cozmic Posted April 22, 2013 Report Share Posted April 22, 2013 Hi all I am toying with the idea of tuning the 230 cid engine in my 1955 Belvedere I am keen to keep the flathead 6 as opposed to fitting a v8 partly because the car is completely standard and also because it is quite an unusual engine here in england. The main points I need to know is If I use twin carbs what carbs do I use ( I have seen various units used) and any ideas on jetting etc can I keep the 6 volt positive earth ( I would like too ) I am really only looking to make the car a little more "peppy" and the look not looking for big power gains Many thanks for any advice / ideas / opinions or comments Charlie Quote Link to comment Share on other sites More sharing options...
Scruffy49 Posted April 22, 2013 Report Share Posted April 22, 2013 Only reason to not use 6v is if you were to add modern accessories. Quote Link to comment Share on other sites More sharing options...
greg g Posted April 22, 2013 Report Share Posted April 22, 2013 (edited) Well its a 3,7 liter engine, If I am not mistaken jaguar, and AH had engines in that displacement range equiped with 2 and in some cases 3 SU carbs. If you have some welding skills or know someone who does, an intake made of tubing could be fabricated for mounting a pair. Since they have adjustable main jets, tuning for the flathead should be a fairly simple thing. It would require that the exhaust manifold heat riser chamber be blocked off but that is not hard to do. You can also pep up the engine by having the cylinder head milled to increase compression ratio. 30 to 50 thousanths is usually where most folks go. No reason to change the 6 v positive unless you are upgrading accessories but I run a portable 12v battery jumper pack and it powers the GPS for over a week and the radio for three days or so. If you haven't anyone with welding ability, contact member moose of this forum, and he can set you up with just about any intake you can imagine. Mounting a less restrictive muffler and larger diameter exhaust plumbing can also pick up a bit of zip, or at least it sound that way............ Edited April 22, 2013 by greg g Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted April 22, 2013 Report Share Posted April 22, 2013 Greg is right, with the availability of numerous dual carb logs in the UK a little fabrication and welding skill could go a long way in pepping up the Engine. 3.7 does not seem to be a large motor these days but they have many similar late models that turn out some remarkable performance and HP numbers. Moderate 200+ in non interference fit and way way more with interference fit engines..your call on the amount of damage you are willing to risk on a broken timing belt..I am replacing my 3.5-6 (218) flatty for a 3.7 6 (226) at this time..some 100+ increase of HP...not to mention the countless other modern upgrades...but..my car came without a engine or transmission and an attempt to install R&P steering that was just a tad out, the PO told me prior it was incorrectly done..so again no biggy to me..as it was the only mod attempted..the car was well worth grabbing .. While not really a performance minded option, but for cruise and economy you can gain some KPH's by swapping out the rear gear..also as in the UK lots of OD assemblies should be available to you that will reside behind the tranny and before the drive shaft..look to one of these also for updating.. Quote Link to comment Share on other sites More sharing options...
cozmic Posted April 22, 2013 Author Report Share Posted April 22, 2013 Cheers for the replies guys like I said to be honest its as much about looks as it is performance, I was looking to use maybe edgy tappet chest covers, cylinder head and manifold, it was for this style of manifold I was interested in finding out about ie what carbs and jet size etc Many thanks guys Charlie Quote Link to comment Share on other sites More sharing options...
greg g Posted April 24, 2013 Report Share Posted April 24, 2013 when using stock carbs, thee is really no need to mess withthe main jets. As they are analoge devices reacting to air flow going through the carb. when mounting 2, the fule is subjected to half the air flow of one so the fuel reacts to the half signal in a linear fashion, Half the air can only pull half the fuel through the jet. The intermediate power jets react to a vacuum signal, with two carbs the signal is again halved. the only item usually needing adjustment is the accelorator pump, as they are mechanical, reacting to linkage movement. But they also have three mounting points. usualy selecting the mount that provides the shortest stroke is the way to go with a dual stock carb installation. 1 Quote Link to comment Share on other sites More sharing options...
