What setup should I choose, ,331,or 347?

Joemon5.0

Member
Mar 23, 2019
31
2
18
44
Long Island
I am in between in whether to take my old 302 block out and take it to the machine shop to get it stroked bore, or should I buy a short block that is stroked with everything in place and balanced already( pistons, crank, etc). What is the more cost effective way going about this? What stroke should I go with 331/347? Also I am thinking to put in a turbo or supercharger in the future, will that be too much HP for the original block to handle? thanks!
 
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08GT500

Active Member
Jul 12, 2018
465
52
38
Massachusetts
Hi,
You’re questions are within an area of which i’m involved in, any further questions, feel free. Happy to help however I can.
What are your budget and performance desires/expectations for the motor, what year is the motor, what car do you have in mind, and E.G.; “Drive it daily 30 miles to work, seek 20MPG, install slicks on weekends & blister the 1,320 in 10 seconds”, etc.(?)
Your present & future plans weigh considerably in conveying my best suggestions as to what build would work best, approaches & who best to build it for you, in your best interests; costs, anomalies, longevity.
If there’s a local & reputable automotive machine shop near you with a linear history, that’s generally your best bet. More costly than buying online, but interactions throughout the build, specifics as desired, face to face communication is priceless.
Under ideal build circumstances, especially modified, any fresh motor has potential to encounter issues, you’d prefer the shop that built it right there to back that up as well I’d imagine. Who wouldn’t? Shipping a crate motor back is a major ordeal, and you’ll incur fees. I’ve watched it happen.
My family has 2 shops (began in the 1950’s) both since expanded, steady stream of work..
Online purchases from remote Businesses:

I’m not biased, I’ve inspected some crate motors & some were consistently correct, evident they took pride in their work..
There ARE Businesses that do a proper job, are few in number, you’ll incur around the same costs as a trusted local shop. ‘
Top shelf’ builds (High HP) motors are generally where I’d have confidence, where they’re run and tuned, dynotested prior to shipping. Again, a failure occurs, where do you turn for spontaneity?mnm

Pre-85, 86’-93’ 5.0 H.O. Roller Motor issues:
.
Stress cracking from the right front valley to block face vulnerability in builds above 450(+/-) HP is the block’s weak link. Block face girdles available to bear partial load shifts that figure closer to 550HP. I’d personally seek an [email protected] those levels.
Undoubtedly the Biggest concern of stock internal issues are the 5/16” Rod bolts used. 2 Bolt mains & a cast crank. No reason fog
You’re going Steel crank, H or I beam shot peened steel 3/8” rods.ARP Main & Rod studs, good Cap’s and a Stud girdle is more than adequate to the blocks 450HP. cutoff,
revving into 7,500 RPM’s. Converting to 4 Bolt mains is also an option,
Another direction is a 351W. More stout. Stroked to 427 CID, you’ve bigblock Torque on tap, even mildly built. Aluminum Dart blocks prices also affordable now, there’s a host of options... Once you reply with figures & budget, it becomes much easier.
Keep in mind Uncertain of your year, the 86’-93’ Roller Fox blocks can handle 450 Crank HP, that’s 380-390 RWHP. Tuned with Stickies Planting, 3.73’s, around a 10 second 125-135 MPH 1/4 Mile Foxbody.

Forced Induction vs. Normally Aspirated:

Apples & Oranges. Going with a supercharger/Turbo gives you strong, solid linear feet Torque & HP. You can run a 9.5-10:1 static C.Ratio, have a low PSI boost to remain within block limits & fare excellent.
Larger upfront cost, but may be run with lower cost GT-40 heads, even E-7’s.
it’s fairly counterproductive to set up the Heads & Cam size to run N.A. now and possibly bolt on F.I. down the road.
What Cam qualities work best for high performance & sound appeal are very different for F.I.and N.A. builds. Overlap, occurring when both valves duration is high for a very short period of time, when run with a F.I. setup creates a leak path for a significant amount of boost entering the combustion chamber through the intake valve, lost by escaping through the exhaust valve that’s still open.
Next, the heads you’re seeking to flow well for CBC normally aspirated are a large cost, as well as the high flowing intake upper/lower (or the Intake if you’re planning on carburetion). There’s no need to have large ports with F.I., as you’re compressing the charge & ramming it into the cylinders.
Throttle response is lost due to the larger ports sought out for a strong N.A. build’s ability to breathe in large amounts of A/F mixture, using only the vacuum created by the Piston’s downward travel. A supercharger would actually have far superior throttle response and function with stock E-7 heads & the stock a 500HP build & revved them to the moon & they never cease to amaze.
 

