36 running rich

B

bgalla

Member
This is a 36, entirely stock,21 stud engine with a Stromberg Carb. It runs like a top, but I only get 8-9 MPG. Checking two plugs next too each other they both are black so I must be dealing with a rich mixture. Is this totally the carb? If so what is the most common cause of a rich mixture in this 97? Thanks Bruce
 
Easy part first: How long do you leave the choke when starting / warming up ? Does it truly go in all the way when you push it in ? Has timing been verified ?
 
PS - you can locate / print the Stromberg manual from the company web site; this includes easy to understand idle jet adjustment instruction
 
As mentioned look at spark. Not saying a flathead is a super efficient motor. But you should get a bit better then that. Lot of factors including compression.
 
Suggest you remove both of the main jets and the power valve. Nearly all are stamped with their size. Stock size is .045 main & 65 power. It is possible the power valve is leaking.
 
Thanks for the advice. I did check the choke and it opens fully. It runs fine but I have not rechecked the timing since I started driving it, only about 150 miles ago, after rebuilding the engine completely. I did rebuild the carb at that time. I don't know about the power valve, but does one need a special tool to remove it? Sorry about the delay in response but was out of town yesterday. thanks again
 
You need a special tool for the main jets only. It is available through Stromberg on their web page.
 
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