When i see crankshafts for my 350 i am building, i see

steel and forged

i know forged is better, but when is it you should buy a forged crankshaft?

also when i view the steel crankshafts the only one it lists for a 350 says:
3.480'' stroke

while forged ones have
3.250'' Stroke
3.480'' stroke
3.750'' stroke


how do i determine which stroke i need? or is their no determining factor besides a longer stroke is better?

 

not sure what the steel would be, i'd guess forged also but there is cast steel. cast also includes nodular iron and the more common cast which i think is gray cast.

 

If you have a 4" bore block (350 block) then:

3.25" stroke = 327
3.48" stroke = 350
3.75" stroke = 377

Most often, people put a 3.75" stroke in a used block that needs a new bore, which makes that usually come out to a 383.

Let me give you a little bit of advice. First, you're in California; so if you want to continue to be able to drive your car on the street, you'll have to build it in such a way that it will pass emissions inspection. That means that you will have to use an induction system that was available in your year of car (not truck, must be a passenger car), or later; and whatever engine you put in it must have all emisions-related devices installed and operating. That includes your stock computer.

That puts an upper limit on what you can expect in terms of RPM capability and power. You can't put a carb on it, because carbs weren't available in 89 or any year after that. You could put TPI on it, but in some one of these posts you said you didn't want to to do that. That leaves you with TBI.

You'll have to have a functional EGR system, which means your heads will have to have the exhaust crossover port in them to carry the exhaust gas to the intake; or you'll have to rig up some way to plumb exhaust gas to the intake externally, like the Corvette version of the L98 had. Since your car didn't come with that, it is an instant visual cue that your motor has been "tampered" as they like to call it, and you will fail, and you will then have to go through the "smog referee" process. You might or might not get certified by the referee. If you don't, it's off with those heads, and back together with some that have the stock hookups.

With any TBI that exists, 300 HP is all you're realistically going to get out of it. At that small of a power level, you don't need a Motown block, you don't need a forged crank or even pistons, you don't need 6" rods; all that is just a giant (and I do mean GIANT) waste of money. Use a stock 350 short block from the junkyard. Just get yourself a TBI truck motor, throw away the heads, rebuild it with hypereutectic flat-top pistons, and you're good to go for about 1/4 of the cost of all that race-car stuff you're posting about.

Get yourself a set of the 64cc version of the Edelbrock Performer heads (which have a CARB number), a set of their TES headers BUT NOT FOR TBI (I'd suggest getting the ones for a 89 350 TPI), a Comp 260AH-14 cam, use your stock intake and the truck TB, and get a decent manufactured exhaust system BUT NOT FOR TBI (again, a 3" cat-back such as Hooker, Flowmaster, Dynomax, etc. etc. etc.), and a high-flow cat. You'll need some incidentals like rocker arms, push rods, etc.; but what I listed pretty much covers the major components.

That recipe will get you as close as close to 300 HP as you're going to get, and will pass CA smog with no problems if tuned properly. In fact the stock 305 chip might work just fine with the correct 350 injectors. And, you'll have about $2500 in the whole job instead of $7500 or more.

Which will leave you some money to do some of the other things that need to be done to make the car (car, not just the motor) fast; like gears and a decent torque converter.

 

thanks for the post, i enjoyed reading it. however all parts I have chosen are 50-state legal

but first, on topic, if i get a used block(which i pretty much already decided, Can I keep the 3.48" stroke? or should I go up to 3.75"?

In another post, someone recommended the holley pro-jection
manifold but it would need a different egr valve. is this bad for inspection?

or maybe an edelbrock carb manifold with a tbi adaptor plate?


in worst scenario, could I always just put the stock intake manifold on for smog puposes? im not trying to cheat the system because I am buying 50-state legal parts.

 

all the parts you have choosen are emissions legal, but they are all about 5x more expensive then you need. listen to RB83, he'll give you the straight truth

 

i am not ignoring his advice. thats why im asking should i get the 3.480" stroke or 3.750" stroke pistons?

with the 6" or 5.7" rods?



the engine will be bored .030" over for a total 4.030"

 

Once again:

3.48" stroke = 350
3.75" stroke = 383 (when the block is .030" over)

Which do you want? What's your budget? How much grinding are you prepared to do on your block if you go to the 400 stroke? What rods are you planning on using? (influences the grinding question greatly)

What we're trying to tell you, is that you need to do a whole lot more research, and understand what you're doing, and understand that there's a whole lot more costs than what you order out of the catalog, and that the farther you go from stock (stock for a 350 is 3.48" stroke, 5.7" rods, 1.56" compression height) the more opportunities for hidden unforeseen gotchas you'll run into. You simply aren't ready to pick up the phone and start ordering stuff yet, even if you think you are. You aren't aware yet of how much you don't know yet about what you're talking about getting into.

