Hey guys, I picked up this 1968 YE 400 block today. in doing so my truck broke down and I was pre-occupied with the temporary repairs that were made to get it and the engine home.anyway i missed the fact that the deck surface is pretty badly pitted. can any of you tell me if this is too far gone?
The problem is I don't even know how much can be milled off. The piston comes right to the top already. Ive seen worse on boat engines and they use jb weld and aviation seal. they run fine, but was going to build a good 500hp engine out of this. (or as close as I could get with out major investment)
Not sure if I can use high comp pistons now let alone build this block
Should have checked for cracks if it's been sitting out in the cold with a water in it. Worst case you may end up buying custom pistons if they have to trim the deck down more than .062". How bad are the cylinders?
Cylinders arent too bad at all. If I was to bump the engine over by hand with a little snake oil I'd bet they would polish clean. Minor surface rust. Block was on a stand in a garage. It looks more like a failed head gasket and poor coolant maintenance.
Yes I had a block that water sat in a cylinder for years. Ended sleeving that one. My machinist did an awesome job. Almost impossible to tell he even put a sleeve in.
The piston height can be deceiving. Get a dial indicator and clean a couple of the piston tops off so you can get a good reading. I'll bet you can mill .030 or more. Might take care of that pitting but you should know what piston you're going to use and the CI before so you don't go too far. That being said...there is no way to make a 500 hp engine out of a 400 for cheap unless you own a machine shop and a parts store. Good luck.
Hey bob. Thanks for the info on the pistons. I dont own a machine shop. Wish i had even half of those tools. This block started with 340hp 10.5:1 you don't think going to 11.5, a good cam, rpm intake, 750 carb and headers will get me close? I'm considering mildly porting the heads too.
I think you'd be better off taking the thing apart and assessing what you have before planing too much. Those pits look too deep to me, but that's just a pic, maybe not. To get a good seal you need the block and head surfaces to be flat and clear of all deformities. Yes you can sleeve these blocks, but if it's not the numbers matching block you have to save why bother? That and all the other work needed is a lot of money for a unknown block. If the block tests out OK great, build away, but to start a build with a block with multiple discrepancies may not be money wise. 500 HP cost a lot of $$ and 11.5:1 compression ratio, even with aluminium heads, will take race gas to run. You'd have to be an artist to get an 11.5:1 engine not to detonate with the junk they call gasoline these days. I built my engine to 500HP but it cost more than I paid for the car, and I did all the work myself. I'm not trying to discourage you but one must be realistic. I hope the block checks out good on the inspection and you build a great high HP engine. Just my opinion, I'm not an expert.
Made 615 hp with my old +.030 400 with my tiny 220 cfm 16 heads with 12.75:1 compression. There's another 400 with iron heads in the works that will blow people's minds.
Made 615 hp with my old +.030 400 with my tiny 220 cfm 16 heads with 12.75:1 compression. There's another 400 with iron heads in the works that will blow people's minds.
on 93 octane??? Thats all I run in the car now and it doesnt have half the mods I want to do to this engine. anything passed 12 concerns me. You'd think I'd have the best/freshest gas out here because of the refinery in NJ but that doesnt seem to make much of a difference.
I think you'd be better off taking the thing apart and assessing what you have before planing too much. Those pits look too deep to me, but that's just a pic, maybe not. To get a good seal you need the block and head surfaces to be flat and clear of all deformities. Yes you can sleeve these blocks, but if it's not the numbers matching block you have to save why bother? That and all the other work needed is a lot of money for a unknown block. If the block tests out OK great, build away, but to start a build with a block with multiple discrepancies may not be money wise. 500 HP cost a lot of $$ and 11.5:1 compression ratio, even with aluminium heads, will take race gas to run. You'd have to be an artist to get an 11.5:1 engine not to detonate with the junk they call gasoline these days. I built my engine to 500HP but it cost more than I paid for the car, and I did all the work myself. I'm not trying to discourage you but one must be realistic. I hope the block checks out good on the inspection and you build a great high HP engine. Just my opinion, I'm not an expert.
I agree and disagree. yes the block needs to get checked. if its screwed then I need to source a new 1968 block.. this is the higher HP block for 68. there were several 400 flavors in 68 but there was only 2 higher hp choices 340hp and 360 hp for the 400 in 68 as far as i am aware. this is a factory 340 hp block. No its not a "VIN matching" engine but it is year matching to my car which is a hell of a lot better than the 1965 389 someone shoved in it! the goal is to get the entire car back to 1968. I want to try and save it because of the higher output and because its what I purchased. granted I got the whole engine, carb to pan for $400, my engine builder thinks its possible to deck it. I have my doubts, as we all do so we will see. I appreciate the input though. The pics can be deceiving. if it was stock build i'd use aviation sealer and put it back together.
Yes you definitely want to use it if it checks out OK after inspection and the machinist can deck it clean, especialy since you already own it. If the decking brings the pistons to zero deck height , that's a bonus in my opinion, as long as the manifold fits afterward. Wont be able to tell what you have until you take it apart and thoroughly inspect it.
As far as the aviation sealer, stock or not I wouldn't use it to seal the heads, but that's just me. Just my two cents and opinion, others may disagree.
Yes you definitely want to use it if it checks out OK after inspection and the machinist can deck it clean, especialy since you already own it. If the decking brings the pistons to zero deck height , that's a bonus in my opinion, as long as the manifold fits afterward. Wont be able to tell what you have until you take it apart and thoroughly inspect it.
