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Damon Lewis' 1977 Can Am

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4 barrel intake for 1978 301 engine


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Is there a four barrel intake that Pontiac made for the 301 cubic inch V8? I’ve got a 1978 Pontiac Bonneville Brougham four door sedan and was wondering if there was a factory 4 barrel intake. I still have the 2 barrel intake but would like to get more power out of this little engine as much as possible

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  • 3 weeks later...

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Pontiac did make a 4 barrel for the 301. Message me, I can help you out

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That is correct - Pontiac did make a 4-barrel intake for the 301 for the Trans Ams and Turbo Trans Ams but you have to use the one specific to the 301 or 265 V8s and not one for the more common 326-455 engine family. The 265/301 has a shorter deck height and a number of other changes that were made to save weight and be more fuel efficient after the 70s Arab Oil Embargo. As a result, a regular 4-bbl intake won't fit properly.

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  • 4 weeks later...

Frosty,

 

     I was tuning up my engine in my 1978 Pontiac Bonneville Brougham the other day and I noticed that I in fact do have a 4 barrel intake with a 2 barrel adapter with the EGR valve mounted to the adapter behind the carburetor. What would need to be done to mount a 4 barrel carburetor on this engine? It’s a Y code engine and it is factory original 2 barrel but I understand that the W code engine was a factory four barrel. Is it possible the intakes were different between the Y and W code engines even though the Y code has an adapter for the 2 barrel?

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Is the carb that's on it a dual jet? If it is, that funky spacer/adapter is still on a 2 barrel intake. Not sure what the purpose was for doing this instead of just having a normal 2 barrel carb on it. If it is a 4 barrel intake with a 2 barrel adapter then that saves you the hassle of finding a 301 4 barrel intake. The 4 barrel doesn't make a big difference performance wise. On my 77 Grand Prix 2 1/4 dual exhaust and rear gears made a bigger difference. 

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What ratio of gears did you use? I thought of seeing if a 2.72-1 ratio would fit the housing. That gear set was used in the Chevy pickups that had the Oldsmobile 350 Diesel engine. I had a 1978 Silverado that came from the factory with the 350 diesel but I installed a 1962 327 with two bolt main bearings that had a two barrel carburetor and it was really good on fuel coupled with that gear set and the turbo 400 transmission

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I had 2.41 gears, now running 3.23's. Got a rear end, rebuilt it and then installed it. That way car was only tore apart for 3-4 hours. Acceleration is much better and still cruise on the highway without revving it to high.

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On 6/18/2021 at 10:23 PM, 1978 Bonneville said:

Frosty,

 

     I was tuning up my engine in my 1978 Pontiac Bonneville Brougham the other day and I noticed that I in fact do have a 4 barrel intake with a 2 barrel adapter with the EGR valve mounted to the adapter behind the carburetor. What would need to be done to mount a 4 barrel carburetor on this engine? It’s a Y code engine and it is factory original 2 barrel but I understand that the W code engine was a factory four barrel. Is it possible the intakes were different between the Y and W code engines even though the Y code has an adapter for the 2 barrel?

I suspect the reason for the 2-barrel intake to 4-barrel carb was the difficulty in finding a 4-barrel intake for a 301. There are no afternmarket 4-barrel intakes that I know of for the 301. A company called TTA Performance now specialized in performance mods to the 301. They may be able to help you find one.

https://ttaperformance.com/

On 6/19/2021 at 12:00 AM, 1980Ttops said:

Is the carb that's on it a dual jet? If it is, that funky spacer/adapter is still on a 2 barrel intake. Not sure what the purpose was for doing this instead of just having a normal 2 barrel carb on it. If it is a 4 barrel intake with a 2 barrel adapter then that saves you the hassle of finding a 301 4 barrel intake. The 4 barrel doesn't make a big difference performance wise. On my 77 Grand Prix 2 1/4 dual exhaust and rear gears made a bigger difference. 

Mostly like the person could not find a 4-barrell intake for the 301. They are hard to find if you can't find a wrecks Turbo Trans Am in a bone yard. Pontiac's intakes are really rather good. Pontiac was able to take the 135 HP 2-barrel 301 and take it to 155 HP with a 4-barrel naturally aspirated, and 210 with the turbo.

On 6/20/2021 at 3:09 AM, 1978 Bonneville said:

What ratio of gears did you use? I thought of seeing if a 2.72-1 ratio would fit the housing. That gear set was used in the Chevy pickups that had the Oldsmobile 350 Diesel engine. I had a 1978 Silverado that came from the factory with the 350 diesel but I installed a 1962 327 with two bolt main bearings that had a two barrel carburetor and it was really good on fuel coupled with that gear set and the turbo 400 transmission

A tall gear (numerically lower) gear ratio is great for highway mileage and economy but terrible for racing or pure seat of the pants satisfaction. So 2.72:1 is great for highway mileage but horrible for drag racing or getting off the line quickly. Lowering the ratio to somewhere between 3.23 and 3.73 will be a good compromise.

On 6/20/2021 at 8:07 AM, 1980Ttops said:

I had 2.41 gears, now running 3.23's. Got a rear end, rebuilt it and then installed it. That way car was only tore apart for 3-4 hours. Acceleration is much better and still cruise on the highway without revving it to high.

3.23 is a good gear. I prefer the 3.55 I have in my Lemans but that is a matter of preference. If I decide to add an overdrive transmission, this will work out very well.

Edited by Frosty
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There is a guy on Louisville Craigslist with a 301 4 barrel intake for sale, post ID number 7329444771. He is willing to ship, he is a straight up fella. I know that the intake is in good shape, I traded it to him. His phone number is in the post. 

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That's the one, I should of posted the entire link to make it easier to find. 301 4 barrels are becoming harder to find, probably won't last long.

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Yeah, reading the post, it is not obvious that he is selling a 301 4-barrel intake manifold. He doesn't state that in the text of the ad either.

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