The first steps in building a motor are:
1. Establish a goal; HP, ET, lap times, class rules, etc., whatever is is in your particular case.
2. Put together a realistic budget to get to that goal, allowing for machine shop work, and lots of incidentals.
3. Choose parts that are consistent with the goal; not overkill like Motown blocks and stuff like that for 300 HP TBI motors, and not "underkill" like trying to build a 750 HP nitrous motor with a stock cast crank and stock rod bolts. Either of those is guaranted to bring disappointment one way or another.

Do you have a step 1 and a step 2 yet? Would you care to share them with us so we can help point you in the right direction?

Incidentally, if this is going to be a new block, why are you going to have it bored at all?

 

Ok Here is my goals you asked for it

1. minum of 300hp/300tq (would go for 350/350 if plausible)

street legal in california.

I want to get into the high 12's

2.my budget is anywhere up to 5grand and that is inlcuding everything.

And From another post, I decided I am gonna go to the junkyard and pull a 350 and have it bored.

with 3.480" stroke @ .030" over, This would be a 355 correct? so should i just stick with 3.480" / 5.7" pistons?

and another question, both pistons and crankshafts have a stroke. do these numbers have to match up?

 

oh and dont worry, im not gonna just start buying all the parts.. after I just get a basic on how I have to match the parts, then I am gonna buy the block first, and get that all prepped before anything else. this is gonna be a 2004 project

 

OK, that helps.

Yes, if you bore a 350 block .030", the result comes out to 355 CID. It's still a 350. It's not some special displacement that needs its own special name to show how special it is.

Here's how the whole stroke, CH, & rod length thing works:

The block has a specific height, from the centerline of the crank to the deck surface. In a stock Chevy small block, that height is 9.025", -.000 +.015". Ideally you want your pistons to come exactly to the same plane as the block deck (called "zero-decking"... a machine shop procedure, costs money, has to be done after you have your other parts.) Therefore, the sum of half the strok, plus the rod length, plus the compression height, should equal 9.025"; if it doesn't, then the block would need to be decked to get it there.

In the case of a 350, the stroke is 3.48", so half of that is 1.74". That's how far upwards of the crank centerline that the rod journal center moves to put the piston at top dead center. Stock 350 rod length is 5.700" nominal, and stock 350 piston compression height (the distance from the centerline of the wrist pin bore to the nominal top surface of the piston) is 1.560". Add those 3 numbers up, you will see that it comes up to 9.000"; which means that typically in a stock factory 350, the piston is around .025" - .040" down in the bore at TDC.


You're not going to get into the 12s with 300 HP unless you lighten the car seriously - like to 2800 lbs or so. I don't think you can get one of these cars down to that weight with all its glass and sheet metal.

You'll be very disappointed in what you end up with unless get rid of the grocery-cart rear gears you have, and get rid of the stock torque converter that pins the motor RPM down to 1400 RPM at the line and prevents the car from launching. 300 HP at the flywheel in one of these cars lightened about as far as most people want to take their daily-driver rides, which is about 3200-3300 lbs, will get you to about mid-high 13s with traction... which will lead to an issue I haven't even mentioned yet, namely suspension work.

No motor will work well unless you do those other things, and the exhaust all the way from the heads to the street. Take those things (gears, converter, exhaust) and subtract their price from your budget up front, otherwise you'll end up with a motor that can't do any better at moving the car than the one that's in there now, and no money left over to take care of the problem. OBTW, none of those things is against CA smog regulations, if done right.

 

thanks, i copied that down..

and I already have 3.73 posi and headers with cut out valves. so that fixes that problem i think?

all i want for now is the hp and torque from the engine. and I can worry about ugprades later.

 

also do you go by the stroke of the pistons or stroke of the crank?

 

Stroke is produced by the crank. You match the pistons to the crank and rods. The advice matches what we know about the car. If that's not accurate, update it.

Which reminds me, my bad, you don't need a converter with a 5-speed.

 

OK I updated that.

I found cheaper pistons (not forged since I dont need forged)

but these ones dont give a C/H

how can i find out the compression hight?

http://www.jegs.com/cgi-bin/ncommerc...51&prmenbr=361

can you tell if they will be fine for the job?

 

The stock chip seems to be a real hit or miss affair. A few people have stuck some serious engines under a stock efi sytem and it worked great. For most, though, the stock tuning jsut wont cut it. The setup RB gave is relativly mild but it still probably wont get along well with the stock calibration. Its definatly recommended that you get the necessary hardware to burn proms. The overall cost is relativly small compaired to the cost of the engine and youll get the most out of your setup. A good place to start would be the 9C1 cop car .bin and tune with that. If it hasnt already been mentioned, youll need a new aftermarket fuel pump capabile of delivering good flow to around 30 psi or so. The stock one is garbage and it wont be able to supply the necesary fuel flow to feed the motor. Like said above, use the 454 BBC tbi or the holley 670 with 65 pph injectors for starters. With increased fuel pressure they should be able to feed the motor adiqatly. If not you can always upgrade to the larger injectors.

 

The compression height is "implied" in the description.... 350, 5.7 rod. Pretty much has to be stock.

Those would work fine; others that would work would include the Sterling brand (Speed Pro). http://store.summitracing.com/partde...STL%2DH345NP30 for an example