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Discussion Starter #1
Hi, Wondering if anyone offhand know's what the specs are for factory BBC L29 valve springs. Look to be a beehive design with no dampner and were designed for a roller lifter however I have a new set here and was wondering if they would be fine for a 5000 rpm 0.515 lift (CB XM 262H 12) flat tappet engine? Thanks!
 

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I would measure the installed height on your head then take a spring over to your local machine shop and have them measure it at the height and at max lift. 85 to 100 pounds on the seat and 250 to 280 at max lift should be about right.
 

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Yeah! I would do that if I had retainers but if they are good enough springs I will buy retainers and if not, I won't. Not a very common top spring diameter and perhaps OEM is the only retainers that fit without machining. I will check on Thursday at work, I thought I checked and did not see valve spring specs but I will check "Mithchell on Demand" again and if that doesn't work check with a rebuilder. Thanks for pointing out the "right way" but just trying to find out if what is here is worth further investment! thanks!! :welcome:
 

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mine floated at about 5000 rpm. I switched to the zz502 springs with adjustable valvetrain and it went to 5800 before float. Then I changed heads to Edelbrock performer TBI with larger valves with DelWest TI retainers and Comp 914 springs, but still using factory type hydraulic roller lifters and it got to 6300 before float.
 

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I see, no retainers. Yes, you need a retainer to get the installed height right.

Slow ride, when you say yours "floated at about 5000", are you referring to a set of those L29 beehive's? And if so, what size cam did you use with them? And do you still have the beehive retainers?
 

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Not trying to change the subject but how did the l29 heads work for you? This is going to be a 489 CID MkIV with L29 heads, 10/1 cr, roller rockers, gear drive, Head and Main studs turning a 2.68 ratio on an airboat prop. Hopefully I can accomplish everything I need to do at 1500-4000 RPM, Thanks, and if you do have those retainers laying around??
 

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The heads were all done making usable power by 5500 on my 454, even with the bigger cam and good intake. They should make good torque on you larger engine at low RPM, just be careful about detonation they don't need much timing. Mine ran best with only 30 degrees total.

I don't have any of the stock valvetrains parts anymore. The stockers were standard valvesprings not beehives. Maybe they changed later on, but my '97 didn't have them.
 
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