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Dr. Greenthumb
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My ol' man has a 306 with TRW pistons, and TFS heads. I had a extra set of AFR 185's. So I said I'd let him try them. To see if they would work any better for him than the TFS heads. Not having a pushrod length checker on hand we used the best guess stock pushrods. They worked, but I could tell the valves werent opening all the way. My brother had this setup before. My dad got the shortblock, and I got the heads. He brought us the correct pushrods(Same he used in it). The problem is now he has a PTV clearance issue. My bro said he had to shim every other rocker. Im assuming theyre stock replacement forged pistons ,and the relief isnt big enough for the 2.02's on the intake. I would just stick the stockers back in, but theres an issue with the rockers coming off. Whats the correct way to resolve this issue ? If shimming is what needs done, how do you know how much, and how do you do it ? Thanks in advance. I never had any issues like this before.
 

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Either get a piston with more valve relief in it or try and find someone that can fly cut your TRW's or go back to the previous set up. You can't correct PTV clearance issues with shimming the rocker.JMO!
 

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Dr. Greenthumb
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Discussion Starter #3
Thats what Ive been trying to figure out. I know you can adjust your lifter preload that way. I've always used shit that works together. So Im even more clueless on this than I am normally. lol I've heard of it on the pedistal mount stuff, but not on adjustable rockers. Thanks for the reply man. Anyone else ?
 

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JShelton's post is right on the money. The pistons are the component that needs modified for the additional PTV clearances. Jacking with the valvetrain geometry will only lead to more problems /headaches.
 

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My ol' man has a 306 with TRW pistons, and TFS heads. I had a extra set of AFR 185's. So I said I'd let him try them. To see if they would work any better for him than the TFS heads. Not having a pushrod length checker on hand we used the best guess stock pushrods. They worked, but I could tell the valves werent opening all the way. My brother had this setup before. My dad got the shortblock, and I got the heads. He brought us the correct pushrods(Same he used in it). The problem is now he has a PTV clearance issue. My bro said he had to shim every other rocker. Im assuming theyre stock replacement forged pistons ,and the relief isnt big enough for the 2.02's on the intake. I would just stick the stockers back in, but theres an issue with the rockers coming off. Whats the correct way to resolve this issue ? If shimming is what needs done, how do you know how much, and how do you do it ? Thanks in advance. I never had any issues like this before.
Two seperate issues. Correct the PTV clearance last. Make sure you are at full lift when you check the PTV. You should get the rocker issue done first. You want to shim until the rocker is giving you a nice even mark on the tip of the valve in the middle. Use a black marker to achieve this. You need a checker spring (cheap from your speed shop) in place of your springs.and one of the adjustable push rods to do this while you shim. Send the adj push rod out to get the correct set, or measure and call your shop if they have them in stock at that lenght. Once you get that done check PTV and go from there.

Also, what is your PTV clearence?
 
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