Wrong cams

[PeterSLC]

I've got a 1973 450SLC, while doing some engine work I noticed it had cams for a M-116 3.5L engine (4600 and 4700), instead of the cams for the M-117 4.5L engine (5200 and 5300).

Does anyone know why someone would have installed these cams in this engine and what effect it would have on performance. The car wasn't running right and burns an very excessive ammount of gas, which is why I was working on the car.

Thanks
Peter

[230/8]

Sounds like someone was trying for a bit more performance. Search the forum and you'll find several conversations about cam specs for the older V8s. The 3.5 cams have been sought after to improve engine performance.

230/8

i had a 1975 450 SEL with the same issues, only the owner replaced the cams because one was worn flat as this engine so often does, he went to the junk yard and bought a set from a 1976 450 SEL that was the first year they went from D-jetronic to the CIS, the cams were different, and caused the exact same issues, we replaced them with another correct set and all was well.

[PeterSLC]

Carson356--your car also ran rough and burned a lot of gas?(smokes from the excess).

When I bought the car it ran a little rough, but had good compression. The previous owner hadn't had the car long and thought it just needed a tune up. I'd gave the car a great tune up -- still smoked and used too much gas. Then I replaced all the D-tronic sensors, checked the injectors, replaced the trigger points -- still smoked. Then I rechecked the compression (fine), replaced the timing chain and rails as well as the tensioner and did the valve guide seals since I had the engine apart -- still smokes, burned gas. Replaced the manifold pressure sensor -- still smokin'.

I was really doubting my mechanical abilities at this point and popped the valve covers back off to check the cam timing -- to make sure I hadn't missed a tooth or two when feeding on the new chain, and to check the valve adjustment. I checked the numbers on the back of the cams, and looked up the settings in the book;

My car -- engine number 117.982-12-000719

according to the book, should have cam numbers 5201 and 5301

but the cams in the car are 4601 and 4701, which according to my book are for the M-116 engine.

boo-hoo.

You think I could just get them reground to the right spec?

i had exactly the same issues, no wrecking yards in alameda? that is where i would start.

[PeterSLC]

Found a set in Stockton (for $200 each).

Thanks Ray.

Peter

if you are not in any hurry to get them, i can get them for you for less, about half that let me know. Ray

[PeterSLC]

Hey Ray, I'd love it if you could find me a cheaper pair of cams! Just let me know what you need from me. (I do Paypal on eBay too)

Thanks,
Peter

i will look tomorrow and see what i can locate, what is your time frame for completing the repairs?

[PeterSLC]

The valve covers are off and awaiting new cams. I need to rebuild the power steering pump and swap out a non-functioning odometer, maybe I'll do that while your looking.

Thanks,
Peter

[tosbt]

This was a big subject on the Vintage thread a while back. Many including myself wanted improved performance on our 4.5 109/108's and suggested that the 3.5 cam would provide such. Tomguy is now in the process of installing the complete heads from a 3.5 to his 4.5 108. I would think that many other components would have to be changed also, such as the injectors as to much gas would flood the smaller chambers. From what you guys are saying sounds like this has been tried before.