I read a lot of threads concerning the Stromberg 97's and trying to gleam some info about jetting for altitude. Currently I'm at 5500 ft. with a well build FH, 284ci, 3x2 on Navarro intake and the 97's have #65 PV and #45 Jets and progressive linkage. So this is my starting point and it's running fat. Recommendations please.
Uncle Mike says I can fill in for him... Rule of thumb is one jet size smaller for every 2000 ft above sea level on a single carb. Three of 'em changes things a little... I'd go .043 in center carb and .042's in ends. Perhaps # 67 powervalve in center with # 69's on the ends. I'm at 4400 ft with .042's and 69's on my 2x2... Just right.
I know that air is thinner so you reduce the fuel..Max is on the money..I'm also thinking, make sure your getting lots of air through you filters.. Engines are big air pumps and need the air.. Duane.. Let us know how it run with the jet and P.V. change..
Just read Flathead Ford V8, Perfomance Handbook by Joe Abbin. In the book they dyno two engines very simular to mine both produced HP #'s over 200 with triple 97's @ 5300 Ft. That got my attendtion and the one that produced 217 hp used #43 jets and 65 PV. So what I've done is to order two sets #42 jets and one #43. I'll keep the PV #65 for now until I can see the results of the jet change. I'll post results as soon as I get them.
HD74, rather than swapping out jets to adjust, buy some jet adjusters, (leave your .045 in)..With the adjusters you will beable to fine tune the 97s.. Duane..
Changes and observations, used #43 in the center carb and #42 in the outboard carbs. If I only use the center carb, It feel like it pulled like the old stock FH, by third gear I'm going about 35mph maybe 40. If I kick in the secondarys it pulls very strong in 1st and 2nd gear, but the rpm's fall off quickly when I shift into third. It takes a bit but the rev's do come back up. Then the secondary's start to work again. Well thats the result of the change. What say you?
What kind of gas do you have in Colorado these days? If it's 10% or higher ethanol, you probably need to step up a size in jets, trying the center carb first. Also, you might try putting all the links on the "W" setting and get it to idle on all three, with the progressive coming in a bit sooner. Better yet, just run straight linkage and dial them all in. I'm not a huge fan of adjustable jets... Where's the baseline? Keep dancing with it & let us know how it goes. Not that it makes a big difference, but are these New 97's or originals?
So I guess there are a lot of things to mess with before I do another jet change and I'll give some of your suggestion a try. I think we're at 10% ethanol these days and these are the new vintage 97's from Stromberg. Thanks.
Another up date, after changing the jets and putting some miles on the road I found I was pinging in the headers. So changed the timing from 10 deg advance to 5 and the pinging is gone. Still running rich but I think it will be fine for the next 1K. I got to say it's fun to hear this thing pulling with the triple 97's.
New update, changed a few things. First changed the timing found the guys @ H&H set the total advance at 30 deg. The motor didn't like it up here in the mile high state. So today set the timing 3 degs. intial and 21 degs. total advance with the 2nd weakest springs. Than changed the center carb idle jets to #42's. After the test ride I feel I'm getting closer, but not quit there yet. Rain ended any further adjustment for the day. Anyone else chim in.
The Jalopy Journal
