[b]Engine Swap Advice[/b]

[theSman]

I have to replace the engine on 1972 porsche 911T 2.4T . The engine in the car at present is a MFI setup.

I have been offered a 2.4T engine with triple Zenith carbs , will this engine be relatively stratightforward to fit or will any modifications need to be made i.e fuel pump , fuel lines , accelerator linkage etc etc Or will be it easier to replace the Zeniths with the MFI setup ?

Any suggestions / advice will be appreciated ?

Thanks.

[Gary71]

I believe the MFI 2.4 (US) is more powerful than the Euro Zeniths, and more reliable!

If it was mine I'd swap the MFI over (assuming it all works OK?) to the new engine as I believe the internals are all the same.

Then rebuild the old one and put it back in again

[Lightweight_911]

Swapping the mfi onto the carburetted engine will necessitate changing the heads too - they need the threaded holes for the injectors...

[Gary71]

OK scrub my post Guess putting a carb engine in isn't that bad?

[fourteener]

your carbed engine will also require the camshaft sproket to drive the MFI pump.

[davidppp]

I agree.

By the time your work out the amount of rebuilding needed, it is uneconomic.

What exactly is wrong with the old engine?

If it only needs a "normal" rebuild, this might be a better option..though not cheap...budget 1.5-2k for parts plus 1 to 1.5 K for machining and labour..more if you need new pistons..

If the MFi needs work, it will be very costly however..

It is very simple to put the carb engine in..nothing needed except a low-pressure pump... a facet will do fine....

You can remove the fuel fiter, and all the engine electronic gubbins, and it will look normal..

Kind regards
David

[theSman]

Thanks for the replies and suggestions. I think I'll stick with the straight engine swap. Will the fuel pump already fitted work with engine with the zeniths ? What fuel filter will I need ? Any wiring issues involved ? and will the accelerator linkage to the engine require any mods ? The old engine had a nearly new clutch , this can be transferred ?

Thanks

[Lightweight_911]

The clutch is a straight swap & the throttle linkage will mate up with the 'new' engine - with the engine & box out it would be the ideal time to check the condition of the throttle linkage 'coupler' & associated parts mounted on the front end of the transmission casing. If the rubbler 'coupler' looks at all suspect, replace it with the later type (which has a metal surround).

The existing (mfi) fuel pump operates at too high a pressure for carbs so this needs to be replaced with a lower pressure version (as David pointed out above); fuel filter can be a universal in-line type.

[Gary71]

My '72 had no filters so when I refitted the engine I put this one the side of the bay. Just went through the boxes at Halfords until I found something suitable.



Definitely do the throttle linkage coupler when you are there, this was the cause of my first breakdown... the kids are my second...

[theSman]

Where can I get hold of a low fuel pressure pump to replace the high pressure MFI fuel pump (to use with the Zenith engine)? Also the new engine has the carberettor linkage bar missing between the two Zeniths and the small linkage bar from one of the Zeniths (from right hand Zenith carb ) to the linkage bar just mentioned ? Does anyone have any of these items for sale ?

Thanks

[Gary71]

A facet Red top will do the job.

Try http://www.fuelsystem.co.uk/

No spares on the linkage I'm afraid.