What do you guys think about a sbc 400 60 over runing on the street. Flat top pistons and a mild cam. Think I would have a lot of over heating problems. I can get a deal on this just built motor..
It's a deal because it's lifespan will likely be quite short. Buy 5 oil filters now, and I bet you will still have one or two left when you are pulling the motor back out of the car.
There is a good reason you're getting a 'deal' on it. Think about that. Even a std. bore 400 sbc is not a good choice for a reliable daily driver. They're just too unforgiving in even the slightest of warm weather. I've owned many of them over the years and I've never had one that didn't overheat on me at least once and put me in a bind. You just can't trust em. They're great for drag racing if you're after maximum cubic inch, but I wouldn't recommend one for anything other than that type of application. Edit: many machine shops won't even bore one .060.
Not enough info to tell if this is a deal. First, what year block? GM updated the number of coolant holes in the deck surface during the 400's span of years. All headgaskets have the extra holes. Most builders that know would update an early block with these as part of the build. As to being .060 over, some blocks can go there safely, but most will not. the only way to tell is to have sonic checked the bores before boring.
Thanks guys ...The motor is sitting in a machine shop. All machine work done, block crank and pistons, flex plate and balancer. Externally balanced with the sheet. Motor is a 511 cast code 70-80 motor 4 bolt main 3 freeze plugs with the steam holes for $1800. He also has a 40 over motor all machine work done bare block for $600.
I'd p***, 4bolt main and 60 over is just not good. Now as to the comment that a standard bore 400 is prone to overheating I just have to say.....My grandmother had a 71 impala with a 400 and air in south east Mo., she drove that thing for many years without a cooling issue.
I've had 400 small blocks out here in the desert of Southern California, where it regularly stays over 100 degrees for weeks and weeks, and I have never had one overheat due to the design. I've ran them as thin as .040 over and never had a lick of trouble. They're great engines, and I laugh when I hear all the caution that people have about the 400 small block. The blocks are siamesed, and if you do a couple of tricks to the deck, run the right head gasket, and drill the steam holes in the heads, they work great. I have seen m***ive amounts of nitrous go through factory iron 400 blocks and they hang in there just fine. I think .060 is pushing it, though. You could have it sonic checked, but due to the normal core shifting that factory blocks have, I would guess that it would be marginal. It might live for a long time, but then, maybe not. That's a tough call. I used to buy every 400 I could find, and a lot of us out here ran 'em back in the day. The 4-bolt blocks (-511) were the weakest, and the 2-bolt blocks (-509 and the -817) were the strongest. An -817 with aftermarket 4-bolt caps was the combination to have if you were running a factory block. Engine building legend Joe Sherman made a living building stout 400 small blocks when everyone was scared to death of building one. He convinced me. Joe would sometimes even use the factory 5.56 rods and spin 'em to 6500!
The keyword there is "grandmother" - I'm sure she probably never gave it hell or pulled a big trailer with it...lol.
All of the 511 code blocks that I've had needed this modification: http://www.chevyhiperformance.com/techarticles/90678_small_block_400_cooling_tricks/
I've been running a 400 in my T bucket with a 2 core radiator out of a mitsubisi truck & never had it run above 210o in traffic, going to the beach in 97o days!! I do run a electric fan & leave it on all the time. But I never heard of anyone running one .060 over! JimV
I ran a 2 bolt 30 over with 5.7 rods for years, it's stiLl runnin. Beat it up and cooked it at the Woodward Cruise once or twice. It would stumble and detonate for a while til I could get some air to it. Get it sonic tested and if it checks out grab IT OR THE 40 OVER. gOOD MOTORS ALL DAY LONG
509 block+.040, 10.2 comp., World Sportsman 200 heads, 700R4, 3.90 gears. Weiand anti-cavitation water pump. Robert Shaw high-flow thermostat. GM hipo pulleys from 370hp-350. New Harrison copper radiator. It dropped 10 degrees when I changed to the Hi-po pulleys. I believe the water pump one is smaller and they have deeper groves. ran 12.90's at the track and drove it almost every day for years.
