Miller OHV. Conversion on A or B owners

[KiWinUS]

Hi guys I am a v8 guy but have just resurrected this B engine with a Miller OHV conversion and a Loveless blower. Started for first time yesterday but no idea what timing should be set at. I put degree marks on flywheel and there’s a hole on bottom I have a mark so can use timing light. Need some guidance please on initial timing and full advance. Has a Vertex mag with 20* built in advance.

[nkaminar]

Real pretty. I would guess north of 120 horsepower. You will get more torque but the power will come from more rpm.

The overhead configuration does not have the advantage of the Ricardo head design with the increased turbulence. So it will need more advance than a flathead. I will guess at 30 degrees but the way to tell is to adjust the timing for the best performance without too much advance that will ruin the rod bearings in short order. I will say that the increased pressure from the supercharger will mean that less advance is needed. I am going to assume that someone with more experience will chime in.

I am also going to assume that you will start the engine with an electric starter and never by hand cranking. In that case I would set up the starting advance to about 5 degrees. Some members are going to protest and say that that will put too much stress on the ring gear and Bendix, and they may be right.

[Y-Blockhead]

Wasn't the initial timing for a Model B set at ~15° BTDC? I don't think 5° BTDC will be too hard on the starter.

[nkaminar]

Blockhead. The flathead B engine has the advantage of increased turbulence from the Ricardo designed combustion chamber. The overhead valves do not have this so they need more advance.

[Jim Brierley]

I have done dyno work on the new Serr Miller, and have run early, iron Millers. They need lots of advance to run properly. On the dyno we ran 45 degrees, and the same on my mild street-driven Miller. With a blower You probably shouldn't need that much, but I'd think 40 or maybe a little more. I ran a Mallory distributor with advance and set the initial at 25 degrees. Never had trouble starting it, no kick-back at all. If your mag has advance weights you should be fine with similar settings. Have fun!

[Y-Blockhead]

Sponsored Links (Register now to hide all advertisements)

Originally Posted by nkaminar

Blockhead. The flathead B engine has the advantage of increased turbulence from the Ricardo designed combustion chamber. The overhead valves do not have this so they need more advance.

I get that. I was referring to you saying 5° being hard on the starter and flywheel. But it is all good.

[nkaminar]

OK, sorry. I misinterpreted what you said. From what Jim said even more advance when starting is OK. Like you said, 15 degrees when starting.

I have a friend in California with two overhead heads that I would love to have, but I cannot afford them.

[KiWinUS]

Thanks for all the great help guys.

[KiWinUS]

Originally Posted by Jim Brierley

I have done dyno work on the new Serr Miller, and have run early, iron Millers. They need lots of advance to run properly. On the dyno we ran 45 degrees, and the same on my mild street-driven Miller. With a blower You probably shouldn't need that much, but I'd think 40 or maybe a little more. I ran a Mallory distributor with advance and set the initial at 25 degrees. Never had trouble starting it, no kick-back at all. If your mag has advance weights you should be fine with similar settings. Have fun!

Great help thanks Jim.
Yes the mag has 20* of advance just rebuilt by my friend Rodger @ Joe Hunt. I have also converted to full pressurized oil system. Stromberg carb for now but I have a Winfield to fit one its running great as is. Again Thanks.

[Jim Brierley]

Winnfield's are great, once you get them adjusted correctly. If you are running only one, it needs to be at least a 'C' in size, CC or D would be better.

[nkaminar]

Having access to a dyno testing facility would be a great way to set the timing and the jets on the carburetor. Here is a video of a 1927 Bugatti on a dyno and the work the owner did to get it from 60 hp to 90 hp. For reference, 90 hp on the 1,500 cc engine is equivalent to about 200 hp on a Model A engine. The owner adjusted the air/fuel ratio and the timing and removed a restrictive inlet elbow. I saw the same model Bugatti for sale yesterday for about $800,000.

https://www.youtube.com/watch?v=1rwEHJQg2wk

[updraught]

Originally Posted by nkaminar

Having access to a dyno testing facility would be a great way to set the timing and the jets on the carburetor. Here is a video of a 1927 Bugatti on a dyno and the work the owner did to get it from 60 hp to 90 hp. For reference, 90 hp on the 1,500 cc engine is equivalent to about 200 hp on a Model A engine. The owner adjusted the air/fuel ratio and the timing and removed a restrictive inlet elbow.

Looks like a Winfield updraught size D and a guy that knows how to adjust it.

[ThirstyThirty]

what kind of bearings? inserts. I would start off with low initial timing, add in as you get a feel for the engine and how it performs as the timing is increased. blown engines do not need the amount of lead a reg (NA) engine runs...

[updraught]

>>blown engines do not need the amount of lead a reg (NA) engine runs...

How does that work? Lead stops detonation and the blower would raise compression.
A blower on a flathead only needs a couple of pounds pressure.
The blown Bugatti in the video seems to be running methanol.

[mercman from oz]

B engine with a Miller OHV conversion - KiWinUS

[nkaminar]

Updaught, I think he was referring to the lead (advance) in the ignition, not the metal. With higher pressure in the combustion chamber the flame travels faster so less advance is needed.

[Richard Knight]

Very interesting dyno video. Impressive power gains for sure. But something to always keep in mind is when extracting the most power you can from an engine also may shorten the engine life. Knowing what the internals look like on that Bugatti engine I think these guys are pushing their luck! Imho

[KiWinUS]

Originally Posted by Jim Brierley

Winnfield's are great, once you get them adjusted correctly. If you are running only one, it needs to be at least a 'C' in size, CC or D would be better.

Again. Big thanks. The Winfield we have is an SRR also have an SR. sorry I don’t know Winfields at all yet. So any help much appreciated. I’m pretty good with carbs Cheers.

[ModelA29]

Originally Posted by KiWinUS

Again. Big thanks. The Winfield we have is an SRR also have an SR. sorry I don’t know Winfields at all yet. So any help much appreciated. I’m pretty good with carbs Cheers.

I've been on the learning quest since I picked up a Winfield manifold a couple months ago. I haven't heard of an SSR - only the S and SR (in addition to his earlier carbs) which is the S with a different bowl with an accelerator pump. Winfield really tailored his carbs. They came in A AA B BB etc with each step being a larger venturi. They are very adjustable - even the accelerator pump. There are a couple gurus - one rebuilding and the other making new parts. There are some videos on YouTube. If you have a Winfield manifold check the bottom. It will have a casting number and stamped letters calling out which carb it fits. I was able to get a nice complete SR-BB to match my intake. Scour the internet you'll find a lot of info. You'll want to make sure you are using the correct parts and not mixing A with AA or B etc. There are a couple sources for gaskets. The guy here in the states (but he doesn't have the accelerator pump diaphragm - yet) and a guy in Germany with the diaphragm on FleaBay.

[updraught]

Originally Posted by KiWinUS

Again. Big thanks. The Winfield we have is an SRR also have an SR. sorry I don’t know Winfields at all yet. So any help much appreciated. I’m pretty good with carbs Cheers.

This is a CC, check on the throttle body.
https://forums.aaca.org/topic/381978...-d-carburetor/
The bowl looks a bit dodgy as to whether it is a U updraught or D downdraught and a B or a D size.