I went to go look at a 400 Pontiac engine that was on the local Craiglist....something seemed odd. The guy sent me the casting number and it was a 509 block SBC400 and head casting #'s were for a '70-'71 400 chevy. The guy swears it is a Pontiac and it was in his '71 Chevy truck. He pulled it out because he wanted a 350 Chevy in his chevy truck. I look at it and sure enough...a 2 bolt 400 sbc 509 2 freezeplug per side motor. Oilpan to Holley carb/manifold combo....he wanted $400 for it and it was running when he pulled it 1 month ago. Antifreeze in the block looked clean and green, oil was black and thin. I'm wondering if this little jewel maybe the way to go with a 6-71? Anybody running a blown 406 chevy? Way back when, I remember guys having cooling issues with these motors but if memory serves me it was mostly due to not having put steam holes in the head or wrong headgaskets when they got rid of the junk heads for those hot 2.02 setups everyone was wanting. I was doing some research and I guess the 2 bolt motor is the more desirable and this casting number seems to be one of the better ones. Seems to be as many fans of the biggest sbc as there are for the nay-sayers Any info on these motors would be appreciated...good, bad or personal experience
I LOVE 400's! When people go from 6 cyl to 8 cyl, they up the capacity of the cooling system. But noone does this when going from a 350 to a 400. Hence the bad rap. More cubes/power=more heat.
Awsome bang for the buck for sure! Pulled a staight 6 out of a 64' malibu wagon and slapped in the 400. Big power, zero cooling issues. My favorite G.M. power plant...
The 2-bolt block is desired so it can be machined for splayed 4-bolt caps. The factory 4-bolt blocks are said to be weaker and can crack in the main webs. I say get it and run it. You can be sure it is a SBC vs Pontiac by checking two easy methods: 1. Pontiac has the intake raised above the valley, on SBC the intake is also the valley pan. 2. Pontiac has the water pump that bolts onto the front cover, whereas the SBC water pump bolts onto the face of the block.
I had a 400 small block in a 78 Monte Carlo...with 2:29 gears it would rip the tires to shreds from a stand still. Amazing torque and overall power. Wish I still had that car!
I'm sure it is a SBC, over the phone I was tring to find out what it was and this joker didn't understand anything....I asked if he was going to change the intake would he have to pull the distributor (SBC) or would the manifold come off without yanking the dizzy (Pontiac).....he said he ain't changing the manifold.?????
I'll second what 383 said.. I've been looking at a 400 also and so I talked to the next door machine shop guy about it. you can run any heads on it, but unless you are racing he suggests that you drill the steam holes in whatever head you use. 400 heads of course will have the steam holes. He also said the webs on 4-bolt mains are actually a thinner casting and therefore turning a 2-bolt main to 4-bolt is better for ultimate strength. He also said if it needs to be machined more that .030 it needs to be sonic checked. There's not as much meat to play with on 400s. The cooling system was also brought up, suggesting I find a big radiator if I go with the 400.
Defiantly go for it, I have a fully built 400 sitting in the corner of my garage and I'm just dying to put it in something, how could you even think of p***ing up a motor that has the weight of a small block but the torque of a big block.
Awesome motors can be made up to a 421 without much problem with 3.875 crank im building a 406 with AFR heads and 6" rods in my 48 chevy pro street i highly recomend them those good factory core motors are getting harder to find! and just remember when doing your heads to just have them drilled for the seam holes and you will have yourself a kick *** little motor that will shock the hell out of you with the torque and hp they make even compared to a big block ecs when you get to stroking them in a light little package ! good luck
you can offset grind the crank and use 327 small journal rods to make a stroker, i forget who all makes pistons for this setup but there out there, ran a 400 in a pulling truck for years.
You can also destroke these motors using a 350 crank and rods(main bearing spacers or special thicker bearings copensate for the larger main bore) with stock 400 replacement pistons, preferably flat tops. See, they shortened the rod in the 400. Makes a 377, I believe, and revs like a 350.
I just put a 400 in my T bucket, it had a 350 that spun a bearing & i can't beleive the differance in power & speed!!And its all stock except for headers, 3 dueces & SS ignition!! Car went from being pretty quick to "funny car" fast!!lol I say don't **** with it, put it in & see how it runs!! JimV
I'm so tired of SBC that I can't stand it but, If you want somthing to run, it's the only SBC to have. MPO!
WOW! Thanks guys. I'll get this block checked out and see if I have a good base or not! I'm thinking I can't go wrong by putting a huffer on this motor. Big cubes and forced induction in a 2400 lb car? Sounds like a recipe for a fun factor of 10+. I have an extra set of floater 5.7 rods w/ ARP bolts waiting to go in a project so I may go this route instead of the short 5.56 rods. Seems alot of people like the 6.0 rods. Pistons are available for any combo I would run. I also have a set of fresh 461's with 2.02/1.60's. that can go get some steam holes drilled in them! With the no accessory bolt hole heads and a 2 freeze plug block it could be made to look like any 283/327 setup with a little creativity.
Be sure to check the crank. Most 400s came with a cast crank and it will not agree with the loads generated from a large gilmer belt. Also, blow off the 6.0 rods on a blower motor. The piston pin will be right in the middle of you ring pack and cause more headaches than it is worth.
revs better than a 350. I had one with dart heads, screamed to 7k and was a street killer. too bad the car was cursed.
