Exhaust manifold

[Mazzini]

I had problems with both the down pipe flange and the flange on the manifold and yes it is a real PITA to get at/remove the three fixings (they may be Allan headed set screws or studs with nuts)
You could try first removing the engine mount then the nuts securing the manifold to the head, move the manifold away from the engine which gives you a little more space.
I don't think you can get the manifold off complete with the downpipe attached to it if the head is on, I know you can refit it attached to the downpipe with the engine still in if you have the head off as I just did it although I have not refitted the head yet.
If you are going to strip the engine why not remove the head while the engine is still in the car, its also so much easier to remove the engine with the head off.
A word of caution, be carful removing the three bolts on the flange, the cast iron is very brittle and a piece can break off very easily as I found out! I managed to source another one but they are quite scarce.
Here are a couple of threads that mention the manifold.
engine-exhaust-cooling-f39/exhaust-gasket-s3se-t22784.html
engine-exhaust-cooling-f39/exhaust-manifold-bolts-should-use-locktite-t22985.html

Dear Brian,
Thank you for taking the time to reply, your comments and advice are appreciated.
Great idea about removing the head first, it's been that long since I last removed the engine from an Elan I'd quite forgotten. The company that worked on my car last said that the manifold had cracked, more likely they had cracked it trying to fit it - they were fitting a new transverse pipe and silencer, anyway that used up my spare manifold. Thanks again for the links.
Have a great traditionally cold and wet Easter bank holiday weekend
Mazzini

[rgh0]

would you experts agree that the tight bends and to angular joints will restrict the flow?

The pipes and bends look like the original tubulalr manifold. This orignal manifold was really to small in diameter for the engine and going up to bigger pipes gives a signficant improvement especially on a developed engine. i guess Lotus made it the way they did to fit it into the space available. Bigger pipes usually need a chassis cut out to fit.

The tightness of the bends is not is not very critical whats more important is maintain a constant or expanding cross section for the flow. Angulalr joins if they create a cross section reduction should be avoided.

cheers
Rohan

[billwill]

This is an exhaust manifold from an early Elan. Do they fit later Lotus engines as well? Such as a 1973?
Or,
Other than Federal cars are the exhaust manifolds the same up thru '74?
Thanks in advance,
Mike

My 1967 S3 Elan Coupe had one of those manifolds originally. In fact I only changed to the twin forked tubes as recently as 2001.

[Mazzini]

I had problems with both the down pipe flange and the flange on the manifold and yes it is a real PITA to get at/remove the three fixings (they may be Allan headed set screws or studs with nuts)
You could try first removing the engine mount then the nuts securing the manifold to the head, move the manifold away from the engine which gives you a little more space.
I don't think you can get the manifold off complete with the downpipe attached to it if the head is on, I know you can refit it attached to the downpipe with the engine still in if you have the head off as I just did it although I have not refitted the head yet.
If you are going to strip the engine why not remove the head while the engine is still in the car, its also so much easier to remove the engine with the head off.
A word of caution, be carful removing the three bolts on the flange, the cast iron is very brittle and a piece can break off very easily as I found out! I managed to source another one but they are quite scarce.
Here are a couple of threads that mention the manifold.
engine-exhaust-cooling-f39/exhaust-gasket-s3se-t22784.html
engine-exhaust-cooling-f39/exhaust-manifold-bolts-should-use-locktite-t22985.html

Well the engine and box are out. It wasn't a terribly elegant solution, but I removed the head and pulled the short motor and box out. The manifold is still attached to the down pipe...I have no idea how to put the manifold back when the motor has been rebuilt! I may wimp out and go for a tubular affair.

[types26/36]

.I have no idea how to put the manifold back when the motor has been rebuilt! I may wimp out and go for a tubular affair.

1. Well I have fitted the engine block in the bay.
2. I have fitted the downpipe to the manifold with allan screws.
3. The manifold (complete with downpipe) has been wrangled in and is laid loose resting away from the engine (not attached to the centre pipe)
4. I will then fit the head.
5. The manifold will then be tightened to the head.
6. Lastly the centre exhaust pipe and silencer will be fitted.
My car has the removable lower chassis brace and I doubt the manifold with downpipe could be slotted in if this brace was not removable.
Some people do not like fitting the engine without the head first but it does not bother me.
If I were to refit the engine with the head on then I would do the same by fitting the manifold with downpipe first and just keeping it pushed to the side as I lowered the engine in, with the engine mountings off and with a bit of fiddling I?m sure it would not be a problem.

[Mazzini]

Dear Brian,
Thanks for the inspiration. The engine has done 47,000 from new, but it was pouring oil from every gasket. I work away a lot and to save time I've asked Paul Exon to rebuild the engine, so it'll come back complete. I'll take your advice and build up the manifold and down pipe and then drop the engine and box in.
Many thanks,
Mazzini

[Sea Ranch]

These cast exhaust manifolds, like Brian's above: were they fitted to other cars, or is it specific to the Twin Cam?

I'm looking for a cast manifold without the extra emissions boss/ports (used with the Strombergs, I believe). So I'm looking for an SE spec, dual square outlet cast exhaust manifold for use with my Weber head.

Any thoughts? Can I look further afield than the Twin Cam community, or not?

Thanks,

Randy