The Ford Barn

Jack Innes · 05-15-2010, 02:47 PM

Hello, Has anyone had any experience with the primer system often seen on early race cars that is composed of a hand pump and one or more fittings threaded into the intake maniflod? My main question regards the manifold fittings - are they just normal fittings or some kind of nozzles?

The attached picture shows an engine that is almost impossible to start by hand. Once running the BB1 carb is gravity fed & works very well with the added length on the manifold. A primer would help, I think.

Layden B · 05-15-2010, 03:12 PM

Unless you have an impulse coupling on your magneto, you may not be able to spin the engine fast enough to get a spark.

Layden B · 05-15-2010, 03:15 PM

A primer system does just the same as the choke on your carb. It richens the mixture. Pre 1920 there were some carbide gas priming and starting systems but I am sure you don't want to get into that.

Jack Innes · 05-15-2010, 04:56 PM

Thank you Layden, There is an impulse coupling on the Bosch mag & good spark. The engine starts fine when it has been runnning recently since there is still mixture in the cylinders but after sitting over night you need to "windmill" the engine through a few revolutions to draw the mixture up the long manifold even with the choke on & a couple of shots of the accelerator pump. This engine has high compression pistons as well as the RAJO head & is fairly fresh & tight. I would rather squirt some gas into the manifold than any more nitro under my tongue!

I have seen an acetylene starting system & you are correct, I do not want anything like that.

This engine runs out well & has done so for several years. The starting became a problem when I added the brass extension to eliminate an electric fuel pump. The "Ram" effect of the long manifold is quite noticeable as well. I have added a starter
to get around the cold starting problem.

Layden B · 05-15-2010, 06:41 PM

Try the age old Model T trick of reving the engine a bit then turn off the ignition. This will prime the cylinders with more gas than stopping on dead idle and be more likely to start up next time even if left to get cold.

Jack Innes · 05-16-2010, 09:09 AM

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Attached is a picture of a fuel primer. This one was made by Lukenheimer.
Many older light aircraft have these to aid in hand starting. I am looking for 2 pumps plus whatever the fitting(s) should be in the manifold.

05-15-2010, 03:12 PM	#2
Layden B Senior Member Join Date: May 2010 Posts: 300	Re: Manifold Primer Unless you have an impulse coupling on your magneto, you may not be able to spin the engine fast enough to get a spark.

05-15-2010, 03:15 PM	#3
Layden B Senior Member Join Date: May 2010 Posts: 300	Re: Manifold Primer A primer system does just the same as the choke on your carb. It richens the mixture. Pre 1920 there were some carbide gas priming and starting systems but I am sure you don't want to get into that.

05-15-2010, 04:56 PM	#4
Jack Innes Senior Member Join Date: May 2010 Location: Brooklin, Ontario Posts: 704	Re: Manifold Primer Thank you Layden, There is an impulse coupling on the Bosch mag & good spark. The engine starts fine when it has been runnning recently since there is still mixture in the cylinders but after sitting over night you need to "windmill" the engine through a few revolutions to draw the mixture up the long manifold even with the choke on & a couple of shots of the accelerator pump. This engine has high compression pistons as well as the RAJO head & is fairly fresh & tight. I would rather squirt some gas into the manifold than any more nitro under my tongue! I have seen an acetylene starting system & you are correct, I do not want anything like that. This engine runs out well & has done so for several years. The starting became a problem when I added the brass extension to eliminate an electric fuel pump. The "Ram" effect of the long manifold is quite noticeable as well. I have added a starter to get around the cold starting problem.

05-15-2010, 06:41 PM	#5
Layden B Senior Member Join Date: May 2010 Posts: 300	Re: Manifold Primer Try the age old Model T trick of reving the engine a bit then turn off the ignition. This will prime the cylinders with more gas than stopping on dead idle and be more likely to start up next time even if left to get cold.