So, it was running OK with the old bearings but you put new bearings in and now they are burning up?  If that is the case, I would be suspicious of the new bearings; maybe try a different bearing manufacturer?

Ryan, welcome to the forum and sorry to hear about the trouble.  If your engine ran fairly rough with the original cam, it could be that it was a fairly aggressive cam and required a spring load that is too high for proper break in of the new cam and lifters.  Can you give us some details on what your springs look like?  For example, are there two round coils in each spring, or one round coil and one flat coil, or something like that?

Best way is to take one of the springs off and have it checked at a machine shop to see what pressure it provides.  It is not hard to remove springs while the heads are on the engine, just a little tedious.  It does require a spring compressor tool for on-engine work, and after removing the spring you will have to reinstall the retainer and keepers, and measure the installed height of the spring.  The shop will use that to measure the pressure at the installed height.

The problem also could be as simple as you got a bad set of lifters that weren't heat treated properly, seen that before.  Beware of ebay specials.  You can also get a set of cam and lifters that have been previously broken in; Oregon Cam Grinding comes to mind; I think they offer that service.

In any case, whoever you used the first time for the cam and lifters, try someone else.  There have been big changes in ownership of the large aftermarket manufacturing companies that supply cams, lifters, and everything else related to high performance, and it is no longer guaranteed that these companies will provide a good quality product.  Good luck on the repair!

I got a valve job and bowl cleanup done on one chamber in order to get flow numbers, and I was pleasantly surprised by the results.  Especially the exhaust port did better than I thought it would.  I had tweaked the stock design just a little bit, and it seems to have made a significant difference.  Still not as good as my SE heads, but better than a lot of FE exhaust ports that I've seen:



After getting the head back from the shop I checked the chamber volume, and this was also a surprise, it was much lower than I expected at 55 cc!  I will have to make a modification to the chamber machining program to get a little more volume.  The upside there is that it can only help the flow.  Pictures of the chamber and the port cleanup under the valve are below.  Please excuse the yellow grease in the chamber and near the valves; that is left over from cc'ing the chamber:

All tunnel port intakes have the port widened at the pushrod tube.  My intake adapters do that also.  Jon Kaase says that the tunnel port is the only head that actually picks up flow with the intake attached.  Haven't flowed one myself, but I respect Kaase's opinion.

Flow numbers and valve details for the exhaust side of the SE head are shown in the link below:

https://fepower.net/simplemachinesforum/index.php?topic=7336.0

Also, no reason that the tunnel ports I'm making wouldn't flow in the 360 cfm range with some porting.  But my info for stock tunnel port heads is that they flow around 330 cfm, and that is what I'd expect mine to do. 

Hi Jay

Some Questions:

What valve sizes will be used ?

With the SE exh port, you mentioned about a 250 cfm flow rate, Question: Is that as cast or will they need to be ported ? And if that flow rate is as cast, about how much more if ported ?

Also, with the SE exh port design, what if any decrease in shock tower clearance would there be in say a Mustang or Cougar, not that there's that much to begin with.


And I read where you said the Tunnel Port valve spacing will be used, thinking out loud, bore dia min would be 4.230". Also, the wider rocker stands will be required.

You can use any valve size up to 2.300" on the intake and 1.75" on the exhaust, based on the valve seat sizes that I'm using.    Common valve sizes are 2.25" on the intake and 1.75" on the exhaust.

The SE exhaust port flows 250 cfm with just a good, 5 angle valve job and a cleanup under the bowl.  No porting or enlarging of the port is required.  I haven't ported a set so I don't know what they are capable of, but that is enough flow on the exhaust to support 900 HP, which is quite a bit more than the intake port can support. 

Shock tower clearance would be the same as for any FE head.

Reducing the valve sizes would allow you to go to a smaller bore size than a stock 427, but the chamber is designed for a 4.25" bore so you would have some overhang at the top of the cylinder if you went smaller than that for bore size.

That's an excellent torque number, reflecting the IR intake.  Certainly more power and torque would have been available with a jet change, but I think HP would have been limited by the size of the carbs.  Those 48 IDAs just don't flow enough air to get much past 600 HP.  I wish that 58 IDAs would be more readily available, they would make a big difference.