Anyone know where I can get a core plug for a 1.260" diameter hole? Will a 1.250" core plug work? I want a permanent solution, I don't want to just put a 1.250" core plug in the hole and have it held in place with sealant.
I just need to plug the hole for the road draft tube on the top of the block behind the intake, so I am open to other ideas about how to plug this hole.

 

Do you have a draft tube you'd be willing to sacrifice?

Many moon ago I had to have a PCV kit installed on the '57 when we moved to California. It included a cap that bolted to the block like the draft tube did, with a PCV hose nipple on it.

Another possibility would be to take a 1/8" piece of plate, cut it round so it covers the hole, drill a hole in the middle of the plate, slab some silicone on the top surface of the block and bolt the plate down.

 

Since it's just a crankcase vent tube, pick up an expandable rubber plug and stick it in the hole. It's not like it's a pressurized gallery such as oil or coolant.

Something like this



http://www.poolproducts.com/SPP/prod...9SP0003&FNM=92

 

I wish I had the vent tube, but I don't think the engine ever had one, since it started life as a marine engine. It was one in a pair, mine used to be reverse rotation.

I'll try the your suggestion first, maybe with a 1-3/8" or 1-5/16" hole saw, then it will already have a hole in the middle.

Stephen, I almost think that at max engine temp that the rubber might start to get soft and smell. But that plug does cost less than a third of what a hole saw costs.

 

Operating temperature of the engine is around 180*. I doubt the plug would be harmed at that temperature. Most rubber can survive 400*. Your transmission oil gets hotter than anything the engine can produce (except the exhaust) and there's lots of rubber seals in the transmission.

Your rear main seal should be made of rubber. There's rubber in the water pump etc. Sure they all dry out eventually but it takes a long time.

 

I think I might use a 195* t-stat in this engine, I have an Afco double pass 31x19 radiator, and a team-g water pump. I would think that since the back of the enigine is not cooled, it would be closer to oil temp, maybe 220-230.

But when you say it like that, it seems stupid for me to think rubber might not last.

 

The plug is to plug a hole for crankcase ventilation. It's not in direct contact with coolant or oil pressure and gets oil spray thrown at it from the lifter valley. It's only going to get as hot as the metal of the intake.

 

Yes, I know this, which is why I think it would see 220-230*, since there is no coolant in the back of the intake or that part of the block, just oil.

A rubber plug (in this situation) kinda sounds like something that belongs in this thread: https://www.thirdgen.org/forums/body...tto-thing.html

 

Coolant goes around the hot spots of the engine such as the cylinder walls and the heads. The crankcase vent hole is nowhere near a hot spot. Since it's at the back of the block, nobody will see it anyway.

If your oil reaches 230*, you've got more serious issues.

 

I know it isn't a hot spot, but it also doesn't see any coolant, but I just try to be a little cautious to help avoid any future issues.

Do you guys know if stock windage tray main bolts will work with an aftermarket windage tray? My engine has stock windage tray bolts, but the windage tray was taken off the engine and stayed with the boat.

 

I was hesitant to recommend one of those freeze plug repair plugs because I wasn't sure the rubber would be compatible with oil.

 

See if your local parts supplier has a 32mm frost plug.

 

I went to Napa today, no 32mm freeze plug. The only one I could find online was on ebay, in a 10-pack. I'll order those up.

 

I have a 327 in my 89rs and a 1.250 core plug works fine. It's been in there for 3 years and no leaks. I have done this on 2 327s and a 283.

 

I don't think that a 1.25" core plug would have worked for me. I measured one when I went to Napa to see if they had a 32mm plug, and the OD of a 1.25" plug was under 1.26".
Anyways, I already ordered 10 32mm plugs (I could only find them in a 10 pack), and I'll post up my results.

 

Just an update: I received the 32 mm plugs last week, (or maybe earlier this week?) maybe I'll find time to install it next week.

 

or just keep the road draft, and use the sexy early 60s corvette valve covers

 

I currently have the engine all sealed up, I'm waiting to install the core plug untill I have more reason to unwrap it.

 

As promised, I will provide a conclusion: A 32mm freeze plug works perfectly!