Distributor driven directly from crankshaft or via camshaft/chain???

[donnchad]

For 351 1990 5.8L V8 EFI engine is the distributor rotor driven:

(a) directly from crankshaft?????
OR
(b)Is it driven from chain driven camshaft?????

 

[Fellro]

Camshaft is driven by the crank by chain at 1/2 rotation, which then drives the distributor

 

[donnchad]

Camshaft is driven by the crank by chain at 1/2 rotation, which then drives the distributor

Thank you. So you are saying (b) is the correct answer???

 

[SuperCab]

Yes B would be correct

 

[donnchad]

It would be best to direct drive from crank. Chains are never great. Why not do all timing using gear drives direct from crank??? More accurate and less wear and noise?????

 

[Fellro]

Location, location, location... If you crank drive it, the distributor then has to be down low, generally in front. Also, the distributor relates more to valve opening than piston location really. The distributor needs to turn at half the rate the crank does, as does the camshaft, so the gear reduction is also already handled. Can you imagine the size the gear would have to be to get a 1/2:1 reduction?

 

[CowboyBilly9Mile]

It would be best to direct drive from crank. Chains are never great. Why not do all timing using gear drives direct from crank??? More accurate and less wear and noise?????

It's been done, it was in a line of Chevy str8 sixes from the early 60's known as Turbo Thrift and yes, noise was one of the concerns with the two-gear setup. The best solution actually is a direct drive from the crank, it's been done for several years now, it's what technology delivered (eliminated wear parts replacement, eliminated an assembly altogether, no timing adjustment needed/accurate timing over life of vehicle, improved driveability, emissions, etc) and the benefits of mass production (low cost) put in the publics hands, this solution is known in the Ford world as EDIS.

 

[Sparky83]

my old truck had the distributor run right off the crank... imo it was the most annoying thing possible... straight 4 and the distributor was buried under the intake... only way to access it was through the wheel well and even then you were working on it in the blind since you couldnt see it once your arm(s) hands were in there... least on the V-cyls engines with the distributor on top and running off the crank you can atleast see what your doing.. makes the job 100000000x easier when trying to get the timing set right...