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Old August 23rd, 2023, 04:24 PM
Prowbar Prowbar is offline
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Join Date: Dec 2020
Location: Friesland, the Netherlands
Truck: 1965 GMC 1500, 478 V6, SM420
Posts: 386
Rep Power: 183
Prowbar is a jewel in the roughProwbar is a jewel in the roughProwbar is a jewel in the roughProwbar is a jewel in the roughProwbar is a jewel in the roughProwbar is a jewel in the rough
Default Re: '65 GMC 1500 project. From the Netherlands

Over the last few days, I reassembled the engine and front end. Started her up and broke in the cam.

Modified the intake manifold as per James' instructions, thanks for the tips James.

Took her out for a test drive. This thing pulls like a freight train... Literally twice the power of the 305. And amazing throttle response. Had her up to 3200 before I blinked. Need a rev limiter badly, going to buy an MSD 8727CT when the vendor here gets it back in stock. This is a HEI rev limiter that can be set between 3000 and 9900, so ideal for this application.

Also found out that these Walker 18230 mufflers choked up the engine pretty badly. They neck down internally. Immediately ordered Walker 17613 mufflers. These have internal baffles but do not neck down. Advertised as Mega Flow. Should be quiet when cruising but loud when you step on it.

Also found out that the SM420 trans can use new bearings... Never noticed it on the 305 because of the lower power output.

The stock clutch seems to hold up though, which kind of surprised me.

Haven't even tested it on gasoline yet, it should have even more power compared to propane.

So to anyone considering rebuilding a 305... Ditch the thing and get a bigger V6... You won't regret it.

Videos to follow.
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