Valvetrain advice needed - Impala Tech
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post #1 of 4 (permalink) Old 10-21-2019, 04:19 PM Thread Starter
Join Date: Sep 2019
Posts: 20
Valvetrain advice needed

Hey guys,am currently building a motor for my 66. Have a 350 block, been bored .030 over, just got back from the machine shop(honed, everything checked,cam bearings,polished crank all for $300ish)installed new mains with good oil clearance. Ok what im working with for heads are some good ol camelhumps(461s) with big valves. Want to keep it in the era so dont want to buy better heads as of yet. My question is what should i be looking for in a cam,springs and what not. Want a little choppy idle- power from idle-1500 through say 5500. Also if it matters i have edelbrock 2101 intake,holley 650 carb and dynomax mid length headers. Been around engines since i was little but this is my first build for one of my own cars, and cams have my head spinning.
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post #2 of 4 (permalink) Old 10-22-2019, 12:18 AM
Join Date: Aug 2008
Location: Miamisburg, Oh.
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For what they are, in era, I like the 461's. Used to have a set on my 327.

Anyway, it would help to know your rear end gear ratio - but from what you've provided, I'd look for a cam that has around 212-225 Net Duration at .050 lift. Go for the lowest "gross duration" you can find that meets those Net Duration (.050" lift) specs.
The Comp Cams Thumper *might* fall into this category, or you may need one just under that due to that 5500 cap you have, which is a good cap for those 461 heads in all honesty. (maybe a touch more) You'll be totally happy with that as long as you're not running a pokey 2.73 rear end gear.
For what it is worth - any cam selection you make would be hindered with a 2.73 or 3.08 rear gear in your car.
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post #3 of 4 (permalink) Old 10-22-2019, 08:55 AM Thread Starter
Join Date: Sep 2019
Posts: 20
Thanks for the advice! Heres the thing as i forgot to include in my post. Ill have a rebuilt th350 done by the time i get the motor done(hopfully,depending on my honeydo list) i will be searching at the local junkyard sometime for a new rear end as the character i got this from had put a B.O.P rear end in it with the 5x5 bolt pattern. Im shooting for 3.73 gears if that changes anything. I will be using the car mostly for cruising in rural MN so no big cities,etc.
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post #4 of 4 (permalink) Old 10-22-2019, 11:28 AM
Join Date: Jan 2006
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It isn't a BOP (well it could be as the AAW made rears are all alike) it is a newer rear end. In 1990 GM went to 5 on 5 on all of their big cars. So every corporate ten bolt will be the same from that point forward in time until they dropped rear wheel drive in 2000 when GM introduced the Lumina called an Impala (W-body platform). The bolt pattern is actually 5 x 127 mm. The studs are not half inch fine thread as many think, but metric (12 x 1.5 torqued to 75 ft/lbs).

You need to find a 1965-71 Spicer 12 bolt from out from under a B-body car. Most have already been found and cut down to fit under a Camaro by now (currently; on Team Camaro, there is a user asking others how they cut down their Impala 12 bolt rear ends down to fit the smaller Camaro so you had best start looking soon). From 1972 and up GM stopped buying from Spicer and purchased all of their rear ends from American Axle Works.

Big Dave
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