SD1 cam in a 4.6 V8 with a distributor?

Jekyll · Post by **Jekyll** » Fri Dec 13, 2013 7:09 pm

It seems there's a good few people here who seem to pour data out of memory, so just a quick quiz question from the ignorant one

Would an SD1 cam be any good in a 4.6 V8 adapted for distributor? Would this be a benefit or a deficiency performance-wise? Obviously there's a problem of the distributor end being held in place more or less by the teeth of the dizzy gear wheel, but that I think will be solved by machining a slot so that it is held in place just like in a 3.5/3.9 V8.

I assume an SD1 cam would be a benefit over the standard 3.5 V8 cam in that engine, but not sure of the 4.6, although common sense suggests ratios remain the same, just the volumes grow, so theoretically this should work out as well...?

Not sure if above makes any sense, ignorant might be an understatement here

RoverP6B · Post by **RoverP6B** » Sat Dec 14, 2013 7:49 pm

It would depend on what you want to use the vehicle for. The 4.6 litre engine, what will it be running in?

Personally, I would not use a camshaft designed for a 3.5 litre engine in a 4.6 litre.

I run a 4.6 litre with a distributor, regraphed for the engine, in my Rover. The camshaft was custom made, the profile designed for the 4.6, but ground onto a blank featuring a nose.

Ron.

Blown v8 · Post by **Blown v8** » Sat Dec 14, 2013 8:09 pm

Mines a 4.6 block,SDi heads(bowls re shaped ) SDi front cover,distributor,
I took my blower cam from my old 3.5,and used it in the 4.6 block,it's now a 5.0L, but still my original cam !
So the answer your after is yes

Jekyll · Post by **Jekyll** » Mon Dec 16, 2013 7:55 am

Thanks for both comments - the engine is going into my little Land-Rover rat rod, a SI 86", so no particular concerns about high performance, this will be just an occassional music for the ears

The heads will be from an SD1, the timing cover from a 3.9, there will be a boxer manifold on top, it's a bit of a bitsa really

Jekyll · Post by **Jekyll** » Wed Jan 22, 2014 11:33 am

Looking for 3.5 SD1 camshaft/valve timing figures - any ideas for figures best-suited for my intended hotch-potch combination of parts?

Off to look for a Haynes manual as every place I googled seems to point the uninitiated to the Holy Book of Haynes.

sidecar · Post by **sidecar** » Wed Jan 22, 2014 5:22 pm

If you don't care about performance that I don't see why a 3.5 would not work (unless its knackered). Your heads are going to lower your CR anyway so you will also loose performance from that.

Jekyll · Post by **Jekyll** » Wed Jan 22, 2014 5:31 pm

In fact we decided to use 4.6 heads instead. Aren't we all doing it mostly for the fun of it rather than as an effort for the maximum possible specifications?

Yesterday's status report:

Jekyll · Post by **Jekyll** » Thu Jan 23, 2014 1:45 pm

Found this while googling:

According to Haynes the valve timing for an early 3.5 is as follows:

Inlet opens 30 Deg BTDC
Inlet closes 68 Deg BBDC
Duration 285 Deg's
Peak opening 112 Deg 30min ATDC

Exhaust opens 68 Deg BBDC
Exhaust closes 37 Deg ATDC
Duration 285 Deg's
Peak opening 105 Deg 30 Min BTDC

Later 3.5's changed and then there were further revisions for the EFI engines. The valve timing for a standard 3.9 is as follows:

Inlet opens 32 Deg BTDC
Inlet closes 73 Deg ABDC
Duration 285 Deg's
Valve peak 104 Deg ATDC

Exhaust opens 70 Deg BBDC
Exhaust closes 35 Deg ATDC
Duration 285 Deg's
Valve peak 114 Deg BTDC

Does anyone have these data for SD1 V8 with carbs? Thanks for your time

DaveEFI · Post by **DaveEFI** » Thu Jan 23, 2014 5:58 pm

My BL manual for the S2 SD1 says:-

IO 30 BTDC
IC 75 ABDC

EO 68 BBDC
EC 37 ATDC

Jekyll · Post by **Jekyll** » Thu Jan 23, 2014 7:07 pm

Thanks, Dave, much appreciated!