[marks73ta]

I found this motor and went and put money down on it. I go to get it on Monday. It was built sometime early '61 and placed in a '58 Pontiac that was raced with a three speed. It comes with the 504306 '61 Super Duty heads, early bolt pattern manual bell housing and full clutch. It was a '59 block but they used a '60 front timing cover to get the water pump/cover that did not connect to the front of the heads. I didn't get the engie code either but again I get it on Monday. If the builder was racing it I'm hoping to find a 4 bolt block and maybe, if I'm really lucky, SD internals. Like forged crank and pistons. Not sure when the good SD rods came out but I think it was after this time???? I'll know more Monday as I tear it down. Mark L

[Safari Larry]

Great find. I think you mean 540306 heads.

Caution, the '59 block is a "reverse flow" block, not the same as a '60 "conventional flow" block. I don't know this for sure but I suspect the engine will have over heating problems in the rear cylinders. That's because the conventional flow block water passages force more water to the rear cylinders than a '59 reverse flow block would. See this link and scroll down to "Engine Differences in Reverse Flow and Conventional Flow" where it compares a 56 block deck (same as 59) with a 60 block deck.

[Txbobcat]

It sounds like a good find

[Steve Barcak]

Keep us posted Mark

[marks73ta]

Thanks Larry for the FYI. Plus it's interesting that you mention it because the motor was run/used as it is for quite a while. No idea if the original builder is anywhere around. Maybe the guy I'm getting it from has more info. You may be right. It will be interesting to have the '59 block and my '73 400 block side by side and really look hard at the differences. I'm sure if it really presents as a problem it can be fixed with plugging and redrilling the deck water holes etc. Or even tapping in a water exit at the back of the block to even out the water exiting. But that is way down the road for me at this point. I'm more excited to see what's inside this thing. I've got everthing (I won't go into detail, LOL) in me/on me crossed for good luck. Hoping to find those elusive rare parts. We'll know tomorrow. Mark L

[65nss4spdGTO]

Mark,

Let me know about the heads. My dad tells me that the "306" heads showed up on some 59 389 engines for guys that were connected.

Calvin Hill
Hill Performance
708-250-7420

[mechanickeith]

Well,,,I had a blast today.Went for a ride, helped tear down a motor & got fed twice!!!

Thanks Mark!!!!!

[Jack Gifford]

However... you ain't sharing any part numbers with us?

[marks73ta]

Calvin, although this doesn't prove anything, your Dad may be right?? Jack I just took a while to write up the reply.
Tom. They appear to be totally untouched. I got the motor home today and dismantled it. Heres some pics. Thanks to Keith Collier for helping to tear it down and take pics along the way.











We found the block to be a 4 bolt '59 casting. Got excited as we pulled the first rod/piston and we discovered it had the good Super Duty rods but with pressed pins and cast pistons. Then pulled the rest of the rods/pistons. Then we hoped to find a forged crank but it turned out to be cast. Plus it was showing some repaired damage and normal performance work. Something had broken (rod?) and banged up a counterweight that had been ground to clean up the damage. Some extra weight for balancing was welded in the original drilled balancing holes. And the crank is .010/.010. Took a lunch break all excited about the heads, the four bolt mains, and the good rods. Then when we returned to do more work Keith goes, Oh OH. He was looking at one of the other rod/piston assemblies that we removed after finding the good SD rod, and we discovered that the rest of the rods were a hodge podge collection of the older less desirable rubber rods. So it turned out that we had only one good SD rod. Then Keith (damn you Keith) points at the number 7 cylinder and says, "sleeved". Sure enough. Although the pistons showed an .020 over bore, number seven was sleeved. So whatever broke must have done that damage too. The engine was equiped with solid lifters and cam. But there are no telling stampings or marks denoting what the cam is. You can see I got a nice set of Cal Custom rocker covers too.

Mark L

[Safari Larry]

Great pics Mark, good view of the pinned studs! Interesting engine. Got a pic of front of engine?

#7 sleeved, that's the rear most cylinder. Could it be that there was inadequate cooling in the rear of engine that caused the piston to disintegrate? I would be suspicious of the "conventional cooling" used for the "reverse cooling" block. Did you find any modification of cooling ports between block deck and heads?

I can't quite make out the last number on the head date code. Looks like it may be "9" which would indicate 1959. The head 540 casting # prefix would be inconsistent with Pontiac part number prefix 540 first used in 1961 (See this link). If the heads are '59 then I have to wonder why did they convert the engine to conventional cooling. If the heads are '61 then the distributing tubes used for reverse cooling may not fit in the heads which would be reason to convert to conventional cooling.

