New cylinder head

[HCA]

I now need another hot water take-off point, but after the mess I had to make in removing a core plug before, I think I will go ahead and go for a new cylinder head.

I have a choice of one where alloy is line bored for the cams, or another that has cam bearings. The latter makes sense and is easier if I were ever to have cam bearing troubles, but do cams give trouble on these heads (assuming they are well serviced and oil galleries are not blocked)? The car is a +2 and I doubt will ever be raced or revved more than 6k...

Which variant should I opt for on the basis that the line-bored one is a little cheaper. With the replaceable bearing type, I take it that if the bearings are ever replced, they will need to be line-reamed, yes?

Thanks for any advice!
Hal

[tonyabacus]

Hello Hai

Can we ask why you need another water take off and its purpose before you go ahead with your purchase
Tony

[SimonH]

As far as I’m aware the ones with shell bearings don’t need reaming or anything as per a set of crank shells. The line bored one should be fine as the metal technology has moved on a lot since the 60’s and no engine has the cams with separate bearings these days. Up to you at the end of the day but I’d just go for whatever is the better deal

[HCA]

Hello Hai

Can we ask why you need another water take off and its purpose before you go ahead with your purchase
Tony

Yes Tony - it is for a tap, but it has to be the plug between 3 and 4 exhaust port! I had hoped to use the plug above the distributer, but it did not work to plan. That plug was virtually welded in the head so I dare not attempt another!

[tonyabacus]

Hello Hal
I can see the plugs you are speaking about and although we now know it is for a tap of some description, can you be a little more specific as to why you need another hot water take off and what it is that you are trying to achieve.

Sorry to be pedantic, but perhaps if we know the above someone may come up with an alternative solution rather than an expensive new head. I don't know what those plugs are cemented in with so taking them out even in a new head (if that is your intention) may be as problematic as you have already encountered.

I wonder if Rohan may have a suggestion as he seems to have quite a knowledge of these heads and may know how these plugs were fitted, perhaps worth a PM to him.
Tony

[Vic]

I just removed those pipe plugs from a Stromberg head I'm working on. They are 3/8 inch pipe thread and have red Loctite on the threads. The next challenge is the 5/16 inch square tool needed. I ground down a 3/8" socket extension to fit and heated the head with a heat gun to relieve the Loctite bond. All 4 pipe plugs easily came out, after being heated.

Vic

[Vic]

Just for fun, I should mention where this head came from. A local salvage yard has had this 1974 Lotus Europa Twin-cam Special sitting in their lot, they claim for 30 years. Original paint, no collision damage, engine dismantled. My buddy and I purchased the car at an auction for $820 and I purchased the engine from him for $300. The reason for the engine dismantle? A cast iron lifter bore had rotated and a cam lobe was nicking the edge. It had to have been noisy and I don't think the previous owner ever found the cause of the noise. I'll use this engine in an Elan.
Vic

[HCA]

Thanks for your persistence Tony! The reason for that particular port is for a remote heater tap, but the one I have is quite long and not quite fits anywhere else (yes, look for a smaller tap...)

Rohan gave several suggestions when I had difficulty with the first plug, noting that it would either release itself or be a total failure. It was the latter - 70s alloy and iron plugs obviously not a good mix!

Thanks for the concern about the expense, but do not worry as I am committed to spending a bit on a new engine - I have a wad of money that a red devil on my shoulder is telling me to go out and buy that ZR-1 with the LT5 engine that I have hankered after for years, but Mr sensible on the other shoulder is telliing me that I do not need a paper bag full of trouble! So as to remove the temptation, I am going to build a touring twin cam from new components, add on a Voigt box, and this will be my last build! (It not actually hugely expensive when I take into account that my existing engine will have some offset value). And hopefully it keeps me away from those ZR-1s

[benymazz]

Thanks for your persistence Tony! The reason for that particular port is for a remote heater tap, but the one I have is quite long and not quite fits anywhere else (yes, look for a smaller tap...)

Rohan gave several suggestions when I had difficulty with the first plug, noting that it would either release itself or be a total failure. It was the latter - 70s alloy and iron plugs obviously not a good mix!

Thanks for the concern about the expense, but do not worry as I am committed to spending a bit on a new engine - I have a wad of money that a red devil on my shoulder is telling me to go out and buy that ZR-1 with the LT5 engine that I have hankered after for years, but Mr sensible on the other shoulder is telliing me that I do not need a paper bag full of trouble! So as to remove the temptation, I am going to build a touring twin cam from new components, add on a Voigt box, and this will be my last build! (It not actually hugely expensive when I take into account that my existing engine will have some offset value). And hopefully it keeps me away from those ZR-1s

A little bit of topic drift but I picked up a ‘94 base model in August (LT1 engine) and it’s… good. A good car but nothing exceptional. Fantastic for cruising around in style but pushing it to the limit I find that the car is hard to “read” and you have to trust in its ability to grip the road rather than getting confidence-inspiring feedback like you do in a Lotus. At the end of the day the C4 is a early 80s chassis design and it struggles in some areas. Ride quality is like a sheet of plywood with wheels. The wide front tires create vagueness in steering input at turn-in. Climbing over the door sills into the car resembles stepping over a bulkhead on a submarine. But your mileage may and likely will vary as the ZR-1 was truly ahead of its time when it came out and was the flagship of GM’s engineering department. There is a reason its development code name was King of the Hill and it earned its reputation as a supercar killer. Despite my somewhat lukewarm attitude to the C4s they are still fun cars and I’d be lying if I said I don’t want to own a ZR-1 too


Just pray for no gearbox issues. The ZF S6 that GM used in the 6 speed C4s was only used in two cars- 1990-1996 Corvettes, and the Lotus Carlton. Parts - if you can find them - are very expensive.

-Ben

[HCA]

Hi Ben - you describe the C4 with accuracy! I had a huge crush on muscle cars and as you say, the ZR-1 was king at the time, but I had moved off onto other things by then. I am particularly interested in the variant that had the LT5, and vowed one day I would get one and badge it 'Lotus-Mercury ZR-1' to give credit where due. But not good fiscal sense! I did not know that about the gearbox it used, but have heard from owners that parts for the box are scarce.

Thanks SimonH - however the decision has since been made for me as QED, where I shall buy everything, only sells a version with bearing shells...

[SimonH]

Sounds fair enough reason to me!

Btw, you wouldn’t happen to be the same Nick who came over and had a look at my caterham 21 years ago would you?

[HCA]

Um, no - I am Hal, not Nick

21 years ago, I was moving my lets-waste-loadsa-money on muscle cars to MGBs and Minis...my foray into Lotus is only recent!

[SimonH]

Ok, I thought you might have been. That nick went by Hal as well. A caterham 21 was how that should have read. He had a nice collection of cars

[Andy8421]

Thanks for your persistence Tony! The reason for that particular port is for a remote heater tap, but the one I have is quite long and not quite fits anywhere else (yes, look for a smaller tap...)

Hal,

I recall reading (but can't find the link) that balancing the waterflow around the engine / head is a black art, and Lotus spent some time ensuring that all parts of the head received adequate flow. You might want to be careful that you don't end up disturbing the balance if you have a heater take-off from somewhere that Lotus hadn't anticipated.

Good luck.

[HCA]

Interesting point Andy!

Certainly I take it on board and if anything is amiss in engine cooling, I will know a possible cause. Thanks! In truth, I do not need a heater where I am presently, and the current arrangement of hot water control once it is in the car is not acceptable, so the heater now is just blanked off! But I am mindful that heat should be available at least, so a tap at the engine is best. I