Need a mechanic for for U20 in Pacific Northwest

[311tony423]

I need to deal with my chain rattle. My engine was rebuilt years ago and is/was still running strong. The mechanic I used to rebuild it overlooked the fact that the head thickness (lack thereof) would cause a chain rattle.

I live North of Seattle (Bellingham) and am looking for a mechanic experienced in this matter. I don't want to take it to Canada so I am hoping for someone reasonably close. Even Seattle-Olympia would be ok...

I am sure it needs a thicker head gasket installed and possibly the cam lifted. I usually work on my own car but this is something beyond my confidence level.

Also, it has been running great for years but last year It has been very low power and acting like a miss fire. I stopped at a mechanic during my trip last year and he could find nothing wrong. It ran well when I pulled out but started running like s**t shortly after. I had to rent a u-haul truck and trailer to get home. Could it possibly be the distributor? There doesn't seem to be any play in it.

Any suggestions? Thanks.

[spl310]

Hit up Greg Burrows. He is somewhat near Seattle, so he may know who could help.

[311tony423]

I tried all of my detective skills and can't find a contact for Greg.

Also: I should add:
Everything about my engine and fuel delivery is pristine. Fuel filter is new and I have newly rebuilt carbs from z therapy. Points, cap, coil, are new. I addressed the usual suspects so to speak. I should have given more info.

It's definitely the usual chain rattle from having the head shaved a bit. It must have been done prior to my ownership as well. I've had the car for 20 years now.

My main concern is the chain tension, the other problem can be figured out along the way.

[GeoffM]

Hi Tony,
You may want to contact Ross at Sports Imports. Right around the corner from you had a good resource. Plus you could join the rest of us at the shop for BBQ. Even if you don't want to cross the boarder, Ross would know a local mechanic in Bellingham.

[spl310]

Greg Burrows is Gregs672000 on here.

[311tony423]

Thanks GeoffM, not that I can't cross the border, just something else...

Thanks spl310, PM sent.

[JohnnyMac]

It is easy to inspect the Evil L and see if the chain is hitting it. You can also install shims on the tensioner with minimal mechanic skills.

[311tony423]

Thanks, already did the shim thing. I can hear it rattling each time I rev the engine a little. When it hot it rattles slightly at an idle.

[Gregs672000]

Tom, got your PM. I am south of Seattle, so a quick run up to see you would not be super quick... A day project anyway.
If the head is cut, which it sounds like it has been, then the towers need to be shimmed... How much is the question. Without it off, I think we're gonna have to do a best guess... Some one here needs to suggest a method of estimating it, as if we can avoid pulling the head lets do so... You may not need the thicker gasket if she's not knocking or you can control it to your satisfaction with good gas and octane boost if needed (my engine is 11.7 to 1, runs on pump gas with occasional boost in very hot weather, BPR6ES NGK plugs without the extended tip vs the other plug available for the Roadster).
People freak out over removing the cam towers, but they are pinned and should not be a big issue if done progressively. You are capable of doing all of this stuff once we figure out what shims to get. If the engine is rattling at idle, then the tensioner is not getting enough oil pressure or the head is cut more than the tensioner can adjust for at low oil pressure. We want to make sure the oil hole to the tensioner is not covered by the gasket.

Post a pic (or text them to me) of the upper chain guide and the damage to the L. I want to see the cam gear too. Initial plan would be to get a shim measurement, then put the engine at TDC or close, stuff a rag down the front of the engine to keep things from falling in, then remove the tensioner, check for a gasket (if present, does it cover the oil feed hole? If no gasket, then that caused it to leak a little. I make new gaskets out of thick notebook paper wetted with oil, making sure the oil feed hole is uncovered. If the oil gasket is intact, you can reuse it). Now, mark the relationship of the chain to the cam gear, remove the gear and attach it to the L as designed, number your rocker arms 1-8 (don't skip this step!), if needed number the tower caps, then remove the caps, the cam, then the towers. Install the shims, install the towers without completely tightening the bolts, install the cam, lube the caps, install the caps and again snug them down but not fully tight. Spin the cam by hand to make sure it turns no problem, then tighten down the tower bolts, spin cam again to check binding, then tighten the caps to check for binding... The cam should spin by hand without binding. If it binds, loosen some cap and /or tower nuts and keep playing with it until there is no binding or acting like its hitting a high spot as it turns with the caps tight. Reinstall the cam gear/chain, rotating the cam until it lines up with the pin. Reinstall the rocker arms you can to their proper previous place (the reason for the numbering). Remove the rag, spin the engine so you can install the last few rocker arms, Stuff the rag in again, reinstall the tensioner, consider cutting off the L with a hack saw (oiled rags in the engine etc to protect), remove the rag, adjust your valves (6 in 8 ex cold, will be 8/10 hot) and fire it up!
At next oil change see if you have the oil filter tube or not... Will help keep oil in the filter for cold starts.

