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400 SBC 509 block bored.030 over.

H

Hez Johnson

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I just cracked open my 400, and noticed it had been bored over .030, and it had small scoring on the cylinder walls. Is the block salvageable? The scoring is very minimal. I can barely feel it with my fingernail. I was going to see if boring it out .010 more will round out the scoring, so any feedback will be nice.

-Jay
 
.040 400s aren't bad. If you had to hone it .010 over stock.

Someone drag guys will run up to .060 overbore but they build heat quick.

Why did you crack open? What's the engines history?
 
The reason I tore apart the engine is because i noticed it has been running pretty bad lately, and i found out it was a bent push rod. Im also building it to be a torque monster. And when i saw the cylinders, I used a caliper dial to measure the bore, and noticed it had been bored .030 over. Then I saw the cylinder scoring. I can barely feel it with my fingernail, but I want to bore it more. That scoring isnt bad. So my question is, being bored .030 over already, will boring it over another .010, to .020 be bad? I have a 4 core radiator and a tranny cooler. Im going to run a cooler thermostat if i run into any heating problems. The block is a 509 casted block. is the block junk?
 
It can be honed to .040
Nothing special about a 509 block. I've read where guys like them but I personally have never noticed anything better or worse from them
 
Hez Johnson said:
Im going to run a cooler thermostat if i run into any heating problems.
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Just as an FYI, the thermostat sets the engines minimum temperature, it has no bearing on maximum engine temp. If an engine overheats due to something like an overbore, the only cure is to push more fluid through it, or move fluid through the engine faster, or suck more heat out of the coolant stream via a more efficient heat exchange through a better radiator/fan setup. Or a combination of all of them.

IMO bore as little as possible...overboring provides so little benefit in terms of power production (especially at the risk of thin walls, increased heat problems, etc), it's at the bottom of my list of mods to do to make power. If you were thinking that way.

Maybe I dealt with a lazy machine shop, but they weren't willing to bore my engine anything other than the obligatory .030" in any case. I either wanted .010 or .020 (can't recall, but there were pistons available) in the thought that I'd rather have thicker cylinder walls for the next rebuild. I suspect its more about setup effort than ability to cut .010" accurately, but I'm not a machinist.
 
Nothing wrong with .040.

At .060 or any type of high dollar build, I would probably spend the extra to have it sonic checked before investing too much money. I know of a few guys that have bored them to .080 and used block fill up to the freeze plugs for race use only and they have held fine. I've also seen guys crack blocks with no overbore so that's why I suggest the sonic test.

If its just a mild/ stock street motor, I probably wouldn't be the least concerned.

I agree with dyeager535 that I try and bore as least as possible; usually .020, .040, .060 so that I or the future owner can get one more rebuild out of the block.

There used to be some shops that would do "remanufacturing" of blocks by putting all new sleeves in each bore and returning back to standard bore. I know that they did some 400's but I don't remember what it looked like with the siamese bores. Supposedly, the sleeved blocks were extremely strong and none of my friends had any issues. Probably not being done much anymore with all the LS motors opening up the supply of core SBC blocks.

As far as heating or cooling problems, I have run 4-5 400 blocks over the last 20 years and while they may run a few degrees hotter over a comparable non-siamesed sbc, it isn't anything to fret about. Regardless of motor size, use the right fan, radiatior, cap, pump, etc and you'll be fine. Seems like most of the guys I knew that had the overheating problems either ran their cooling system from their stock motor or had a heavy load for extended period of time in their old truck that was undermaintained.
 
Punching eight sleeves into a block? I think I would just find another core.

Martin
 
Hez Johnson said:
The reason I tore apart the engine is because i noticed it has been running pretty bad lately, and i found out it was a bent push rod. Im also building it to be a torque monster. And when i saw the cylinders, I used a caliper dial to measure the bore, and noticed it had been bored .030 over. Then I saw the cylinder scoring. I can barely feel it with my fingernail, but I want to bore it more. That scoring isnt bad. So my question is, being bored .030 over already, will boring it over another .010, to .020 be bad? I have a 4 core radiator and a tranny cooler. Im going to run a cooler thermostat if i run into any heating problems. The block is a 509 casted block. is the block junk?
Click to expand...
.

If an engine has heating problems and you install a cooler temp t-stat it will run even hotter. Alot of people don't understand how the cooling system works.
 
My 400 is .040 over and with a big radiator it does just fine so far.

The cooler thermostat won't do anything more. Just put a standard 180* or so.
 
I use to run a built 400sbc . ex drag race motor .

I used a stock 3 core 81-91 tall rad in the truck . I ran shroud / no shroud / mech fan / clutch fan . never had problems with temp . always was 195-200* . unless heavy play time with gas pedal .

and was in a long bed with 1tons 4.10 and 38" swampers with th350 tranny and 205 tcase.
 
Good working cooling system should be fine for anything you are wanting to run the truck. If your worried run a electric fan to assist the clutch fan when the going gets slow..
 
Deuling said:
The only time mine even goes over 180 is when I run in 4hi.

I started running in 4lo more often and she keeps nice and cool.
Click to expand...

Adam. Where do you run your temp sender? Im currious because ive just finished up running some cooling ststem tests on a 406 engine. And was watching temps in various places
 
I am running a 406sbc that is 30 over. It is 10.2:1 with a comp 264hr cam. It has aluminum heads and intake which have had a lot of porting. The engine is blue printed and balanced, crank and rods are forged, crank has been trued and re heat treated, reused hyper pistons since we only had to hone the cylinders this time. It is built as a torque monster. It starts pulling hard at 2,000 rpm and screams to 5,000+ with the roller setup.

I run a 165 thermostat and it runs at 160-185 when the weather is in the 70's and 80's. I run 91 gas and 22 degrees of centrifugal advance at 3,000 rpm with 10 initial, and another 16 for vac. advance. I don't have any pinging issues with only the truck loaded down (79 C20 long bed th400 Gearvendors, 4.10 14bff, 33" rear tires). I haven't towed with it yet.

I would not go back to a 383 or 350 vs. the 406. The torque on a well built 406 is nuts vs. the smaller sbc's. I would not want to bore more than necessary. 400 blocks are getting harder to find. Depending on how much machine work was done on your block, it could get pricey to later have to replace the block and fit the internals to it, vs. being able to bore it again.
 
And I totally agree with a built 406 vs a 383 or 350.

I just did one with out steem holes with angled milled old 350 circle track heads. Gonna try it. Ive read and heard pros and cos and seems it can be done. So far its ran on a run stand and doesn't overheat.

Its .030 over and shoulda gone .040. But its a learning engine. I know how it would have been with stock heads or a closed chamber.
 
I have all autometer electric gauges. I run the temp off the passenger's side head. I ran it off the intake before and I had the factory gauge off the driver's head.

The worked over edelbrock heads on my 406 DO have steam holes. The previous build on this 406 did run warmer, but it wasn't hot, and it had a lot of details that needed fixed. I ran the 383 with the same heads and intake, but it was before all the porting.
 
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