I am in the process of putting a new cam into my 68 302-4V engine. The engine was rebuilt in 1975 when it had 75,000 miles and it now has 100,000 miles. Looking down into the intake passages I can see a lot of carbon build up on top of the valves rising up the stems. So I am taking the heads off to remove the intakes and clean. Straight forward enough.

The question brought up is since these heads do not have hardened seats, and the heads are off, this seems like the time to have it done. At 25,000 miles since it was done do I really need to do anymore than that. The springs and retainers were set up for a higher lift cam at the time. The guides have only 25,000 miles so are they an issue. Can say that this car will be lucky to see another 25,000 miles in the next 25 years.

 

I'd check all the cylinders psi and see where your at first. If the cylinders are ok then I'd just take them apart, clean them up and put it back together. Make sure you buy a good quality intake gasket and retorque it a few times. A leaking intake gasket will crud up the back of the valves quickly.

 

Ah, that would seem too easy and it turns out it is. Took them to the shop yesterday and went back with the old time machinist to take them apart. Went to the two that had some oil contamination and found both valve guides worn. Back in 1974 they knurled heads and in the long run not the best thing to do back that was all there was.

Long story short the heads will have bronze guides put in along with powered metal exhaust seats and finally a valve job replacing only the valves needed. Springs and retainers are good to go with the new cam.

 

Make sure you tell him you want him to make sure all the valve tip heights are equal, within .005" When you start putting in a few seats and few valves in it's time consuming to make them all come out right and have the right spring height on each spring.

 

Turns out all the guides need to be done. A couple of the guides have the tips broken off from using a dull tool back in 1974. The exhaust seats have been really mucked up which would force the machinist to use a different size hard seat. I don't know what the guy was doing but those seats look like crap. There was port work on the pocket to smooth things out. All in all the machinist told me it would hit $900 to put them back into top condition. Less for satisfactory condition. At which point both him and I saw the answer. New aftermarket heads with everything done from larger valves to better flow.

 

That's taking the bull by the horns. Good decision!

 

A update on my cylinder heads. I purchased Eagle Iron or Iron Eagle, who cares, from Dart. Really nice work to be sure. After wrestling with getting them on and getting the headers back on I noticed something. The bolt holes for the alternator and power steering pump are 9/16" f*^$%ng big. Antone see a problem with that considering Ford used 7/16 for the alternator and 3/8 for the power steering pump. My wife said I shouldn't get angry. She is Filipina where they just take it, Thais wear a cool heart on the sleeve and an Irish/American like me let's all hell break loose and then some. Needless to say there are going to be repercussions over this if Dart doesn't have a good solution. Since they came from Summit they are on the hook for the return. Dart is on the hook for a new web site "Sbf Ford heads from Dart suck".

 

Did you consider a helicoil?

 

Well if Dart pays for it then I am all ears.

 

Solution after talking to Dart, Summit and the local speed shop. They are called thermactor plugs in two different sizes to get down from 5/8-11 to 7/16 and 3/8.

 

Cool. So you don't have to pull the heads back off?

 

No I don't although I gave the guy a small piece of my mind. Told him that they have a nice 2 page PDF that list what gaskets to use, what head bolts to use, what torque values you should use and a few other things. So why isn't this thermactor plug listed as a needed item for early 289/302? He knew what I was talking about.