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70Chal392
'55 301 typical bore?


I don't have a sonic check guy near me and was wondering how far these have been bored out? I like the idea of a 365cid motor, but it is going into such a light car that the extra inches really don't matter too much to my son and I. What bore would you recommend for piston availability and cost? We will be using triple five 354 heads. This is going to be a mild build for street rod type use. Thanks for your help. John and Henry
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on: Mon 09 of Mar, 2015 [17:57 UTC] reads: 26839

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70Chal392
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Re: '55 301 typical bore?
on: Mon 16 of Mar, 2015 [16:43 UTC] score: 0.00
UPDATE:
Tossed the 301 block into the trunk of the Camry for a Seattle trip (3 hours away). DG Machine in Auburn said they might work me in for a sonic check on Thursday or Friday
great guys, they did. A good block overall. Lowest reading was .175". About 4 other low readings in the .180 to .185 range. Most readings were near .220". By slightly shifting the bores away from the low readings, it will be plenty strong, for our street rod-style build. For less that 30 cubes, it would be foolish to try for a 331 bore (.1825" over bore from 3.63"). After reviewing all the readings, I would say that these blocks are NOT under-bored 331 castings, though very similar to '55 331s in nearly all respects, except for the big cast in "W" on the sides and another one on the valley pan flange.

.030 over = 5.0L Hemi





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George
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Re: Re: '55 301 typical bore?
on: Mon 30 of Mar, 2015 [15:29 UTC] score: 0.00
After reviewing all the readings, I would say that these blocks are NOT under-bored 331 castings, though very similar to '55 331s in nearly all respects, except for the big cast in "W" on the sides and another one on the valley pan flange.
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Makes sence where they have a separate casting numbers. The "W" seems to show up randomly on blocks

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hemipwr202
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Re: '55 301 typical bore?
on: Tue 10 of Mar, 2015 [23:47 UTC] score: 0.00
> I wouldn't go anymore then it takes to clean the cylinders up. A good street cam and a 4bl-don't over carberate. You will have a very powerful/dependable motor. Keep compression 9 to 1 to 10 to 1.

Don't tthink you would be able take a 301 out safely enough to get to a 365.


Todd

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70Chal392
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Re: Re: '55 301 typical bore?
on: Wed 11 of Mar, 2015 [03:57 UTC] score: 0.00
> > I wouldn't go anymore then it takes to clean the cylinders up. A good street cam and a 4bl-don't over carberate. You will have a very powerful/dependable motor. Keep compression 9 to 1 to 10 to 1.
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> Don't tthink you would be able take a 301 out safely enough to get to a 365.
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> Todd

Thanks for your reply Todd. Good advice...street rodding is often "all about the look" and hemis have that in spades....hmmm Hemi 5.O

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George
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Re: '55 301 typical bore?
on: Tue 10 of Mar, 2015 [15:07 UTC] score: 0.00
The "555" heads are '55 331. Havn't seen any reliable info on weather the cyl walls were adjusted in for the smaller bore or if it's just an underbored 331. I'd recommend a minimum overbore if no sonic check is available instead of going nuts with the boring bar.

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70Chal392
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Re: Re: '55 301 typical bore?
on: Wed 11 of Mar, 2015 [04:03 UTC] score: 0.00
> The "555" heads are '55 331. Havn't seen any reliable info on weather the cyl walls were adjusted in for the smaller bore or if it's just an underbored 331. I'd recommend a minimum overbore if no sonic check is available instead of going nuts with the boring bar.

Thank you for your reply George... and the correction on the heads.

Can't imagine them adjusting the casting for the 301...I thought boring to 331 at least would be easier to come up with "off the shelf" pistons.

Crazy to think I could get away without a cu$tom pi$ton order.

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George
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Re: Re: Re: '55 301 typical bore?
on: Wed 11 of Mar, 2015 [15:00 UTC] score: 0.00
> Can't imagine them adjusting the casting for the 301...I thought boring to 331 at least would be easier to come up with "off the shelf" pistons.
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> Crazy to think I could get away without a cu$tom pi$ton order.

You never know with Mopar, they added mounting ears to the one year only '56 270 Poly block for instance! I see the attraction to installing 331 std pistons, but...the advertised C/R is 8.5:1 for the '55 331, a number of hemis when actually measured have come out with a lower C/R, in some cases close to a full point low. Could be 8.5 but might be as low as 7.6......


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