Regarding your miss... I suspect the distributor needs some lube or mechanical intervention (broken spring? Gummed up workings?), but we'll get to that after its up and running again.

Hope this helps. I MAY be able to make a trip north sometime, but to do this we would need to have the proper shims in hand. If the engine still rattles after we have shimmed the towers and tensioner, then we may have an oil pressure problem. I think it will stop rattling however...

I am happy to help via phone, especially if we can schedule a time.

[311tony423]

Wow, lots of info. Thanks. I'll get working on it.

I once inquired with a reputable online Datsun parts supplier about shim options and he insisted that the head has to come off to perform the cam tower shim job. I've never pulled the head off but that didn't sound right to me... Was he correct?

[sports imports]

head thickness can only be determined by measuring the head once its off. Thickness of head is needed to know what size shims are needed to make up for the missing thickness. Rocker arm geometry changes when you shim the towers because the thickness lost has come from the bottom of the head, not under the towers or the top of the head.

Ross
sports imports

[sports imports]

Greg Burrows mentions cutting off the evil L but if this is hacked off, you cannot do the job Greg details. If someone has cut off the upper guide L that needs to be there ,in order to hang the cam gear and chain , you cannot perform the procedure. If your chain is rubbing on the upper guide, cutting it off has not resolved the issue. Sometimes its as simple as bending it gently out of the way. Other times its because the chain is stretched, or lack of oil pressure in the upper tensioner ( or oil pump), or the head is too thin. removing the L is a short term solution that does not address the problem.

Ross
sports imports

[Gregs672000]

Generally agree with Ross that it makes the job different, in that you can no longer use the L as intended and in the future would need to press the chain against the chain guide like is done with L series engines (where I first learned how to do this). I have no L (cut it off as it was scored) and have used a wood paint stick piece that was sharpened some to fit between the chain so it pushes the chain against both sides of the guide to hold the chain in place and keep it from falling into the engine (I've done this for 30 yrs). Not a perfect answer, but exactly what Nissan suggested for L series engines, and beats ventilating your hood! (I think Nissan used a special tool to hold the chain, but in essense it was what I made out of wood).
Regarding the proper measurement of the head, I cannot comment as I have no knowledge (thus my request for guidance on that issue, with the goal of avoiding removing the head if we could as it costs more money and time... but if that is what is required to do the job right, no problem! But now we're in to a new head gasket, manifold gasket, possibly head bolts or studs, etc... just sayin!). "Rocker geometry" and its impacts are controversial. I am well aware today of what proper cam timing can do for the engine. However, my machinist has noted that "rocker geometry" makes no significant difference in lift or duration, but if it is bad enough that it causes the cam to wipe off the rocker pad then you have a problem. Different lash pads are available but it can be hit or miss on what size to get, and if the cam is ok on the rocker it may be fine, though one may want to consider getting the rocker arms resurfaced if the wipe pattern is considerably different (two piece rockers only, others cannot be resurfaced as yet).
In summary, I would do what ever is necessary to determine what shim is needed. If it is decided that the head has to come off, then it can be determined if a thicker gasket makes sense (as noted I run high compression on the street, there are pros and cons). Once shimed, the rockers can be blued to determine the wipe pattern and decide if they need to be resurfaced or if different lash pads are needed. Once we figure out if the shims and shiming of the tensioner eliminates the chain rattle or not we can figure out what direction to go to address that issue if needed. We dont know if the chain is stretched, but if it has been 50k miles then we should consider replacing the chain when (if) the head comes off (and looking at gears etc, that was why I wanted a pic of that gear). Owner reported the car ran great before so that suggests the compression can't be stupid high or he probably would have mentioned having to run octane booster all the time and/or the engine knocking etc. Oil pumps rarely fail and can be changed by dropping the pan, so no issue there (I'm sure my pump has seen over 200k miles and it works fine. All of them read near zero at idle on the gauge, but have pressure). So, I'm approaching this step by step with the knowledge that we don't know all the needed info to fully determine a direction yet.

To be clear, I am not suggesting that just cutting off the L solves the problem, but keeping a compromised L in there can certainly result in engine destruction, and I for one would rather not have that occur. When I first bought this car the cam cover was welded as was the oil pan, and it no longer had the original block... she had come apart violently at some time! The L was a great idea, but flawed in execution, and not repeated on the L series engines. I have a buddy who just bought some parts cars that happened to have a new upper chain guide in the box... try finding one of those! No idea what he would want for it, but I bet it is NLA (?).

[311tony423]

The engine was completely rebuilt about 10yrs (10k+) ago. This included a new B camshaft, nos timing chains and gears ($$$$), as well as guides.

Thanks for everyone's input. This definitely influences my plan of attack. I'll pull the valve cover off and take some pics in the next couple days.

[311tony423]

Too bad a quick measurement from the bottom of the head to a factory mark can't be made to determine the loss of girth, thus indicating a head gasket thickness...