Can a 305 be turned into a 350 or a stroker

[gretchen/jason]

I know a guy who will part free of charge with a second gen 305 . Can the block be turned into a 350 by changing the heads or maybe boring it out some . How about a 383 out of a 305 can it be done . it would save me 600$ on buying a 350 block to do a stroker or such .

 

Also do 350 heads fit a 305 ? All in all im looking for a deal on a block to redo another supercharged 350 or maybe a supercharged 383 .

 

Jason

[SilentNight1647]

No, a 305 cannot be made into a 350 by boring it or changing the heads. The 305 has a way smaller bore than a 350 and was cast as entirely different block. The only way I know of to make 383 is 350 block 30 over with a 400 crank and rods. You can also make a 377 out of a 350 but that is an aftermarket job. As a general rule heads on any conventional SBC will bolt onto any other SBC in the world some things may not line up right and you may lose some functions like steam holes or bolt holes for accessories but they will almost always bolt up and work. And $600 for a block sounds steep, I buy cores for $100 a piece and have them prepped for another $100 to $250 I'd shop around if I was you. Good luck with your project though are you going with a roots blower or something more like a Vortech setup?

[gretchen/jason]

Cool that answeres all my questions on a 305. Im going with a roots stryle blower . wow a 100$ or so for a bare block i do need to shop around a bit more 600$ was quoted for a bare block this is why i asked about a 305 turned into a 350 .

 

So i know where i need to go now a 350 block thanks for the advice .

 

Jason

[280zwitha383]

What would keep you from putting a 400 crank in a 305?

 

edit: (besides being a waste of money)

[defrag010]

400 crank in a 305 will make a 330-ish ci stroker, but it's not an ideal power combo due to the bore being so small with that big of a stroke.

 

also, fyi, it was said above.. a 377 is a 400 with a 350 crank. All you need are special bearings, and you can do it with stock parts.

[Alf]

As stated, a 305 can not be bored out to a 350. 305 bore is roughly 3.75" and a 350 is 4", you would have to bore it .250" over, .060" is about the max you can go. Another note about 305's is that the cast iron used in the blocks doesn't have as high a nickel content as the earlier 350's, like the 010 blocks, and they wear faster. Also, all 305's have two bolt mains.

 

It is possible to use a 400 crank in a 305 to stroke it, I'm pretty sure it comes out to a 331, somebody sells the kit. However the small cylinder of the 305 limits the valve size you can run and shrouds the valves much more than a four inch bore.

 

$650 for a 350 block is rediculous, I've bought four bolt 010's for as cheap as $40, just be patient and keep searching for a deal.

 

If you happen to stumble accross a 400 but still want to rev, you can make it a 377 with a 350 crank, 3.48" stroke, or a 350 with a 307/327 crank, 3.25" stroke, bearing spacers are needed though.

 

Good luck, and remember, don't settle, get what you really want.

[280zwitha383]

If you happen to stumble accross a 400 but still want to rev, you can make it a 377 with a 350 crank, 3.48" stroke, or a 350 with a 307/327 crank, 3.25" stroke, bearing spacers are needed though.

 

 

Destroking is a nono

[defrag010]

nothing wrong with de-stroking, it all depends on the purpose of the motor..

[datsunlover]

Hell man.. I just had an '010' block (previously bored to a 355) BUILT for $600!! Mild cam, new bearings/seals/gaskets/valve job/ect and I just have to put a carb on it! The builder was a guy I know, and he owed me $500 but he had a good core and some parts lying around, so I kicked in another $100 and I have a freash motor sitting on a stand.. now if only the garage wasn't so cramped and full of crap... (undergoing garage renovations...)

[bschiltz]

Destroking is a nono

 

And why is that? I'm not trying to start anything, I'm honestly curious.

[Guest chevy280z]

There is no replacment for cubic dollars, and yes it sux!!!

