I heard somewhere that Scat cranks are now made in China. Anybody know if that is true? That would be my concern.
Hey Brandon, thanks for the picture! I was trying to find my digital camera so i could post some pics...my daughter seems to have "borrowed" it.... to further the great info being shared on this thread....yes, the 400 block is "siamesed" bore..that is why we vent the water/ steam from the back of the heads... As for the solid vs. hyd. debate?? well, my only issue here would be maintenance. if you like getting a look inside your motor on a regular basis.. go with a solid cam..if you want to set lash and forget about it, go hyd. Also , let us not forget how stroke relates to cam duration.. same duration in a 302 ( 3") stroke will produce rough, choppy idle and low vac. in a 350 (3.48") stroke , less chop, more vac.. in a 400 (3.75") stroke, almost smooth idle....the reason for this is time the valve has to travel related to piston movement..So,,,long stroke needs more duration... just to add to the fun here ! if you could find an old duntov 30-30 cam ( early corvette , z28 ) this cam was designed for a 3" stroke. put this in your 400 and let the fun begin.. As a side note, for a few years i was heavily into IMCA modified racing. this is a class where your motor can be "claimed" by another competitor if you finish well. as a result of this rule LOTS of motors get built using leftover,used, mismatched parts. sometimes even trash can parts! so when you have a cam that was perfect in your 350( 7800 rpm, tons of power etc) and you slide it into the lowbuck 406 and it sounds pretty mild..thats when you go back and research the whole stroke vs.duration thing.. Last topic.. rod length... stock 400 =5.65"..use only as a last resort( 400 rods are the achiles heel ) common rod lenghth =5.7"easy to get pistons for the 400 using 5.7" rods. 6.0" better, but as stated earlier the pin gets up into the oil ring area. this can be a pain... for you math experts...the formula for rod ratio escapes me.. the ideal combination of bore, stroke,rod length= rod ratio...the 327 4.0x3.25x5.7 is the best of the factory combos...taking this out further a 350 really likes a 6.0" rod and the 400 should use about 6.2".. it's been done before, with pretty good results..But 2 big problems come up . 1, the pin is way up into the ring pack.2, the cost of custom pistons is very high.. Bottom line is build a 400 with 5.7 rods, use good fasteners, and keep it below 6500 rpm.. Any crankshaft that is priced less than $700. or so is most likely chinese made. Scat and Eagle etc. are good cranks for the money. For a street/ mild performance motor the budget cranks work just fine. You want to shop for one that is finished machined here..As an alternative you can buy an offshore finished one and send it to your local grinder to straighten/ finish.. We are talking about a street car/ hot rod motor, right ? dave
62, this is clear as mud? Let me see if I can fill in some gaps. The short rods(stock 400) in addition to increasing cylinder wall wear rates(side loading), puts the rod/stroke ratio in a range that produces peak torque lower in the rpm range than a 350, so targeting the cam to take advantage of this will have the added advantage of being a nice freindly driver and won't stress the combination to the point of desruction, after all, the 400 is taking the small block design to the displacement limits, that big bore made them siamese the cylinders, then in an effort to remove the heat in these spots they drilled what we call steam holes, the coolant actually changes state as it travels up to the heads, hence the recommendation of the tubes running to the front(not sure this is nescessary, but I've seen it done with 1/2" stainless tubing and really looked sharp). One point not brought up; when drilling whatever heads you use, yes, use the head gasket as a pattern to determine where to drill, the inner hole is drilled straight, but the outer hole is drilled at an angle to reach the coolant pocket by the spark plug. If using factory Chevy heads, stay away from the lighter castings. Look at the lower edge of the head, the heavier castings will be straight except for a plce to miss the dipstick.
Dave posted before I could type my rambling thoughts, but I totally agree with him. He brings up some very good points, the larger the displacement, the bigger demand for the good stuff, air and fuel, and what better way to introduce them than with a solid cam! Hydraulics are a compromise design that addressed complaints from ordinary folks about noise and having to have routine adjustments. We are not ordinary,are we? A solid always produces more area under the curve(dyno sheet) and by limiting your rpm's to 6500 you should not have a maintenance problem. I've run solids in 99% of my toys and only when they got beat on real hard did I notice a slight tappet noise, indicating the need to run the valves, a somewhat enjoyable ritual that amazes your freinds and impresses the girls!
