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<div> <font size="2">Excellent write-up Tony!</font><br>
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<div> <font size="2">Glen</font><br>
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<div style="font-family:arial,helvetica;font-size:10pt;color:black">-----Original Message-----<br>
From: Tony Drews via Fot <fot@autox.team.net><br>
To: Alec Buchan <agb@compsnw.com>; fot@autox.team.net <fot@autox.team.net><br>
Sent: Mon, Jan 18, 2021 5:20 pm<br>
Subject: Re: [Fot] Weber help and/or advice<br>
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<div dir="ltr">Alec, in my experience (also a TR-4), you can make just as much power <br clear="none">with a well tuned set of SU's as with Webers. My dad (Jack) ran SU's, I <br clear="none">have Weber 42's (came with the car). We were virtually the same speed / <br clear="none">power. Took us both a while to get there and required running on the <br clear="none">Dyno to dial them in.<br clear="none"><br clear="none"> From what I understand, the "Cannon" intake manifolds are considered <br clear="none">the best. I discovered that the 42's (which are rare as hen's teeth) <br clear="none">take the same internal bits as the 40's, so I think the advantage is <br clear="none">more psychological than anything over the 40's. I ended up with the <br clear="none">biggest chokes (venturi) that would fit - I think 36 mm was as big as I <br clear="none">could go. I do have a set of 45's that I keep threatening to spiff up <br clear="none">and try. I suspect that going to a 38 mm choke would be the hot ticket <br clear="none">for my engine. Depending on the build, 40's work pretty well. Big <br clear="none">bore, billet crank, hairy cam, high RPM would probably benefit from 45's.<br clear="none"><br clear="none">What I found on the Dyno is that there's a ton of power in just getting <br clear="none">the mixture right across the rev range. I ended up with pretty small <br clear="none">air correction jets to keep it from going lean at high RPM's. I <br clear="none">probably gained around 20 HP just by tuning the carbs.<br clear="none"><br clear="none"> From what I understand, comparing jetting from one engine build to <br clear="none">another is pretty haphazard, it's best to tune it to the specific engine <br clear="none">rather than just copy someone else's jetting. Also, I believe the <br clear="none">emulsion tube can make quite a bit of difference, so just comparing main <br clear="none">/ air jet sizes if you're not running the same emulsion tube kinda <br clear="none">invalidates the comparison. In my case I just used the emulsion tubes <br clear="none">that came in the carb's and didn't try alternates. I believe the big <br clear="none">differences in those is more for part-throttle driveability which I <br clear="none">generally ignore. If I can drive it to the grid it's fine, otherwise <br clear="none">it's pretty much just wide open or closed, not a lot of part throttle. <br clear="none">But other drivers may use more part throttle and so the emulsion tubes <br clear="none">would be of greater importance.<br clear="none"><br clear="none">I love the looks of the webers, but Jack was able to get decent mixture <br clear="none">control with SU's and some slighly custom needles - I think he took RB's <br clear="none">and skinnied down the tips to be more of the RA needle profile there. <br clear="none">He also ran 0.104" jets to get enough fuel out (stock is 0.100"). We <br clear="none">would draft each other at Road America, so were pretty close in overall <br clear="none">power.<br clear="none"><br clear="none">I'm not quite sure what kind of advice you're looking for - should I do <br clear="none">it or not? What specific setup should I get? What carb settings should <br clear="none">I start with? None of these have cut and dried answers in my opinion.<br clear="none"><br clear="none">Should I do it? Maybe, but you can also get similar results with good <br clear="none">well tuned SU's. The webers look awesome though.<br clear="none"><br clear="none">Which setup to get? Partially depends on the engine build. I suspect <br clear="none">you'd be happier with 40's on a decent manifold with a decent linkage. <br clear="none">If you have a monster motor you'll want 45's.<br clear="none"><br clear="none">Starting setup? If 40's, 36 mm chokes, possibly 150 mains with about <br clear="none">130 airs is roughly where I ended up (need to dig through the expensive <br clear="none">box of brass bits to verify). No idea what emulsion tube or accelerator <br clear="none">pumps I'm running.<br clear="none"><br clear="none">One advantage of the webers is that they DO have accel pumps, so getting <br clear="none">the engine started on a cold day without the choke is easier than with <br clear="none">the SU's.<br clear="none"><br clear="none">I found the tuning of SU's to be more obvious than the Webers. I used a <br clear="none">couple of books and Teri Ann's website to get a good understanding of <br clear="none">what I was doing with the Webers. The big aha for me was understanding <br clear="none">that the main jet affects the mixture across the entire rev range while <br clear="none">the air correction affects high RPM mixture more than low RPM mixture. <br clear="none">Changing the air correction does also affect lower RPM mixture so they <br clear="none">need to be tweaked in combination with each other. Getting the air <br clear="none">correction small enough that it didn't lean out at high RPM but big <br clear="none">enough so it didn't richen at high RPM was my key, then I tweaked the <br clear="none">main jets for max power and maybe went a step richer to keep the pistons <br clear="none">un-molten.<br clear="none"><br clear="none">Regards, Tony Drews<br clear="none"><br clear="none">On 1/18/2021 2:54 PM, Alec Buchan via Fot wrote:<br clear="none">> It looks like I am moving up a group and in order to not maintain my <br clear="none">> 'blue caboose' moniker, I am looking at converting to Webers. Moss and <br clear="none">> Pierce sell a 2 x 40 DCOE kit but I've also located a 2 x 45 DCOE kit <br clear="none">> (not from Moss or Pierce). looking for recommendations, if you might <br clear="none">> be so kind.<br clear="none">><br clear="none">> On a side note, the few of us here in the PNW are looking forward to <br clear="none">> seeing all you 'front of the packers' in Portland this summer.<br clear="none">><br clear="none">> Kindly,<br clear="none">><br clear="none">> Alec Buchan<br clear="none">> Bellingham, WA<br clear="none">> '62 TR4 #5 (aka the Blue Caboose)<br clear="none">> _______________________________________________<br clear="none">> <a shape="rect" ymailto="mailto:fot@autox.team.net" href="mailto:fot@autox.team.net">fot@autox.team.net</a><br clear="none">><br clear="none">> <a shape="rect" href="http://www.fot-racing.com/" target="_blank">http://www.fot-racing.com</a><br clear="none">><br clear="none">> Donate: <a shape="rect" href="http://www.team.net/donate.html" target="_blank">http://www.team.net/donate.html</a><br clear="none">> Archive: <a shape="rect" href="http://autox.team.net/archive" target="_blank">http://autox.team.net/archive </a><a shape="rect" href="http://www.team.net/pipermail/fot" target="_blank">http://www.team.net/pipermail/fot</a><br clear="none">> Unsubscribe/Manage: <br clear="none">> <a shape="rect" href="http://autox.team.net/mailman/options/fot/tony@tonydrews.com" target="_blank">http://autox.team.net/mailman/options/fot/tony@tonydrews.com</a>
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