Progress with jets on holley 94

Tom's36coupe

Tom's36coupe

Well-known member
Did some testing and running with different jets yesterday. First up, took out the 56 and put in 51 jets. Went for a drive and the car ran just ok, seemed to not want to get going from take off. On the highway it ran good, but the same thing when you hit the gas, a little slow to respond. The next size I had were 54's. Noticed a change right away, no more hesitation and the same for 50-60mph on the highway. Drove for about 15 miles, stopped at my garage and checked plugs. Light tan color, looked good. I am going to put some more miles on it this way just to see how it runs. Might try the pv's some time soon with smaller jets to see the difference but hate to go backwards. I think with my 3/4 race cam and low vacuum I might run into a problem with the pv's. Thanks to Charlie and Ken for the tips and advice, we are all lucky to have these great guys who are so willing to help out us Flathead lovers!:D
 
If you don't use the power valves, you definetly need the larger jets. A 3/4 cam should still have plenty of vacuum if you use 4.5 power valves. In my opinion, it is the only way to go. Then go back to your 49 or 50 jets.
 
My camshaft is a crower 3/4 race from the old Motor City Flathead, has 383 lift with 250 duration at .050. Not sure what my vacuum is at idle but will check it out. Is that a "big" cam for specs?
 
Yes, that is HUGE cam if you have correctly reported the specs. Will work best in a monster size engine at high RPM.
 
I am running twin 94's on the 40 Merc in my roadster. It has an Isky 77 cam and has plenty of vacuum to keep the power valves closed at anything but WOT. I am running two 6.5 PVs and .051 Jets and find that it is still too lean at part throttle. As soon as I open the throttle enough for the PVs to open, it runs great. I am going to try running .053s tomorrow. My plugs look good but I can't come up with any other explanation for the popping and hesitation I get at part throttle other than it is too lean.
 
More running today, checked the plugs before I started which was around town driving, the tip was black. Hit the road and went about 12 miles at 55-65, checked them, nice and tan, seems to be running fine but now might like to advance the timing just a bit. Runs much better now with the Mallory actually giving me correct advance.
 
I set up the 97 I put on my 28 model A using an air fuel ratio meter from summit racing,it was an Inovate brand.
It made it very easy to see when the pilot jets came in,when the mains were operating and then the power valve.one thing though,you can spend hours ,more like days testing and geting the miixture right.
I had a bung welded in the exhaust but you can get an attatchment to clip up the tail pipe.
Lawrie
 
Lawrie I put adjustable jets on a few of my Strombergs. I adjusted them with an exhaust analizer. Can also look at the front plugs on each side. They are both feed from a differant side of the carb depending on whether you have an aluminum or steel intake manifold. G.M.
 
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