Adjusting the fuel pressure on a mechanical pump

Dan B. · Post by **Dan B.** » Fri Dec 18, 2009 6:35 pm

Some time ago while surfing vw sites, I came across an interesting thread and was wondering if it was possible. This particular person said he adjusts the fuel pressure on his mechanical fuel pump without the use of a fuel regulator. The guy says he adjusts the pressure thru the use of additional fuel pump gaskets. He claims the pressure straight out of the box with one gasket (normal installation method) between the new pump and the plastic base below the pump was 3.5 psi. Installing an additional gasket lowered the pressure to 2.3 psi. Adding an additional gasket (3 gaskets now) lowered the pressure to 1.3 psi. He reasoned adding additional gaskets reduced the stroke on the pump rod. This caught my eye because I am installing a 1776 motor with a pair of kadrons, and 1.3 psi is near the pressure where the kads run the best (1.5psi). I have heard from others if you can avoid a installing a pressure regulator do it. What do you guys think about the additional gasket idea? Dan

GotManx · Post by **GotManx** » Fri Dec 18, 2009 6:59 pm

That's an interesting way of trying to adjust the pressure. I've always used the cheap adjustible pressure regulators and they have worked fine. The numbers on them do not always correspond with the actual pressure, so I usually keep changing the dial until gets to a point where it seems to work well. I guess you could do the same with the extra gaskets, try two and see if that works and if its not low enough add another one.

theManiac · Post by **theManiac** » Fri Dec 18, 2009 9:35 pm

Hey Dan, I did the same thing on the 1600cc engine in our buggy "Xena" & the 1904cc in our 71 VW Bus "Lucy"! Both sets of my Kadrons were prepped by "Mr. Kadron" aka AJ Sims. He recommends using a fuel pressure regulator, however, he acknowledged that the "gasket trick" has worked many times before too. I added 2 extra gaskets to each one & have not experienced any "high fuel pressure" problems, normally associated with a stock mechanic fuel pump.

Dan B. · Post by **Dan B.** » Fri Dec 18, 2009 10:30 pm

Howdy Michael, Funny you brought up AJ Sims. He setup my kads which are still waiting for me to run them for the first time. I like the extra gasket idea, I just need to get a pressure gauge going when I run the motor and see where I am stock pressure wise. Which linkage are you using? Stock or his Lowbugget unit?

theManiac · Post by **theManiac** » Fri Dec 18, 2009 10:45 pm

I never did check the fuel pressure of either fuel pump, just added the extra 2 gaskets & have never had a problem. On both vehicles I'm using the SCAT linkage, which is what AJ recommended, before he started having the Lowbugget linkage made. Also, I do not run the cross-over tube between the carb manifolds on either one. I also have the fuel bowl vent extensions on both sets. Both sets of carbs have performed flawlessly, about 30,000 miles on Xena & 20,000 miles on Lucy.

Dan B. · Post by **Dan B.** » Fri Dec 18, 2009 11:05 pm

Glad to hear your kads have been working so well. I had my kads tuned with the vent kit along with his "air top kit". Any chance of a picture or 2 of your scat linkage? I am thinking of switching over to the scat also and am curious how the linkage bolts up in the engine block/ carb area. Thanks.

Dave & Gail · Post by **Dave & Gail** » Fri Dec 18, 2009 11:07 pm

Dan, there is a good feature in Dune Buggies and Hot VW mag April issue.

Dan B. · Post by **Dan B.** » Sat Dec 19, 2009 12:25 am

Dave & Gail, Wow, That article pretty much hits it right on the head, my question and the answer. In fact it brings to light more fuel delivery issues. Thanks for the heads up on the article.