3.5 V8 Component Clarification.

Technical questions and answers
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buckbeaumont
Posts: 2
Joined: Wed Jun 23, 2021 11:49 pm

3.5 V8 Component Clarification.

Post by buckbeaumont »

Hi Guys,

Cheers for accepting me into the group! Lots of good information on here :)

I'm in the process of restoring a 1981 Stage One 3.5 V8 and seeking some clarification on some parts in the engine.

1. After pulling the valve assemblies out I can't see any valve stem oil seals on either head? Did this come factory or has someone already been in here before me and forgot to put them back?

2. On the top of the intake manifold there is a triangular water sensor. Is this the primary water temp sensor? Does anyone have the part number for the triangular sensor?

3. My intake manifold has an intake temp sensor. Does this mean that it was an EFI manifold?

4. On the front side of the intake manifold there is a tube that looks like it is cast/screwed in. Upon removing the welch plug on the underside, the tube has corroded severely. Can someone explain exactly what this tube doe and is it possible to run without it? If not, what is the best way to go about removing and replacing it... Looks rusty as hell.

Appreciate the help in advance :)

Buck
Attachments
Intake Manifold
Intake Manifold
Screen Shot 2021-06-25 at 9.55.51 am.png (165.74 KiB) Viewed 393 times
Valve Guide
Valve Guide
Screen Shot 2021-06-25 at 9.47.53 am.png (163.59 KiB) Viewed 393 times
map1275
Posts: 1010
Joined: Mon Jul 21, 2008 2:48 am
Location: Brisbane, Australia

Re: 3.5 V8 Component Clarification.

Post by map1275 »

Look in your parts book, electronic scanned copies are free.

1. Formal stem seals like you might find on an A or B series motor (a boot over the valve guide) don't arrive until years later.

2. The OTTER is standard to all carb models and expensive to replace. This is a bimetallic switch, not a temp sensor. The temp sensor on the front of the manifold is what feeds the gauge.

3. Not sure what you mean by an air intake temp sensor? Can't be EFI if it has two big holes for carbs to bolt up.

4. As per the parts book, you have an emission control manifold with the longer fitting. This unscrews from the casting. The long tubes are extremely expensive and the short tube will suffice. Connects to the fitting on your radiator. I think it's 1/4 UNF if extraction goes wrong.

However after re-reading, which pipe are you referring to? The one as above, the one below the manifold which is bolted to the underside (5/8) or the one that runs inside, for most of the manifold's length. This internal tube and it's outside fitting are NSP (Non Serviced Parts).
buckbeaumont
Posts: 2
Joined: Wed Jun 23, 2021 11:49 pm

Re: 3.5 V8 Component Clarification.

Post by buckbeaumont »

I appreciate the reply. I've attached a close up of the pipe I'm talking about. The one that bolts to the underside of the manifold is fine, it's the one that looks as though it is cast into it that runs the length that I'm referring to.

It okay on the outside but the tube on the interior of the manifold it has corroded fairly heavily.

Cheers!
Attachments
Close up of pipe.
Close up of pipe.
Screen Shot 2021-06-25 at 8.14.06 pm.png (212.02 KiB) Viewed 375 times
map1275
Posts: 1010
Joined: Mon Jul 21, 2008 2:48 am
Location: Brisbane, Australia

Re: 3.5 V8 Component Clarification.

Post by map1275 »

From memory the external hose fitting will unscrew. But there's nothing but round to grab so you may destroy the old one getting it out. The internal tube you'll have to fabricate. As used manifolds are relatively cheap you may find it easier to replace the assembly.
map1275
Posts: 1010
Joined: Mon Jul 21, 2008 2:48 am
Location: Brisbane, Australia

Re: 3.5 V8 Component Clarification.

Post by map1275 »

This may well do:

https://mgbhive.co.uk/product/90611532- ... ater-pipe/


scroll down on this one:

https://www.ukmgparts.com/catalogue/mgb ... t-manifold

appears to be the item but for whatever reason the hose end is shorter. At least it's listed.
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