327 questions....250hp vs 300hp

MoboMac · Poncho Master!

327 questions....250hp vs 300hp

4SPEED427 · A Poncho Legend!

250 hp was a 4 GC. I have seen mixed reviews on fuel line size for it but my experience (although it's all newer than 1964) has been 3/8" line on all 327's.

MoboMac · Poncho Master!

Guess I should add...that 64...is the year I'm asking about...

Urban_suburban · Poncho Master!

My factory equipped 327 250 hp have 3/8 fuel line and run through the tunnel on the frame.

CdnGMfan · Canadian Poncho Superstar!

A link that is worth checking out is the GM Heritage site for Vehicle Information Kits: https://gmheritagecenter.com/docs/gm-heritage-archive/vehicle-information-kits/Chevrolet/1964-Chevrolet.pdf

Go to page 61 in the PDF file for Fuel System info. It doesn't mention the fuel inlet size, but it does say the 250-horse has a sintered bronze filter in the carb inlet, while the 300-horse has a glass bowl with a paper element. The 250-horse has a square bore carb (Carter AVS or Rochester 4GC?) with a 1.06" primary / 1.25" secondary venturis while the 300-horse has a larger Carter AFB with 1.25" primary / 1.56" secondary. Manual vs. auto affects carb selection as well.

MoboMac · Poncho Master!

Thanks for everybodys input....

I bought a 64 CS....with non-original motor.....with a 3/8" line......guess I will run the #'s through Oshawa....and find out....for sure...

4SPEED427 · A Poncho Legend!

Let me check my book before you spend the money Brian.

4SPEED427 · A Poncho Legend!

Well, looking in the parts book at least, I see where the fuel line parts seem to be different for 283 and 327, although it never specifically states 3/8" or 5/16". I can't imagine why there would be a difference in the fuel pipe clips etc other than the size though. Even the tank sending unit is different, although there it says with or except dual exhaust. Are all 300hp dual? Are all 250hp single?

MoboMac · Poncho Master!

The 300hp was dual exhaust.....and I can't believe that a 4bbl 327 would have come with single exhaust...250 OR 300hp.

I'm thinking the 300hp had 2 1/2" front pipes.....

OURWAGON · Guru

MoboMac wrote:
The 300hp was dual exhaust.....and I can't believe that a 4bbl 327 would have come with single exhaust...250 OR 300hp.

I'm thinking the 300hp had 2 1/2" front pipes.....

300 had the 2/12 with afb and 250 hp was 2 inch with 4gc

DonSSDD · Canadian Poncho Superstar!

In the older than 64 x frames, the dual exhaust cars ran the line through the tunnel and under the passenger side control arm and were 3/8, single exhaust was 5/16 and ran down the outside of the frame at the rear and the inside at the front. If they had a different sending unit, the difference was likely the 5/16 or 3/8 line size.