RyaNCSU1

Looking at purchasing a set of Doug Herbert heads. 2.02 intake 1.60 exhaust. They say they will clear hte pistons but I want to make sure they will. Stock bottom end on an 87 5.0. Planning on running a cam with .510 - .550 lift tops. Havent decided yet.

I thought I had seen somewhere that only the TFS heads will clear a stock bottom using 2.02 valves.

mjr46

most likely you'll run in to issues in the brow area, you'll need to verify ptv for sure

RyaNCSU1

One feature that is good and bad in these heads is that they are 64cc chambers. Not great for compression but should give me more room for the valves? Guess I may stick to the smaller range in the cam as well to help with the clearance, maybe .520's somewhere.

mjr46

chamber size has nothing to do with ptv clearance, nor does cam lift, it's all about cam timing

RyaNCSU1

Would think having the larger chamber size would recess the valve that much more into the head? No? Im obviously just learning. By your statement I could even have the heads milled down to 60cc to help the comp. and have no impact on the vtp?

Maybe I will go that route and just go with a less aggressive cam with very little cam advance.

mjr46

milling head will up compression, mill it to much and intake alignment issues will result, you want assurance, a custom cam can be designed to work with a stock bottom end and 2.02 valves

redemption

just get some playdoh putthe heads on with 2 rods in. crank it over 3 times slowing makng sure there is no binding, then take off heads and measure gap between playdoh were valve compressed, im trying to remeber. i think tis .090' and above you want

w8less

clay it up and check for yourself. every motor is different so even if it did clear on someone elses doesnt mean it will work for yours

RyaNCSU1

thanks