dual valve springs too much for a stock cam?

redwing89

redwing89

Club Member
i was taking a closer look at the valve springs on the heads that i got from my most recently purchased 302... its an 87 engine with stock e7's. i knew these heads looked unusually clean on the inside under the valve covers. but now im figuring out that these heads have what looks to be dual valve springs. you can see one spring coiled inside of the other on the valves. so these heads must have had some work put into them... my question is. since im running a stock cam on the engine they will be going on. will the seat pressure be too much for a stock cam with dual valve springs? its good insurance to know these heads are set up for a bigger camshaft, and i guess its not impossible to install one at this stage of the build...
 
2011-02-22_15-24-25_957(1).jpg.jpg


this is what the head looks like you can see how there's springs on the inside. the heads i pulled off this engine does not have those.
 
redwing89 said:
2011-02-22_15-24-25_957(1).jpg.jpg


this is what the head looks like you can see how there's springs on the inside. the heads i pulled off this engine does not have those.
Click to expand...

What really matters is the spring weight. You need to have the pressure checked by an engine shop to determine what you have. Then you can make the decision of whether or not there is too much pressure. My 2 cents...........
 
well the engine i pulled these heads off of has a presumable stock cam. but thats just from looking at the timing chain and gears. the timing chain has a considerable amount of slack in it... i wonder if that could be from running a set of heads like this with too much spring pressure? im taking them to a machinist at BMI tomorrow and see if he can do that kind of check with the heads off of the engine.
 
those look like actual springs to me. usually a damper is a "flat" coil spring.... if you get that. as long as the spring has enough clearence and doesnt coil bind, and has a good amount of seat pressure, there shouldnt be a problem should there? it seams like a higher seat pressure would be good, keeps the vlaves from floating. i am asking a question myself.
 
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i did a little research on it... the main debate about it is lost torque due to more stress on the crank having to push up valves with more spring pressure... but others say that's not true due to roller valve trains having less friction properties, and dual valve springs DO help prevent valve floating.
 
its not a flat tappet. this is an 89 roller motor. it has roller lifters and a hydraulic roller camshaft. it also has crane cams 1.7 roller rockers
 
You can never have too much pressure if the rest of the valvetrain can mechanically support it. I would have one of the valve springs tested so you can see how much pressure you really have. You can't really tell by looking at it.
 
yeah i dropped the heads off to our local machinist. he said it would be too much stress for a stock FLAT TAPPET cam, but he says it should be no problem with a roller motor.
 
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