Found my Builders

Having a builder you can trust and one who will answer all your stupid questions is invaluable!! I say good choice on the 331. Even though the oil loss debate with the 347 is just that. . . highly debateable, the 331 is a good revver

How much force is it? Or how much more than a 331 is it? Or do we know its just "more"?


Anyway, good to hear you found a good place. Keep us updated with the progess!

I have neard nothing but good stuff about Heintz from a few people I've met that have had their work done there.

Cool man good luck....

SeventyMach1 said:

Well, I don't really know that, lol. But I just know that the rod ratios (angle of the connecting rods) are different. They're more "spread out" (or downward, if you will) on the 347's. In turn, the crank is pushing the rod at that angle .... pushing the piston into the side of the cylinder wall.

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Yea i know how the argument goes so i wont try to start one But i will say that a qualified engine builder can and will build a 347 that will run and last just as long as a 331 or a 306. This argument is fed by guys who build 347s who dont know what the hell they are doing....and the complaints obviously come from guys with problems. I've heard of a 306 being crap after 60 miles...but the rod ratio isnt blamed then is it? Nope, its the builder. But for some reason when 347's mess up, its the rod ratio and not the builder? And the funny part of all the threads about this argument is that its all "theory". Yes it will have "more" sidewall loading...but there has never been anything documented to prove that its makes a lick of difference. If the idea is so solid, why hasnt it been proven? Because its too hard to...too many other variables will come into play with an engine and how it wears before side loading does.

Every engine has its role into a specific combo and im sure you'll be happy with your choice! The key is the engine builder i think...not necessarily the engine u pick although obviously they both matter. It seems from what i have read and from what i have learned from talking to pros...the bigger the stroker kit, the tighter things get and the more IMPORTANT small details get. On a 306 you might get a way with a little laziness, just like a 351, but on a 347 or say 427, the builder better be on the top of his game so that the motor is right. After all the shortblock research i have done....i'll stick to having shortblocks assembled for me, lol, it gets too complicated and too critical. Filing rings is not something i would trust the average joe to do. Neither is boring a block. I've heard about how some shops cant even bore a straight cylinder, let alone file a ring correctly. These are the shops that the bad 306's and 347's come out of i think. If you went to a shop that is reputable and can actually perform the work(which it seems u found one) then i dont think it would matter which shortblock you got as they would all be of the same quality and probably last just as long if treated equal. Besides, the performance and pushing our motors to the limits will wear the motor before the rod ratio.

Did ya know you could do a 347 with a 331 piston? Are you planning on revving the 331 any higher? Will it need a different gear than the 347? What are your goals for it? I know 1 thing guys like are going with 331's to rev them higher or to use in blown applications...both of which would cause more wear than a lower revving 347.

Its about the whole picture...not just the shortblock. It starts with the guy putting it together, then its the motor, then its the car, then its the gearing, then its the treatment of the whole thing as 1 unit.



Sorry for the rant

SeventyMach1 said:

I'm not sure I follow your question here Nate. Are you referring to bore? Or are you talking about the height of the piston? I know they're both a 4.030 bore (and I'm sure you do) ... so I'm assuming the latter.




Yeah, the most common debate is over oil consumption & how some kits have the wrist pin intersecting the oil rings. I think this is stupid, since the new kits aren't even made like that anymore. However, my concern arose when I heard about the rod ratio affecting the side load. Just as you, I have no way of "prooving" that it has no effect. Unfortunately, I dont have the time/money to do some trial & error. I have NO room for error. I want it right the 1st time & have a long lasting engine. I've never heard of a side load problem with the 331. I have for the 347. Does this mean it's true? No. But I don't want to find out the hard way.

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331-
3.25" Stroke
5.400" rod


347-
3.40" Stroke
5.400" rod

or a 347 can be used with a 5.315" rod.....

rick 91gt said:

Built properly they both will not burn oil, that is a myth. The shorter rod uses a 1.175" piston same as a 331, the long rod uses a 1.10" piston and the rail supports.

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http://bbs.hardcore50.com/vbulletin/showthread.php?t=29893&highlight=347+331+piston


So basically using the shorter rod lets you use the 331 piston. Hope that clears up the confusion.


I hear ya on the trial and error....thats something that is between you and the engine builder. Someone like Rick...will tell you that the 347 he builds will not burn oil. So if it does, well your problem is with him. A builder who says a 347 will burn oil is probably someone who isnt comfortable building it or simply cant. Obviously u dont want to have them do it. But i think the word needs to come from the engine builder...not from forums. I talked for a long time with Ed C, Brian at AD, Jay Allen, and my engine builder. They all said pretty much the same thing which didnt really help me that much...it left me with the choice. Why? Cause with the options, they all would be just as good. They all would work just fine in my application.


So my best advice would be to go with what your engine builder thinks is best...cause if there is a problem...you dont want there to be any type of argument.


:SNSign:

SeventyMach1 said:

Thanks a bunch Nate. Yeah, I did know that about the pistons/rod length. I just learned it recenly though, when I saw someone post how Rick built theirs with the short rod. I will take heed here & talk it over with my builder. If he feels confident in building a 347 & tells me that there will be no side load, oil consumption, or longevity issues .... I may end up doing the 347 afterall.

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No problem man. The thing i like about forums is it gets you thinking...although there are always HUGE piles of BS to surf through. The best thing you can do is to try to figure out the ideas for yourself, then talk it over with a pro who actually does this stuff as a living. Thats where the true knowledge is learned.


One other thing i thought of while sitting here doing homework was that in all the arguments about a 347 "wearing out" faster than a 331 because it has so much more side loading...i've never seen 1 professional step in and say "yes, this is true. A 347 wil not last as long." Seems like every last professional and engine builder, like Rick above, says that if properly built, a 347 will be just as good. Now...the key word is IF...cause it doesnt happen a every time. And i think when it doesnt, well thats where these internet rumors originate.


Good luck man and be sure to keep us updated!