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Half filled hard block 400 sbc cooling issues

23K views 29 replies 18 participants last post by  stock z/28 
#1 ·
Has anyone done a half fill on their 400 small block and ran it on the street? Any cooling problems? Har far did you fill it with hard block?
 
#3 ·
I did it before I had the block bored and decked, filled right to the bottom of the freeze plug. No cooling problems because the heat is generated in the head (Dart Pro 1 Aluminum) and upper portion of the cylinder. Run 185-190, got it to 200 once at a cruise. Use a 4 core Desert Cooler and a 2200 cfm electric Flexlite fan:yes:
 
#4 ·
As Mike said, I have filled quite a few that saw some limited street use, not a "normal" everyday type of car, and I have not seen any significant issues.


I would think the oil temps would increase and the piston and/or cyl temps would increase as well, so I would possibly keep that in mind in regard to application and tuning, if it were me.




Good luck

Jeff
 
#18 ·
Hi Ron,


Just on a side note Ron, I have no doubt that oil absorbs a lot of heat from valve train components, especially at high rpm.


I "think" I learned a bit about 30 years ago on a Chev truck that I towed my race car with.

It was just a chev 1/2 ton with a 350 block with 400 crank and rods that I had ground the mains on to fit ( common today but kind of unique back then). I welded an oil temp fitting in the pan while it was off.

When I started driving the truck as I said I think I learned a lot about what causes the oil temps to go high (atleast on this truck and about every other vehicle I have played with in this regard). Basically it was engine load.

If I just started the truck on say a 30 degree day and let it idle untill the water temp was 180 the oil temp would hardly reach 120.

I could drive it around town about all day and the oil would hardly go over 170-190, but if I drove it on the highway at 60-70 mph the oil temp would hit 240. If I was towing on the highway it would run about 260-280.


I guess Im rambling but my point is that in my opinion the oil is basically carrying the heat from the engine bearings (and to some degree the pistons) and they (again in my opinion) generate a lot more heat when a load is applied.


I suppose to some degree the valve train sees a higher temp under these conditions, but my preception is the load on the bearings.


Im probably way off base on this, but the highest oil temps I generally see on street vehicles is when towing or a similar relatively low rpm high load situation. Oil temps get high but the coolant temps stay constant
 
#10 ·
Half Filled hard block 400 sbc cooling issues?

Hey Now. I have done this for years. The engine runs cooler because the coolant is only going to the Hot part of the block and heads. Heat is generated in the upper portion of your engine, not the lower part. As for oil temps. Mine were cooler, by 22 degrees at gage reading. Note that engine oil also helps cool your engine. Also this does help strenghthing the area around the main webs. Engine temps 190 with 180 thermostat. Ambient temps. 110 to 118. This also includes city and country driving, with auto trans. Fill to the bottom of the freeze/welch plugs an the side of the block. Note I run a destroked 400 = 377 ci. Respectfully, "Bill's" II
 
#15 ·
filling a block



Filling a block is when you use a concrete like substance fill, that you pour into the water jacket of your motor.
The idea is to strengthen your block from the inside.
One of the main benefits is to control bore flexing.
Most people do two different types of fill.
1. Street fill-you fill up to the bottom of the lower freeze plugs.
2. Race fill- you fill to the bottom of your water pump holes.
All fills should be done "Before" you do your machine work.
Just a short version, I'm sure someone out there can explain it better than me.
Hope this helps. Mike

Remembers guys,it's our responsibility to teach.
 
#19 ·
Maybe so. Not the case in my race fill. Oil temps increased 65 degrees. Same 25 min. cruise same everything else expect block filler. It has all ready been stated the motor becomes one heck of a heat sink once hot, great for the cold days a the track not so great for a True Street Eventt:(
 
#16 · (Edited)
The vast majority of the ones I do are to within about 3/8 of an inch from the water pump opening.


I generally use Hard Block, but there is an epoxy that I like a lot better.

As far as the oil temp goes, I can only say that on all of the engines that I have filled that have an oil temp gage there has been a marked increase in the oil temp after a pass.

