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In many cases because the springs are matched to the cam and valve float isn`t supposed to occur until at a given RPM, isn`t always the case. Weight plays a role, as does spring frequency and of course, how much abuse do the springs have on them. I would snatch the valve covers and do some comparing and get the width of the spring and compare it what Crane recommends to see if there even in the ball park. Some guys try to shave a few bucks and use flat tappet springs on a roller cam and it don`t work, they have to be roller cam springs. If you find the springs are smaller in diameter than what is recommended, the heads will have to be removed and the spring pockets enlarged.
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The heads are Dart Pro1, so I think they are ready for 1.55" springs already. Crane only recommends a 1.46, so I'm hoping that I'm okay there.
THe guy that put them together for me does sprint car heads normally -I just assumed (wrongly I guess) that he could street heads no problem. I will pull a valve cover and do some checking. I don't even remember seeing that they were double springs or not - but I don't think they are. That might explain a bunch. Anyone have any preferences on valve springs for a street motor? |
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So here's the problem; Crane does not have a spring that will work for me. I called them to no avail.
I took a spring out last night, and found out that they are indeed just single springs with dampers. 1.46" O.D., 1.80" installed height, but that's pretty much all I know. The spring tester we had at work is now missing. Crane tech support said I needed 125 lbs on the seat, and around 390-400 open pressure at 1.200 height with my 1.6 rockers. The only spring I can find to do this is a TFS-31400414 dual spring. Its specs match up nicely, but my problem is the inner spring inner diameter. It is stated to be .720" for that spring. When I measured my retainers, they are .750" dia. for the small area. Here's my question: Will that .030" interference hurt anything? Or do I have to buy new retainers to go with the springs? Any help would be much appreciated! |
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reworked spring pockets
I have seen water leaks when the spring pockets are reworked THe chevy expert in our shop always checked casting numgers berore doing and head work
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A buddy a work told me i should just plan on new retainers - the trick flow retainers are .69" on the ID for the inner spring, which is .720, so that should work. Just didn't want to spend the extra $46 but I guess that's how it goes. Thought about confronting the head builder are letting him know whats going on, but not sure how he'd receive it either. I gave him the cam card when he built them, so there should not have been a question of what spring the cam required. |
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Common sense would lend me to think you'd take the spring to the person that installed the springs and have them check them out.
Myself, I have never hear a noise on an engine that floated the valves unless it was the piston hitting the valve. IN addition, a cam that needs a spring with 115 on the seat and 300 some odd lbs open likely isn't make too much power at 6500 RPM anyway. I'd suspect it's quite a ways past peak power. Trying to rev, or wanting to rev, to 7500 RPM with those spring specs is almost silly. If I were going to spend the money on new valve springs, given what I know works time and again on the dyno, I'd upgrade to a beehive style spring and retainer, upgrading to titanium for the retainer. |
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