Removed camshaft won't go back in

[RawlinSTR]

Hi all,

I recently bought a (nearly) complete L26 engine from someone who had it running well in their car before they took it out and sold it to me.

I've stripped the engine to do all the gaskets etc.

I removed the E88 cylinder head and took the camshaft out so that I could do the valve stem seals.

After doing the valve stem seals, I went to put the camshaft back in, and could get it through the first 4 cam towers fine, but found I couldn't get it into the 5th cam tower.

Got a straight edge and put it through the cam towers instead of the camshaft and found that I could rock the straight edge from side to side (meaning that the middle cam tower is higher than the end towers). I put the straight edge along the cam cover gasket surface and the story was the same, and then with the straight edge on the fire face, you can see light through the middle section.

Could anyone give me some guidance on what the next step is from here? Could this sort of thing be corrected with some machining work?

I'm a complete novice when it comes to cylinder head machining, so it would be useful if anyone could point me in the direction of a shop who could guide me.

Any advice is appreciated,

Thanks,
Simon

 

[Albrecht]

If the head is warped/bent (as it sounds it is...) then it's a fairly big job to correct it properly. It involves heating the head up in an oven and bending it back to as near straight as possible, and then some machining.

Just machining the block-mating surface flat won't fix the problem with the cam bearing surfaces, so it might be better to source a replacement head. E88s are pretty easy to come by (I've got a stack of them in the garage) so it could be the cheapest way out.

 

[RawlinSTR]

If the head is warped/bent (as it sounds it is...) then it's a fairly big job to correct it properly. It involves heating the head up in an oven and bending it back to as near straight as possible, and then some machining.

Just machining the block-mating surface flat won't fix the problem with the cam bearing surfaces, so it might be better to source a replacement head. E88s are pretty easy to come by (I've got a stack of them in the garage) so it could be the cheapest way out.

Thanks for the reply Alan.

You've led me onto the second part of the story:

I have a N42 head which has the valves and valve springs in, but no cam towers/camshaft/rockers etc.

I was thinking that I could transfer the cam towers/camshaft/rockers over from my E88 onto the N42. I know that the factory service manual tells you not to unbolt the cam towers from a head, let alone transfer them over to a different head, but I've also read success stories of torquing down the towers slowly and ensuring that the camshaft turns freely.

A few questions that this idea raises:

1. Is transferring the towers and cam from one head to another a feasible solution
2. Would the camshaft (E30) from the E88 perform well in the N42 head
3. Would the larger valves in the N42 head foul on anything on the L26 (P30) block?

Simon

 

[ben240z]

Did you take the cam towers off the head while doing the stem seals? if so are they back on in the correct order. If the cam came out it should go back in

 

[RawlinSTR]

Did you take the cam towers off the head while doing the stem seals? if so are they back on in the correct order. If the cam came out it should go back in

I didn't touch the cam towers before trying to reinstall the camshaft, knowing how important their order/ alignment was. I have a feeling that the head being torqued down to the block kept it straight enough to run okay.

Also, pushing the cam out of the carriers at the beginning was quite difficult (it sort of 'popped' out) and there was some resistance to it turning even after I'd removed the rockers, so I guess I should have spotted this was going to be an issue from that point.

 

[jonbills]

should be fine to move cam towers between heads - bolt pattern is the same on all heads as far as I know. Only prob could be if your cam needs an oil spray bar and your towers aren't drilled for it.

 

[Albrecht]

I have a N42 head which has the valves and valve springs in, but no cam towers/camshaft/rockers etc.

I was thinking that I could transfer the cam towers/camshaft/rockers over from my E88 onto the N42. I know that the factory service manual tells you not to unbolt the cam towers from a head, let alone transfer them over to a different head, but I've also read success stories of torquing down the towers slowly and ensuring that the camshaft turns freely.

A few questions that this idea raises:

1. Is transferring the towers and cam from one head to another a feasible solution
2. Would the camshaft (E30) from the E88 perform well in the N42 head
3. Would the larger valves in the N42 head foul on anything on the L26 (P30) block?

1. As you've noted, Nissan don't advise it but it CAN be done if you are careful, methodical and a bit lucky... I've done it successfully myself but it took some fettling to get the cam rotating as freely as it should (and it needs double checking with the head torqued down).
2. Stock E30 type cam from the E88 will work in an N42, but it's not exactly going to set the world on fire. I'd consider an aftermarket cam if you can run to the cost? Even if all else is pretty much stock.
3. You might get away without notching the bores on the L26 block if you use a stock cam, but it is still marginal. The 35mm exhaust valves usually require the bores to be notched on anything smaller than 86mm bore in my experience.

Good job you have the N42 head handy as the E88 sounds like it's too warped to save. However, I'd recommend building a complete engine unless you are just trying to get the car on the road. You're half way to an L28 already with the L26 block and crank (you can bore it to L28 spec) and the N42 head would suit that better. I can give you a set of decent used L28 rods and pistons if cost is a worry?

 

[RawlinSTR]

1. As you've noted, Nissan don't advise it but it CAN be done if you are careful, methodical and a bit lucky... I've done it successfully myself but it took some fettling to get the cam rotating as freely as it should (and it needs double checking with the head torqued down).
2. Stock E30 type cam from the E88 will work in an N42, but it's not exactly going to set the world on fire. I'd consider an aftermarket cam if you can run to the cost? Even if all else is pretty much stock.
3. You might get away without notching the bores on the L26 block if you use a stock cam, but it is still marginal. The 35mm exhaust valves usually require the bores to be notched on anything smaller than 86mm bore in my experience.

Good job you have the N42 head handy as the E88 sounds like it's too warped to save. However, I'd recommend building a complete engine unless you are just trying to get the car on the road. You're half way to an L28 already with the L26 block and crank (you can bore it to L28 spec) and the N42 head would suit that better. I can give you a set of decent used L28 rods and pistons if cost is a worry?

That's very generous of you, but for now I'm trying to get something cost effective together to get the car on the road so that I can move it about easily (I'm likely to be moving house soon).

In the future when I have the time/ space/ circumstance I'd like to do a complete engine starting with an L28 (potential for 3l etc.), so I don't want to spend too much getting this engine running now.

If I'll have to notch the block for the N42 then perhaps I'd be better off finding another E88 from somewhere, and saving the N42 for the future.

 

[Jimbo]

having been doing line boring for camshafts for many years in a reputable factory messing about with cam bearing locations is a massive no no!
you need to have everything bored straight to the fire face, after this the caps are removed and the cam is inserted with the whole thing being aligned.
you have a compounded issue there with that one warped head. removing the towers onto another head would require the line boring doing again as theres no guarantee the caps will be aligned on the new head to each other or even the fireface.
if you get lucky you might just wear a couple of towers/caps rapidly so its a loose fit.
worst case you tighten it all down and the cam will be locked solid.
on top of that if it does rotate the alignment being out may cause friction on the cam bearing surfaces causing it to seize.
if seen plenty of snapped cam shafts from much newer vehicles to know how important setting all this up is and thats on 3/4 pots so a lot less stress than a 6 pot.
if you just wanted to move it about i would be tempted to put the bent head back on with a cheap gasket and torque it back down this should bring the bend back down and then the cam should go back in until you can either find another head or get yours machined properly.

 

[Albrecht]

If I'll have to notch the block for the N42 then perhaps I'd be better off finding another E88 from somewhere, and saving the N42 for the future.

I'm happy to donate a usable E88 to the cause. You'll have to pay for the cost to ship it though, unless you want to pick it up from north London area?