71 GMC Longhorn, compatible engine and transmition - Page 2 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**davischevy** · 12-06-2018, 10:06 PM

Good eye.

trac209 · 12-06-2018, 10:41 PM

I would definitely rebuild the engine and trans. Both have readily available parts and that 402 will have all the power you will ever need.

JerryIndy2112 · 12-09-2018, 04:43 PM

These are carb #

JerryIndy2112 · 12-09-2018, 04:44 PM

Well, here they are

Ozark Tim · 12-09-2018, 04:56 PM

That is off a 73 with a 454
Your original would have been like a 7041208

**jocko** · 12-09-2018, 04:57 PM

7043507 = 73 454 C20/30 with CA emissions
OOPS! sorry, simo post

JerryIndy2112 · 12-09-2018, 05:08 PM

Ok, still a similar carb. Will that change anything about rebuild kit. I will rebuild it next month or so.

**Steeveedee** · 12-09-2018, 10:18 PM

The rebuild kit will likely be the same. But the metering rods, jets and some internals will be slightly different. There is roughly a 10% difference in the demand that the engine will place on the carburetor, for a 402 Vs a 454. To me, that's a pretty big difference. That's why there are so many part numbers. I'd recommend talking to a carburetor rebuild specialist to make sure that you are dialing it in for your application, and why having the correct part number (properly rebuilt) is important. It may work just fine for you, because you're not drag racing. But having the right equipment can give you the best mileage possible (for instance). It might cost $300 to get there, but at the price of fuel, it will pay for itself pretty quickly.

12-06-2018, 10:06 PM	#26
davischevy Senior Member Join Date: Sep 2008 Location: Harrison, Arkansas Posts: 9,786	Re: 71 GMC Longhorn, compatible engine and transmition Good eye. __________________ other Larry Build thread, Arkansas K10 https://67-72chevytrucks.com/vboard/...=755797&page=5 The ability to speak several languages is an asset, but the ability to keep your mouth shut in any language is priceless.

12-06-2018, 10:41 PM	#27
trac209 Registered User Join Date: Dec 2011 Location: winnipeg Posts: 1,107	Re: 71 GMC Longhorn, compatible engine and transmition I would definitely rebuild the engine and trans. Both have readily available parts and that 402 will have all the power you will ever need.

12-09-2018, 04:43 PM	#28
JerryIndy2112 Registered User Join Date: Nov 2018 Location: Indianapolis Posts: 130	Re: 71 GMC Longhorn, compatible engine and transmition These are carb #

12-09-2018, 04:44 PM	#29
JerryIndy2112 Registered User Join Date: Nov 2018 Location: Indianapolis Posts: 130	Re: 71 GMC Longhorn, compatible engine and transmition Well, here they are Attached Images

12-09-2018, 04:56 PM	#30
Ozark Tim Registered User Join Date: Aug 2004 Location: Oakville, MO Posts: 1,018	Re: 71 GMC Longhorn, compatible engine and transmition That is off a 73 with a 454 Your original would have been like a 7041208

12-09-2018, 04:57 PM	#31
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,933	Re: 71 GMC Longhorn, compatible engine and transmition 7043507 = 73 454 C20/30 with CA emissions OOPS! sorry, simo post

12-09-2018, 05:08 PM	#32
JerryIndy2112 Registered User Join Date: Nov 2018 Location: Indianapolis Posts: 130	Re: 71 GMC Longhorn, compatible engine and transmition Ok, still a similar carb. Will that change anything about rebuild kit. I will rebuild it next month or so.

12-09-2018, 10:18 PM	#33
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,082	Re: 71 GMC Longhorn, compatible engine and transmition The rebuild kit will likely be the same. But the metering rods, jets and some internals will be slightly different. There is roughly a 10% difference in the demand that the engine will place on the carburetor, for a 402 Vs a 454. To me, that's a pretty big difference. That's why there are so many part numbers. I'd recommend talking to a carburetor rebuild specialist to make sure that you are dialing it in for your application, and why having the correct part number (properly rebuilt) is important. It may work just fine for you, because you're not drag racing. But having the right equipment can give you the best mileage possible (for instance). It might cost $300 to get there, but at the price of fuel, it will pay for itself pretty quickly. __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA



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