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A technical Q about my 248/248 cam setup

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#23 ·
Well the Track got rained out so better luck next week. On a side note put the other 248 cam in with the 3 tooth method and pulled the spark plug wires and cranked it like 15 times to get Oil Pressure, and lube the Top End. Now engine won't start because I flooded it ( I hope). So I pulled the Spark Plugs and I'll let it sit a couple of hours and hope she starts up. Just hope I did'nt mess anything up trying to work so fast.
 
Discussion starter · #25 ·
Yeah you probably did flood it. On a side note the COLD engine should start up initially like always, BUT, be aware that you will need to *help* it stay running for the first 10 seconds or so by feathering the gas lightly. You'll be able to tell when the engine will be able to idle on its own because you'll feel it smooth out.
 
#26 · (Edited)
I think I really messed something up. Got it started but it smokes like hell, won't hold idle, and valvetrain is noisy as hell. Probably bent a valve by the sound but I don't know where I would of went wrong i've done this job plenty of times before. Just got this Motor installed less than a Month ago. Would it of been possible to jump teeth just by removing one cam?
 
Discussion starter · #27 ·
Are you sure you didn't go the wrong direction and go 5 teeth? You couldn't have bent a valve because at 3 teeth the lobe separation is closer to stock than at 4 teeth, it's just a little on the advanced side instead way on the retarded side.
 
Discussion starter · #29 ·
Also, I'm not sure why you found it necessary to dry crank the engine. You shouldn't have had to remove the cam or undo the cam journal bolts or anything like that. Just removed the gear in order to move it UP one tooth and bolt it back on. Is this what you did??
 
#30 ·
I was running 240/248 but I have another set so I pulled the 240 intake cam, marked where the cam gear was and moved it 3 teeth counterclockwise and than installed the other 248 exhaust on the intake cam gear.

I just pulled the valve cover and put the engine at TDC. Distributor is pointing at no 1. There are two colored links on the upper chain. Mark on intake cam gear is two teeth counter clockwise from colored link on left and exhaust cam gear is one tooth counter clockwise from colored link on right side. So I must be one tooth off so is this enough to bend a valve. Sorry to Threadjack Bmoses.
 
Discussion starter · #32 ·
No no, nobody's threadjacking here. :) I should have posted some tips to avoid engine damage because that is a real possibility when messing around with cam timing. But ususally what I do is disregard the timing marks on the chain (or even whether the engine is at TDC) because you don't really need to take these things into account. I used a paint marker every time to mark the CURRENT relationship every time. And then I whenever I make an adjustment I make them relative to what I'm currently at at that time. Then, finally, I turn the engine a few times by hand to make certain there are no problems such as valves hitting pistons.

Glad to see you got it set up right. Does your engine lope at idle now? I agree totally that it pulls GREAT from low RPMS.

I have gone a step further and filed down the cam gear slot towards the retarded direction in order to get a few degrees away from exactly 3 teeth. And then I just kinda wedged some scrap metal on the other side of the dowel pin to take up the space and bolted the cam gear back on. So, I'm at about 3.1 to 3.2 teeth retarded on my setup now.

Anways, keep posting your thoughts. :)
 
#34 ·
so in the end, 3 teeth is better power than 4 teeth?

3 teeth = even more power down low, with some loss at the top
4 teeth = noticable losses down low with some gains up top?

i didnt really like the 4 teeth method because it made launching (which the KA is very good at) very hard because of the noticable torque loss. i even ran 248 248 cams on my KA-T setup. man, the torque loss was even more noticable but the gains up top AMPLIFIED! the turbo would hit full boost at 3.5k rpms (with a t3/t04e) then at 5.5k rpms, the engine pitch changed and it sounded like a different motor, kind of like a VTEC crossover :). it ABSOLUTELY RIPPED after 5.5k, thats my opinion about the 248 248 with 4 teeth method, i have yet to try the 3 teeth method on the KA-T... ANYONE try it yet?
 
Discussion starter · #36 ·
I have faith that the 3 teeth method provides more total power through the whole power band and it delivers that power band down low, from nearly idle on up to about 5K or so. I think that, if matched with a quick spooling, smaller turbo, such as a t28 or something like that the amount of power and torque in the lower ranges should be phenomenal (sp?). Also, as miked808 said, the turbo should make up for lost power in the upper range as well.

Overall, I just feel that at 3 teeth the power is emphasized MORE in the lower rpms than it is at 4 teeth in upper rpms. Again, I think this is due to the long, torquey stroke of the KA engine. The complement of any additional power that is gained by a cam change is better utilized by the KA engine in the lower RPMs. I hope I didn't lose anybody with those deep thoughts there for a second. :) (Oh the lope is cool too. :) ) I can't wait to start getting turbo parts. I'd like to use the 3 teeth method with a quick spooling turbo and see where that gets me.
 
Discussion starter · #38 ·
Yes it does give you a lopey idle, but it's not bad. It's very streetable. I don't think I've ever had it die once it's hot, or even when it's cold for that matter. However you do need to help it on COLD startup for about 15 seconds or so. Then it will idle high on its own.
 
Discussion starter · #39 ·
It's been a while since I've been able to check this thread, but Miked808, I had been thinking about your comment about these cam settings in conjunction with a turbo. Here's what I think. I think that the 3 teeth setting would not be an optimal setting because of the long amount of overlap it provides. From the best of my knowledge, you don't want much if any overlap with a turbo setup. Most of us can bolt on a turbo to a stock cam profile and still realize large relative gains, but I think in this case, we are talking about a rather extreme amount of overlap; certainly more than what was designed by Nissan for stock. On the contrary, I think the 4 tooth retarded setup would be optimal because of the lack of overlap. I think this would result in the turbo spooling much faster and the engine being overall more efficient at its job of producing power. So, the two things I will certainly do before going turbo is reset the cam gear to 4 teeth retarded and reset my base timing to stock or maybe even a few degrees retarded on it as well. I'm hoping to be able to tune my own ROM by then though and adjust the timing maps in software.
 
#40 ·
bmoses said:
It's been a while since I've been able to check this thread, but Miked808, I had been thinking about your comment about these cam settings in conjunction with a turbo. Here's what I think. I think that the 3 teeth setting would not be an optimal setting because of the long amount of overlap it provides. From the best of my knowledge, you don't want much if any overlap with a turbo setup. Most of us can bolt on a turbo to a stock cam profile and still realize large relative gains, but I think in this case, we are talking about a rather extreme amount of overlap; certainly more than what was designed by Nissan for stock. On the contrary, I think the 4 tooth retarded setup would be optimal because of the lack of overlap. I think this would result in the turbo spooling much faster and the engine being overall more efficient at its job of producing power. So, the two things I will certainly do before going turbo is reset the cam gear to 4 teeth retarded and reset my base timing to stock or maybe even a few degrees retarded on it as well. I'm hoping to be able to tune my own ROM by then though and adjust the timing maps in software.
Click to expand...
hi, i have a quick question about this. Should i set my timming to stock if i did the 3 teeth and my car only has bolt-ons and would i be required to use the highest octain gas i can get at the pump? Also, just want to make sure but if i did the 4 or 3 teeth, either way, i will turn the cam counter clockwise, right?
 
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