We ran 400 blocks in our modified(s), 0.030 over. One was .060 over, but it was an early block, 70-71. our machinist would install plugs in the deck holes and mill the block to use the early pistons at zero deck and 5.7 rods on a 350 crank (377). with 461x heads it had 14.5 compression (methanol). No overheat or wall distortion after 3 years of running it at 6800 rpm....we had a 366 for special races......
I ran a 60 over 400 for years in my 66 wagon. Never a problem. Why would you think overbore/thin cylinder walls make for overheating? If anything they would run cooler because the cylinder heat transfer is quicker. Most of the heat in the engine goes through the heads. You can block fill up to the casting plugs without affecting cooling on all the SBC. Just wondering the reasoning.
Thanks, that's the same question I was wondering about. Maybe distortion of the bores due to lack of wall thickness?
if you run iron heads without the steam holes, the top end has insufficient coolant flow below 3000-3500 rpm, where most street rods don't live during normal driving. The temp. guage is usually in the head, or intake so you get the hi temp reading. Many people have made this mistake over the years, & I suspect you have too. The steam hole oversight is the very reason 400's have gotten the bad rap for being overheaters. Some production blocks have gone as far as 4.200 (.075 over with sonic checking. I have an 817 block that is .045 over (4.170) that is over .200 thick on the thrust side, .180+ thick on the non thrust side, and #7 & 8 cyl. have small spots @ 45 degrees in the .150 range, it runs 180-200, in traffic with a small 4 row early Mustang radiator in our 56 Chevy G***er. 400's have also been victims of improper cam selection (given their stroke/rod length) for years, which can real havoc on water temps too. I've seen countless times where some street fodder has built a 400, and used a 30/30 Duntov, or an L79 350HP/327 cam, and complains about performance, mileage, and overheating. Since when is a cam designed for a 3.00 or 3.250 stroke with it own piston speeds/dwell time, the hot ticket for an engine with a 3.750 or larger stroke and its entirely different cam timing needs!? Too many times, cooling problems are also created by the wrong thermostat, no thermostat, the wrong restrictor, pulley ratio, or the wrong radiator, **** even a bad distributor curve can do it! It pisses me off when someone makes a statement like "all 400's are a bad choice for the street". Chevy put em in p***enger cars/trucks for 9 years. A 4.185 bore is not a good idea on any 400 without sonic checking cyl. wall thickness first! Pound for pound a PROPERLY built 400 "street engine will do everything any other small block will and more!
My biggest issue is buying any engine that's at it's maximum bore size. There's just nothing left if for some reason you ever had a requirement to bore it again. It makes it a throw away engine if it ever needs more work. I try to leave something when I build a motor, so I'm not tossing it when it wears out.
No problems with my 509, 406, Dart 200 heads NO STEAM HOLE in heads, runs 185-190 in my OT El Camino. When my machinist told me not to drill the alum heads for steam holes I thought he was nuts, talked to a lot of builders and to Dart all said not a worry on alum heads. Runs great and never over heats, saying all of this I would Sonic check the block for a good nights sleep. I also wanted to add something, if this is a 5.7 rod you may have to buy a reduced base circle cam...adds more cost to Hyd Roller in my case.
Very good point, especially when you are paying said block, instead of it being a freebie. PS. if the engine builder can supply a good sonic check report on the.040 block, that would be the better choice. As expensive as machining blocks has gotten, it would be money well spent to sonic any questionable production block.
Well I went in to buy that 400 40 over this morning and somebody bought both the motors up already I guess he who hesitaes loses out. My loss pissed me off😞 Posted using the Full Custom H.A.M.B. App!
For a street engine probably .110-150, for a race type engine .150+ especially in the thrust areas (12 & 6 o'clock leaning over the fender). Remember that since 400's have siameses cyl.walls at 3 & 9, they ate twice as thick there. A production 350 block, pre '78-'79 @ std. bore, is usually in the .170 range. Dart SHP blocks are advertised as .230 min. @ 4.165 (.040 over 400 bore), these blocks are a great value, and should be seriously considered for anything in the 600HP+ range. Aluminum race blocks only have sleeves in the .125-.150 range, this is shocking to me. A 427 Ford had a standard bore of 4.233, at 4.280 (just .047 over), its common for non thrust areas to be in the .090 range!
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