248/232 cam swap at TDC

[~4N~]

Would anybody happen to have a picture of the 248/232 cam swap at TDC? Or can you please tell me how the cams should be aligned? I'm getting some S14 cams in a week or so, and it'll be my first time doing something like this, and I wouldn't want to mess up.Thanks for any help.

[~4N~]

Sorry, I missed the stickied thread above. So is this what the cam swap should look at TDC?

[DjPantsSpecR]

yes.

[~4N~]

So the cams don't point directly away from each other like the stock setup does?The S13 exhaust cam on the intake seems to be rotated slightly clockwise.

[2.240s]

hey keep me posted on how you like this swap once its installed and running, thinking of doing the same...

[~4N~]

Well, in the first picture, there is an S13 exhaust cam on the intake side, and an S14 exhaust cam on the exhaust side, so that's probably why it's different, but I'm not entirely sure if it's supposed look exactly like that.

[~4N~]

Alright, thank you.So whenever I install the cams, I should put the S14 exhaust cam in the same position as my current exhaust cam is, and then when I install the S13 exhaust cam on the intake side, the timing mark should be rotated three teeth counterclockwise from where the stock intake mark would be, right?

[DjPantsSpecR]

no, this is ridiculous.

okay, FYI, a sticky exists becasue it is generally agreed to be true. the fact that there arent 200 posts after it saying "OMG i bent my valves" indicates that its probably going to be correct.

and it is right. the only thing thats wrong with your reasoning and your little ms paint picture is this:

you counted the zero position as 1. your picture shows you rotating back only three teeth. you count the first tooth you move as one, not the standard position.

i should know, i do this weekly. i know it so well that if the dot on the gear lies between two chain links, then there will be 6 chain links pot to pot. if the dot lies between pins on a chain link, there will be seven links pot to pot. using the pictures as an example, the first picture is the 7 chain linkes pot to pot, and the s14 picture is the 6 links.

so i would delete that picture, as there is a reason we have stickies, and 240sx owners that know what they are doing answering questions.

so put the s14 exhasut cam in the stock position. and then when you put the 248 on the int side, take the cam gear in its stock location, and rotate it one tooth at a time CCW.0-start1- after youve moved one tooth2- after two3- after 34- move here and stop.

and yeah, they wont sit in the same position, the 248 rotated on the intake side sits funny. ive gotten the most power out of it from advancing it 5 degrees, which would leave me to believe it is already too retarded. i have some math to back this up, but i cant verify its validity, and im still working it out. i dont believe the general consensus that it opens 1.7 degrees btdc.

[~4N~]

Well, if it's alright, I will post up some pics of my cams when I do the swap tomorrow, and you can confirm if it's correct.

[Raxephon]

no, this is ridiculous.

okay, FYI, a sticky exists becasue it is generally agreed to be true. the fact that there arent 200 posts after it saying "OMG i bent my valves" indicates that its probably going to be correct.

and it is right. the only thing thats wrong with your reasoning and your little ms paint picture is this:

you counted the zero position as 1. your picture shows you rotating back only three teeth. you count the first tooth you move as one, not the standard position.

i should know, i do this weekly. i know it so well that if the dot on the gear lies between two chain links, then there will be 6 chain links pot to pot. if the dot lies between pins on a chain link, there will be seven links pot to pot. using the pictures as an example, the first picture is the 7 chain linkes pot to pot, and the s14 picture is the 6 links.

so i would delete that picture, as there is a reason we have stickies, and 240sx owners that know what they are doing answering questions.

so put the s14 exhasut cam in the stock position. and then when you put the 248 on the int side, take the cam gear in its stock location, and rotate it one tooth at a time CCW.0-start1- after youve moved one tooth2- after two3- after 34- move here and stop.

and yeah, they wont sit in the same position, the 248 rotated on the intake side sits funny. ive gotten the most power out of it from advancing it 5 degrees, which would leave me to believe it is already too retarded. i have some math to back this up, but i cant verify its validity, and im still working it out. i dont believe the general consensus that it opens 1.7 degrees btdc.

Removed my "little MS Paint Picture" so as to not cause confusion.

DJ, Thank you for correcting me

[DjPantsSpecR]

yeah, that really made me sound like a c***. and for that i apologize, i realize youre just looking out for people bending valves.

However, when i first did the 248/248 swap some 2 and a half years ago, then info out about it was wrong. i had never swapped cams before, and a site that had info about it was wrong. they had the cams rotated only 3 teeth.

i did it too, using this advice and picture. it didnt run, so i started messing with t, thinking i had missed a tooth. i ended up screwing something severe enough as to bend 12 valves. i learned like 40 lessons that day.

the site that had the info had performed this swap on a non- running KA. they were passing this advice off as if it worked, but they hadnt run the motor left, they figured out a month later when they swapped it in, that they were off by one tooth. one tooth wont make you bend valves, i know that. however, when its the first time youve ever done it, and you get lost, and you didnt know you shouldnt turn the crankshaft without turning the cams, and you forgot to check by hand.... so on and so forth. mistakes, mistakes, mistakes.

lessons = mistakes. thats why i barely pass my classes....

but in reading what i wrote i was a little *****, and thats not necessary.

[~4N~]

When I completely rotate the engine, should the cams always be one tooth over on the chain?

[DjPantsSpecR]

one tooth over? i think it takes something like 1300 or so rotations until the cam marks will line back up with the timing marks on the chain.

i just got back from a weddin so im obviously drunk, but i think i know what youre saying. i think what youre asking is if you rotate it one complete turn of the crank, will the cam "dots" or marks still be in line with the off color links on the chain? then no, it'll take over 1000 rotations to get them back to the spot.

i've worried about it too, and trust me this question has been asked by many worried cam swappers.

plus you KNOW that if you post a pic of the cams, and you post a pic of the crank mark and the distributor at the same time, i will tell you if you look good. i never wanna see anyone bend valves for bull**** advice again... *knocks on wood*

[sunnys14]

gosh i remember when i did this 2 years ago... guess what i got for christmas? santa got me bent valves as my present.

[KATwo40]

Here's how I align all DOHC cams.

1. Throw instructions out the window.2. Train my eyes to ignore the dots and colored chain links.3. Install lower chain and intermediate sprocket.4. Slip crank gear onto crankshaft and index to TDC.5. Install upper chain and make sure that: a. Both cams have #1 lobes pointing nearly 180* apart (tips pointed outward, as close as possible to being parallel to the head deck). b. Upper chain is tight on top, and driver side, leaving slack on the tensioner side.

6. Release tensioner and install covers.

Start car and drive.
Modified by KATwo40 at 9:03 PM 12/8/2006

[DjPantsSpecR]

thats how i do it too, but thats not all that helpful to someone who doesnt know what they are doing, especially when swapping cams.

and then especially when you get into adjustable cam gears. lobes will move significantly.

[KATwo40]

I disagree. I think it's MORE helpful when swapping cams, because sometimes the gears don't quite line up correctly (i.e. running twin exhaust cams), in which case the marks have even less value.

Additionally, whenever an adjustable gear is used, the gear should be set to 0* for installation, then loosen and rotate the cam to the desired degree setting.