400 bore and some other ???'s

[firefighter3516]

okay everyone I am not good with engines. I have a 400 77 casting and heads, that was just sitting in a 74 charger that I picked up. I took the heads off to look at it and it doesn't even look like it has ever been run maybe a crate motor I don't know. Well with the heads off and the pistons on the bottom of the stroke I measured the bore at top and bottom and come up with 4.346 well the big block book I got says it should be 4.34 and my parts store guy says it should be 4.342 which is correct and if is is 4.340 is there any concern with it being .006 over or if it is 4.342 being .004 over. Also even though it doesn't look like it hasn't been run would you still put new rings and bearings in it. when I get it tore down completely I will post pics of the pistons and all so maybe ya ll can help me with Id of the componets. Also the book says that a 77 casting cant be bored but .020 over is this true says all others can be bored .060 over?

Thanks
Joey

[chargerbr549]

The standard bore on a 400 is 4.340 rounded off and the 440 is 4.320 as far as overboring take a look at 440source.com they should be able to tell you all you need to know and as for most performance engines a sonic test is recommended before overboring the block.

Kevin

[dukeboy_318]

ive got the same book, that info but 77 blocks is false, here read this  http://www.440source.com/blockinfo.htm  ive got a 77 blcok that going to be bored .030 over

[firefighter3516]

yeah I looked at that page dukeboy & chargerb549 thanks I see they say there is no such thing as thin wall block. Oh and  what about the over bore I am a machinist and .006 is a lot to me and I didn't see anything on 440source about that.


Joey

[firefighter3931]

Joey, have you measured the pistons yet ? They could be bigger than 4.340 so you need to do that to see how much piston to wall clearance you actually have. The general rule of thumb is .001 clearance for every inch of bore diameter so in a 4.34 bore you should have at least .0045 piston to wall. You have to account for thermal expansion....if the pistons are too tight once the engine reaches operating temp...there will be big problems. 


Ron

[firefighter3516]

Thanks Ron I will measure them when I get the motor out of the car that is when I get a hoist and stand. And I will let you know the results. And thanks for everyone else all so I love this board I have learned alot just doing some reading everyone is very helpful

Joey

[dukeboy_318]

 firefighter3931, could he be getting a measurement of the wear of the cylinder???  It could be just woren that much which could throw the numbers off,  i had a 318 while back that had the same issue, overbored by .003 so i guess its possible.

[firefighter3516]

I measured the bore at the very top of the bore where the piston doesn't even make it to and the the middle and the bottom and it all measures withing .0002 all the way down. There shouldn't be any wear at the very top where the piston doesn't make it should there???

[dukeboy_318]

no it shouldnt be, do you know of the history of the motor if its ever been honed or anything?? have you measured the pistons yet?

[firefighter3516]

I dont know the history of the motor but to me it might be a crate motor. I had pulled the head off and the valves are new and there is no oil residue anywhere that I can see. I have go the lift or stand yet to be able to pull the motor and like I said it is just sitting there and is not bolted to anything. here is a pic

[firefighter3931]

Just a followup on the original question. According to the Chiltons manual...the stock bore on a 400ci is actually 4.342 and not 4.340 as i originally thought. I haven't messed with a stock 400 in years but i seemed to remember that the stock bore was slightly bigger than 4.34 and the book confirmed it. 

Joey, let us know what you come up with after you mic the pistons. 


Ron

[firefighter3516]

okay ron as soon as I get it out I will let yall know I hope to maybe get the lift and all this weekend. Hey what about it being a crate motor with the possibility of never being run by the pic  there usually wouldnt be a sticker with a bar code on it like that if it wasnt a crate would it.

[Charger-Bodie]

okay ron as soon as I get it out I will let yall know I hope to maybe get the lift and all this weekend. Hey what about it being a crate motor with the possibility of never being run by the pic  there usually wouldnt be a sticker with a bar code on it like that if it wasnt a crate would it.

actually , some of the later 70s chrysler stuff had that bar code stuff from the factory install, not that that dismisses youre theory 

[dukeboy_318]

check the numbers on the drivers side of the block and on the id pad next to the distributor, that will at least give you a year it was made

[firefighter3516]

I have already done that it is a 77 casting with matching heads.

[dukeboy_318]

could be just a replacement motor from a dodge dealer or autozone, something like that if you get a chance to pull the pistons, check inside the skirt, there will be some numbers followed by the chrysler pentastar if its factory.

[firefighter3516]

okay everyone got the lift and stand today and got the motor tore down and this is what I have came up with. Top of the pist is 4.315 the skirt is 4.340 piston numbers inside of skirt are 3671052  12  09104 on the other side 3671053 conecting rods are DF34 MS405 the other side 173769. Conecting rod bearings DH CLEVITE 77 oter side 10  03 CB 527P STD. Cam has 920389 and 123 stamped on the end. Crank has 4027172-4 and CFD on it.  After getting in to the motor it looks like it might have been rebuilt but doesnt look like it has been run since it was.
As alway Thanks for the help.

Joey

[dukeboy_318]

according to those numbers, id say its been rebuilt, as long as the cylinders look good, id get new gaskets and run it.   

[firefighter3516]

can anyone tell me what the numbers on the end of the cam are do they tell you what it is? What about the crank what kind of balancer am I going to need for it???

Joey

[firefighter3516]

Oh yeah dukeboy_318 after pulling it apart I would agree with that I think it has been into because there are pipe wrench maks on the oil strainer tube and I dont think they would be there from the factory.

Joey

[firefighter3931]

can anyone tell me what the numbers on the end of the cam are do they tell you what it is? What about the crank what kind of balancer am I going to need for it???

Joey

Joey,

Sorry can't help on those cam numbers. You could pull it and measure if you were really curious.

The crank should be a cast iron piece unless it has been swapped out at some point. Cast crank motors use a different balancer than a forged crank....so it's important to identify which one you have. Here's a pic to help you.


Ron

[firefighter3516]

okay ron I have the cam out. So how do you measure a cam I brought my calipers home today but I dont know where to start. I also looked at my crank today and I have a cast crank so when I order I balancer I just tell them I have a cast crank right and what about the flex plate??

Thanks for the help
Joey

[firefighter3931]

To measure lobe lift you first need to measure the base circle of the cam. The opposite side of the lobe peak (heel of the camshaft) has to be miced out....measure from the center core to the peak and record your number. Now you measure on the opposite side at the peak of the lobe and record that number. Subtract the small # from the big # and you will have your lobe lift specs. Multiply the lobe lift by your rocker ratio and you have the actual valve lift.

This procedure only tells you how much lift the cam has...nothing more. Lobe seperation angle and duration are measured while the cam is in the block with a degree wheel and dial indicator. That is a lot more complicated process.


You will have to order the dampner for an external balance engine.  As for the converter there are 2 options...the stock setup uses a weighted converter and neutral balance flexplate. The weights on the converter are needed to bring the engine back into balance.

Option #2 is to use a neutral balance converter and a special B&M "external balance" flexplate. This flexplate has a scallop cut out which corrects for an external balance condition.

I prefer option 2 because the B&M flexplate is very strong and will not break/crack under hard abuse. Most high quality converters come in a neutral balance so going with the B&M plate makes life easier...and safer.


Ron