[mechanickeith]

As Marks picture shows,,He has a matched set of 306 heads. Both have date code of A171. They have tall 7/16 studs that are drilled & pinned. They have the old style double nut adjuster locks on them. Chambers have been opened up around the intake valve to un shroud them. The block is a 4 bolt main with the chamfer on the deck at the intake area. Yes,,,number 7 has been sleeved but it looks like it was a quality repair. From looking, it has a lot of run time on it but still in pretty decent shape for the year. As stated, cam is unknown at this time. The numbers have been ground off of it. I guess the odds were one in eight on pulling out the only SD rod on the first shot. Got it out & were pretty excited to see all the correct markings. After lunch we kept going & then I went to get more pictures & found that the rest of the rods didnt look like SD rods. Some had a faint GM on them & some had no mark at all. Pistons have L2085 stamped on top with .020 Motor had the old style oil pump with the floating pickup. Timing chain set looks like the old Tempest 4 cyl motor chain. All in all, was a great day!! Mark has a great set old school 306 SD heads with a 4 bolt main block to boot!!!

[mechanickeith]

Larry,,,here is a better view of the head date code. Both are A171. Also, here is a shot of the front of the motor before everything was pulled off. I saw nothing on block or heads that looked like modifications to the cooling system. L2085 piston

[Safari Larry]

More great pics Keith. You guys are having TOO MUCH FUN! 59 block, 60 front cover, 61 heads, an interesting combination. Mark got some good and relatively rare parts, including the 306 heads, 4-bolt main block, valve covers and bell housing (bolts up to 1955-60 engines).

Was there much wear or problems in the cylinders?

[marks73ta]

I'm so thankfull that Keith there to help in the tear down taking the pics. He got some great shots. I'm terrible at doing a tear down and taking pics.
I just looked close at the bores and I can feel a slight ridge but I can't catch a finger nail or a wire pic tool (O-ring removal tool) on anything. I'm sure I could reuse it the way it is if I had to. The sleeved bore may have been done after the engine had been bored .020 and then hurt because I feel no evedence of a ridge there. Although the difference in the steel liner versus the cast iron cylinder material could account for less wear.
This is the stamped front block numbers on the upper passenger side.



859P
1764

Then down next to the water pump where later blocks have the vin number.

C023319

Just in case anyone knows the '59 engine codes. I haven't been able to find it in any of my books yet.

This is a shot of the one good rod that was in the motor.



According to McCarthy's book the real well centered and very distinct raised GM on the shank denotes the SD rod. The other rubber rods are very indistinct and or missing all together. Also, on the SD rod, the side shank forging lines are roughly ground and almost haphazardly cleaned up where the rubber rods have a much cleaner and possibly narrower forging line.
The block shows evidence that it has never decked. The factory bore to piston tolerence markings (C,B, and D) still show under various cylinders.

Well anyway. I do have one SD rod to my name, heh.

Mark L

[tom s]

Larry,although they are 61 heads they have a 55-60 water pattern!A real bastard head.Tom

[PRC]

It is my understanding that the '61 SD engines used reverse cooling even though all other Pontiacs used conventional cooling starting in '60. You can see the water inlets on the front of these heads for the reverse cooling. The question is; why did the engine builder plug these inlets and use a later water pump? It seems he would have been better to use the 55-59 waterpump and retain the reverse cooling. Larry's theory is probably correct for the reason for the damage to cyliner 7.

[PRC]

What type of intake manifold is on that engine? I can see it is cast iron. I use an aluminum '61 SD tri-power intake on my '59 block and heads.

[Safari Larry]

Originally Posted by tom s

Larry,although they are 61 heads they have a 55-60 water pattern!A real bastard head.Tom

That's what I suspected Tom, assuming we are referring to the interface between the head and block. On the head top side, 61 water interface to intake manifold is different so intakes don't interchange between 60 & earlier heads and 61 & later heads. 59 and earlier heads used (needed?) the water distributing tubes in the heads for reverse cooling. The 1957-59 water distributing tubes will fit in 60 heads allowing head interchange between 60 and earlier years. I don't know if the water distributing tubes will fit in 61 heads. If they do not, then 61 heads would not be appropriate for an engine set up for reverse cooling.

[Safari Larry]

Originally Posted by PRC

What type of intake manifold is on that engine? I can see it is cast iron. I use an aluminum '61 SD tri-power intake on my '59 block and heads.

Interesting I thought the water interface between intake and heads were different. I've heard some after-market manifolds were set up for interfacing with either 60 & earlier or 61 & later but I didn't think the Pontiac manifolds interchanged. But this wouldn't be the first time I was wrong!

[Bill Eveland]

Any pics of the front of the block when you got the 60 cover cover off to show what was done to use that on a 59 block? I thought the reverse cooling holes had to be changed to standard but didn't really see how to do it.