? Then you might still be able to recoop some $$ later when you drop in the 434, by selling the 305 as rebuilt.

And yea, I remember having the most disposable income in my life when I was in high school. No rent or utilities to pay... Holy cow, I was made of money...

 

I definitely do, but I don't know what else to do.

I don't mean to hijack this thread but hey...


I idle at 600-700 warm, the IMS screws are trimmed as low as they can go without stalling.
I've got my primaries 2 stages rich, stock secondaries (needs to go richer).
I've got the pink (8") springs on the secondaries control.
I'm running 10* base timing and ~34* total timing.
Vac can on distributor on a ported vac line.

 

Why do you think it needs to go richer?

Where is your accelerator pump set at?

 

thank god i dont have one of them non-high tech non computer controlled things

but anyways, anyone know the max bore out possible on a 305? is it .40 or .60? cuz theres some beuty pistons on ebay 60 over forged. im sure it doesnt matter what year of block eh?

http://cgi.ebay.ca/5-0-305-SBC-Forge...QQcmdZViewItem
no one bid on them, or i will cut you in half with a hubcap

 

You might be able to get .060 out of it. The cylinder wall thickness should be measured to find out.

Why forged pistons, though?

 

How much is boring going to cost you? That's some serious money tied up in a block when you can just get a 350 which will give you:
more power
basically same gas mileage
some form of resale value

 

I hope you didn't bid on those already...

Seriously, you're just throwing your money away. What makes you think you even need to replace the pistons in your 305 at all? And, what makes you sure your 305 can take a .060" overbore?
That's a serious waste of cash there.. $100CA for the pistons when the smoke clears, if you're lucky, $200 for the bore/hone... $300 to get you what? Nothing IMHO.

Hey token, have you tried using a 3 wire O2 sensor for tuning mixture? Makes things really easy...

 

never bif on them, i was just wondering cuz i can get my block bored cheap, just knowing forged pistons can hold alotta nitrous is always an alternitive.

but if it cant take the bore, obviosly i wont bif on them

 

It can probably take the bore, but it would be a waste of money on a "temporary" engine.

 

acc pump is the biggest available nozzle and on the highest setting and it's still not good enough. When I floor it, the car bogs and tries to die. In fact, it will die if I don't use a big enough nozzle. It's not a timing issue, I am almost positive.

oh and, after about 4000 rpm the car is noticeably weaker.

 

Increasing the size of the pump nozzle decreases the duration of the pump shot, dumping the whole volume in at once, which might not be what you want.

Have you done any empirical testing to measure the effect of changing jets? Timed acceleration runs or anything? What cam are you running?

 

No, I'm doing this the backyard mechanic way... since I don't get traction anyway it's useless to go to the track right now. But I did not know that about the pump shot.


I'm running a cc305 cam (220/230, .544/.544, 114lsa) with +2 primaries and neutral secondaries.

 

Any reason you've got such a big cam? Your vortec heads probably don't have the flow numbers for a cam that size. Not really a great match for a 600 CFM carb, either. In any case, the cam probably wants to idle faster than 600-700 RPM, and would want a whole lot more stall than 2400 RPM.

Oh, and your spring controls the primary enrichment, it doesn't affect the secondaries at all.

Try the vacuum advance on unported vacuum.

 

Oh my heads are well ported. The valve sizes are stock however, but eh. Yeah it does like to idle a little bit harder than 600-700... The car is a daily driver so the converter is quite nice for having to be driven anytime I wanna go somewhere. If this was a track-only car I'd go 3200-3500. Sure beats the hell out of OEM.

Which enrichment springs do I wanna use? stiff or weak?

 

Porting doesn't add much to the performance of vortecs reportedly, and could even hurt them. What's the grind number of the cam? CS276HR14? that's not as big as I was thinking, but still.

You'd still want more stall in a daily driver. Too low of a stall loads the engine down before it can get up into its powerband to start the car moving, and you get no torque multiplication. Going to a smaller diameter converter would also make it less "slippery" for street driving.

Pick an enrichment spring that's rated for about half your idle vacuum. It should keep you from going rich too early on part-throttle acceleration, but but will still enrich soon enough that you don't have to open the throttle too far before accelerating reasonably. It's mostly an individual preference thing, though.

The accelerator pump is still a big killer of city mileage, too.

 

First off, do you plan on putting TPI on a 434?

Second, why in the hell are you rebuilding a 305? Really, you can pretty much build a 350 for the same friggin price! Why **** with a boat anchor? At least if **** hits the fan with this "434" you have a motor in your car that can be built up anyways.

I just don't understand, maybe some people don't want to go fast or have the potential to go fast.

 

come on guys, don't pick on us people that rebuild a 305, besides aren't we all guilty of saying that one thing, come on i know you know it, heard it working at the parts store all the time.....

"its a chevy, there all the same"

$50 for forged pistons, thats an good deal, bore and hone runs $15-17 a hole here, kinda a waste of money in the end, but he may need a good back up motor, and it seems to me that when a person doesn't change the computer the car runs like total crap so he may wanna keep the stock engine, thats why i rebuilt my 305, i was originally gonna keep it tbi, but a4160and points later, and i wished i built a 350

 

Let him build his 305 if he wants. Different strokes for different folks. Why do Civic owners dump so much money into their cars? Maybe they should just shoe-horn an L98 in there.

 

But if I have a smaller diameter nozzle in my pump, it will die when I mash out. I don't get it.

 

That be some thing to see. might even be worth a pic

pennock's rebuilding a 305 or any engine for that matter is great expriense, just take some precautions like others so its not a lost investment, once that 305 hits the back burner theres bound to be a 350 looking for a new set of heads and cam

what you have planed for the little monster?

 

305 t.pi 350, theyre both horribly weak, the motor is temporary, no point wasting money on a new block and heads. I have money to spend on interior, paint, rimz, and stuff, the big motor is just at the dyno shop, slowly collecting bargain performance parts, it prob wont be in till next next winter.

 

Even less point wasting money on new rotating parts and machine work.

 

305 re ring, bearing and gasget s are $150 and maybe stick a lt1 cam for 30 bucks in for added boot, nothing wrong with a little head port, free block machining (oil ports, coolant passages)
total : $180 bucks for about a 230 horse motor.

350 used block and heads crank pistons, $750 gasgets and re ring $150, new prom $120, new injectors $100. augh and maybe about 250 horse? who cares, both horribly pathetic motors, none of witch i would be proud to hammer around town thinking im speed racer.

not to mention, money, student, beer on weekeds, houseboat trips, and traffic tickets, plus other car accesory,s insurance.. a 350 with 20ish more horse power for more money just doesnt add up in my simple mind, considering im changing the motor in a few years anyways,. oh and yes the motor will be carbed by then, unless i become miricle tuner 5000 and some crazy intake that can support it comes out.

 

hmm, this seems a little off. The machine work would cost the same. The 150 will damn near cover the rebuild parts, if you go cheap. lt1 cam, same. Junk yard injectors are cheapo. Sorry, it just doesnt add up. If you are paying 750 for a builder core, you are getting screwed, big time.

 

I would just like to mention that I have built a 305 before, and it turned out to be a huge waste of money. I'll let you discover that for yourself though dude. Best of luck.

 

There's your problem. Beer 7 days a week is the way it should be done.

I picked up a cleaned and honed roller 350 block from my machine shop for $125. 750 is way out in left field.