[Mwieczorek]

So, I have a 1966 421 block with 4 bolt mains. It has been bored to 4.180" (I bought it like this). I did have a friend who is a retired machinist check it with his sonic tester. He laughed and said "you can run it like this, but you can't bore it much more". Fortunately for me the bores are round and straight and there is no ridge. This engine was not together long, previous owner had cast rods in it and spun a rod bearing. It's a shame because he spent some money on block prep. It was line bored, decked, etc... It was running 670 heads with some ancient TRW domed pistons (if anyone knows the specs on a TRW 1765P +060 piston I'm all ears)... Best I can calculate his compression ratio was 12.1:1.

The crank was already cut 0.020" and I can't get 0.030" under bearings, so its out. I do have a 455 crank in my stash. It is stock and would clean up with a 0.010" cut. This is going in a 66 Bonneville with a 3.08:1 limited slip rear end and TH400. It's a heavy car, so I need some low-end torque to get it moving.

Now... I'm not totally broke, so I'm going to spring for a set of "decent" rods. I've been looking at the Summit H beams or the Eagle SIR I beams. Seems like either will do the job with a $100 or so difference in cost. I'm leaning towards the H beams because they use a floating pin...

Pistons... What to do here? Pickings look pretty slim anymore. It's the KB Hypereutectic slugs for around $600, or DSS or Icon forged... That decision partly depends on heads. Are the KB Hypereutectic pistons good to go? I'm not planning on using nitrous or a blower or turbo.

Heads... I have several choices. I have a set of 1968 15 casting 72cc heads that have been ported and fitted with 2.11/1.77 valves. They have, bronze guides, positive seals, springs that will go to beyond 0.500" lift, etc... They're probably the nicest ones to use. I also have a set of ported 6X-4s with stock 2.11/1.66 valves. Those would also work, they have a set of Spott's high lift springs & retainers so they can handle .500" lift easy.

Here is one thought... The 72CC heads with 30cc dished pistons (with the piston 0.010" in the hole and a 0.030" gasket) would leave me around 9.5:1 static CR. That ought to be safe to run on 93 octane... Or the 6X-4s could be made to work with a little effort and run with flat tops and put me around 9.7:1 (assuming 93cc chambers, 7cc valve reliefs, pistons 0.010" in the hole, 0.030" head gasket). Is there any real disadvantage to running the smaller chamber heads with dished pistons?

Whatever I get for pistons and rods, the whole rotating assembly is going to the machine shop. The crank needs to be cut and I'm going to have it balanced properly. I even have a nice early style harmonic balancer to go to the shop with it. That way I can re-use all my stock accessory drive bits.

The bumpstick... What do y'all recommend? I'd love to go with a hydraulic roller, but given that I'm buying pistons/rods/bearings/gaskets/oil pump/etc... I don't see it in the budget. Has anyone had any luck with Paul Spott's cam kits on ebay? He has a 041 clone or a 068 high lift that caught my eye. I would buy the kit with lifters that he recommends to be safe. I will be using an engine run stand so that I can break in the cam before it goes in the car. That way I can check it for leaks and whatnot too.

What is the best route to go with the rear main seal? I know the rope seals aren't what they used to be. I don't mind springing for a BOP seal. I see they sell a 2 piece, a 1 piece, and a rope seal. What do you guys use? IIRC I have to have the crank seal area cleaned up to run a modern lip seal, but left as-is to run a rope seal.

For induction... I have a complete 1966 Tripower setup so its going in the car. Exhaust will be RARE long branch manifolds and exhaust (again, I already have it so its going in the car).

Thoughts?

[tom s]

I have been using Autotec pistons from Paul K on this site.Tom

[tom s]

Piston

[Baron Von Zeppelin]

You might have to fill in the exhaust crossover ports on the 6X heads to use the 66 intake.
Then rig up a manual choke cable

The 15's might be a better choice and will have the more vintage look .

Today's 93 is equivalent to glory days 100 octane.
Pontiacs with advertised 10.25 CR advised the use of 100 octane (old octane formula) .

[Kenth]

No need for filling the crossover channel using Tri-Power intake on 6X heads.
Just block (or fill) the "dead hole" above the crossover channel.
Then the original choke will be just fine.

[Joe-Touring]

Many say that the KB hypereutectic pistons aren’t the greatest, in the specs for the pistons it states that you need to file the ring gap VERY large. I’ve heard multiple times that you want to go even larger than that. I bought a blown up 455 that had the KB hypers and it popped a crown off one piston. For whatever reason, those pistons require a massive gap

[Joe-Touring]

Posts 47 and 48 in this thread address your dish question:

https://forums.maxperformanceinc.com...=869465&page=3

Sounds like a big dish ends up making the combustion chamber less efficient, forcing you to run more timing advance. And likely making less power.

