Some tuning questions

[dad's deuce roadster]

Guys, the status or our work to bring our father's 32 Roadster hot rod back to life is that it is now mechanically all there. The latest items being a real exhaust system and proper plug wires, i.e. solid core which the coil can now provide sufficient spark through vs the carbon that we used in our teens not knowing there was any difference in wires. Also, we added a pressure regulator to get pressure down to about 1.5 psi for the Strombergs. The engine is running nicely but rich. This brings me to a few questions.

First, the engine is a 59A, likely 1939, stock crank, bored 0.040", dual vintage stromberg 97's on a Navarro intake, Sharp heads, crab style distributor.

Question one, what is the best way to set the timing?

Question two, the engine is running rich - looking at setting the idle mixture, it seems it's pretty similar to, forgive me, tuning the Q-jet on my Vette, start at 1.5 turns in, then make 1/4 turns on each in or out as needed until peak RPM is found. Is that correct and is there anything more to it?

Question three - if we need to swap jets, what would be a typical for size for the the engine set up.

Thanks,

[Ronnieroadster]

The ignition timing can be adjusted slightly on the two bolt crab dist on the front of the engine. If this is what you have you will see on the drivers side of the outer surface of the housing you will see a small hex headed screw sitting on a triangle plate. This plate is what you move to change the timing of the engine. To do this you loosen the screw just enough so this plate moves. Do not remove the screw which is attached to the plate just loosen it.

I suggest you mark where the plate is sitting in relation to the small cast in pointer on the dist housing prior to going any further. Once you have this plate marked where its set presently the next step without the engine running you can now loosen the screw and see how hard its going to be to effect movement. When you feel confident you can move the set screw and plate then start the engine and move the plate in the direction the engine RPM increases do this a little at a time. After each slight movement check how the car performs.

The answer to your question on how to adjust the two Stromberg's is still the same as answers given to you in your earlier post. The best way is by first using a Unisyn gauge if you did that step then a vacuum gauge is the next step to the fine tuning of the two carbs. Using the vacuum gauge its a simple process when the four screws are adjusted correctly the highest vacuum reading is what you will see on the gauge.
The carb adjustments will take a while to get the feel for but once you have them set it will be worth the effort.

The jet size is not so easy to answer however first you need to see what size the jets are presently. Stock size in the 45 range for two carbs on a relatively stock engine should work. The spark plug brand and heat range is another area you may need to look into.
Ronnieroadster

[dad's deuce roadster]

Ronnie, thanks for the reply. I did buy a uni-syn unit. So we can go with that. I just wasn't sure if there was some way to get close first and then use it. Thanks for clarifying that.

[_51ford_]

Im new here and would love to see some pictures of the family roadster!

[dad's deuce roadster]

Originally Posted by _51ford_

Im new here and would love to see some pictures of the family roadster!

First drive in 40+ years

[solidaxle]

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Very Cool.


Did you get the timing and carbs adjusted?

[dad's deuce roadster]

Not yet. We pulled the tops to check where the fuel was cutting off. One was too high. So, given that we pulled the carbs to check them out in general. We found one gasket leaking. And since we had them at that level we opted to drop down to 43 jets and are waiting on them. Yeah, I know, backwards, but it's winter.

Question there though, we are checking to see if the heat risers have been plugged, something we were not aware of sometimes being done in the past. Was that to keep the air in the manifold colder for more power. But if so, I would think it would only lead to rich running when the engine was cold. Would that be correct?

[petehoovie]

Originally Posted by dad's deuce roadster

First drive in 40+ years

[solidaxle]

Did you verify the 97's had 45 main jets?


You stated that you brought your Dad's 32 back to life. Was it sitting for a long time without running?

[Bill OH]

Ronnie Roadster gave you good advice on the ignition timing and the carbs. He told you 45 main jets, stock size and that that is what I use on 2 97s plus 71 power valves. 43 jets will stumble from a stand still - to lean. 45 jets and 65 PV is toooo rich - will bog. Use 45 mains and 71 pv, assuming you elevation is not more than 5000 ft. I am at about 600 ft above sea level. Idle mixture screws I have 1 turn out.

For timing, you can put a pointer with respect to the crank pulley and establish TDC using the hard stop method - pulling the right head and putting a hard stop over a piston or putting a zip tie thru a spark plug hole and mark the crank pulley for TDC. Both methods can be found on Fordbarn.

[dad's deuce roadster]

Solidaxle,

Yes the jets were 45's. The engine sat for 40 years. It was fully torn down, baked, magnafluxed. Crank, cam (3/4 race), rods replaced with used but in spec stuff. Kept the 040 overbore pistons. New crank bearings, new valves, used in spec adjustable lifters. Rebuild guided by a guy in the business for near 60 years.

