3.5/4.5 V8 parts interchange - PeachParts Mercedes-Benz Forum

nomsg · #1 07-27-2006, 04:34 PM

I'm new to site, but have question for anyone with 116/117 motor knowledge.
Will 3.5 cam bearing surfaces fit 4.5 cam bearing towers ?

Tomguy · #2 07-27-2006, 04:40 PM

Yes. Although your best course is to use the 3.5 towers matched to the cams, or new towers, because wear patterns on the old towers will not match wear patterns on the "New" camshafts. Also, be aware of the two different cam designs: One cam design has the oil supply groove in the last bearing of cam itself, the other in the last tower. These are not compatible with each other. Past that, they are 100% compatible.

Also be aware that cams from a hydraulic ball stud engine will not work on a mechanical stud one, and vice-versa. This can be solved easily if going from hydraulic to mechanical studs by removing the hydraulic ones and installing the mechanical ones. The other way around tends not to work because the heads usually do not have the oil pasages for the studs.

nomsg · #3 08-08-2006, 02:56 PM

Thanks for your reply. Sorry to be so long getting back to you but personal matters have had me away. Any way, back to your reply, I'm presuming from
what you said, 3.5 towers will fit 4.5 heads. The rest of the valve gear is in good condition as far as rocker to cam surfaces, so I'm not intending to replace ball studs or rockers. Basically, I'm trying to confirm 3.5 new cams & towers will fit to existing 4.5 heads in 79 450 SLC & that 4.5 cam sprockets are compatible & timing marks will align as before. I do intend to replace cam
oiler fittings, timing chain, tensioner & upper rails, but hopefully nothing else unless I'm overlooking something. What do you think ? regards.

Tomguy · #4 08-08-2006, 04:21 PM

If you need to replace cams because they were worn (not for performance), you WILL need to change the rockers.

If your 3.5 source cams came from an engine with mechanical ball studs, you WILL need to change them (remove the hydraulic ones, replace with mechanical).

If you don't change the rockers, your new cams will be eaten apart by the soft worn rocker surfaces in no time.

nomsg · #5 08-09-2006, 03:11 PM

Got your message. This is a performance swap, not due to wear, however it sounds as though new rockers would be a good plan, along with adjustable
ball studs. I guess the unanswered qustion is whether all this stuff will fit to
79 450 SLC heads & will 4.5 sprockets fit & timing marks align as before. thanks.

Tomguy · #6 08-09-2006, 06:57 PM

Everything will fit great. For the best performance on your 450, if you have the entire 3.5 engine, swap the whole top end (heads and all). Trust me - you will be glad you did.

nomsg · #7 08-10-2006, 05:22 PM

Thanks for your input. Unfortunately, I don't have a 3.5 motor. The cams will be new, along with the rest of the valve gear. Why do you suggest the 3.5 heads, as the intake & exhaust valves are identical for 3.5 & 4.5 ? Is there some advantage to flow or exhaust ? Just curious. Thanks, jackson

Tomguy · #8 08-10-2006, 06:34 PM

Higher compression -> more power!