1975 Mercedes W116 v8 Conversion......The Mercstang

in #mercedes8 years ago (edited)

For some unknown reason I always wanted to put an old school American v8 into my Mercedes.
So when the straight six started acting up I made the decision to give it a crack.....that was two years ago!

This has been my first attempt at a job like this and a mechanic I aint! Id be lost only for the help of my mechanic friend Pommy John who has been instrumental in the build, Although I swear he lets me do things wrong just so he can take the piss!!

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The straight 6 m110 engine and box were actually heavier than the new Windsor 302 and c4 transmission so I may lower the front end 30mm to get it sitting nicely. I was never a fan of the way the Merc squatted slightly to the rear.
We ripped out the old engine and went and sourced a reco 302 and c4 from a guy here in Darwin.

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Quite the lump

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The nice fresh 302....

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The guy I bought it off was good enough to throw in a few accessories and the tail shaft with the engine. The tail shaft was easy, the same length as the Merc one so I just got the Yolk swapped over to match the Merc Diff
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I originally wanted to go for a Clevo 351 but couldn't find anyone that already did that swap on the net so I stuck to the 302. Mainly because I found this...

In the comments section 1Randyful (the owner) said he had dramas putting a c6 transmission in there so recommended using a c4, I used the c4 and only had minor issues with a cross member...

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Cross member behind where the engine mounts are was fouling on the bell housing.

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Roughed in, in the end I got an engineering mob to weld a piece in, they cut out a section directly under the bell housing and welded in a flat piece to create some space.
Below is the old Engine for reference..20160211_142540.jpg

So the next issue was engine mounts, as this is a fairly rare kind of conversion I couldn't find any place that did mounts to suit my needs so it was back Wilkinson engineering for some custom jobbies.IMG-20160513-WA0017.jpg

Basically some plate with a solid bar with a hole through the middle welded on

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In the end I took out the Merc mounts completely and got some 30mm thick Poly type plastic mounts made up to ensure a tight fit and that enough clearance was left for that pesky cross member. Maybe there is a better option available transmission wise. It would of been nice not to have all that hassle.

Speaking of hassle....The engine came with some extractors

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We tried to chop bits off and get the engine in with something for the exhaust guy to work with but he said it was too tight around the steering box so in the end I got some manifolds

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And painted them up...real perty like....

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But that's not all folks!! The steering box on the Merc is quite large so the starter motor was also fouling

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I tracked down a starter on ebay that could be adjusted to swing in closer to the engine, after a bit of fiddling that did the trick nicely

http://www.ebay.com.au/itm/Ford-SB-289-302-351-Windsor-Cleveland-2-Bolt-Mini-Muscle-2-5Hp-Starter-Motor-/371900431762?hash=item5696fe3d92:g:sZ4AAOSwWWxY-bUy

A bit of fucking around yes but she got there in the end, As you can see in the pic the transmission mount was pretty simple, a piece of hardened steel cut to suit from a cardboard template and drilled out to accommodate the original c4 transmission mount.

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Another issue we had was the clearance for the air cleaner, a pretty easy fix, just got a 2 inch filter and a recessed bottom for the filter housing.

Once she was in it was apparent that the accessories wouldn't do

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Pretty dank looking so I tracked down a mob on ebay that do nice setups like this....

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So that was the way to go

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The kit was pretty good, just had to shim out some mounts to get her straight and true

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But......

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Living in Darwin in Australia, AC is a must......that pretty compressor sitting too high has to get relocated....

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That's on the long finger, what I'm hoping is that deleting the mechanical fuel pump and replacing with a Holley electrical one will of created enough space for the engineering guys to CNC me a bracket.

Next was tracking down a radiator and thermo fan setup, in the end the best fit was from an s14 Silvia paired up with two 12 inch electric fans and shroud.
Pretty easy setup to get in, custom mounting brackets had to be made.

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One issue we did have was that the Switch for the fan was mounted on top of the manifold and being where it is means that it takes an age to turn off as all the hot water settles at the top where the switch is.

The solution to that problem is a little device to slot into the radiator hose at the top of the radiator, hopefully that does the trick

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One thing that was kinda tricky but rewarding was getting the accelerator to operate the carby properly, I originally tried to use a cable but was only able to get half throttle out of the carby for full throttle at the peddle.
The solution was a bell crank setup

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Paired up with a universal throttle linkage

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I used the original Mercedes setup from the firewall back and altered the setup mounted to the firewall to suit the bell crank assembly, If you zoom in on the pic you will get what I mean.

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Electrically it was pretty straight forward, MSD all in one distributor was great except its slightly too tall so fouled on the Bonnet, that's another long finger jobbie hoping to find a bonnet from a 6.9 that has a slightly bulged profile.

So that's all for now, its still ongoing but there is light at the end of the tunnel.......

Hopefully you can learn from my experience.......