08GT500

Active Member
Jul 12, 2018
465
52
38
Massachusetts
Hi,
You’re questions are within an area of which i’m involved in, any further questions, feel free. Happy to help however I can.
What are your budget and performance desires/expectations for the motor, what year is the motor, what car do you have in mind, and E.G.; “Drive it daily 30 miles to work, seek 20MPG, install slicks on weekends & blister the 1,320 in 10 seconds”, etc.(?)
Your present & future plans weigh considerably in conveying my best suggestions as to what build would work best, approaches & who best to build it for you, in your best interests; costs, anomalies, longevity.
If there’s a local & reputable automotive machine shop near you with a linear history, that’s generally your best bet. More costly than buying online, but interactions throughout the build, specifics as desired, face to face communication is priceless.
Under ideal build circumstances, especially modified, any fresh motor has potential to encounter issues, you’d prefer the shop that built it right there to back that up as well I’d imagine. Who wouldn’t? Shipping a crate motor back is a major ordeal, and you’ll incur fees. I’ve watched it happen.
My family has 2 shops (began in the 1950’s) both since expanded, steady stream of work..
Online purchases from remote Businesses:

I’m not biased, I’ve inspected some crate motors & some were consistently correct, evident they took pride in their work..
There ARE Businesses that do a proper job, are few in number, you’ll incur around the same costs as a trusted local shop. ‘
Top shelf’ builds (High HP) motors are generally where I’d have confidence, where they’re run and tuned, dynotested prior to shipping. Again, a failure occurs, where do you turn for spontaneity?mnm

Pre-85, 86’-93’ 5.0 H.O. Roller Motor issues:
.
Stress cracking from the right front valley to block face vulnerability in builds above 450(+/-) HP is the block’s weak link. Block face girdles available to bear partial load shifts that figure closer to 550HP. I’d personally seek an [email protected] those levels.
Undoubtedly the Biggest concern of stock internal issues are the 5/16” Rod bolts used. 2 Bolt mains & a cast crank. No reason fog
You’re going Steel crank, H or I beam shot peened steel 3/8” rods.ARP Main & Rod studs, good Cap’s and a Stud girdle is more than adequate to the blocks 450HP. cutoff,
revving into 7,500 RPM’s. Converting to 4 Bolt mains is also an option,
Another direction is a 351W. More stout. Stroked to 427 CID, you’ve bigblock Torque on tap, even mildly built. Aluminum Dart blocks prices also affordable now, there’s a host of options... Once you reply with figures & budget, it becomes much easier.
Keep in mind Uncertain of your year, the 86’-93’ Roller Fox blocks can handle 450 Crank HP, that’s 380-390 RWHP. Tuned with Stickies Planting, 3.73’s, around a 10 second 125-135 MPH 1/4 Mile Foxbody.

Forced Induction vs. Normally Aspirated:

Apples & Oranges. Going with a supercharger/Turbo gives you strong, solid linear feet Torque & HP. You can run a 9.5-10:1 static C.Ratio, have a low PSI boost to remain within block limits & fare excellent.
Larger upfront cost, but may be run with lower cost GT-40 heads, even E-7’s.
it’s fairly counterproductive to set up the Heads & Cam size to run N.A. now and possibly bolt on F.I. down the road.
What Cam qualities work best for high performance & sound appeal are very different for F.I.and N.A. builds. Overlap, occurring when both valves duration is high for a very short period of time, when run with a F.I. setup creates a leak path for a significant amount of boost entering the combustion chamber through the intake valve, lost by escaping through the exhaust valve that’s still open.
Next, the heads you’re seeking to flow well for CBC normally aspirated are a large cost, as well as the high flowing intake upper/lower (or the Intake if you’re planning on carburetion). There’s no need to have large ports with F.I., as you’re compressing the charge & ramming it into the cylinders.
Throttle response is lost due to the larger ports sought out for a strong N.A. build’s ability to breathe in large amounts of A/F mixture, using only the vacuum created by the Piston’s downward travel. A supercharger would actually have far superior throttle response and function with stock E-7 heads & the stock a 500HP build & revved them to the moon & they never cease to amaze.
Edit; “ A supercharger would actually have far superior throttle response and function with stock E-7 heads & the stock a 500HP build & revved them to the moon & they never cease to amaze”
Ok, last paragraph edit, Wanted to convey the resilience of the 302’s. To answer the stroker question, the 331’s tend to be a bit better at the higher rpm’s, 347’s make good use of the torque across the low & mid ranges, little piston slap with certain short skirt pistons, similar to what the 68’-69’ SBC L-79 327 Motors had running the long stroke (same block for 302, 327, 350’s).
Good luck!
-John
 

Hoytster

I don't dare do that to my Knob
10 Year Member
Dec 30, 2002
792
510
134
37
Cornwall, PA
www.hoytspot.com
If you ever plan on being north of 450rwhp, then I would plan on an aftermarket block and rotating assembly now. With either stroke, half decent heads, and forced induction, it will be easy to eclipse that mark. If you want to stay N/A, I would go right to a 347 stock block for street use.
 

