More Lt-1 questions

[James W.]

Hello folks,

Two questions--let me pick your brains

1.) Is the air cleaner base assembly different on a 1970 Lt-1 vs. the open element air cleaner base on a 1970E 350? The reason being when my 350E base is installed on the Lt-1 carb/manifold set-up, the crankcase vent tube can't reach it's fitting in the right hand valve cover. Do I need a new Lt-1 specific air cleaner base.....or a different elbow and hose? The catalogs seem to suggest there is a specific Lt-1 air cleaner base.....why, is the tube on the bottom of the base longer?

2.) When attempting to re-connect the fuel line from the "y"-block to the fuel pump, the fuel line (the correct Lt-1 line) appears to be too short to reach the location of the 90 degree fitting on the fuel pump. Bear in mind this is the 350 fuel pump, not an Lt-1 fuel pump. Is the 90 degree fitting on the Lt-1 fuel pump in a different position than the 90 degree fitting on the standard 350 fuel pump? If my 90 degree fitting could be rotated about three inches, it would connect up. The standard 350 fuel pump also has three inlet/outlet fittings on it, while the Lt-1 fuel pump appears to have only two fittings...what gives? If I need to swap in the Lt-1 fuel pump in order to connect it up, what happens to that third line?

As always, your help is certainly appreciated!!!! Best Regards, Jim

[Jim T.]

Re: More Lt-1 questions

James the base engine used a QJet spread bore type of carb, your LT-1 had a Holley. I don't know the actual differences in the open element bases for these two carbs.
I do know that the 1970 later model year dual snorkel base for the QJet can be used on a Holley 6210 650 spread bore double pumper with only a slight modification.

[Joe L.]

Re: More Lt-1 questions

Hello folks,

Two questions--let me pick your brains

1.) Is the air cleaner base assembly different on a 1970 Lt-1 vs. the open element air cleaner base on a 1970E 350? The reason being when my 350E base is installed on the Lt-1 carb/manifold set-up, the crankcase vent tube can't reach it's fitting in the right hand valve cover. Do I need a new Lt-1 specific air cleaner base.....or a different elbow and hose? The catalogs seem to suggest there is a specific Lt-1 air cleaner base.....why, is the tube on the bottom of the base longer?

2.) When attempting to re-connect the fuel line from the "y"-block to the fuel pump, the fuel line (the correct Lt-1 line) appears to be too short to reach the location of the 90 degree fitting on the fuel pump. Bear in mind this is the 350 fuel pump, not an Lt-1 fuel pump. Is the 90 degree fitting on the Lt-1 fuel pump in a different position than the 90 degree fitting on the standard 350 fuel pump? If my 90 degree fitting could be rotated about three inches, it would connect up. The standard 350 fuel pump also has three inlet/outlet fittings on it, while the Lt-1 fuel pump appears to have only two fittings...what gives? If I need to swap in the Lt-1 fuel pump in order to connect it up, what happens to that third line?

As always, your help is certainly appreciated!!!! Best Regards, Jim

Jim-----


1) Yes, the tube is different. As a matter of fact, tube configuration and orientation is the main difference between the various "drop down" air cleaner bases. Once-upon-a-time, GM sold an air cleaner base with "loose" tubes and plugs. This air cleaner could be configured for just about any application. It's long discontinued, though.

2) The base 350 for 1970 used a "long canister" style fuel pump. This type fuel pump does have THREE fittings on the base. The larger nipple is for the fuel inlet, the smaller nipple is for the fuel return line, the threaded fitting is for the fuel outlet to carburetor.

The LT-1 did not use a long canister fuel pump (it was the only engine for 1970 that did not). It used a fuel pump with only TWO fittings-----a nipple for the fuel inlet and a threaded fitting for fuel outlet. There was no provision (or frame fuel line) for fuel return. The LT-1 pump did use a long valve chamber for the inlet, though. In any event, to use an LT-1 fuel line from the pump-to-carb, you need to use an LT-1 fuel pump. Any other pump will likely have the outlet in the wrong location to work with the LT-1 fuel line. So, you need to obtain an LT-1 fuel pump which is available.

[Jerry B.]

Re: More Lt-1 questions

Hello What Is The Part Number For The Lt1 Aluminum Intake Thank You

[Joe L.]

Re: More Lt-1 questions

Hello What Is The Part Number For The Lt1 Aluminum Intake Thank You

Jerry-----


I assume you're talking about CASTING number (which appears on the manifold) versus the FINISHED part number (which appears nowhere on the manifold and is usually different than the casting number).

The casting number for LT-1 intakes varies by year. They are as follows:

1970-------3972110

1971-72----3959594

[Jerry B.]

Re: More Lt-1 questions

Bare With Me,i Am Learning How To Navigating The Internet Also Would You Advise The Part Number Thanks

[Joe L.]

Re: More Lt-1 questions

Bare With Me,i Am Learning How To Navigating The Internet Also Would You Advise The Part Number Thanks

Jerry-----

OK, I don't know where you'll be able to "navigate" to with these but here are the PART numbers:

1970-----GM #3972114

1971-72---GM #3991004


The GM #3972114 was replaced in the 80's by GM #14044836. The latter part number is a SIMILAR but not identical manifold.

The GM #3991004 was discontinued without supercession.