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heeeellp meeeee. halfassed 400 sbc brains

3K views 19 replies 11 participants last post by  78 monte 
#1 · (Edited)
okay now, if you're in my fan club you know i have this 1974 400. well, after staring at it for over 6 months i just tore into it and this is what i found. true 400 with 882 heads.(stock????)

like new, i mean like never ran, main and rod bearings dated '92
(i've only looked at one each)
new lookin oil pump that has never seen oil, ditto dist bushing
thin caked on oil on rods and crank
brand new, never seen oil in the galley, head gaskets
thin caked on oil all over the push rods and rockers and heads
lifters look like total crap, caked oil etc
cam looks like hell
cylinder walls have never been honed, VERY small ridge visible
timing chain cover doesnt look like its been off, but had new intake gaskets because last guy put a 2bbl intake/carb on it
oily sparks plugs that seem to match the heads

did somebody actually just rebuild the whole bottom end, why put old heads on? but they did just that. i know i need to check ou the heads and i plan on making this my second port matching job and first pocket port job.

Q: So: should i pull the pistons out and re ring it? that means pull out all of them and the crank as well. pistons are dished, and have four notches for vavles on each side of each piston. there is no noticable movement in the cylinders of any of the pistons. if i have to pull out the pistons, shouldn't i just get flat tops and what will i have to do/get as far as the notches go. i dont think you'ld need notches with big 76cc 882 heads, but i dont know nothin bout 400's:surprised. and as far as the steam holes go, the heads have them, but the hole for the water is as big as a BB in the gasket. should i enlarge to the size of the engine/head holes??? i am building this just for an interum engine for when i pull the 350 out of my camaro to build, but in the end it is going in my 40 tow truck, so i want the mill to last awhile. this was really a halfassed motor rebuild. my usual, crap:spank: i always inherit somebodys BULL crap, why couldnt it have venolia pistons and 'lumee heads?:p this engine supposedly came out of a 74 caprice. it has sat, unrun in a van that followed me home last year for at least 7 seven 7 years!! these heads are good to go on unleaded gas i believe. ALL REPIES APPRECIATED, BUT ONLY IF YOU SOUND LIKE YOU KNOW WHAT IN THE HELL YER TALKIN ABOUT!! other ones still appreciated, just not as much:rolleyes:
 
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#2 ·
Hey Bull. 2 actually; if it was me, and time and $$$

If it's gonna go in the wrecker, I don't see any reason not to go ahead and build it. you won't be sorry......
I dunno about the water passage, I've wondered the same myself, wth is that gasket passage so dang small?

this response should NOT be construed as a claim at knowing what i'm talking about.
 
#3 ·
allrighty bull calm down dude. anyways, sounds as if someone slapped a crank kit in it and let it ride at that. You can`t reuse the head gaskets, or at least I would not, too much risk. if your looking to just let it run as a everyday driver and worker, just build it stock with a small torque cam and let it ride. as for the steam holes they shouldn`t be bigger on either side deck or heads, they should match the size of the gasket. the 882`s were stock on most 400`s, I`d use`em for boat anchors as 400`s already run hotter than other small blocks and these heads are light casted and crack prone. if you run different heads have a machine shop drill the steam holes, nothing to it. the 400 is a great torque engine and are a beast in performance form. I`d say hone it, rering it and go, I wouldn`t take the chance of firing it off and the rings be shot and it smoked like rip, if your gonna run the 882`s, a flat top piston will work nicely, just get a set with the 4 valve reliefs and your set. I know what I`m talking about, sometimes.
 
#4 ·
If you are going to use this thing for a workhorse, don't use flattop pistons as they will up your compression ratio even with the 882 heads,if the bores are decent rering it, never try to reuse head gaskets, for $35.00 you can buy a whole set of Victor or ACL gaskets for a 400 sbc, this will save you a lot of problems later on. best bet is to get a rering kit (with pistons?) from Summit or the west coast guys. The water holes are restricted by the gaskets on all small blocks, it's how they controll the internal flow of coolant,make sure you have steam holes in the heads, 882's can be good heads if you port match them, they are known as the best of the worst chevy heads. Sounds like you purchased a USED CAR LOT rebuild.
 
