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i had decided to go with a 331 combo for my car at a price of 2650 from local machine shop. very good engine builders.
but now i have a chance to go the 347 route at 2250 with stud girdle on it already. engine has 400 miles on it. this is the new kit from chp that the oil ring doesnt intersect in other words shorter rod length. i am in a quandry about what to do.
my car is a daily driver and thats the way i want to keep it. i am not sure the 347 can do the daily driver miles i am looking at. i usually do about 300 per week mileage.
does anyone else have a daily driver 347? any opinions would be appreciated. i know this is the novi forum but everyone has always been helpful here..figure this is a good place since i am sure someone else has 347 experience.
I have heard good things about the revised 347, (with the oil rings away from the wrist pin hole). I have even heard that gas milage is the same or better and dependability is great. If built for a daily driven car all of its low end power potential is alone worth it. Just keep in mind though if you want a blower later I'd go with the 331 instead. The 347 is a good N/A engine and the 331 would make a better blown engine.
well here is the problem again, i already have a novi1000k and since i am on somewhat of a budget. by the time i got the 331 and all the parts i need, the cost is like 3500 for the shortblock=
block vatted, cleaned, bored, line honed,stud girdle, and injectors, build it. so the price is high but i can get the 347 for 2400 with it built, ready to bolt in also has stud girdle and injectors.
so hence my big decision. also the 347 has i beam forged rods in it. i kind of wanted the h beam rods instead.
any more suggestions.
thanks
Oh I see, well the 347 is not a bad engine to install a blower on, you'll have tons of power. What heads are you using? The only reasons I mentioned that a 331 would make a better blown engine was because of its shorter stroke. But if you have a cylinder head with a good sized combustion chamber then the 347 would work fine also. I know a guy with an 87 coupe and he has a fairly mild 347 with 8 psi and that car gets crazy in third gear it's almost scary lots of torque. On a centrifugal blown engine typically a shorter stroke will take advantage of the higher rpm's needed to build max boost. But a 347's stroke is only 3.4" anyway the only thing I'd be concerned about is the increased compression caused by the longer stroke.
thanks, i think i will probably go with the 331. it seems like the favoring opinion of everywhere i have read. to much side wall pressure with blower and 347..
Well I have heard the same also with the 347 and the side wall pressure but I don't think you'd have to worry about it until you have 10+ psi. besides a 347 is only overbored .03 I don't think you should worry if you used all of the right stuff when your building it, just talk to your machine shop and let them know what you plan on doing with the set up
After reading a lot of posts and getting info from a couple top notch(Pro Stock level) engine builders, they have convinced me that the whole rod stroke/side load issue is a bunch of BS. Sure it makes sense and is fun to think about but in reality its not really a BIG issue unless you have some totally odd ball combo. They even did a test on rod stroke ratio and it yeilded little to no gains at all. Im talking less than 2 hp....
If you go with the pre-assembled Coast 347, you should have your machine shop tear it down and check the balance on the rotating assembly. Friend of mine got bit by this, his new 347 streetfighter shortblock, as assembled by Coast, gave him major problems until he tore it down and got it balanced correctly. FWIW if it is a street driven centrifugal car I would just have a long rod 306 built and be done with it, put the money saved toward heads & intake.
--
CJ
[EDIT]
:bonk:
From Dept. of Major Corrections:
My friend David told me that upon further investigation, his problems stemmed from a local machine shop assembling his Streetfighter stroker kit, it was not an assembled shortblock from Coast. I felt it was important to differentiate this point. Here's some teardown shots: http://users2.ev1.net/~schwarze/must...k/347teardown/
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