Ronnie,

Thanks for chiming in. All input on what's working in similar setups is useful. What heads, crank, and manifold you using. We have Sharp heads, 3/4 crank as noted above, and Navarro intake.

[Bored&Stroked]

When you say it is running "too rich" - how is it that you've determined this? The idle mixture screws only influence the idle mixture - nothing else. Are you load-testing the engine out on the road and reading plugs after you run it hard, put the clutch in and kill the ignition? You can't run it hard on the road, then take a nice leisurely drive back home, put it in the garage and check plugs - they will tell you nothing about the actual mixture (rich/lean) under driving conditions. What they'll usually show you is that the plugs are carboned up and appear rich . . . what you're seeing is probably NOT the truth.

Also, checking plugs for coloring is difficult these days - due to the highly refined fuels that we're all running. I don't think I've seen a nice "chocolate brown" plug with modern unleaded fuels for many years. So, other methods need to be used.

I added an O2 meter such that I can accurately see the AFR under different conditions - this is the BEST way to do it, but takes some work, some parts, etc..

[dad's deuce roadster]

We're getting it back together with the carbs hopefully clear of leaking fuel. With the needle valves leaned in better it's idling much better. But we had only a short on period, i.e. never warmed up. Lousy weather of date. We'll keep on the path we're heading down. Not steps is let it warm up and use the unisyn to sync the carbs. Latest question though is it was mentioned to us that a lot of these rods from the 50's had the heat risers plugged. We didn't know about this so never checked. But before pulling the manifold we wondered would that have any effect after the engine was warmed up.

[Bored&Stroked]

Plugging the heat risers (if both are plugged) will cause the intake to stay cool and will influence how the car runs in really cold weather. In some situations, the lack of heat to the intake and carbs can cause them to "ice up" if you're out on the road in really cold conditions. Also, it usually takes the car a bit longer to warm up and idle correctly when you don't have heat risers.

Also, it depends on whether or not your manifold even has heat risers - most 2-pot manifolds do, but some do not. If you're just driving the car in non-winter conditions, won't make a big difference whether you have them or not, though you may need to use a faster idle on first start-up and maybe a bit more choke (if you have that hooked up). It will really not influence tuning once the engine is warm.

[dad's deuce roadster]

Originally Posted by Bored&Stroked

Plugging the heat risers (if both are plugged) will cause the intake to stay cool and will influence how the car runs in really cold weather. In some situations, the lack of heat to the intake and carbs can cause them to "ice up" if you're out on the road in really cold conditions. Also, it usually takes the car a bit longer to warm up and idle correctly when you don't have heat risers.

Also, it depends on whether or not your manifold even has heat risers - most 2-pot manifolds do, but some do not. If you're just driving the car in non-winter conditions, won't make a big difference whether you have them or not, though you may need to use a faster idle on first start-up and maybe a bit more choke (if you have that hooked up). It will really not influence tuning once the engine is warm.

Thanks Bored. That certainly makes sense.

[Flathead Fever]

There is order to a tune-up. The points are set first (dwell). That is because the point gap effects not only dwell (the amount of time the points are closed) but it also effects timing. Dwell effects timing, timing does not affect dwell. Second you set the timing. If you ever have the heads off, you can find TDC #1 and make a timing mark and pointer. Using an adjustable timing light, you will be able to adjust the timing off of that TDC mark just like a modern engine. You turn a dial on the timing light that brings the mark back to TDC and then you read the degrees on the timing light you tunred thre dial to find your amount of advance. Do not buy a timing light that is not adjustable. Timing effects the air fuel mixture adjustment so timing must be done before you do the final adjustment on the carbs. Remove the linkage from the multiple carbs, making sure that they each carb has an operating return spring. If you ever start an engine with a carb with no throttle return spring at all, you will never make that mistake again. 0 to 10,000 rpm in less than a second when the engine vacuum pulls the throttle plate all the way open. Close both carb throttle plates and then just equally open them a little. Run the air fuel mixture screws in gently and paint a little mark on them so you can keep track of how far they are open as you are backing them out. Then back out all of the air fuel mixture screws maybe 3/4s turn, it might take 1 1/2 turns. Start the engine and hopefully it will idle. You might need to change the adjustments some to get it too idle, just keep everything turned out or in the same amount on all carbs. Go back and forth with the idle speed screws until your Uni-syn is the same on all carbs. The only thing that tool does is make sure the throttle plates are all open the same amount at idle. Once you get the throttle plates adjusted so its idling at a normal rpm. Use a small propane bottle, slightly opened it, and pass it over the carbs. If the idle goes up its too lean, if it goes down its too rich. Make the same adjustments to all A/F mixture screwas, maybe an 1/8 to a 1/4 turn at a time. Each time after the A/F adjustment you will probably need to go back with your Un-syn and reset the idle speed. Do the propane test again, going back and forth between the A/F mixture adjustment and the idle speed adjustment, When the idle speed is where you want it, and the addition of propane (just the slightest amount) has no effect on the idle rpm you're not too lean and you're not too rich. Now you can also richen the A/F mixture screws a little bit more, maybe a 1/8 of a turn to compensate for daily temperature and altitude changes. Then hook your linkage back up, adjust it so it attaches to the carbs without moving the throttle plates from where.
you set them with the Un--syn. Mash th pedal to the floor and make sure the carbs are opening all of the way. Install a double return spring for safety. That's just beginning to carb tuning, then there are different power valves, accelerate pump settings and jets. Make sure the carbs you're using all have the dame size parts in them before you start any of this.