[bschiltz]

Welcome to HybridZ

 

My point is thus: If you can increase the number of RPMs an engine can turn by X ammount by de-stroking it and that lets you run a cam/intake/head setup that gives you greater high end power, why is this bad? I think this is especially valuable if you are running a forced induction setup when the extra RPMs can mean the difference between compressor #1 and larger compressor #2. It really does boil down to the purpose of the engine, just as Defrag said.

[280zwitha383]

Oh man, I didn't mean to start a discussion....

 

My point is thus: If you can increase the number of RPMs an engine can turn by X ammount by de-stroking it and that lets you run a cam/intake/head setup that gives you greater high end power, why is this bad?

 

Is that even probable/logical? Why would decreasing your cubic inches/stroke make it more probable to make more power at any rpm? Why not make what you have turn the rpms you desire? Why do you desire high rpms?

 

 

 

I think this is especially valuable if you are running a forced induction setup when the extra RPMs can mean the difference between compressor #1 and larger compressor #2. It really does boil down to the purpose of the engine, just as Defrag said.

 

Again is that even probable/logical? How many more rpms would you have to pull to compensate for the loss of displacement. Making more rpms on a smaller motor does not mean that you will need more air than a larger motor making fewer rpms. And, really how many rpms are you talking about gaining? 1000? 1500?

 

In my mind I cannot justify it under normal circumstances. With the money and time spent on destroking the engine you could have just as easily made the original combination handle the same rpms. You could absolutely make the original combination just as efficient.

[280zwitha383]

I played around a little with the cfm calculator here:

 

http://golenengineservice.com/calc/calccarb.htm

 

Basically what I came up with just as a comparison is that between a 327 and a 350 the 327 has to turn 500 more rpms to equal the 350 (at 500 less rpms):

 

350 @ 7000rpms = 708cfms @ 100%VE

327 @ 7500rpms = 709cfms @ 100%VE

 

This is actually not AS significant as I thought. However, you have to remember that the 350 will make more power up to its 7,000rpms. I guess the catalyst is how many NET rpms you would actually gain from destroking. When I say net I'm referring to the difference between a similarly built stock-stroke engine and a built destroked engine. Do you think that with good internals you could really rev a destroked engine THAT much more than it's counterpart? I am not saying that it's not doable because it is, but IMO it's bordering on counterproductive in a best case scenario especially considering that with the same money you could have at the very least equal power (at fewer rpms) with a properly matched setup.

[defrag010]

Again, you're looking through tunnel vision goggles.. Different types of motors and racing use different types of engine combinations. circle track, drag racing, street motors, etc.

 

It's not just about max airflow in CFM through the motor, it's about powerband, the affects stroke and bore have on things like ignition timing/detonation, and the characteristics of the car and how it will be raced.

 

You don't want to put a 4.25" stroke 434 smallblock torque monster in your 1800lb road race/autocross car just the same as you don't want to put a high winding 283 behind a glide in your 3200lb camaro drag car.

 

Do you think that with good internals you could really rev a destroked engine THAT much more than it's counterpart?"

Absolutely, by quite a bit.

 

De-stroked engines have been used successfully in all forms of racing, from pro stock to nascar for years and years. 331's were BIG back in the 80's, and even the nascar engines of today use very short stroke/big bore engines suited for sustained high revs. What about F1 motors with their 1.5" stroke and 20k+ rpm? Not only do they make more power than 99% of the cars you see on the street, but a purpose built F1 car even with its short stroke will dominate most any non-purpose built car you can throw at it at drag racing, road racing, autocross, and probably most any other type of race. The kind of logic you're using on the importance of displacement only applies to a small section on the Pie chart of racing.

[Kechup]

Im putting a 377 with a T76, it will make less torque and HP down low but on the big end it will SCREAMMMMMMMM. That should be a good combo for a 2600lbs car with small tires, it will help the car hook up at the track hopefully. All makes and cube motors can be fast if done right, trying to get the last bit of HP & TQ down to the ground or out of a motor is were stuff like de-stroked comes into play. My 2$.

