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Old June 3rd, 2016, 09:53 PM
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TJ's GMC TJ's GMC is offline
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Join Date: Mar 2015
Location: Cave Junction, Oregon
Truck: 1964 GMC 1500 LWB Wideside 305E V6.
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Default Re: 305E Intake mod.

Been driving Crustine everyday to work and back and so I thought I'd do a review:

So, a stock 67 305E engine was advertised at 152 hp and 280 torque(?). That's with a small 2 barrel and small single exhaust.

My 1st step was a 600 cfm edelbrock adapted to my 305's 2 barrel intake using and old MR. Gasket 4 to 2 adapter. I figure about a 20 hp and 15 torque increase. Also a little more mid-rang and top end. But to much carb for single exhaust. So about 172 hp and 300 torque.

2nd step was dual 2.25 exhaust with flowmaster 40 series mufflers and 2.5 tail pipes. An increase was also felt with that as well....bout another 15 hp and 10 torque. So estimated power from last would be 189 hp and 310 torque.

Now the final. Scouted a 351M intake and milled it out. And again I felt a rather Large increase....I'm gonna say another 25 hp and 15 torque because it was noticeable. So 214 hp and 325 torque now after the manifold mod.

Could I be to high? Probably....but that motor is producing Much more power than before. And it's the baby!

Little more review......
Starting is Super easy. Two pumps of the gas and full choke...half a turn and it's sitting at a 1000 rpm warm up idle. I normally push the choke in to let it warm up at 700....anyhow, starting is effortless. Cold idle is 500 warm is 700.

Did do a plug check and plugs are burning the fuel nicely.

So was all this worth it for a 305 V6? I think so. The power increase justifies the work involved in my opinion.

And Yes a Magnum intake will bolt directly onto non-magnum heads. You will want to use 305 intake gaskets though.

Well that's it guys! Anything else you wanna know just ask....I think next I'm gonna make headers or try some magnum manifolds. I need a stinkin dyno!
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"Excuse the rust I use my truck"
1964 GMC 1500 305E/sm420 4 barrel intake mod and dual exhaust.
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