That propane enrichment idle test is the gold standard used to adjust all carburetor, idle A/F mixtures. In CA, shops that do smog tests are required to all have a propane bottle when the State comes inspecting, and they do show up. It really is the best way to set the idle mixture. You can do the same thing by just spraying ja "little" carb spray or starting fluid into the carbs to see what effect it has on the rpm.

[Ronnieroadster]

That's a well written example of one extremly long way to do it. I imagine a billing by the hour shop would do it this long drawn out way. However using a vacuum gauge to set the idle mixture screws is a heck of a lot easier than using propane especially if its windy out side remember this is a back yard Hot Rodder. But heck what would I know.

Ronnieroadster

[Flathead Fever]

Originally Posted by Ronnieroadster

That's a well written example of one extremly long way to do it. I imagine a billing by the hour shop would do it this long drawn out way. However using a vacuum gauge to set the idle mixture screws is a heck of a lot easier than using propane especially if its windy out side remember this is a back yard Hot Rodder. But heck what would I know.

Ronnieroadster

I can do the propane test faster than I can describe it. I am little wordy when I write. We were a fleet; we didn't bill anybody by the hour. 400 company vehicles with five company mechanics. We were there to service the fleet cheaper than anybody else could, and we did, nobody could come close to our cost per operating mile.

I would bet there is not five minutes difference between a vacuum gauge and the propane method. The propane can be used for checking throttle shaft leaks, base plate leaks. any vacuum leaks. You're verifying that the carb is actually lean by also running the propane around the intake system to make sure there are no vacuum leaks before you start tweaking the carb. It just takes a minute. It's more of a diagnosing tool than one used to set ups carbs but it works great for adjusting the idle A/F mixture. The wind from the fan does not blow the propane away, so I doubt a backyard breeze would. I used the propane outside all of the time when a stall was not available. Even if I did adjust it with a vacuum gauge, I would double check it by passing the propane over the carb. It just takes a few seconds. It's also good way for beginners to verify their adjustments.

If a carb was running just fine where the screws were originally set and now it doesn't run well, you have to ask yourself what has changed. The screws did not move, so why all of a sudden is it lean or rich. Is the idle jet plugged, does it have a vacuum leak, is power valve leaking. If you start adjusting before you have done a little diagnosing, you might mask a problem by changing the A/F mixture. The propane was the only tool allowed in a CA smog shop for adjusting the A/F mixture You also had have a tachometer, vacuum gauge and an adjustable timing light... It doesn't matter if its old 97 carb or a feedback computer-controlled carb the propane is the preferred way to adjust it. The air resource board wanted us to adjust the A/F to the maximum rpm at idle and then lean the mixture out, so the addition of propane would raise the rpm by 50. That produced engines that were emission friendly but so lean they would barely idle if you turned the air conditioning on. We could not do it on a 4 cyl engine. The propane can also be used to find the maximum rpm and then adjust the mixture slightly to the rich side. It's pretty accurate to where you could adjust it with an expensive 5-gas analyzer. Or you just hook a vacuum gauge up and adjust it to the highest vacuum. That works too.

[dad's deuce roadster]

Flathead,

Thank-you very much for that in depth description. It certainly covers it. On the propane issue, if you'll forgive the reference to a GM, the latter quadrajets, such as on my 80 vette were also supposed to have idle mixture set this way. But it was not for optimal idle. The method was to set the mixture screws to some number of turns out. Then feed some propane into the air filter cover. The RPM was supposed to increase a certain amount, a few hundred RPM, but I forget the number. If it was less than that, then lean some more. The intent was to purposefully set the mixture lean for emissions. The screws ports were then supposed to be plugged. It explains one reason Q-jets got a bad name with lousy idle and stumble on hitting the throttle.

So that I don't get into too much trouble for bringing this up in this forum, I want to mention that over at the Vette Forum, there are photos of the our 32 Roadster. The vette guys enjoyed them. One offered me a '71 vette project car and about $20k in parts towards it's restoration in trade for the deuce.