RB26, install cams... Pull head or not?

[boostedh23a1]

Hey guys Im thinking about swaping the turbos on my setup which would mean throwing cams in the old lady. Has anyone installed new cams and PROPERLY shimmed them with the head installed, or is everyone pulling the head to do it?

[Ramius83]

If you are just installing Tomei Poncams that don't require milling out head for clearing the cam lobes, then leave the head on, definitely. Even when it comes down to shimming, you "should" be within specs for the most part, and moving a few shims around will usually work.

If you are installing anything over the Poncams lift, then usually you have to mill the head for the cam lobes to clear. You will DEFINITELY need to pull the head so the metal does not go down into the engine.

[boostedh23a1]

Yea i know about the lift and head clearance, I am more consirned about trying to shim the cams, seems like it would take hours to do that with the head in the car.

[Ramius83]

Shimming is not fun with the head in or out of the car regardless. Pulling the head just for a simple Poncam install would be silly and a complete waste of time, except you could install an A/M metal headgasket then. Most of the time when installing Poncams, the clearances are nearly spot on anyways, so shimming doesn't usually take long with those....

[julio]

Let me know if you need any shims, I have some left over from my cam install. I can get them to you way faster and cheaper than any vendor.

[boostedh23a1]

how about you come help me change these things. lol im not looking forward to it.

[julio]

how about you come help me change these things. lol im not looking forward to it.

Installing correct shims is easy.

1. Take out stock cams
2. Measure stock shim thicknesses
3. Install aftermarket cams
4. Measure clearance
5. Do the math to determine what shims you need.
6. Wait 1-3 months for shims from Australia/Japan (hence buying them from me )
7. Remove aftermarket cams
8. Install correct shims & aftermarket cams

It is best to create an excel spreadsheet to keep track of your measurements and to do the math. Just make sure you install the cams correctly so that they don't snap like a twig.

Installing Procams or any other different base circle cam is only slightly different.

[boostedh23a1]

Whats the best way to not hit the piston with a valve while your doing it? is there a spot where not all the cylinders will be tdc?

[gawdzilla]

here's what i did, and hopefully will work for you too.

install your new cams, cam sprockets, and timing belt. turn the motor by hand to check each cylinder's valve clearance and write them down. hopefully everything works out here within specs, and you can stop.

if there is anything out of spec, return the motor to tdc and remove the cams. for the valves that are out of spec, measure those shims and determine your new shim size. reinstall everything, including the timing belt. check again, verify to make sure everything is ok.

again, with "drop-in" cams, they are usually just that.. drop in. usually you do not need to re-shim. if your head was already out of spec and in need of a re-shim, then you needed to do it anyway, so do it

[boostedh23a1]

you think the poncams 260 would be ok for a bit with stock turbos, I'm thinking of doing it in stages. Then im gonna put on either gtss twins or a small single.

[julio]

you think the poncams 260 would be ok for a bit with stock turbos, I'm thinking of doing it in stages. Then im gonna put on either gtss twins or a small single.

Poncams have shown to improve the entire powerband, not sacrifice low-mid for top end as many aftermarket cams do. It is the cam I would suggest for anyone under 600hp, but even big HP RB26's use them with great success. The price for a set just dropped too.

[boostedh23a1]

Yea, I saw that so i ordered them. Wish their dump pipes would drop too...

[boostedh23a1]

Do you still have those shims?

[julio]

Ok, I inventoried my 25 shims. Let me know what you need. You will need to decide what clearance you want to run on both the intake and exhaust. Intake is .045", exhaust is .038" (both with a .003" tolerance from the FSM). There are reasons to run them both tighter and looser than the spec calls for, but its up to you.

[boostedh23a1]

Julio where do you live? If its close i can fly up there and get em. Anyone have any around SC/GA area? I will post my thicknesses here in a second. I have rearragned them about 6 times now and have all but 1 on the intake side good.

[boostedh23a1]

Ok, here is my list.
Round to the next thickest size available i guess.
2.97
2.93
2.94
2.93
2.85
2.88
2.87
2.86
2.86
3.3
Total of 10.

[boostedh23a1]

Nissan part numbers pn followed by thickness
(1) 1322905u72 2.98mm
(2) 1322905u69 2.935mm
(1) 1322905u70 2.950mm
(3) 1322905u64 2.86mm
(2) 1322905u65 2.875mm
(1) 1322904u19 3.310mm
(1) 1322904u17 3.28mm

thats 11 (grabbing one of the slightly smaller ones incase the big one is too big.)
Can anyone get these?