Can you tell BB cars apart?

Are there any differences from L34 to L78 BB cars other than the obvious?I mean things like sending units for example,or would it be impossible to tell them apart without paper work or original drive train.

Paul

Greetings,

Without the drivetrain you could measure motor mounts, but other than that and the obvious (heater box and such) I don't think there's really any other way to know for sure. Your best bet is to find a build sheet of some-sort.

Jason

L34 is BB as well Jason.

For the standard hardware, your only clue - if you're sure everything else is correct for a factory big block - is to look at the fuel lines assuming they are still original.

An L78 will have a single 3/8" line. An L34 will have a dual line setup - a 3/8" feed and small 1/4" return.

If the car has the optional factory tachometer, the yellow/redline will be the next clue. There is a difference between the L34 ad L78.

Allen

Check the fuel line clips. Often people delete the return fuel line. But reuse the old clips. L78 clips will not have the extra slot on the bottom for a return line. Earl

Thanks Allen 396 & MNYenko thats what I was hoping to find out.

Paul

An L78 will have a single 3/8" line. An L34 will have a dual line setup - a 3/8" feed and small 1/4" return.Just curious. Why would an L34 have a fuel return line and not an L78?

Just curious. Why would an L34 have a fuel return line and not an L78?

GM used a return line on the Q-jet four-barrel carbs (L34 396/350hp and L48 350/300hp) but did not use one on the Holley 4-barrel (L78).

A factory SS 350 should also have the dual lines.

I don't know enough about the differences in the carbs to explain why the difference in fuel lines.

An L78 will have a single 3/8" line. An L34 will have a dual line setup - a 3/8" feed and small 1/4" return.
Allen

So this 75 I just bought has a single 3/8" fuel line, does that make it an L78?
:D :D

GM used a return line on the Q-jet four-barrel carbs (L34 396/350hp and L48 350/300hp) but did not use one on the Holley 4-barrel (L78).

A factory SS 350 should also have the dual lines.

I don't know enough about the differences in the carbs to explain why the difference in fuel lines.Gotcha! Thanks!

Just curious. Why would an L34 have a fuel return line and not an L78?

The L78 uses all the fuel there is none to return LOL!!!!:eek:

So this 75 I just bought has a single 3/8" fuel line, does that make it an L78?
:D :D

Sure it does....one of one!!!:D

wilma

I'm not sure how far this research topic ever made it but there may be a difference in number of leafs in the rear springs between the two. My original springs on my L-34 had 4 leafs and so does a friends L-34 here.

That should be F41 suspension option 5 leaf is F40.

My friend's L-34 has the rear sway bar and 4 leafs.

Yes that is F41 heavy duty suspension.

The return fuel line was a polution control item. Solid lifter L78 motors would have had a smog pump. So no need for return fuel line. Earl

My 68 has 5 leafs on driver and 6 leafs on pass side. single 3/8 fuel line and it don't like to stop quick or turn fast....:D

Biggest difference is that L78's are usually only seen from the rear. Many people take pictures of the back of L78 cars so they know what to chase...:D Black paint only makes them faster....:rolleyes:

Tommy:)

My 68 has 5 leafs on driver and 6 leafs on pass side. single 3/8 fuel line and it don't like to stop quick or turn fast....:D

Biggest difference is that L78's are usually only seen from the rear. Many people take pictures of the back of L78 cars so they know what to chase...:D Black paint only makes them faster....:rolleyes:

Tommy:)

Hey Tommy.....when ya git a second, could ya send me some of that stuff yer smoking? I'm just about out.:eek: :D


Don

Hey Tommy.....when ya git a second, could ya send me some of that stuff yer smoking? I'm just about out.:eek: :D


Don

At least we know it's good?

Could anyone post some pics of L34 return line?

Thanks Paul

How many pictures do you need?

http://www.chevynova.org/RonBentz/NNN291.jpg.html

http://www.chevynova.org/RonBentz/NNN298.jpg.html

http://www.chevynova.org/RonBentz/NNN158.jpg.html

http://www.chevynova.org/RonBentz/NNN086.jpg.html

Holy talk about fast.

Thanx Paul

When I first bought my 69 big block car, it had a Holley carb, an electric fuel pump, and the fuel return line was not hooked up. One part at a time, I put it all back to stock. With a Q-Jet carb installed, but without the return fuel line hooked up, there was a vapor lock problem. The engine wouldn't idle when hot. I lived with it like that for several years. Hooking up the stock type fuel filter with the return line completely cured the problem.

When I first bought my 69 big block car, it had a Holley carb, an electric fuel pump, and the fuel return line was not hooked up. One part at a time, I put it all back to stock. With a Q-Jet carb installed, but without the return fuel line hooked up, there was a vapor lock problem. The engine wouldn't idle when hot. I lived with it like that for several years. Hooking up the stock type fuel filter with the return line completely cured the problem.

Really?! Wow, that's great information to know! My L34 has that same vapor lock issue occasionally, and no return-line fuel filter setup.

I believe the F41 package is the 5 leaf springs.
M

My 70 L78 car had the original 4 leafs in it and the F41 (sway bar package) as well. If you look at them closely, the individual leaves are thicker than the leaves on the 5 pack, just my 2 pesos SULLY

Really?! Wow, that's great information to know! My L34 has that same vapor lock issue occasionally, and no return-line fuel filter setup.

Allen,
With my stock fuel line and fuel filter setup I never had a problem and I spent a long time at idle at Car Craft a few years ago in 90 plus degree heat!
That's what I thought Marlin that the Yenkos had 5 leafs with the sway bar.

I could be wrong ,but I pretty sure F41 has 4 leaf and G32 is 5 leaf.Kinda strange that the heavy duty stuff is 4 and the regular is 5.

Yea, I can only go by what I've seen on the '70 Yenko Deuces - all are 5 leaf with F41 - and my '69 BB car, also 5 leaf but no F41 to my knowledge. I agree that the 4 leaf version has thicker leafs than the 5 leaf version - why they didn't just stick to one or the other is beyond me :(
M

what option is mine ? Six on pass and five on driver side. :confused:

Tommy:)

I believe that was the optional Hillbilly package. It should have come with maxed out air shocks and N50-15 on chrome reversed wheels also.

All this info was to help figure out this new BB car and I think my new car is an L78 car there is no return line only single line out.

Thanks Paul

I believe that was the optional Hillbilly package. It should have come with maxed out air shocks and N50-15 on chrome reversed wheels also.



YEEEEEE HAAAAWWWWW :D :D

Tommy:)

Unfortunately on this site no thread is safe from levity.:D :p