Most of these engines are bracket type motors and these guys pay very close attention to the oil temp for consistency sake. A few actually epoxy heaters to the bottom of the pan to aid bringing the oil to temp if the weather is fairly cool.


One f the other drawbacks is that it seems to be harder to cool the motor between rounds with a filled block. Most use an electric water pump and fan and it does seem like the filler holds a lot of heat and takes a while to cool it.


As far as it "shrinking" goes, I have seen a couple of cracked blocks that I filled start to seep in the crack after a season or two. Sealer stopped the seep fairly easy but it makes me wonder if the filler stays "expanded" as well as I would hope.



Jeff
 
#20 ·
Which epoxy and is what is the procedure?
Mike
Mike, cant tell you the actual name or brand of epoxy because the labels are removed from the containers when I get it.

As far as procedure goes I mix it with a drill and a stirring device (its a 2 part system) untill its blended and pour it in.

I have used shavings off of my head/block mills to add to it at times.


I like it real well, but its expensive compared to Hard Block.


If I was "guessing" its a Devcon product but I dont think they want liability for the product in this application, and thats why the supplier removes the labels, and he may not wanting me to go direct to the source. Either way I get it in two "plain" containers.


I "think" there is a Super Stock racer selling a similar if not better product than this now. I will see if I can find some info on that.


Jeff
 
#27 ·
I helped put togother a .060 over 400.The block was filled to the bottom of the water pump holes.Steam holes used the in the heads.It's a mild motor 10.5:1 compression,.450 lift cam and 882 heads.It's a 71 nova.

In the summer time we ran the motor without a thermostat.If you did run one it seemed to runner hotter than I felt comfortable with.In the winter time I stuck a 160 t-stat in it and the thing runs fine...
 
#25 ·
Hate to bring this back from the dead but what is the benefit of adding the shavings?

Also how much power do you guys think a high nickle content 4 bolt main Block could handle if filled to the freeze plugs? Not the internals just the block itself.

Thanks guys,
Kevin
 
#26 ·
The reason I added the shavings was to try and equal the density/consistency of the actual cast iron, but it was probably pointless.

I have never really seen a "high" nickle content 4 bolt block (with a couple possible exceptions) so I have no idea what power you could get by with.


I never really look at it like that.
 
#28 · (Edited)
I'm wondering about the expansion /contraction differences between all the fill methods. Is there a way to do the short fill without having to re-size the cylinders? I have an .060 over 4 bolt block in my circle track racer and the pistons are already fitted. I'd like to try the epoxy but not if it distorts the bore after curing. I would think you'd bolt a block plate on during filling/curing?

Harblok says their product neither expands nor contracts.
Hardblok also claims Epoxy curing agent is corrosive and other concrete based products shed gypsum which can damage water pumps.
http://www.hardblok.com/m/HardBlok_flyer.pdf

I've also heard of a product called EPIREZ Heavy Duty Polymeric Backing Grout (5137)

and EMBECO 885 which Darin Morgan recommends.

Any comments or input on this?
 
#29 ·
Wouldn't the filler prevent the lower half of the cylinder from expaning from heat? I would think once the engine got hot, the upper part of the cylinder would expand but the lower half wouldn't due to the filler, which in turn would create an ever so slight "cone shape" for the piston to run in. Maybe its such a slight amout it wouldn't matter?
 
#30 ·
I would not disagree with you on this, as a matter of fact in my opinion in about all engines the cyl wall will expand differently at actual operating/load temps and distort differently from both the load and temp change.

I think if you experiment a bit with the combination you may get better ring seal at load with a cyl that is not necessarily "straight" at room temp/no load.

Paul, I think Hard Block used to say that their product would not distort a cyl..

I have filled previously finished blocks with it and after about a week of curing a hone of about .001" or less will usually remove most distortion that may/or may not have been caused due to the filling. I would not sweat using it like that.

I generally bolt a couple of old (resurfaced) heads on the block and let it set for about a week.
 
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