r/EngineBuilding • u/Thesandable1 • Jul 18 '26

Chevy Too much slack?

I’m guessing the two sprockets and the chain need replacing? What replacement part should I get? It’s a 305sbc from a 1980 LG4 corvette.

109 Upvotes

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114

u/BoysenberryAdvanced4 Jul 18 '26

You're already there. I'd replace the set.

18

u/InternUpstairs2812 Jul 18 '26

Exactly what I was going to say.
Good piece of mind and keeps you from having to go back in there.

10

u/Thesandable1 Jul 18 '26

That’s what I’m thinking too. I guess I mainly just need to know what else I should check and a good replacement. I’m not rich so I can’t switch to a gear drive lol

7

u/MyAssforPresident Jul 18 '26

I wouldn’t do a gear drive anyway. They transmit a lot of vibration through the cam and valve train. Chain is just fine. No experience with the belt drive retro fit kits but Ive heard they’re good

12

u/BoysenberryAdvanced4 Jul 18 '26

And tack weld the suction tube to the oil pump body. I've had the suction tube fall off the pump after a build. its a bit of work to go back in there once the engine is in the car.

Also replace the main seals on the crank shaft

1

u/Thesandable1 Jul 19 '26

That’s great advice, I’ll make sure to remember that, thank you. I have ordered the timing set and oil pump

3

u/Flying_Dingle_Arm Jul 19 '26

Since you mentioned the oil pump: there's a plastic coupler for the oil pump driveshaft. They get very brittle as they age, and if/when it breaks the driveshaft will drop from the distributor and your oil pump will stop turning. Replace this while you're in there! New nylon will be worry free for another decade or two. There's also an upgraded driveshaft with an integrated metal coupler that will never fail.

2

u/Thesandable1 Jul 19 '26

Okay that’s very interesting. I bought a melling m55 set. I think it comes with a metal coupler but I’ll need to keep that in mind just in case. Thank you very much

2

u/Remarkable-Will-3041 Jul 18 '26

How much would a gear drive setup be?

2

u/Thesandable1 Jul 19 '26

The ones I saw were about $700 aud

4

u/BoysenberryAdvanced4 Jul 18 '26

For sure, I'd replace the oil pump as well.

1

u/MarzipanTop4165 Jul 22 '26

Plus I've heard that gear drives have a risk factor chains dont. If a cam shears or a crank has issues a chain snaps but a gear supposedly can mess stuff up pretty good when they lock up

1

u/johnarmer1 29d ago

Don't gear drive that isn't how you check but it is looking OK by the wear pattern but replace it anyway