The 117.983 vs. 117.986 Question, Version II

[STORMINORMAN]

Having read (both) the threads on this subject from the Search this Forum I'm still wondering if the block, heads, exhaust manifolds, intake, etc. from these two engines will interchange? Specifically, can you use the 450 from, say, a '78 450SEL to replace a 450 in a '73, or vice-versa? I know the fuel-injection systems differ, & that the SL's differ from the SE & SEL versions, but what about the longblocks themselves?

This question is based upon the potential purchase of a running "parts car" W116 that has a different engine model #
(a '76 450SEL) for my '73 450SE.

Thanks in advance for your kind consideration!

[guydewdney]

i had a look at the head gasket for a sel 450 and was going to compare part numbers - to see if they will interchange.








theres TWO PAGES of listings of applications and notes as to which one to use.

so EXACT FULL engine numbers - and anyone with an EPC will be able to tell you. but it will take some work - and you will owe them a beer!

[STORMINORMAN]

...it could vary from s/n to s/n (or year) even within the same engine model #?????????????????????????????????????

In the '70's? Back in those SIMPLE days of yore?

[guydewdney]

thats what it looks like. its probably not, but i'd get an epc off ebay or a member here and spend the time with the research first...

its a two CD set, and you either need two cd drives or a virtual cd creator to run it.

[STORMINORMAN]

Thanks for your info: now I need to do some real investigative work.

I wonder: just how do the engine rebuilders handle this kind of problem?

[Tomguy]

The 3.5 and 4.5 blocks are the same, I believe. Some differences in heads among the 3.5's and 4.5's (3.5 and 4.5 heads are quite different due to combustion chamber size).

Any 4.5 can replace any other 4.5. The most time-consuming task would be changing the heads/manifolds (if you're going from D-Jet to K-Jet or vice-versa, you need to swap the heads and intake manifolds I believe; if you're going from a 108/109 pipe design to a 116 pipe design, you need to change the exhaust manifolds).

That's about it. There are internal differences between, say, the 117.984 and 117.986 (one has hotter cams than the other) but they prove to be a "direct swap" if you change the heads and manifolds out.

[STORMINORMAN]

TomGuy:

Thanks for the info. Your statement "any 4.5 can replace any other 4.5" gives me much hope!

You then get into changing the heads and intake manifolds, going "from D-jet to K-jet, or vice-versa"... I recognize that if you put a complete engine from a post-1976 450SE with electronically controlled fuel-injection (EFI) into a pre-1976 W116 that came with MECHANICAL (CIS) fuel-injection you need to swap the engine & fuel-injection controls, too. That makes perfect sense.

But, (the $64,000 question), are you really saying that a "short block" (albeit a used one) from a '78 will readily accept the heads and intake manifold from, say a '73?

I hope this is not being too dense of me? My previous engine-swapping experience is limited to replacing Chevy short blocks from the 60's & '70's in which just about everything was a simple bolt-on affair.

Thanks for your patience: I was really trying to avoid the EPC exercise, if possible.

Regards!

Norm

[Tomguy]

ACTUALLY... as ass-backwards as it may sound...

The pre-76 4.5 was the one with EFI (electrical D-Jet), the post-76 is CIS (mechanical K-Jet).

ANY 3.5 or 4.5 will accept ANY heads or manifolds from another 3.5 or 4.5, as far as I know, with no issues other than compression ratios and valve clearances - but really only a "Problem" with putting 3.5 heads on a 4.5 (the other way around may neuter the 3.5's power but you wont have valve/piston clearance issues).

You would be MUCH better off to replace the heads, manifolds, AND CAMS on your donor engine (76) with those from your original one (73), as opposed to switching your cars wiring/fuel lines to accept the K-Jet system. After the switch to K-Jet, MB also went with cams that lowered emissions - as well as a ton of power. Although the power difference I notice isn't that drastic (because my timing chain is stretched way too much, most likely), I have gotten an additional 2MPG MINIMUM in additional economy... last fillup I got about 10.5 when, driving with a foot that heavy before ("Testing" the new power) would have given me under 8! I'm looking forward to what I get on this tankful after a (major) valve adjustment, leaning her out a bit and working on the ignition system a bit.

[STORMINORMAN]

...averaged over 11.4 mpg! This was the 1st full tank after completing STAGE 1 of the Auto-Rx treatment for cars with over 100K (and I've got that covered, in spades!).

This stuff really does safely clean up the inside of an engine!

I figured that looking for a complete, running donor/parts car with a better interior (read as "better leather seats") and just about one of every other part I could need was a better way to go than just trying to find things part-by-part if/when I really needed them.

Tomguy: Thanks again!

[Tomguy]

When I say heavy foot, I mean:
I floor it on at least 1/4 of my starts and none of them use less than 1/2 throttle
I frequently floor it, including going up steep inclines, so it downshifts into second gear at, say, 80
I frequently drive at or over 80, and rarely drive slower unless there's a reason (traffic, weather, fear of cops!)

As for clean engine interiors, I couldn't believe how clean the cams and towers (and heads) were on the 116-chassis MB I grabbed them out of as opposed to mine. With 140K on my engine, everything seems to have a brownish "Coat" on it, whereas this engine had no such "coat" (Everything was immaculate to the point of shining!)

[STORMINORMAN]

Tomguy: As they say on TV : "Your results MAY differ..."

Is THAT what those little marks on the speedo are for? My transmission just might not be ready for that kind of exercise, yet.

Seriously, you may wish to investigate the Auto-Rx site, or try "BobistheOilGuy" on your search engine.

[Tomguy]

Notches indicate the top speed (redline) in the gear: 1st notch is about 58, 2nd notch (2 notches) is about 96. My tranny kicks down into 2nd if I floor it at 80, anything over 80 and it stays in 3rd.

[cth350]

The big differences between pre and post 1976 4.5 engines are the fuel injection system, emissions & the hydaulic lifters.

You'll have to compare head gaskets prior to swapping around heads. I believe they are different.

Also, you'll find oilpan & oil filter differences if you change body types (ie 280se 4.5 to 450sl, etc).

-CTH

[Tomguy]

CTH: Head gaskets for the later 450's and the 4.5's in the 108/109 are the same P/N so I would imagine heads would be a straight swap.

The oil pan itself is also the same (108/109/116), I think the only difference is that the 116 has an "elbow" or whatever for the oil filter so it isnt in the way of the subframe - it'd come off easily enough and I would imagine bolt right onto a 108/109 model 4.5 (117.984)

[cth350]

two outta three from memory. Not bad. Different oil pan on the 107s. -CTH