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Discussion Starter #1
I have found specs on the original camshaft in my 66 283. I have verified the lift of the cam and casting number that I have the original camshaft. My question is that the chart I found has a duration with ramps and one without ramps. So my best gues is with ramps = advertised duration and without would be duration at .05” lift. Any insight would be appreciated. I want to look for a new cam that is as close to the original as possible
 

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Discussion Starter #3 (Edited)
INCLUDING RAMPS
INTAKE
open 32.5 BTC
closes 87.5 ABC
duration 300
EXHAUST
opens 74.5 BBC
closes 45.5 ATC
duration 300

EXCLUDING RAMPS
INTAKE
open 12.5 BTC
closes 57.5 ABC
duration 250
EXHAUST
opens 54.5 BBC
closes 15.5 ATC
duration 250

Lift for both intake and exhaust @ valve is
0.3987
 

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Discussion Starter #5
Todays cams all have an adverstised duration and a @0.05 duration and i am trying to relate that some how to the original cam so i can get one as close as possible to the original. The original has a 78* overlap and 114* speration because these short stroke motor had to use exhaust scavaging to help get the flow through the engine so they had long low lift durations with large overlaps
My engine needs to be bored but also since i have a cast crank im replacing with a forge 327 crank making it a 311 adding vortec 062 heads and milling to 62 cc to up compression the vortecs like low lift cams so the original cam works great with this combo. According to everything i can find this cam is the same used in the 250hp and 275hp 327 and hp seems to be based on what heads, intake, carb and exhaust manifold are on it along with compression ratio
 

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Todays cams all have an adverstised duration and a @0.05 duration and i am trying to relate that some how to the original cam so i can get one as close as possible to the original. The original has a 78* overlap and 114* speration because these short stroke motor had to use exhaust scavaging to help get the flow through the engine so they had long low lift durations with large overlaps
My engine needs to be bored but also since i have a cast crank im replacing with a forge 327 crank making it a 311 adding vortec 062 heads and milling to 62 cc to up compression the vortecs like low lift cams so the original cam works great with this combo. According to everything i can find this cam is the same used in the 250hp and 275hp 327 and hp seems to be based on what heads, intake, carb and exhaust manifold are on it along with compression ratio
It's going to be a "small bore 327" so why not install an L79 cam? Looks like the compression ratio should be around 10.5-1 with the small chambers, depending on dome volume.

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=110
 

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Unless you can find a direct replacement type cam you're going to have a hard time finding a new cam that uses the old "ramp" technology. New cams are designed so much better. If you want a stock type 283 cam I'd just be concerned more about it's intended usage / RPM range / vacuum / lift / etc.

Having said all that I run the old solid cams
 

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Discussion Starter #9
first its a overbored 307, chevy created the 307 to replace the 283 as the new chevy base model engine in 1968. A 307 is created when using a 283 bore block (3.875) with a 327 stroke crank (3.25) add 0.030 to the bore you get a 311, second there is such a thing as to much cam, the L79 had much higher compression than i will have. I am looking at 9.5 -10:1 whereas the L79 had 11:1 also larger cams made for larger engine usually dont work the same way on a smaller engine, also lift is to high for 062 vortec heads unless i have extra machine work done to the heads. With stock vortec heads a long duration, low to medium lift cam is my best bet
 

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Like mentioned earlier....call Chris at Straub technologies. He’s done a hand full of custom solid rollers and hydraulic roller cams for me. You won’t be disappointed....
 
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