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I have a 1930 320 cu in 90 HP 8 (according to the engine numbers and owners manual) and want to know the normal operating rpm range so I can find a proper tachometer. I am also looking for the appropriate tach. First time here, anyone else building a Packard speedster? Basing mine on a '28 526 (126 in WB) chassis. Found the '30 straight 8 and 4 speed and installed it. Kept all the wheel base and moved the motor/trans back 18 inches and down 1.5 inches. Moved the steering and crossmembers as required and in the process of building the body bucks for the 2 seater boattail body. The object is to use all period Packard parts (mechanical brakes, stock steering, etc.) as might have been used by a period long distance racer and when its finished drive the hell out of it.
Ron Schuman

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G'day Ron,
to Packardinfo. You're not alone in building a Speedster, have a look at Turbopackman's in the Project Blog Forum:
packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=738&forum=10
There was also a discussion a little while ago with another member who has one.
And another matter, although - Could you please add your Speedster to the Owner Registry together with a pic, any known history and how you acquired it?

Would be helpful to know the tire size and rear axle ratio. Here's some factory data for 1931 with 6.50x19 tires and 4.69 rear axle.

20 mph = 985 rpm
50 mph = 2463 rpm
70 mph = 3448 rpm
90 mph = 4423 rpm.

For the 4.38 rear axle, same tire size:

20 mph = 920 rpm
50 mph = 2302 rpm
70 mph = 3222 rpm
90 mph = 4142 rpm.

By just measuring your tire circumference and knowing the axle ratio you can work out any combination you want. I guess you know that a 5 inch stroke and babbitt bearings aren't conducive to long engine life at much above 2500 rpm or so.

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Found it, there are three posts from Turbo289 on Page 8 of Turbopackman's Project Blog and mentions the Speedster he's building in Nampa Idaho.

I would look for a 5000 rpm tach, which is what I'm also looking for. Something like this would probably be perfect for you, even though it's only 4000 rpm, I don't think you'd ever top it out: Vintage Tach

Thank you,
Looks like it will make for some interesting reading.,
ras

Owen,
Thanks for the info. This Packard stuff is all new to me and thats the kind of info I need to steer this project. If I want to cruise at anything over 50 it looks like I'll need a set of high speed gears.

Thanks Eric,
Looking forward to reading about your speedster project.,
ras

Ron,
for adding your Speedster to the Owner Registry. And thanks also for the history and such, I enjoy these as they make interesting reading.

And I suggest, some here might think I'm pushy but what the heck I can only ask, could you document your Speedster in the Project Blogs Forum? I'm sure it will provide a great resource for others who may wish to do something similar. As well as provide you and us with regular documented updates of progress achieved.

Ron wrote: "...320 cu in 90 HP 8 (according to the engine numbers and owners manual) and want to know the normal operating rpm range..."

Ron,

Good question. I also wonder what maximum sustained rpm is healthy for these engines. I have a 39 320 that seems very unhappy if pushed over what seems like about 2100 - 2200 rpm. These engines make lots of torque. I currently have 4.36 : 1 gearing with overdrive (28% overdrive ratio) for a final drive ratio of 3.14 : 1. With 7.00 - 16 Firestones that are approx. 30 inches tall. The car seems very pleasant at 60 mph. I honestly believe it would pull taller gearing with no trouble at all. I look to drop to 4.09 : 1 rear gears giving a final ratio of 2.94 : 1.

Owen is spot on about the babbited connecting rod bearings being of concern in your engine. As light as your speedster will be, I would gear it to the moon if you want to go over 60 mph for sustained periods.

I would be very curious to hear other opinions from experienced operators of 320 8 cyl. engines on max. sustained rpm.

Your project looks very interesting.

Best of luck,
Jim