[95oldyeller]

i'm lookin to go with a stroker build in the near future and dont know which to choose. by the way the heads i bought are trickflow 58cc. i've either been told or read somewhere before that a NA 331 will net more durability than an NA 347. is there any truth to this and if so, can you shed some light on the subject?

PS according to Scat, with there 331 kit and my 58cc heads the compression ratio is in the 10.4:1 region. will i be alright runnin pump gas?

 

[FiveLiterFox]

NO!

Just go to a 363. More cubes for the $$

 

[cmefly]

I own both a 347 and a 331. There is no reason to leave the extra cubes out. Go with the 347. Pump gas will be fine

 

[1barzx3]

it was an issue in the past, but has since been addressed a long time ago. if you are buying quality parts from a quality company you have nothing to worry about, so go with 347 and don't look back!

 

[331viperbluecoupe]

pump gas is fine

 

[95oldyeller]

okay, thanks for clearin' that up for me. i just looked over at CHP for 347 kits.they say comp ratio is at 10.94:1, will this also be good on pump gas? better yet, how high can i safely go on 93 octane?

 

[Goody_Seven]

okay, thanks for clearin' that up for me. i just looked over at CHP for 347 kits.they say comp ratio is at 10.94:1, will this also be good on pump gas? better yet, how high can i safely go on 93 octane?

331s usually end up with the piston out of the hole, the 347 is usually in the hole. For that compression between the two is about the same 10.4-10.6 either way. You will be fine on 93 with good aluminum heads.

 

[dstolarc]

I'm resurrecting an old thread for more info.

Does the piston pin intersect the oil ring groove in 347's?
Is that a concern if it does?
I too heard of longevity issues with a 347. If they have have been corrected, what were they?
Is there any "problem" with a 475 fwhp, stock block, 2 bolt main 347?
I mean will it hold up to 100,000 miles of abuse?

Thanks
dstolarc

 

[jeffskar]

NO!

Just go to a 363. More cubes for the $$

Or 16 cubes for over 2,000.00$, unless there's a huge sale on aftermarket blocks that can be bored .125 over.

 

[strokeme]

I'm resurrecting an old thread for more info.

Does the piston pin intersect the oil ring groove in 347's?
Is that a concern if it does?
I too heard of longevity issues with a 347. If they have have been corrected, what were they?
Is there any "problem" with a 475 fwhp, stock block, 2 bolt main 347?
I mean will it hold up to 100,000 miles of abuse?

Thanks
dstolarc

Yes
No
Nothing to correct
The stock block is your enemy from a durability standpoint.

100k mile builds are so far and few between because these are 2-3-4k mile a year cars, the vast majority anyway. So it may be a decade or more before your even close to 100k. As for abuse, you would have to define abuse.

At the end of the day, rational thought says there must be a mountain sized pile of junk 347s because they are so bad but noone can find that pile. Kinda like the pot of gold at the end of the rainbow.

Not to mention, it appears noone has a problem with the 363 burning oil and wearing out which is odd since the 363 is nothing more than a 347 with a piston .090 larger in diameter. So every knock against the 347 must apply to the 363 but you never hear it.

 

[dstolarc]

To define abuse, WOT shifts at 6500 over and over. All day at a drag strip then drive home 100 miles in a freeway at 3500 rpm. Rinse and repeat. Would a 475 hp 347 be pushing a stock block?
I thought 500 hp 347's are common...
Perhaps I heard wrong.

dstolarc

 

[strokeme]

There are certainly more that do that than dont, by a massive margin. At the end of the day, its purely a gamble with the stock block 302. If it were a windsor, by all means your odds go through the roof. I think there are many other considerations as well. 5 speed vs auto. Misshifts vs non missed shifts. Letting the clutch fly at 4000-4500 rpm versus foot brake etc etc... Its all a game of odds imo with these blocks, but if one can not afford a dart, or move to a stock block 351, then it all doesnt really matter, you just do it or you dont.

I dont know, everyone needs to sell themselves one way or another regardless of the decisions being made.

 

[dstolarc]

Does a 331 stand a better chance at not splitting a block?

dstolarc

 

[ZSR]

Less stroke is easier on the block

 

[strokeme]

There is no way to measure what if any difference there is between the 3.250-3.400 stroke on a block. Its generally accepted less stroke is easier but how much is pure speculation.

 

[dstolarc]

Thanks for all the input so far Woody. I Really appreciate it!

Of the 331 and 347 Stock block engines that you sold, is there a pretty equal amount of 331's and 347's that cracked or split a block? I understand hp and rpm have a lot to do with it. "My" 331 or 347 won't be a max effort all out race engine. It would be a very stout street engine. I just want to get a feel for what to expect if I buy a stroker.

Thanks
dstolarc

 

[strokeme]

More 347s but that is because in my case, for every 10, 302 builds I do, 8 of them are 347s compared to 331s. So this data is not very accurate imo.


Sent from AutoGuide.com Free App

 

[dstolarc]

Is there a certain hp and rpm figure where the problems begin?
For both a 331 and 347.

dstolarc

 

[Mark O'Neal]

Everyone calls it 500 H/P. I've been doing little Fords since the late 1960s. The current one is about 7 years old, it's a 347 with a Novi 2000. 554 RWHP.

I've never broken a block. RPM is an influence, so is a lousy tuneup.

 

[strokeme]

No idea, there is no data that says this or that.