[84GT-306]

I pulled some junkyard GT40Ps off a 98 Explorer last weekend for my 84 GT. The truck had 140,000 miles and everything seemed to be in pretty decent shape. I'm gonna take them to the machine shop to have them cleaned up and checked out before putting them on. I was also going to upgrade the valve springs. Does anyone have any good reccomendations for new springs that won't kill my wallet? Its for a carbed, non-roller 306 with a stock intake manifold and a aftermarket cam. I'm not sure what the specs on the cam are, but its nothing crazy. Fairly lopey, but nothing extreme. Its also got a 3" single exhaust with no cats. I'm planning on adding some shorty headers soon as well.

Also, I thought about having them mill off about a tenth to bump up my compression a bit. Is this a good idea or no? I don't wanna cause any clearance issues or anything.

I was planning on going with MSD Street Fire multi-angle plug wires to help with the clearance problem. Anyone have any experience with these?

Thanks a lot everyone.

 

[69fastback]

The valve springs depend on the cam specs. The proper way of doing it, would be to contact the cam manufacturer, and have them recommend a spring for the camshaft.

Don't forget to measure for correct pushrod length, after you put the new heads on. I can almost gaurantee they'll be different, and correct valvetrain geometry is crucial for performance, and longevity.

 

[84GT-306]

I definitely plan on measuring for pushrod length. If fact, I just ordered the tool for it and have been reading up on exactly how to measure them. I'd hate to leave any performance on the table because of pushrods...

I know it sounds stupid, but I don't know anything about the cam, other than the brand. The guy I bought the engine from put it all together for his project, then ran out of money and sold everything. I asked him about the lift and duration and all when I bought it and he told me, but that was nearly a year ago and I can't remember. I've tried getting ahold of him to find out, but I don't have his number or email anymore. I deleted all of that stuff like an idiot soon after I got the thing running. I've been kicking myself in the ass for that ever since...

Could I measure lift and try to approximate duration when I measure for pushrod length? Couldn't I just measure how far the spring compresses from when the valve is closed to when it's all the way open, then kinda try to measure how many degrees I've turned the crank while the valve has been open? Forgive me if I sound dumb. I know my way around an engine pretty well, but there is still a lot for me to learn...

 

[fogged306]

You can get an idea of what you have if you use a dial indicator and a degree wheel and measure lift and duration, but an easier way to do it would be to just pull the timing gear and get the part number off the face of the cam. So far that I've seen every cam has it's part number on the front of it. Get that and then do what fastback said. They can tell you what spring will work the best in your application. Getting valvetrain geometry right on pedestal heads kind of sucks but certainly possible. Get a shim kit if you haven't already done so.

 

[holset35]

I have ford racing springs on my p heads and they work very well with my xcam 542 lift