Thanks, this is the kind of info that I'm looking for. As far as the cast 400 crank goes why would it be any different than a cast 350 crank when it comes to using a Gilmer belt? I would think that it would be even stronger than a 350 due to the larger journals on the mains....or is it a lower grade cast material. I did a decode on it and it is a '71 if that makes any diff. I hate the term but "School me" I will be going with a 5.7" forged rod, ARP studs and floating pins.
The cast crank with a "small" snout tends to flex even with the forged crank. A forged crank is more ductile thus more forgiving. I learned this from experience. A buddy built a t-bucket with a blown 350. Went all out on the rotating ***embly except for cast crank. He mounted the alternator low on the motor and when he hit the gas, the harmonic balancer would rise from the stress of the belt and contact the alternator and bracket. As you can imagine, we about ****ped when "sparks" begin to shoot out from the balancer.
also about the 400 i see it hasn't been mentioned yet......it is externally balanced unlike all the other sbc that are internaly balanced........so make sure you get the flywheel and hym. balancer with it.....
Getting a little confused here...I was told that the 509 was the most desirable of the 3 blocks for the 400 due to thicker cross section of the web...when cast it doesn't know what it is going to be due to the fact that the machining operation makes it either a 2 bolt or 4 bolt motor. I can relate to the machining of the outer bolts into the web not being splayed but perpendicular giving it a weaker web than a 2 bolt 509. Works the same way on the 2/4bolt 010 blocks for the 302/327/350 motors but the 010 blocks have a more desirable alloy/nickle content than some of the other blocks. I have 3 of the 010 blocks...1 is a 4bolt and 2 of the 2 bolt versions waiting for splayed caps. Is there any "as cast" measurable difference in the webs of the 511 or 817 blocks compared to the 509 block? Is there a difference in alloys between the blocks Are the 2 freeze plug motors weaker/stronger than the 3 plug motors? I've been told repeatedly to watch for core shift on the earlier blocks.
I have a 400 in our 46 ford sedan,and I cool it with the original 6 cylinder radiator(it's smaller than the flathead radiator)and she runs all the time at 180 The motor pulls like there is no tomorrow. I have looked for another one for Irenes 84 monte SS,but so far no luck. It's a good motor Russ
Curly there's a reason these blocks command a good price and are getting harder to find. As you've already been well informed, some killer combos can be made with it. I'd definitely go with a forged crank, especially if you're going to force feed it. You should be able to get an Eagle or **** for around $400 or so if you shop around. Look at SRP pistons, made by JE. They have a ton of combinations and are a helluva piston for the price. Depending on your head CCs, you'll probably want to look at something like their -16 or -24 CC inverted domes. And since you're buying a crank anyway, you may want to consider doing somethine like I did on my 388 build. Get a 3.80" stroke crank but use pistons w/ a compression height for a 3.75" crank. This zero decks the pistons w/o having to deck the block, giving you a nice, tight quench area by using a head gasket of around .040" or so. This improves overall combustion efficiency, helps prevent detonation, etc. Also, w/o doing the math, it should give you about an additional 6 cubes. With a .030" overbore, this should give you about a 412 cid engine. The 3.80" cranks are a bit more expensive though. When I built the newest engine for my Vette last summer, this place had some great prices on rotating ***embly parts. cnc-motorsports.com But shop around once you have your part numbers, things change. Also, here's a site with some great info to help with selecting parts, calculators for figuring static compression and dynamic compression ratios and such. It's very handy. They also make good pistons. I've never used their forged ones but have used their hypereutectics before with good results. That's not what you want for a forced induction build though.
for 400 bucks and it runs good and its complete?, grab the damn thing no matter which one it is and figure it all out later. They're pretty rare around here and I'd jump on it in a heartbeat.
Oh I already bought it....for 200 bucks After pulling the pan it is a 2 bolt block date code E38 (May 3rd 1978), the heads on the other hand are '71 400's.per casting date and part #s I have heard so many theories on forced induction motors I'm not sure what to believe anymore when it comes to building a lower end. Fact or myth I don't know. Forged rotating ***emblies are not needed for a street blown motor making less than 7 lbs of boost. hypereutectic pistons are fine for a street blown motor, cast cranks will do fine in a street blown motor, most bearing failures in a blown motor are due to excessive RPM's due to how easy it is to rev a blown motor, Detonation seems to be a killer with a huffer. A well built stock motor will gladly take a blower. So many theories..... I have a brand new cast Eagle crank sitting in a box, new Clevite 77 bearings and rebuilt 5.7 rods ready to go...I have been checking out forged versus hyper pistons...and they do make a coated hyper dished pistons that will give me about 8.5:1 I do know that with a 406 it appears that most combos seem to peek out in the 5800-6500 RPM range, seems to me if I'm making 7lbs of boost and staying in the 6g range I should be making gobs of power and torque in a relatively low RPM motor. I've seen 450-525 hp naturally aspirated combos without all the forged internals (All the $$ was in the heads). I'm figuring I could end up building a somewhat streetable motor in the 600-625 hp range with the same combo making about 550-575 in a 355...or about 1hp per cubic inch between the two motors.
The Jalopy Journal
