Timing chain set

[HOTRODJOHN]

Does anyone know if all the timing chain sets are the same. Are the sets for a 305A thru 305E. I would replace both gears and chain. I have a double roller set for a 305E. Just worried about cam and crank size.Thanks

[bigblockv6]

Depending on years there is a difference, it's been a while since I've looked into it but I think up to 1965 they are the same and it changed in 1966.

[HOTRODJOHN]

Thanks, I have a set for a 305E so when I take it apart and they interchange, I will let you know. Thanks for the feedback.

[HOTRODJOHN]

I am trying to replace the timing chain set, On the 305A it is a Gear type versus a sprocket type. I have a complete set of the sprocket type. Does it matter. when I compare the top gears, the alignment hole for the fuel pump eccentric is in a different place.
I also need a fuel pump what is the difference between the 305A pump and the others. I would appreciate any help I can get. John

[bigblockv6]

If it is a 305A it should already have the chain and sprocket timing set setup, the gear type was used only on 401, 432 and 478 engines. 1965 and earlier engines did have a different fuel pump eccentric, fuel pump and different tooth count on the timing sprockets.

[HOTRODJOHN]

I have a 305E motor which has sprocket type, the 305A motor I have has a gear type. Do you think I could use the sprocket one on the 305A motor as long as it has the same amount of teeth. Also, does it matter on the fuel pump I only see pumps for the E,D motors will it work on the A.
Thanks, John

[bigblockv6]

Never seen a gear driven 305 only bigger V6 engines which have a 3 piece gear drive, I did such a conversion on my 478M V6. I'm using the 1966-74 305-379 type chain and sprockets, what was involved with this conversion was to eliminate the center idler gear which is lubricated with engine oil from the same passages that feed the front main bearings. This required capping off the center idler area with a 1 1/8 expansion plug and for extra insurance I also built a plate to cover up the plug, that will require drilling and tapping one more hole in the block and using countersunk fasteners to make clearance for the chain for best results. Though I did get away with using button head fasteners and it was just enough to clear the chain. I would really like to see the timing gear arrangement of your 305A, do you have any pics? One thing to note if you timing gear setup has just two gears and no idler that would mean the cam is spinning the opposite direction over a chain driven setup, so you will also need the 305E cam for the conversion.:thumbsup:

[bigblockv6]

For the fuel pump just use the 305E pump and eccentric.

[HOTRODJOHN]

Thanks, I think maybe you misunderstood what I was talking about, by gear drive. there are 2 gears, 1 large on the top and 1 small on the crank with the chain. I didn't mean similar to a Pet Jackson Gear Drive. I will get some photos of the set-up. Thanks, John

[bigblockv6]

So basically you have the chain and 2 sprocket setup on the 305A and just want to use the one from a 305E?

[TJ's GMC]

Does it look like this?

[HOTRODJOHN]

5155

5156
THE FIRST ONE IS 305A AND THE 2ND IS A 305E. John

[HOTRODJOHN]

The one you have is the same as the one I have on the 305A. John

[HOTRODJOHN]

Sorry, the one you have is the one I have on the 305E. John

[TJ's GMC]

Mine is a 67 305E. The timing set I got from O'riellys.

[HOTRODJOHN]

Yes, The 305A has a single groove gear and the 305E has a double groove gear (sprocket)
Thanks, John

[HOTRODJOHN]

TJ'sGMC, not to confuse you, the one you have is the same as the one I have on my 305E and I have a complete new set-up already for the (E) motor. Can I use it on the (A) motor, I am changing both gears and the chain. John

[bigblockv6]

Use the setup from the E motor along with the E motor eccentric and fuel pump.:thumbsup:

[HOTRODJOHN]

Thanks for the help. What do I use for an eccentric on the E motor when I rebuild it. I can get another chain set but it's the eccentric I would need. John

[bigblockv6]

What you will need is a 1966-74 GMC V6 eccentric, yes they are the same for all the newer V6 engines from 305E, C, 351C, E & M, 379, 401M, 432 and 478M V6.

[HOTRODJOHN]

where are the available from. The 2 eccentrics I have are the same diameter but the alignment pin on the cam is in a different location in relation to the keyway, John

[TJ's GMC]

Pete beat me to all the answers. :nothingtoadd: :lolsmack2:

[bigblockv6]

The eccentrics are not available new, anyone with parts engines for these engines would be source.

[HOTRODJOHN]

Thanks guys for all the feed back I will try to get the parts on e-bay. John