Heat riser necessary?

[stony]

OK so here is where I am on my �49 project�.  Found out today that both my exhaust and intake manifolds are cracked and need to be replaced.  I am thinking that rather than using a L134 exhaust I would use a F134 exaust, without the heat riser, which was shot on mine anyway.  I am not planning to do any cold weather driving, and I understand that the F exhaust flows better anyway.  I see that there could be a support problem, but I am thinking I could make a brace to support the underside of the intake.  Anyway what do you all think?

[athawk11]

The heat riser isn't necessary if quicker warmups aren't needed.  That said, when working, it does have a "Cool" factor that's hard to beat. 

I haven't seen the modification you're considering.  I'm inclined to stay with the original design, but would be interested to see what you come up with.

[aboyandhisdog]

Before I got my heat riser working years ago, I took several drives with it wired full open and full closed.  Honestly, I could not discern a bit of difference.  I would agree with Hawky though that in cold weather it may be of some benefit. 

[scoutpilot]

I don't think you can fit the L-intake with the F-exhaust. I also think you should have a functioning heat riser valve. Tim is correct about the warm-ups. To a point. In order for the Fuel/Air mixture to burn properly, it must be within a certain temperature range. The valve allows that temperature to be reached fairly quickly. On the other end, a valve that is stuck open, or missing, will allow excessive heat to reach the carburetor and will cause the fuel in the bowl to boil. The resulting pressures inside will force fuel past the Metering Rod and Jet causing flooding of the intake.

[athawk11]

ScoutPilot,
Thanks for the additional education, as always.

In an era of computer controlled relays, I just get a kick out of stuff like the heat riser mechanism.   

[aboyandhisdog]

I don't think you can fit the L-intake with the F-exhaust. I also think you should have a functioning heat riser valve. Tim is correct about the warm-ups. To a point. In order for the Fuel/Air mixture to burn properly, it must be within a certain temperature range. The valve allows that temperature to be reached fairly quickly. On the other end, a valve that is stuck open, or missing, will allow excessive heat to reach the carburetor and will cause the fuel in the bowl to boil. The resulting pressures inside will force fuel past the Metering Rod and Jet causing flooding of the intake.

Very possibly why the heat riser had zero effect for me...I use a Solex.   

[scoutpilot]

Not much longer I hope.

[aboyandhisdog]

I know, Scout...maybe some day I will see that engine with a sweet WO on top!  But I'm afraid maybe not anytime soon.  Gotta be patient, right?

[stony]

Thanks for the input.  I have two L134 exhausts and both are cracked.  I am going to braze the crack in the better of the two, to at least get me to a point where the engine runs.  Going to have to buy an intake.  The riser flap was frozen solid, so I am going to plug the holes and make a thin sheet metal block off plate under the intake for the time being.  The other interesting thing that I am thinking about is, I have a YF carb off of my Jeepster L134.  I wonder if that might not be a better carb.  Will have to take a look at both it and my WO.  I�ll try to take some side by side photos.

[aboyandhisdog]

I never knew that the L134 in the Jeepster used the YF.   I didn't think a YF would work on the L134.  ScoutPilot is going to be your go-to guy on that!

[stony]

Yeah I have read that the YF. Was not suitable for the L134.� I was pretty sure the Jeepster had one.� It turns out that the YF was used.� The head on my Jeepster L134 is the same 61 head as my 3A.� The two engines appear to be identical except for the oil pan, distributor (vacuum advance) and intake and carb.� The YF (left) has an obviously larger diameter opening in the base.� I have no doubt that the YF is factory original, so it obviously IS suitable for the L134.� It may have some internal difference with the YF used on the F134 but externally they are the same.
A little more info.� It is a #738SA which may be different than the F134 carb number.
Another interesting thing is that I have not been able to find a carb kit or listing for the YF for a L134, only for the F.  Interesting.

[Lee]

Yes the YF was stock on a Willy�s jeepster, DJ, Henry J. The manifold and throttle linkage is far different than a stock 2A/3A as you can see on the manifold in your photo. I�ve seen the base holes elongated on a YF to fit a W-O manifold but the opening in the manifold is also smaller and I�m not sure your going to see any great gain from it. You will also see the throttle shaft on the YF runs parallel with the crankshaft when mounted on is proper manifold, the W-O runs perpendicular to the crankshaft when mounted on its proper manifold!... Do as you wish, the good people who designed this settup were very smart and creative, I doubt you�ll outdo them [ch128514]

Lee

[stony]

One of the reasons I was curious about the YF is this article http://www.willys-overland.com/Hickey/hotrodL134.pdf where Vic Hickey used a YF and Henry J manifold on a �hopped up� L134.� Just interesting reading