line bore cam shaft?

[lcdyal]

I recently built a ka24de n/a for my 91 240. I had a machine shop port & polish , 4 angle valve job, and shave the head. When I assembled the engine to shop manual specs, I failed to use loc-tite on the camshaft retaining bolts, causing the bolts to back out in a week and also breaking the cam gear end off of the exhaust camshaft and scarring one of the caps. I have found another cam and caps to install but the salvage yard I'm buying it from says that I need to line bore the cam retaining brackets while they are attached to the head, kind of like line boring the bottom end. My plan was to install the new cam and perform a compression test to verify that no valves are bent. Is it really necessary to line bore in this particular circumstance or will I be allright installing the new cam and loctiting the hell out of everything? Has anyone ever experienced this problem before?

[deviousKA]

Well yes, if/when you ever swap bearing caps from another head, you should get it line-honed/bored.

Does the ka24de call for loctite on the cam bearing bolts? Ive never heard of this before and was under the assumption they just required proper torque.

Due to the tolerances that nissan uses on their parts, you may get away without doing the line-honing. This should be thoroughly checked. If the cam spins easily with all the caps torqued (kinda tricky to do with de with valves installed) you might be in the clear but i would have an engine machinist take a look at it.

[lcdyal]

The shop manual does not require loctite on the cap bolts, and it also does not show the torque specs for the bolts. I had to call a mechanic at a local nissan dealership and he said to torque them to about 22lbs. I tightened them all in sequence to the recommended torque. The car ran fine for a week, I didnt realize there was a problem until I was on my way home and lost power. Shortly there after the engine died so I towed it home to find that the cam had broke and the second exhaust cam cap had busted a chunk out of my valve cover. I was just thinking that loctite could have prevented this.

Will I be able to tell if the new cam spins freely enough just turning the engine by hand when I reassemble it.? Or, will I only be able to tell if the engine is running at speed?

One more question. You dont have to line bore it when you change just the cams, so why would you when switching the caps? All the cams are made precisely enough to swap between heads, so the caps should all be identical enough to swap also right?I could be wrong and I probally am so any input would be helpful.

[DGA]

I am in simmilar situation that you are. My exhaust cam snapped off also, but it was not due to the bolts backing out of cam brackets. It was because they were over tightned. Factory manual does not specify the lock tite, but they do specify that the bolts should be torqued to 8.7 lbs. This should be done in two stages. I am sorry to say man, but your cam broke due to overtorqing. This happened to me two weeks after I bought the car. Here is the link to Jim Wolf website that describes how to install cams into KA24DE, and it is a lot better than the factory manual. http://jimwolftechnology.com/w...E.PDF Good luck. Shoot me an email if you want me to email you the factory manual in pdf.

[lcdyal]

Thanks DGA,

I didnt know the torque was so low on the cam brackets. I should have known not to just take a Nissan mechanics word for torque specs. So now I'm waiting on my new cam and bolts to get here. The link you posted is far more detailed than the fsm on the installation of the cams. You have been really helpful.

lc

[DGA]

Only cam cap that that got demaged was my #1 exhaust. It got scratched up when the cam ripped off. I call around the dealerships and found out that they do not sell cam caps seperate from the head. I am sure that if you use a cam cap from another KA24DE that you will be just fine. That is what I am going to do. I will try to take some pictures of the broken stuff.

[lcdyal]

I just got finished reassembling everything and had no problems with the new cam or caps. I had to replace some shims to get back to factory tolerances, but it was not very difficult. Just time consuming.

DGA if you need any extra shims or caps I have a few extra, and a couple extra heads ( the damn salvage yards around here wouldnt sell me just the cam and caps so I've got a lot of extra parts. Just let me know

lc

p.s. I loc-tited the hell out of all the bolts, and then double checked the torque after driving about 30 miles or so and everything checked out o.k. So I suggest doing the same to yours. Good luck.

[DGA]

Hey, I might need a few shims when everything is said and done. My cams have not come in yet, cause I just sent the payment out.

I just cleaned the engine and all the parts last weekend, so I am ready to go with the assembly as soon as the parts come in.

I will drop you a note as soon as I have an idea of what size shims I need. Thanks Icdyal.

[lcdyal]

No problem. I've got probably about 30 or so extra shims. I actually measured each and everyone with a caliper and wrote the sae thickness on them. Just let me know what sizes you need.