[Pop N Wood]

You don't want to put a 4.25" stroke 434 smallblock torque monster in your 1800lb road race/autocross car just the same as you don't want to put a high winding 283 behind a glide in your 3200lb camaro drag car.

 

So I guess you saying if you could have an original Shelby Cobra you would rather have the 289 than the 427?

 

You don't want the 283 in the drag car because chances are it doesn't produce enough power. But why wouldn't the road race car want more power?

 

Throttle response I can understand, but why not more power?

[bschiltz]

Do you think that with good internals you could really rev a destroked engine THAT much more than it's counterpart? I am not saying that it's not doable because it is, but IMO it's bordering on counterproductive in a best case scenario especially considering that with the same money you could have at the very least equal power (at fewer rpms) with a properly matched setup.

 

I totally agree that it can easily be counterproductive and a very expensive way to nowhere. Like I said, I was honestly curious and I don't know all the answers.

I guess I was thinking along the lines of Grumpy's mantra "Match your cam/heads/intake" and a properly matched setup with max power at higher RPMs can deffinately benifit from 1500-2000 extra RPMs. Correct me if I'm wrong, but I think forced induction(especially turbos) are a whole different ballgame.

 

Thanks for that link, BTW. I'd seen it before, but now it's bookmarked.

[280zwitha383]

Again, you're looking through tunnel vision goggles.. Different types of motors and racing use different types of engine combinations. circle track, drag racing, street motors, etc.

 

Ok, that's too vague to really respond to...

 

It's not just about max airflow in CFM through the motor, it's about powerband, the affects stroke and bore have on things like ignition timing/detonation, and the characteristics of the car and how it will be raced.

 

The more air you move through an engine the more power it produces period. So yes in an oversimplified example this is an effective way to measure power output. You can very affectively calculate hp from HEAD FLOW (ALSO IN CFMS!). I REALLY don't know how you can make an argument for powerband AND less stroke/cubic inches at the same time. Sure with a smaller stroke you can run a little more compression or at the same compression not be as likely to detonate. However, ignition timing is simply part of a matched combo and is not really relevant to our argument IMO.

 

You don't want to put a 4.25" stroke 434 smallblock torque monster in your 1800lb road race/autocross car just the same as you don't want to put a high winding 283 behind a glide in your 3200lb camaro drag car.

 

For drag racing I would love to have a 434 in an 1800lb car. If you could distribute the weight in a track car it would be pretty impressive also.

 

Absolutely, by quite a bit.

 

De-stroked engines have been used successfully in all forms of racing, from pro stock to nascar for years and years. 331's were BIG back in the 80's, and even the nascar engines of today use very short stroke/big bore engines suited for sustained high revs. What about F1 motors with their 1.5" stroke and 20k+ rpm? Not only do they make more power than 99% of the cars you see on the street, but a purpose built F1 car even with its short stroke will dominate most any non-purpose built car you can throw at it at drag racing, road racing, autocross, and probably most any other type of race. The kind of logic you're using on the importance of displacement only applies to a small section on the Pie chart of racing.

 

Quite a bit huh? Exactly how much is quite a bit in OUR world. You can't really compare the engines we have in our cars to F1 engines. How often do you have to rebuild an F1 engine under "normal" use? How much money does one of those cost?

Why do you suppose 331s aren't big anymore?

Concerning my little piece of the pie, why don't we at least keep our conversation limited to what is realistic, affordable, and reliable for something that people on this site might actually put in their cars. At the very least I have attempted at some hard evidence that destroking an engine is not beneficial for the most part.

 

I would really like to know at least a hypothetical answer to my question. How many net rpms do you propose you could gain from destroking an engine? Do you not even buy that you would have to crank the destroked engine even higher to compensate for the lack of stroke/cubic inches? Like I say, if you could safely gain 2500 rpms I think you would start benefiting from it. It wouldn't live as long as a similarly powered bigger stroke engine but I could appreciate it none the less.

[280zwitha383]

Gretchen/Jason, I apologize for the tangent in your thread.