[Joe-Touring]

I’ve used the BOP 2 piece with success before. After seeing the Best Gasket graphite seal used on the quote below, I think that’ll be my next setup:

Originally Posted by Verdoro 68

After a few days of drips, I pulled the short block apart again. The lip on the two piece was entirely wet so it was clear it was leaking. I'm still not sure exactly what why the Viton seals gave me so much trouble, maybe It was a combo of little things.

As a last ditch effort, I decided to try the graphite seal. I cleaned the seal channel really well before installing and removed the gasket maker from the anti-rotation holes. I used a deep well socket to set it in place and lubed the surface with some motor oil and assembly lube. I put the crank in place with the cap to test the contact between the graphite seal and the crank. The lube on the seal left a witness mark all around the crank which I took as a good sign. Not sure why I didn't think of doing that with the Viton seals.

I learned from my last several attempts that a bead of black Right Stuff over the rear main cap and on the the edges of the pan do the trick to seal the pan back there. I've had it tilted full of oil for about 8 hours now and there's not a drip in sight. Dare I say it, I'm calling the short block done! Hopefully this seal doesn't give me any trouble when I fire it up.

Stopped by the machine shop of Friday. No progress on the the heads, but he assured me he'd have them for me in the next two weeks. Heard that story before

[Mwieczorek]

Originally Posted by Joe-Touring

I’ve used the BOP 2 piece with success before. After seeing the Best Gasket graphite seal used on the quote below, I think that’ll be my next setup:

Looking at the pics, I wonder if his lack of success with the viton seal was caused by the oil grooved on the crank. The grooves are needed to keep the rope seal lubricated, but you do not want them there with an elastomer lip seal, so they need to be polished...

Still, the graphite rope seal looks like a good option!

Matt

[Joe-Touring]

As far as the heads and cam go, 455s with 6X heads and 041 cam is a pretty popular combo. The 9.7:1 compression ratio you mentioned would be about perfect. Big car with 3.08 gears might be a tad much, I’d guess you’d wanna run Rhoads lifters.

One thing about your 6X heads, sounds like they have OEM valves, generally highly recommended to replace them. Factory valves are 2 piece, with the head welded to the stem. Lot of horror stories about a head popping off and killing an engine.

Seems like you have a good package going together. Here’s a piston option for not much more than the KB hypers:

https://butlerperformance.com/i-2462...tegory:1234832

[Joe-Touring]

Originally Posted by Mwieczorek

Looking at the pics, I wonder if his lack of success with the viton seal was caused by the oil grooved on the crank. The grooves are needed to keep the rope seal lubricated, but you do not want them there with an elastomer lip seal, so they need to be polished...

Still, the graphite rope seal looks like a good option!

Matt

Very possible. Also, depending on your block/cap, the BOP viton seals may require some trimming/fitting. Some people have more success than others.

[Verdoro 68]

Originally Posted by Mwieczorek

Looking at the pics, I wonder if his lack of success with the viton seal was caused by the oil grooved on the crank. The grooves are needed to keep the rope seal lubricated, but you do not want them there with an elastomer lip seal, so they need to be polished...

Still, the graphite rope seal looks like a good option!

Matt

Since that was posted, I had two graphtite seals fail on me. As far as I can tell, it was due to the way I packed them. I've since meticulously installed a one piece BOP - after having the crank serrations polished - and it appears to be holding well. My block has been line honed, so I had to sand down the outer diameter of the BOP to get it to fit correctly. Apparently the serrations on recent cranks are less of an issue, but given the number of times I had this thing apart, I wanted to eliminate any room for error.

Also note that the two piece I installed leaked on the stand during the "tip test" which isn't necessarily a reliable way to measure the installation success because oil can seep past the serrations according to BOP. Regardless, it felt like a gamble to run it if it was leaking on the stand.

Graphtite failure #1: https://forums.maxperformanceinc.com...4&postcount=87

Graphtite failure #2: https://forums.maxperformanceinc.com...&postcount=173

Success (so far) with the BOP one piece: https://forums.maxperformanceinc.com...&postcount=194

Lots of folks have good success with the Graphtite. For whatever reason, I just couldn't get it to work.

My two cents on the pistons - spend the money and get custom ones made so you can get your CR where you want it to be without having the put them in the hole or using a thicker head gasket.