#7 ·
thanks buds.

i never saw the word forged up there,but yeah, i'll toss the gaskets, stupid question anyway. and i mistook the water passages as steam holes, my gaskets have the steam holes, they are on the very edge of the head around the spark plug, arn't they?. but i still have a big question: since 400's are prone to overheating, what would be the harm in opening up the gaskets to match the 3/4" water passage holes in the block and heads? why are they only the size of a BB? it seems like that's prolly the reason they would overheat to me. why on earth would they have holes that big in the metal and they give you a gasket that virtually cuts off flow??

i will pull the pistons and mic the bores, so which pistons would be best, i got one vote for flat tops and one with .020 off the top, do you mean dished .020 vs the factory .030? SUMMIT seems to just have the silvo-lites as their budget brand, i'm thinking TRW would be less moo-la, but i'll have to figure out if it needs boring or not first, but still want to know. what c.r.'s are you thinking i'll be poppin with dished pistons. on a 350, 76 cc's and flattops are 9.2, what would be wrong with that? my truck runs on good regular (it's a 350 w/76+flats)

thanks for telling me 882's were common on 400's i was gonna ask that but didn't. one last Q is that am i correct in thinking the 882's do NOT need new seats to run regular?

thanks, as usual you guys ROCK!:D
 
#8 ·
I have heard that if you increase the size of the holes in the head gasket to match the heads. The water flows to quick thru the heads and block. And does not allow time to cool the block and heads. The gasket acts as a block to slow the water down.

I dont know about the 400. But, My 350 with flat top pistons, heads shaved .010 . cr is about 9.7 to 1 . dont know the chamber size of the heads. going to change them next month.
as for the seats. I would have them checked at the machine shop.
 
#10 · (Edited)
pocket porting

yeah, which is why if i f up i wont be too worried about them. got to start on somethiing. i figure pocket porting's better than pocket pool.:D plus i can take the springs etc with me. i wont be spendin money just time. except on the grinding tools. no one's said if these heads are good as is for today's gas tho.

i got the tired chain off, now i cant get the lifters out of the f'in bores! i spoze i can pound them out after i take the bottom end and cam out. fun fun fun! I get to do it at work too, so it's not so bad.:mwink:

OH YEAH! after sitting for 7 years i can bet cash the water pump is shot: but how bout the power Steering pump? Gas Pump?, anything else i ought to chuck out?? any of this still be good??

Also, no numbers have been stamped into the rod end caps, nor have the mains. Should i be afraid? (where's that "fear" icon?)
 
#11 ·
Bull, don't hammer out the lifters you might mess up the lifter bores. After you remove the rods, pistons, and crank and with the engine turned over, rotate the cam which will move the lifters away from the cam. Then take a some needle nose pliers and reach under the motor into the lifter valley and pull the lifters out gently until they won't go any further. Then remove the cam. Turn the motor back over and push the lifters out the bottom. You'll save scoring the bores.

PS: if that's what you were going to do then ignore me and go have a cold one.
 
#12 · (Edited)
holy crap

no, i meant pound the f'ers out the FROM the bottom. so thanks bra! i got one lifter buggered up on top now tho, but now i know something. you got me just in time!:sweat:

RIGHT ON ENGINE CZAR! piece a cake bra! down to the bare block! up to the pressure washer an then to the machine shop.

you guys were right about the pistons comin out, i dont know what the hell I was thinkin. after sittin for 7 years? COME ON!:nono: the oil rings were frozen up on at least half of the pistone's. guess i must picked the wrong night to quit smokin crack! and to think. i didnt even know the f'ers would go out that way! so now i'm lookin at a total re-build minus the rods and main bearings tho-OUCH! OH WELL, WHADDYA WANT FOR NOTHIN? RUUUBBA BISQUIT???
 
#13 ·
DoubleVision said:
not argueing with you Bob, but if he orders the "rebuilder" flat tops that have .020 off the tops, compression shouldn`t be over a usable range on pump gas with these pistons and a .041 head gasket? as I don`t see why he`d use forged flat tops for a work horse.
I think you guys are underestimating the ability of a 400 to detonate itself to death. Flat top pistons, even with the big open chamber heads will still produce a fairly high compression ratio, couple that with a short duration cam, and a set of cast pistons, you are begging for detonation. Once it starts, things start to melt just like a flashpoint in a fire. 400s don't like detonation, they like to get very, very hot between the bores where there is no coolant and they like to melt {had it happen more than once}
Not to say you can't run more compression, but run some good gas in it or you will be sorry.
 
#14 ·
Bull, I had the same heads on my motor with TRW forged flat tops and it ran fine on pump premium. The compression was 9.2 - 1. What is the numbers on the block and is it a 4 bolt or 2 bolt? There are two block numbers that are Hi Nickel and are two bolt mains. Very desireable for building Hi performance IMSA race engines. If you can get by on no boring or a .020 bore, go for it. Just take your time and do it right and you should be very happy with the motor for a long time.