I'm running a edlebrock 3x2 manifold that has a cross over in it! Are you saying the manifold gaskets are blank or the heads aren't drilled out? JimV
I have built several 400 small blocks and really like them. I have very good luck with a standard melling m55 oil pump. a hv pump is one of those feel good things , but it takes power to spin them and its harder on the distributer. If the clearances are right the oil pressure will be good with the standard pump. I would recomend running a good quality high volume water pump though, like a Stewart or an edelbrock. The increased water flow helps sweep the steam bubbles away and in general helps the cooling. On a street motor even a stought one, the 5.565 rods will make about the same power that the longer ones will. watch your compression ratio cause that long stroke builds compression. a flat top piston and 64cc heads will be knocking on 11.5 to one. If those hyperutectec pistons start to rattle (detonation) they will shatter .(thats why I like forged pistons) a dished piston isnt a bad way to go if its a daily driver kind of thing, then you can run lower octane fuel. The CAT crank is a chinese part and maybe as strong as a stock 400 crank .if you want a cruiser engine that one is probably ok but if you want to race with it Id hold out for one with forged pistons and crank. You will love the torque a 400 makes. The larger displacement makes them swallow more camshaft. A mild cam will make it pull like a freight train in a street car. Doug
oil pumps...high volume takes more power, and often in a stock application will empty the pan on a hard run...best bet is the z28 pump (gm spent a lot of time & $s on engineering, why do we all think we know better than the general ?) melling m65 is the part # for a stock pan..this unit makes 20% more pressure and pumps 20% more volume than the stock ( m55 ).. for the track we like to use the stock big block pump (m77).. it has a bigger pickup tube and more teeth on the gears (less harmonics transmitted to the cam at rpm)..this unit also makes the same psi/volume #s as the m65.... if all is well internaly, stock pump should make 60 psi and the m65 or m77 72 psi (60 + 20%=72)....using the smokey unick rule of 10 psi per 1000 rpm..... 7200 rpm should be plenty. dave
Doug is right on the money on the 400... We had a 406 run 1 season in a stock car running the short rods. It spun 6000 rpm about 12 weekends in a row. You really need to know what pistons are in the motor as Doug stated with compression ratio concerns. I compare a 400 sb to the 396 and 402 bb... The 396 ran great because of free flowing heads and a high compression ratio. i found the idea comp. ratio on a 406 comes with flat topsw and a 76cc chamber. You can't run a big enough valve in a 406 either. I built a flat top piston 406 with 2.05in and 1.6ex valves and a 4.80 lift hyd cam and it was the best street engine I ever had. If the engine you found has dished pistons you an build up a little compression by running camel backs but don't run power pack or 305 heads because it will choke it down to much. The steam holes are for low rpms. We used to plug them in circle track motors because they are a good place for a crack to start and they just are not needed except at idle. If you get one and have to bore it make sure you have the machine shop us a torque plate. This simulates a cylinder head torqued on the block and makes a nice round bore. The thinner walls distort more than a 350... Jeff
So Dave Lewis is against a 400 with a solid cam, and Unclee(fellow Houstonian) recommends a solid cam in a 400. Someone mentioned to use a torque plate when boring a 400, I know in the block I am looking at it said in the ad that was done. To keep everyone on the same page my focus primarily is the "gasser look" & "gasser sound" i.e. tunnel ram with hilborn "bug catcher" gear drive for noise solid cam for noise, and because hydraulic runs out of gas above 5800rpms. At the samtime I don't want all bark and no bite, but I realize it is not going to take much to make a 62 falcon stripped out to haul ass i.e. 375+ horsepower. World or Dart Iron heads you think?
If a flat top is a flat top why do I want large cc combustion chambers? Wouldn't that put the 400 back in the same situation it was in during the 70's dogshit low compression and piss poor performance with big 76cc heads like you mentioned?
A 76 cc chamber will get you in the 9.5 to 1 range for pump gas. The stock 400 came with 76cc but they had a dish in the piston. It depends what you put the engine in too. If it is a heavy car with highway gears it lugs the engine down and is likly to ping. If it is a light car with a 4.11 or 3.90 gear it runs less torque and is less likly to have problems pinging. In the second case you can run 10to1 and have a combo you can live with. Jeff
Dont forget a 400 has more swept volume than a 350 so that means more comp with a 76cc head than a 350 would have.
So because it would being going in a stripped out 62 falcon with 3.73 or higher gears I would be fine with 64ish cc heads...
OK 62....lets tie this thread together with your other one (heads) and get you a bad ass motor ! first, i am not against a solid cam. what i said was if you dont mind the maintenance of periodic adjustments, go solid. i like em ! use the motown heads refered to in your other post.. they are not "TOO" big for a 406.. do the mag/checking thing and match the springs to whatever cam you decide on. drill the steam holes in the head cuz you are going to drive it on the street. plumb the back of the intake for the water bypass. and last but not least, deburr the sharp edge of the combustion chamber before you install the heads. this edge can glow red hot when you are running hard and cause detonation.. just radius the edge, dont try and lay back the chamber wall to match the 400 bore cuz you will end up loosing compression.... Oh yeah, get ready for a wicked launch! you are ordering up a super size serving of torque at the horsepower drive thru window !!! dave
That engine is great. I had one in my 86 chevy truck. It was a one ton crew cab that weighed almost 8000lbs and it run great. Me and my dad built the engine but the compression was too high. I was running 93 octane gas and it was still pinging so i had to back off the timing some, but it still ran pretty good. I had the truck doing 90 with 37's on it, and the truck didn't even shake.
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