516 heads cooling trouble

[tdaver]

Hi folks,

Sorry for the long post, but I am looking for some help here with a long-standing problem.

I have a 1966 440ci block.  This was the first year the block was made and it came stock with 516 heads for this first year only.  I had the block bored 0.30" over and have stock pistons and rings.  Compression is 9.5:1.  I had larger exhaust valves installed in the heads with hardened seats.  For nearly two years, this car has been plagued by overheating.  I have one of the longest running threads on MoparChat regarding overheating

http://www.moparchat.com/forums/showthread.php?t=104288

and the bottom line is that it still overheats.  Going down the road on a hot day, it can stay at about 190F but if I stop at all, it overheats quickly to boiling if I don't shut down.  If you read the posts above you will see I have tried "everything" from radiators (aluminum cross flow), shrouds, fans (flex and clutch), thermostats (low and high flow), timing (19 at idle, 34 full advance), A/F mixture, cracked heads, bad valves, leaky heads gasket.  I have also had a lot of helpful people look at it.  I just overheats.

Today, I took the engine apart.  No signs that this engine was built too tight.  After 2000 miles, the cylinder walls still show the honing marks.  No blocked cooling passages.

I believe the problem is that the 516 heads are a poor match for this block.

Photos of the head gasket on the heads and on the block are below.  There are three cooling passages between the cylinders that do not line up with those in the block.  The only connection is by a very narrow slit in the thin head gasket which gives nearly no flow.  Furthermore, the two lower cooling passages in the block do not even exist in this head.

Nearly all later heads and aftermarket heads used these lower passages and/or better overlap between the upper passages.  I also learned from 440 Source (nice pictures), and the Big Block B/RB Engine Book that the later blocks had these upper passages opened to a "figure 8" shape to increase cooling.

I am about to  have the deck blocked and invest in Edelbrock Performer RPM heads which will not only help my power output but also use these cooling passages.  Before I do this, can anyone else out there tell me they are successfully using this head/block combo or have had similar trouble.  Thanks very much for taking the time to read this post and reply!

[Chryco Psycho]

I have run many engines with that head & block combo & limited coooling with no issues , the problem is elsewhere , si the vacuum advance connected to Ported Not manifold vacuum , is the engine running lean , is the fan on backwards , do you have enough inmitial timing , usually 12-16* , make sure the timing doesn`t overadvance at 2500rpm + though