Anyone have experience with block filler particularly in street driven 400 small blocks? I am currently doing a build up and want to maximize combustion sealing by using Hard Blok water jacket filler and gapless rings. I would use the recommended short fill for street driven vehicles which is just a partial fill prior to having the machine work done. My experience with the current 400 I am running is, with a Stewart high flow water pump and a 190 degree thermostat, I never see temps above 195. I think with the Hard Blok and a good oil cooler, I'd be fine. My concerns are I don't know how good block filler is in regards to long term street use. Will it eventually break down? Will it shift? Can it handle repeated cooling/heating cycles over a number of years?

 

im not sure about how long/well it will stand up, but a couple years ago, before i put a 400 in my camaro, i had been looking around doing alot of research, and found someone that had done that..

he had to install a alum radiator to keep it cool, but once he did, it stayed at the thermostat temp anytime he was moving at all, and didnt get that hot even when idling for a long time. but the stock one made it overheat on him...

 

from what i understand, you should only fill a street driven engine with block filler to the bottom of the freeze plugs so that cooling isn't an issue

 

Thanks guys. I'm hearing the same thing. Good cooling with a short fill will work fine on the street.

 

Is your block bad? If so...find another one.

I think that block filler is a bad idea, except on a track only engine...

Maximize the combustion sealing with quality head studs/bolts and head gaskets...if it doesn't leak through the gasket, it can't get into the water jackets. The block won't "bow" under pressure if that is what you mean.

Is your block bored .040 or less over stock? Then you should be fine.

 

what the hell are you talking about? how did you get the idea his block was bad? why do you think it's a bad idea? block filler on a street engine is more common than you may think.

 

There is nothing wrong with my block. I am at .030" over. Before doing the finish hone, line boring, decking, etc., I am entertaining the prospect of using block filler to stiffen the bore. I will be running right at 10.5:1 compression and plan to run her hard from time to time. I have no doubts about Hard Blok's ability to do the job as far as stiffening the block. I am mildly concerned about being able to keep it cool and I am very concerned about it's ability to handle hundreds....maybe thousands of cooling/heating cycles over the years.

 

It will work on the street. Keep it below the freeze plugs as mentioned. Adds a good bit of weight though.

It's crappy to work with, make sure you don't thin it out to much when using it, it takes forever to set.

If it's worth the peace of mind for your setup, go for it.

Cooling isn't effected much at all.

Make sure your steam holes are good, and make sure the head gaskets have 'em too ( you'd be surprised how many times I've seen this happen ).

Use a replacement alum radiator, a good water pump, and with an electric fan setup you'll be fine.

HTH and good luck, you're gonna love that 400...

 

Having a bad block is the only reason I can think of why someone would actually WANT to fill your cooling passages and reduce your cooling capacity.

Is the term "street-driven" being used in a loose way here? I think of it as a daily driver, not occasionally for ten miles at a crack.


I have some news for you...having a 10.5 to 1 compression 400 and longevity does not require block hardener...

I have personally seen 2 examples of performance 406's that have lasted over 100,000 miles with 10.5 to 1 and 11 to 1 compression.

If you are running NA, then this is a moot point....are you going to be running a 300 HP shot of nitrous? Or a SC application? Then I would consider it...but the advantages of a fully functional cooling system would make the idea of block filler a bad deal.

As for running it hard...is there any other way to run it?

 

first off, street driven is being used in the "daily driver back and forth to work in traffic" sense

secondly, block filler reduces your coolant capacity, but not your ability to cool your engine. besides almost eliminating bore flex (which has just as much to do with the length of bore is as it does the bore's thickness) and giving an engine less vibration, better ring seal, and more power, it also provides a temperature advantage. Most heat in the engine comes from the top inch or so of the bore, so as long as you've got a good water pump and a good radiator to keep coolant temp around 170, the block filler insulates the bottom of the engine so that it's easier to get oil temp up to 210 or so, so both would be at or very near their optimal temperatures, which is good for a small amount of hp by itself...

 

.

 

This is great theory...but reality is different.

There are a few points here.

1. Why not fill the cooling jackets completely? How little coolant DO you need to cool the engine? Why not not rely on just cooling the heads and intake? Because maybe you will do some great damage to your engine by overheating it....

2. So the top of the piston only ends at the top inch of the bore? and when the combustion process happens, thus forcing the piston down into the bore further than the top inch, what happens then? Heat must not go into the block around the whole bore, because heat rises, right?


"the block filler insulates the bottom of the engine so that it's easier to get oil temp up to 210 or so"

3. What, so engine oil doesn't also carry heat throughout the engine as it lubricates? Isn't that why there are oil coolers? and also, have you ever seen where oil circulates in the block? How about the main galley where the lifters sit? How about insulating that?

If you are running serious compression and/or HP in a stock block in a track application and want the added stability, then great.

So wesilva, what is your intended application?

 

forget it, believe what you want, we all know the books on engine design and horsepower are wrong...

 

Those books refer to wringing every last ounce of power from a track engine where 1/10's of a second matter...and some of them are pretty outdated...

I prefer real life here and today block filler just isn't necessary for this application above.

Do you have it in your 350? If it works for every street engine, I woudl be curious to know your response...

 

I've used block filler on more than once occasion. Several of these engines were primarily street driven with alot of drag race action on the weekends.

None of them had any cooling problems.

Now do I think it's needed on a 400 that's pushing less than 500 HP naturally aspirated? No...but of course, I'm not the one spending my hard earned money to build the engine, so it's not my call.

Will it hurt using the block filler if you use it correctly? NO...

Do you really need it on a primarily street / strip engine? No...but if it buys you some peace of mind, go for it.


HTH

 

To ctandc:

I agree wholeheartedly...I might consider using it if I was trying to wring 600 HP out of a stock 400 block...but I have seen also 500+ HP 400 combos in magazines where they don't use it...

In the end...I would focus my HP savings elsewhere...

 

Insurance is basically what I'm after. I intend to drive the car mostly on the street but I will make a some sustained high rpm runs from time to time. The car will see some very limited strip time, several test & tune dates at the local road race course and an attempt at the Silver State Classic in '04. Thanks for all your input!