As far as the aviation sealer, stock or not I wouldn't use it to seal the heads, but that's just me. Just my two cents and opinion, others may disagree.
see, out by me (near the shore) JB weld (shivers ) and Aviation seal are used frequently to fix blocks chewed up by salt water in boats. some of them you'd think were toast as it looks like someone spooned out some metal and these guys go and run the crap out of them for 100's more hours.
if this block has never been machined, what do you think is the max I could take off of it? i sent those exact pics to the machine shop and they think .025 would get it to where the pitting is like its not even there.
on 93 octane??? Thats all I run in the car now and it doesnt have half the mods I want to do to this engine. anything passed 12 concerns me. You'd think I'd have the best/freshest gas out here because of the refinery in NJ but that doesnt seem to make much of a difference.
My current 455 in my bird is 9.4:1 compression and runs on 91 octane all day long. I'm using #16 D ports with a piston that has a 22cc dish. The heads came out to 78cc not the 72 cc that is printed everywhere. Next engine will be aimed to be more of an all out engine and will have as much compression as possible. Race gas is readily available here.
I'm curious why being under 10.0 is the magic number for Pontiacs? The Buick guys routinely talk about higher numbers using factory iron heads.
1968 400 Coupe, verdoro green, black vinyl top 1968 400 Convertible, verdoro green, black top 1971 Trans Am, cameo white, auto 1970 Buick Skylark Custom Convertible 350-4(driver)
Haven't pulled the engine and disassembled it yet.
1968 400 Coupe, verdoro green, black vinyl top 1968 400 Convertible, verdoro green, black top 1971 Trans Am, cameo white, auto 1970 Buick Skylark Custom Convertible 350-4(driver)
The engine I'm working with was a factory 10.5:1...thats 1968 so i cant understand why everyone wants to keep it so low either. I'm aiming for 11.5 myself I just gotta get my sh*t together and finish taking apart the block so i can bring it to the machine shop for final inspection.
The piston height can be deceiving. Get a dial indicator and clean a couple of the piston tops off so you can get a good reading. I'll bet you can mill .030 or more. Might take care of that pitting but you should know what piston you're going to use and the CI before so you don't go too far. That being said...there is no way to make a 500 hp engine out of a 400 for cheap unless you own a machine shop and a parts store. Good luck.
Bob, the deepest looks to be about 1.5mm MAX and thats an estimate by eye with a feeler gauge laying right next to it. there are few deep spots like that and most if not all the really deep ones arent near the cylinder. would be nice if i could save this block!
As long as the pitting isn't excessive around the fire ring and water holes where it can pass by it will be ok. I'm sure once the decks are milled flat it will be fine.
A 1968 factory 10.5:1 engine burned 100 octane gasoline, with tetraethyllead {[ch3ch2]4bp} octane booster[Lead}, Ethyl. In 2015 gasoline is 87-93 octane with ethanol [crap in my opinion]. Your 1968 10.5:1 engine could run trouble free in 1968 as it was burning gasoline with an addative which inreased the octane level of the fuel and in turn one could increase the compression ratio considerably over fuel [gasoline] without lead. We no longer have "Ethyl" which is , to answer your question, why builders are reducing compression ratios from 1968 standards. Then there's the static and dynamic compression ratio comparison. No mater what the compression ratio , it's the cylinder pressure we are concerned with. The higher the cylinder pressure the more power and the more chance of detonation. Static compression ratio is the ratio of the volume of the cylinder and combustion chamber from bottom dead center of the piston to the volume of the cylinder above the piston and combustion chamber at top dead center. [swept volume] Dynamic compression is the volume of the cylinder when the intake valve closes compared to that at top dead center. One could have a high static compression ratio say 12:1 with a lower dynamic compression ratio than that of a 10 .5:1 static engine ,depending on the camshaft. Dynamic compression ratio will be determind by your camshaft. Take an engine with a compression ratio of X and change the opening and closing points of the valves and the compression ratio will be +or - that of the original.
FWIW Dynamic compression is also effected by RPM and does change. for most engines its best not to play the game and go by the static number being no more than 9.5 : 1 If there is a source of ethenol free gasoline that would be the best bet.
I have a sleeve in my 68 YZ block and you'd never know.
The pitting between the bore is going to be a big challenge to keep sealed. Hope with milling the block you get most of that to go away. You might consider a graphite head gasket over the standard fiber reinforced versions for better sealing properties. I would opt for a wire ringed head gasket as well for higher sealing pressure around the bore. Don't use the Multi layered steel versions unless your surface finish very very very smooth.
My block was milled .032 and the piston is still .004 in the hole. Like I said it depends on what Pistons you use. What comp height, what stroke and length of rod, whether the block has been line bored, if the rods are new or r&r'd. You need to figure out how much you want to take off first then tell your machinist if he can get the deck perfect after cutting that much off you'll pay him but if he cuts it that much and it's not perfect you're not paying because at that point the block is a just a door stop. At $150 to cut it you don't want to pay him twice. Whatever, that deck needs to be perfect when he's done. Remember you might have to stud the block because the head bolts might be too long after the trim. Something else to consider is (I just recently went through this) they get crazy dough to trim an intake to fit. One shop quoted me $160. Another was $250. That's just to get the ports to line up. This stuff's no joke. You need to think long and hard about what you're doing and all the consequences. Do one thing and it changes everything else. You wonder why it costs $10K or more for a motor built right?
) and Aviation seal are used frequently to fix blocks chewed up by salt water in boats. some of them you'd think were toast as it looks like someone spooned out some metal and these guys go and run the crap out of them for 100's more hours. 