drillmastertommy Posted April 24, 2013 Report Share Posted April 24, 2013 Hey Charlie, if your looking to use those edgy parts you'll certainly be getting big gains power wise, also expect a large dent in your wallet! Having all these parts fitted to my 218 flattie I can say its worth it though! Earls intake manifold is made for use with twin barrel carbs, Holley 94s or stromberg 97s, I use 94s with 49 main jets and 3.5 power valves, took a lot of trial and error and fouled plugs to find the best setup and if I were to start a fresh being in the UK I would buy a new pair of 97s. No power valves to deal with, only easily sourced jets. Where abouts in the UK are you? I'm rattling around in my old Plymouth near chichester. Quote Link to comment Share on other sites More sharing options...
martybose Posted April 25, 2013 Report Share Posted April 25, 2013 Hey Charlie, if your looking to use those edgy parts you'll certainly be getting big gains power wise, also expect a large dent in your wallet! Having all these parts fitted to my 218 flattie I can say its worth it though! Earls intake manifold is made for use with twin barrel carbs, Holley 94s or stromberg 97s, I use 94s with 49 main jets and 3.5 power valves, took a lot of trial and error and fouled plugs to find the best setup and if I were to start a fresh being in the UK I would buy a new pair of 97s. No power valves to deal with, only easily sourced jets. Where abouts in the UK are you? I'm rattling around in my old Plymouth near chichester. Before I gave up on them and switched to Carter-Webers I tried a dual carb setup with a pair of 97's. I installed adjustable main jets and started fiddling. I never could get my motor to run right at all speeds; it either accelerated well but wouldn't idle or it idled well and knocked like crazy when you stepped on it. I thought about switching to 94's but went the other way instead and haven't looked back. Marty Quote Link to comment Share on other sites More sharing options...
drillmastertommy Posted April 25, 2013 Report Share Posted April 25, 2013 Before I gave up on them and switched to Carter-Webers I tried a dual carb setup with a pair of 97's. I installed adjustable main jets and started fiddling. I never could get my motor to run right at all speeds; it either accelerated well but wouldn't idle or it idled well and knocked like crazy when you stepped on it. I thought about switching to 94's but went the other way instead and haven't looked back. Marty Marty, were you're 97s an original pair or some of the newly manufactured ones from over this side of the pond? Admittedly I never even thought about the carter webers but whilst trying to get setup advice everybody here kept telling me to change the holleys for strombergs because supposedly they are so much more easily adjustable and don't have power valve issues. Stubbornness meant I had to get the holleys to work and with the new jets, lower rated power valves and accelerator pump set to max I get consistent idle and very strong throttle response. Stubbornness sometimes pays! Quote Link to comment Share on other sites More sharing options...
drillmastertommy Posted April 25, 2013 Report Share Posted April 25, 2013 Forgot to mention about 45 rebuilds to get this setting. I can now rebuild 94s in my sleep! Quote Link to comment Share on other sites More sharing options...
martybose Posted April 25, 2013 Report Share Posted April 25, 2013 Marty, were you're 97s an original pair or some of the newly manufactured ones from over this side of the pond? Admittedly I never even thought about the carter webers but whilst trying to get setup advice everybody here kept telling me to change the holleys for strombergs because supposedly they are so much more easily adjustable and don't have power valve issues. Stubbornness meant I had to get the holleys to work and with the new jets, lower rated power valves and accelerator pump set to max I get consistent idle and very strong throttle response. Stubbornness sometimes pays! Mine were original vintage ones that had been overhauled by someone who knew what they were doing. I considered going to 94's because the power valves would respond to lowered vacuum, not throttle position like the 97. With the 97's you had to go to full throttle to get enrichment, when you really didn't need full throttle. The detonation was frightening at part throttle! Marty Quote Link to comment Share on other sites More sharing options...
drillmastertommy Posted April 25, 2013 Report Share Posted April 25, 2013 Mine were original vintage ones that had been overhauled by someone who knew what they were doing. I considered going to 94's because the power valves would respond to lowered vacuum, not throttle position like the 97. With the 97's you had to go to full throttle to get enrichment, when you really didn't need full throttle. The detonation was frightening at part throttle! Marty It sounds like my refusal to shell out over £550 GBP was the right move! Cheers Marty. Quote Link to comment Share on other sites More sharing options...
cozmic Posted April 25, 2013 Author Report Share Posted April 25, 2013 Hey guys many thanks for all the advice and information certainly food for thought. Drillmaster Tommy I,m on the isle of wight but I do get to the mainland for a few events and shows each year so maybe see you at an event sometime. Quote Link to comment Share on other sites More sharing options...
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