380 build questions
October 5th, 2013, 02:01 AM
#1
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380 build questions
Was curious on a couple things when building a stroked Olds 350 to a 380;
1) I was told if you offset grind a standard crank it will make it weak because you're grinding off the induction hardening. I was told you needed to therefore use a 330 forged crank, but I don't recall others who have build 380's mention using a 330 crank.
2) Are there multiple piston choices available to build a 380? So if one had a set of either #8 heads or a set of smaller chambered 5,6, or 7 heads, you would be able to achieve a desired CR by just using the proper sized piston dish?
1) I was told if you offset grind a standard crank it will make it weak because you're grinding off the induction hardening. I was told you needed to therefore use a 330 forged crank, but I don't recall others who have build 380's mention using a 330 crank.
2) Are there multiple piston choices available to build a 380? So if one had a set of either #8 heads or a set of smaller chambered 5,6, or 7 heads, you would be able to achieve a desired CR by just using the proper sized piston dish?
October 5th, 2013, 06:05 AM
#2
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Was curious on a couple things when building a stroked Olds 350 to a 380;
1) I was told if you offset grind a standard crank it will make it weak because you're grinding off the induction hardening. I was told you needed to therefore use a 330 forged crank, but I don't recall others who have build 380's mention using a 330 crank.
No not necessarily. The hardness on most cranks only goes a few thousandths down anyway. Once you grind it .010/.010 it's gone.
2) Are there multiple piston choices available to build a 380? So if one had a set of either #8 heads or a set of smaller chambered 5,6, or 7 heads, you would be able to achieve a desired CR by just using the proper sized piston dish?
1) I was told if you offset grind a standard crank it will make it weak because you're grinding off the induction hardening. I was told you needed to therefore use a 330 forged crank, but I don't recall others who have build 380's mention using a 330 crank.
No not necessarily. The hardness on most cranks only goes a few thousandths down anyway. Once you grind it .010/.010 it's gone.
2) Are there multiple piston choices available to build a 380? So if one had a set of either #8 heads or a set of smaller chambered 5,6, or 7 heads, you would be able to achieve a desired CR by just using the proper sized piston dish?
October 6th, 2013, 05:54 AM
#3
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I'm not an expert like Mark but most seem to use a virgin 330 crank. I am pretty sure an N crank can be used but why? The 330 crank will only cost $550 offset ground, builder supplying the core. Find an extra 350 core to build and use Procomp heads. Having a nice running 350 doesn't make me want my car hauled away for scrap. I can now take my time getting the machine shop to machine it and assemble it right. I can hardly wait to get my 424 short block together.
Last edited by olds 307 and 403; October 6th, 2013 at 05:56 AM.
October 6th, 2013, 09:42 AM
#5
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To add to Mark's post, the nitriding coating is for improved wear properties. It does nothing for strength. Millions of engines run just fine without it. The whole point of using the forged 330 crank is that presumably you are increasing the stroke to get more performance. A forged crank will always be stronger than a cast crank. Whether it's worth the extra effort to get one for your particular build depends on your ultimate use - hard core drag racing or street driver with occasional track use.
October 6th, 2013, 07:09 PM
#6
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Easy. Because one doesn't have a 330 crank ( or matching flexplate ).
Thanks for the info guys. If I end up going with a 380 stroker, it seems I should be fine with a standard crank. If a 330 crank drops into my lap, I would probably use it, but it seems I shouldn't require one though. I'm just looking for a fun small block street engine that will perform well on the street as well as break me into the very high 12's. If I'm at 13.8 right now with my weenie POS 350, I'm hoping to be able to knock off almost 1 full second with a much better build while still retaining great street manners.
Thanks for the info guys. If I end up going with a 380 stroker, it seems I should be fine with a standard crank. If a 330 crank drops into my lap, I would probably use it, but it seems I shouldn't require one though. I'm just looking for a fun small block street engine that will perform well on the street as well as break me into the very high 12's. If I'm at 13.8 right now with my weenie POS 350, I'm hoping to be able to knock off almost 1 full second with a much better build while still retaining great street manners.
Last edited by DoubleV; October 6th, 2013 at 07:14 PM.
October 6th, 2013, 07:32 PM
#7
I think high 12's can be achived with a well sorted out .030 350. I ran 13.3's with a std. bore 350 with flat tops , some bigger valves and a little bowl work , Nothing too fancy . The small carb and tight converter held it back . It ran on pump gas and ran awesome. I think the new combo should scratch 12's. slightly bigger bore .030 , better cam, bigger carb. Still trying to get out to the track to get some results or atleast a baseline.
October 6th, 2013, 08:27 PM
#8
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There is no doubt in the sleightest you can get high 12's with an Olds 350 ( with my stall, gears, weight, traction etc ), but it's more easily achieved with bigger cubes and the bigger cubes would maximize streetability. I would rather have a bigger less radical engine than a smaller more radical one on the street. I do want to keep it a small block though and I don't want to use a 403. So I figure a 380 might work well for me.
October 6th, 2013, 08:34 PM
#9
I have a 512/512 227/234 @.050 cam and it idles great has a fast lopey idle but it idles well in drive, drives awesome runs smooth. But im with you on the mild aspect. Im doing a 9 to 1 355 with a 120 hit of nitrous for the next build once im bored with this 355. Im doing a mild cam, going to 3.42 gears . Got all the stuff for that build just need a reason to build it lol. Im tired of the high stall, tired of the high rpm crusing so my solution is nitrous just for the strip and super mild on the street.
Last edited by coppercutlass; October 6th, 2013 at 08:37 PM.
October 7th, 2013, 09:11 AM
#12
I think a dx build like that is more suited for an all out race car imo. I'm not a big block guy but if I wanted mild and fast I would just go 455. I just think the 434 isn't worth the effort for just a street car. I'm not saying it's junk but dollar for dollar not worth it to me. I would go 455 before I sunk money into a 380 or 434.
October 7th, 2013, 09:54 AM
#13
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What max rpm are you planning on running? I am planning about 9.6-9.7 to 1. I figure the cam can still be mild, run on regular gas and still easily hit 8.95 in the 1/8. Should not be hard with 424 ci and Procomp heads Anymore and my trans and rear will be very questionable. I am thinking 5000 rpm shift points or somewhere close.
October 8th, 2013, 01:35 AM
#14
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Chadman, yes I have thought of a 440 just like John T has in both of his cars, but it's more motor than what I'm looking for and are pretty expensive to build. If Chuck P gave me a deal I couldn't refuse though, then sure!
What max rpm are you planning on running? I am planning about 9.6-9.7 to 1. I figure the cam can still be mild, run on regular gas and still easily hit 8.95 in the 1/8. Should not be hard with 424 ci and Procomp heads Anymore and my trans and rear will be very questionable. I am thinking 5000 rpm shift points or somewhere close.
Last edited by DoubleV; October 8th, 2013 at 02:47 AM.
October 8th, 2013, 04:26 AM
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October 8th, 2013, 06:41 AM
#16
Old(s) Fart
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Look, if you all want to act like children, please take it off-line. This thread started with a legitimate technical question. Please keep it that way. The name calling is neither flattering nor productive, nor do the rest of us really care about is.
October 8th, 2013, 08:14 AM
#17
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I want 8.95 taking it easy. I agree it should be half a second faster at least. I just want to dominate the bottom bracket and have a fun car to drive. I don't want to leave the trans or rear on the track first pass.
Last edited by olds 307 and 403; October 8th, 2013 at 08:17 AM.
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