Joemon5.0

Member
Mar 23, 2019
31
2
18
44
Long Island
Hi,
You’re questions are within an area of which i’m involved in, any further questions, feel free. Happy to help however I can.
What are your budget and performance desires/expectations for the motor, what year is the motor, what car do you have in mind, and E.G.; “Drive it daily 30 miles to work, seek 20MPG, install slicks on weekends & blister the 1,320 in 10 seconds”, etc.(?)
Your present & future plans weigh considerably in conveying my best suggestions as to what build would work best, approaches & who best to build it for you, in your best interests; costs, anomalies, longevity.
If there’s a local & reputable automotive machine shop near you with a linear history, that’s generally your best bet. More costly than buying online, but interactions throughout the build, specifics as desired, face to face communication is priceless.
Under ideal build circumstances, especially modified, any fresh motor has potential to encounter issues, you’d prefer the shop that built it right there to back that up as well I’d imagine. Who wouldn’t? Shipping a crate motor back is a major ordeal, and you’ll incur fees. I’ve watched it happen.
My family has 2 shops (began in the 1950’s) both since expanded, steady stream of work..
Online purchases from remote Businesses:

I’m not biased, I’ve inspected some crate motors & some were consistently correct, evident they took pride in their work..
There ARE Businesses that do a proper job, are few in number, you’ll incur around the same costs as a trusted local shop. ‘
Top shelf’ builds (High HP) motors are generally where I’d have confidence, where they’re run and tuned, dynotested prior to shipping. Again, a failure occurs, where do you turn for spontaneity?mnm

Pre-85, 86’-93’ 5.0 H.O. Roller Motor issues:
.
Stress cracking from the right front valley to block face vulnerability in builds above 450(+/-) HP is the block’s weak link. Block face girdles available to bear partial load shifts that figure closer to 550HP. I’d personally seek an [email protected] those levels.
Undoubtedly the Biggest concern of stock internal issues are the 5/16” Rod bolts used. 2 Bolt mains & a cast crank. No reason fog
You’re going Steel crank, H or I beam shot peened steel 3/8” rods.ARP Main & Rod studs, good Cap’s and a Stud girdle is more than adequate to the blocks 450HP. cutoff,
revving into 7,500 RPM’s. Converting to 4 Bolt mains is also an option,
Another direction is a 351W. More stout. Stroked to 427 CID, you’ve bigblock Torque on tap, even mildly built. Aluminum Dart blocks prices also affordable now, there’s a host of options... Once you reply with figures & budget, it becomes much easier.
Keep in mind Uncertain of your year, the 86’-93’ Roller Fox blocks can handle 450 Crank HP, that’s 380-390 RWHP. Tuned with Stickies Planting, 3.73’s, around a 10 second 125-135 MPH 1/4 Mile Foxbody.

Forced Induction vs. Normally Aspirated:

Apples & Oranges. Going with a supercharger/Turbo gives you strong, solid linear feet Torque & HP. You can run a 9.5-10:1 static C.Ratio, have a low PSI boost to remain within block limits & fare excellent.
Larger upfront cost, but may be run with lower cost GT-40 heads, even E-7’s.
it’s fairly counterproductive to set up the Heads & Cam size to run N.A. now and possibly bolt on F.I. down the road.
What Cam qualities work best for high performance & sound appeal are very different for F.I.and N.A. builds. Overlap, occurring when both valves duration is high for a very short period of time, when run with a F.I. setup creates a leak path for a significant amount of boost entering the combustion chamber through the intake valve, lost by escaping through the exhaust valve that’s still open.
Next, the heads you’re seeking to flow well for CBC normally aspirated are a large cost, as well as the high flowing intake upper/lower (or the Intake if you’re planning on carburetion). There’s no need to have large ports with F.I., as you’re compressing the charge & ramming it into the cylinders.
Throttle response is lost due to the larger ports sought out for a strong N.A. build’s ability to breathe in large amounts of A/F mixture, using only the vacuum created by the Piston’s downward travel. A supercharger would actually have far superior throttle response and function with stock E-7 heads & the stock a 500HP build & revved them to the moon & they never cease to amaze.
If you ever plan on being north of 450rwhp, then I would plan on an aftermarket block and rotating assembly now. With either stroke, half decent heads, and forced induction, it will be easy to eclipse that mark. If you want to stay N/A, I would go right to a 347 stock block for street use.
Hi guys thanks again. As far as parts that I have on the side, I have a Gt40 upper and lower intakes, a pair of used Edelbrock performer RPM heads with 1.6 roller rockers (in which I need to take to a machine shop to clean it up), new timing chain, EV6 fuel injectors, new timing chain. I also have a new rear main seal, oil pump, water pump. I also want to put in a slightly Lopey Cam in it as well. The engine is old so if I’m pulling the motor I definitely want to change seals etc . My question is being that I have these parts is it worth spending the money to get the old block stroked, or just leave it as is and see how I feel with the added bolt ons? What power would I get out of adding those bolt ons? I would be happy with around 300-350hp range for now. (But as far as power goes you always eventually want more!! Lol)In the future I would like to go FI, what can I get out of a stock block using those bolt ons and a supercharger/ Turbo. Thanks again for your time, I appreciate it. Joe. One more thing what else should be addressed, ignition, suspension, brakes? And in what order of importance?