Trees
 
#15 ·
Re: holy crap

Originally posted by bullheimer You guys were right about the pistons comin out, i dont know what the hell I was thinkin. after sittin for 7 years? COME ON!:nono: the oil rings were frozen up on at least half of the pistone's.
Hey Bull,they wern't new pistons and rings were they???The reason I ask is my shortblock was honed and has new pistons and rings,but was built 3 1/2yrs ago and was stored in a machine shop,till I bought it.
It don't smoke at all.
Don't get me thinkin,man!!
 
#16 ·
Re: thanks buds.

bullheimer said:
i never saw the word forged up there,but yeah, i'll toss the gaskets, stupid question anyway. and i mistook the water passages as steam holes, my gaskets have the steam holes, they are on the very edge of the head around the spark plug, arn't they?. but i still have a big question: since 400's are prone to overheating, what would be the harm in opening up the gaskets to match the 3/4" water passage holes in the block and heads? why are they only the size of a BB? it seems like that's prolly the reason they would overheat to me. why on earth would they have holes that big in the metal and they give you a gasket that virtually cuts off flow??
Couple of things. The steam holes are not at the edge of the heads, they are between the bores. There will be a pair between all the bores.

The small holes in the head gaskets on the water passages is to promote priority cooling from my understanding. Maybe someone else can elaborate.

Chris
 
#17 ·
O'Tay!

lessee: okay nairb, now ya got me worried. first off, do you know what my c.r. is with the stock dished pistons? mine are dished pretty deep, and with the 882's which i'm sure, as big as they look must be 76cc, (nice 194's tho) it's got to be LOW! it would have to be lower than the 9.2 w/flats in a 350 wouldnt it? and i am running great on regular as long as it's good gas, no am/pm crap.

trees, it's a 2 bolt, the number is 3951509 which mortec says was made from 74-80. so you are saying rather than the std. .030 overbore to go as small as i can at 020? makes sense cause when it was for sale nobody wanted it if it was 030. the pistons dont have any numbers on them

monte, they were old *** rings, probably stock, loaded with carbon and gunk, so i dont think you have anything to worry about

and chris hey thanks again! now i know what i'm talking about-finally where the steam holes are. i can see how easy it is to drill them yourself.

i am on my way to the machine shop to mic these out and tell you what he thinks my c.r. is stock and with flat tops. it would be nice not to have to change pistons and pay to have them pressed on the rods. i still havent made up my mind to use the stock parts or buy rods and pistons. i will have to wait till my house sells (fix it first) before i spend lots of cash on anything else. a plain jane rebuild could be within reach tho. thanks for all yer help, check back if you want to know the c.r.s :D :D :D
 
#18 ·
Bull, the listed compression ratio for the stock type, recessed head 400 piston which has a 20 CC volume with the stock 76 CC heads is 8.5:1.
If you run flat tops that have a volume of about 2 CC's your up to around 9.2:1 or a hair more. This amount of compression should be safe, but you are right at the borderline of safety at this level of compression. If you go much higher, you'll run into trouble, and for a beast of burden, I want to be able to run the most putrid of fuels through it with no problems. Anyway, 9.2:1 should be safe on pump fuel, but you want to make sure that is your true compression ratio, so you'll really need to CC everything and do the math to get a true compression ratio. How many times have the heads been milled already? Has the block been decked? How high do the valves sit up in their seats? How thick are your head gaskets? Does your crank have a true 3.75" stroke? All of these factors will figure into the equation so by stating that your engine will have "X" compression ratio is just merely guessing.
 
#19 ·
KKIIIIIIIIIIIILLLLLL MEEEEEEEE!

HEY THANKS EVERYBODY, LOOKS LIKE I SOILED MYSELF.

Machine shop guy said true: 8.5:1 stock. his math when he got out his little number cruncher came up to 10.1:1 for flat tops. that should run on premium since my 9.2 350 will run on 76/shell/chevron 87. BBBUUUUTTTT!!!!
Forget it! He looked at my crank, saw the scraping that's taken place on all the counterweights rubbing the block and determined my trust plate on the crank was shot, and would cost more to fix that buying a new crank. he doesnt think they still make thrust bearings in over-size but will check. So: New Crank. STRIKE ONE!
He miked the bores and they are 15 thous over stock, which would be 4.140, which means i would have to have the block all done:bored, cam bearings, installed, decked, honed, etc STRIKE TWO!
Which means new pistons, rings, cam, as well as a valve job/guides/springs, yadda yadda yadda... STEE-RIKE THREEEE! YER OUTTA HERE!! :pain: :spank: :boxing:
got to wait till i fix/sell my house to get that kind of scratch. Love you guys! yer the best. roger wilco OVER AND OUT!:smash:
 
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