valve spring pressure

55caddyguy

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Hi guys, I am thinking of going with the cadco ss250t cam in my 1960 390. I don't know what the spects are for the cam but think they are .486 lift with .274 duration, 112 lobe centre. What valve spring pressure would be required? I figured stock valves would be fine, but was told to bring pressure up to 95# (closed pressure) by a friend. Stock is 60#closed and 155# open. What are the options? Thanks, George. :screwy:
 

55caddyguy

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I will ask he cam guy. I know it has to be matched to the cam to prevent engine failure,resonance, or premature engine wear. I was checking to see if someone had some experience with these for selection. No one wants to be steered down the wrong path. G
 

EZ

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I also bought the Cadco SS250T cam for my 429. I got it from ebay from a guy that bought all the stuff to rebuild his 429 and then decided to go a different route. I saved a bundle!!! ANyway........I had some questions about the correct push rod length and valve springs so I e-mailed Chris at Cadco. Here's his response................

Curtis
New OE length pushrods are $70.
The Stage I springs are around 95 Lbs., and the Stage II are around 120 Lbs.
(on the seat). Stage I should be fine if you'll never be over 5000 RPM. Both of these are a single spring with a dampener. Dual springs are for big cams and high RPMs.

The Cadillac guides are part of the head casting. There isn't a Cadillac specific replacement guide, because they are not generally replaced (because they don't generally wear out). Most people just put the knurled bronze guide liners in if they are worn, instead of replacing the whole guide. A Chevy guide will fit (though you may have to trim it for length). Also, the 'right' guide has to match your machine shop's tools - the guides we use wouldn't do you any good unless your machine shop happens to use the same brand and style of tooling that we use.

When you are checking the spring installed height, turn the checker mic down to .520" shorter (valve lift + VS. seal thickness + ~.005" for safety) and make sure the spring retainer doesn't hit the top of the guide. If it does, cut it down. Not generally an issue with that cam, but close enough it is worth checking.

Chris
Cad Company
Home of the worlds fastest Cadillac
505-823-9340
8333 Jefferson St NE
Albuquerque, NM, 87113

www.cad500parts.com
Web Specials: www.cad500parts.com/specials.htm
Tech: www.cad500parts.com/tech.htm


Hope this helps!!!
 

55caddyguy

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Thanks Curtis, it all helps. I ordered the ss250 cam for the 390 motor from cadco and the spring kit for it. A bit pricey but at least it's a matched set. Thanks for the input. George.
 
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G-681266

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whatever you do make sure you put some type OF a ZDDP additive and keep the valve spring pressures under a 100# at the seat or it will wipe the lobe.
 
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