6066 (1960-1966) GMC Truck Club

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-   -   Timing chain set (https://6066gmcclub.com/showthread.php?t=49516)

HOTRODJOHN July 24th, 2016 12:42 AM

Timing chain set
 
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 July 24th, 2016 01:15 AM

Re: Timing chain set
 
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 July 24th, 2016 05:45 AM

Re: Timing chain set
 
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 August 16th, 2016 03:10 AM

Re: Timing chain set and fuel pump
 
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 August 16th, 2016 03:56 AM

Re: Timing chain set
 
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 August 16th, 2016 04:10 AM

Re: Timing chain set
 
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 August 16th, 2016 04:30 AM

Re: Timing chain set
 
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 August 16th, 2016 04:32 AM

Re: Timing chain set
 
For the fuel pump just use the 305E pump and eccentric.

HOTRODJOHN August 16th, 2016 05:15 AM

Re: Timing chain set
 
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 August 16th, 2016 06:07 AM

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


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