Restarting My '70 Nova Project

BravoXray · Oct 4, 2024

Well, the engine is out, again. Hopefully the last time.

I worked on Wednesday and Thursday getting everything disconnected, I have it down to a science now. One of the hardest things is getting all the cable ties cut off the wiring harnesses, I use a lot of them to keep things neat and away from hot or moving things.
I had Brian stop on his way home from work and help me get the hood off again. He couldn't believe the block was cracked and that I had to pull the engine again.
Pulled it out, got the trans off and hung it on the engine stand. Then, I methodically started removing parts, laying them out on tables, carts and benches. I pulled out the lifters and put them in a piece of 2X4 with holes drilled in it to keep them in the correct positions on the cam lobes. All the lifters and the cam lobes look good, so it was properly broken in. I got it down to where all that is left is to remove the rod/piston assemblies and the crankshaft. I will also remove the dowel pins that locate the bellhousing, because I'll have to go through the process of dialing in the crankshaft/input shaft runout on the new block.
Then there's just a lot of cleaning up, inspecting parts, checking for wear and measuring the pistons so the block can be bored to the correct dimensions. Thankfully, I have a big commercial size parts washer which helps a lot when doing a job like this.
Then, I just have to wait to get the new block.

BleedingOrange · Oct 5, 2024

You.re a very patient and organized man ! Now that the block is out, have you had a real good look at the crack in the block, and any idea why it might have happened ?

BravoXray · Oct 5, 2024

BleedingOrange said:
You.re a very patient and organized man ! Now that the block is out, have you had a real good look at the crack in the block, and any idea why it might have happened ?

I have no idea why it cracked there. When I talked to the tech at the speed shop, he said those blocks were known to have cracking prblems now that they're getting to be over 40 years old, but it is unusual for one to crack there. I do know that when I got the block and removed those two drain plugs, they were really tight, I nearly stripped the heads getting them out. The drain cocks I put in when I reassembled it weren't nearly as tight, and I put thread sealant on them just in case.
It may have been beginning to crack when I got it, but the crack didn't propagate until the engine was run and went through several heat cycles. I know that for the first hour or so it was run, there was no water leak or I would have noticed it. It really didn't show up there until after I changed the heads.
'Tis a mystery.
I'm going to finish the disassembly this afternoon and start cleaning up and inspecting everything.
I went on Summit Racing's site last evening and found all the parts I need to put it back together, and put them in my shopping cart, so I can order them when I will soon have the block.

BravoXray · Oct 7, 2024

I have gotten most all the parts cleaned up and inspected, so far everything looks good, with no surprises.
One thing I did notice on the block was that every cylinder shows that the rings were losing seal at the top of the bore due to distortion from the head bolts. Every cylinder shows the same pattern. Strange thing is that the block was bored and finished honed with a torque plate in place, so I would have thought that would eliminate that effect. Guess not though.

BravoXray · Oct 8, 2024

Regarding the block distortion, I did some searching and found a thread on Hotrodders forum that discusses this issue, and the torque values recommended by ARP for the studs. After reading the thread, I remember that the torque ARP recommended was 80 ft lbs, not 70. I now remember that at the time I thought that was an awful lot of torque when the recommended torque with factory bolts was 60 ft lbs. Considering that the bolts are coarse threads and the studs have fine threads for the nuts, that an awful lot of additional stress on the block.

https://www.hotrodders.com/threads/arp-head-stud-torque-in-stock-sbc-block.191049/

#4 · Jan 20, 2011
If you torque them to 80, the next time you take the heads off, you will see quarter-sized wear marks at the top of the cylinder next to every stud, caused by the deflection. That is too much torque! Studs and 60-65 is fine, even with ARP lube. We torque 15:1 sprint car engines at 60 with studs, ARP lube, and aluminum blocks. The only one we go 65 is the one right in the center.

#6 · Jan 20, 2011
I should add that I did the exact same thing you did-saw 80 in the ARP booklet-only I didn't question it like you did. Wish I would have. I don't know why they say to use more torque than the stock GM torque settings, when their lube is slipperier than oil, which is what GM (I believe) based their settings off of. Maybe because the threads are fine, not course, at the top of the studs. When I did 80#- it was on a 400 block, and the same stud kit as you have-and you could clearly see the wear spot next to every stud on every cylinder the next time I had the heads off. 65 & oil, or 60 with ARP lube is more than adequate on a sbc.

BravoXray · Oct 8, 2024

This afternoon, I decided to put the barber pole stripe on the driveshaft like I had mentioned a while back. I pulled it out of the car, and after a few tries at using string and masking tape wrapped around it to lay the stripe out, I ended up used a piece of masking paper cut 5" wide wrapped around the shaft. That worked much better. I do have a couple of spots where the paper stuck to the black paint and the paper wasn't tight against the shaft, but I can touch those places up pretty easily tomorrow. After all, it's going to be under the car, not out in plain view, so it doesn't have to be perfect.

BleedingOrange · Oct 9, 2024

Interesting info on the arp bolt torque specs. What does the barber pole painting accomplish ?

MossRoad · Oct 9, 2024

It's open for business.

BravoXray · Oct 9, 2024

BleedingOrange said:
Interesting info on the arp bolt torque specs. What does the barber pole painting accomplish ?

Nothing, I just always wanted to paint a driveshaft like that.

MossRoad · Oct 10, 2024

A long time ago they started putting these on the spinners in jet airliners... the idea is you don't drive the baggage cart or walk in front of the engine until you can see this spinner stripe. If you can't see it, the engine is running and can suck you in from a pretty far distance.