LoginThe Carbied Straight 6 Performance Thread. Ol' Skool Inline 6' - Holden 186-202, Ford 200-250 (pre & crossflow), 245-265 hemi
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Post #1
 27th September 2011 - 06:14 AM
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Holden Grey motor, Red motor, Blue Motor Ford 170, 200, 250, Crossflow 200, 250 Chrysler Slant 6, Hemi 215, 245, 265 And everything above, below or in between... . Figure we will see where this thread goes- hopefully far, as the p-plate laws are bringing a lot of young drivers back to old school cars with pre-EFI inline 6 cylinder cars. I love it! Ive had a decent amount of tough cars in my few short years, more than a couple of them straight-6's that ended up quite bruiser-spec, and have picked up a bit along the way. I've started this primarily because I have some open questions about the 265 (4.3l) Hemi 6cyl in my missus Valiant, but the same/similar information will carry over to most or all other similar engine configurations. Basically asking for advice, and giving it out if anyone wants - I'll modify this first post with answers as it goes, if I get any. . Ok so the question is really - How do you make the most out of a carby-fed straight six, on various budgets? I figure that to break it down simply, youve got three or four different stages - 1) Simple bolt on modifications and tune 2) As above, but with head and/or/cam removal 3) As above, but with bottom-end disassembly and modification. And also, 4) As above, but with forced induction or fuel catalysts (Turbo, Supercharging, Nitrous) . For the sake of simplicity, lets stick with the first three, and keep it p-plate legal for now? And I am leaving drive train mod's aside too (diff ratios etc) . The answers are the same across all breeds of engine - 1) Better air intake/filter, better/larger carburettor (or twin/triple carbs), an aftermarket inlet manifold, extractors and exhaust. Possibly things like higher-powered ignition coils, and upgrading from points style distributor to electronic ignition. This, combined with running a high octane fuel and having your carburetor tuned and your ignition timing adjusted, will net you a power gain that you will notice. . 2)As above, but a slightly larger budget might allow for removal of the head to have work done such as a port polish, fitment of larger valves, having the basse of the head milled for higher compression ratios etc. The budget might also allow for a different cam profile, and suitable valve train gear such as different ratio roller rockers, better valve springs etc. . 3)As above, but an even larger budget allows also to have the block stripped down, and the fitment of a different crank/conrod/piston assembly fitted to create either a larger engine capacity, different comp ratio piston heads, or simply better balance for better rev-ability and strength, or to allow for a down-the-track forced induction addition. . All pretty basic stuff, and should be general knowledge to most who own an old car and have plans on working the 6 cylinder. The trick is to figure out where YOU sit in that 1,2,3 or 4 section, and choose your modifications wisely, so that they do work and tie in together with any other mods, and the rest of your vehicle in general. For instance, no point going for a high HP but low torque cam for the 186 or 250 motor in your 2 tonne brougham, statesman or fairlane. And no point going a cam with a high RPM power range if you are only running a standard stall converter in your transmission etc. Dont your compression super high if you plan to add an SC14 Supercharger kit from CRS and so on. . With the missus Valiant, the 265 Hemi, we sit basically in Group 1, maybe a bit of group 2. Happy to do a complete exhaust system, inlet manifold, carbie, intake, and possibly (most probably) a camshaft and compression upgrade, but arent too keen on any port work or oversized valves at this stage due to the high cost and varied results. The question is - which cam, what carb setup, and what sort of exhaust? The car runs decent HP standard. More than Ford's 250 Crossflow and Holdens Red 202, from that same year. So the Hemi straight 6 is a great 6cyl to start with, p-platers!! Putting down anywhere from 150 to 203 and even 218 HP in the sedans, it was the toughest 6cyl you could get. That aside, the 265 Hemi from the E49 Charger put out over 300HP. Same engine, but with a different camshaft, higher compression, triple weber carburetors, and a set of tuned length headers/extractors. Can we see the benefits of basic modifications as found in 1) and 2) ...? THe goal is to get similar power by doing similar mods to bridge the gap between my motor, and an E49 Chargers. The car is a manual, 4 speed. This means i dont need to worry about changing the torque converter in the auto transmission, or taking it into account when choosing cam profile. . I guess what it would be cool to nut out, is - what is the BEST size/type of carb setup for each engine? A big single 2bbl/4bbl or a set of triple carbs? What is the BEST way to raise compression safely and effectively? Decking the block/head, or different pistons? What is the BEST cam profile to run on the various engines, and what is the BEST type of exttractors/headers and best diameter exhaust for decent flow, backpressure, and of course, engine note? Is it WORTH paying $400 for an aftermarket inlet manifold? . So, what are we running out there, and how is it working? Or, what are your plans for your 6 cylinder, and who is doing the work for you? Are some parts on some engines more reactive to modification than others? Ie, any weak points on certain motors that require only small changes for decent results? Any budget ways to make some decent power? Things like the old trick of running hemi rods on ford motors, or putting the 186 head on a 202 for higher compression, fitting distributor setups and carburettors (or even EFI) off later model motors or different breed motors - the Ford Crossflow 250 twin throat weber goes well on earlier ford and holden motors with the single barrel stromber etc. . Plans for the 265 Hemi, in order of inlet to exhaust tract are - Cold air intake using a home-made plenum with 3" piping from the factory CAI point. 465 or 600 Holley 4bbl carburetor. Vacuum secondaries. Big for a 6 cyl, but remember the 300HP goal is as much as a stock 351 Cleveland V8. Cain 4bbl Long-runner inlet manifold with plenum pig (better atomization for more complete fuel burn etc) Standard head but milled to raise compression to 10.5:1, providing this maintains safe valve to piston clearance. Crow camshaft to suit performance engine with higher rev range, valve springs & retainers etc to suit. Standard rocker assemblies. 6-2-1 Extractors into a 2.25" or 2.5" exhaust system, centre and rear straight through mufflers. Advanced ignition timing, and the car will be tuned to run only on premium octane fuel. Standard Electronic distributor, MSD ignition coil, fresh basic plugs and leads. One heat range colder, to suit the adv timing the comp ratio? . Anything else worth a mention? Tips and tricks? Its my first Hemi motor. A concern i have is that the sump only takes 3.5L of oil - not a lot for such a large 6cyl motor, (oil protects not only by lubricating, but also by helping cool the motor) especially one that will see a bit of work. Also, the cooling system is only fairly basic. I would like to fit a larger, baffled sump, as well as a larger radiator with an electronic thermo fan pushing air through, as the engine fan also pulls. The aim is 300HP at the engine. Doable? All this because the missus wants her Valiant to push her back in the seat when she takes off... I think she just wants to match my XB 351  This post has been edited by lil_bobby_260: Sep 28 2011, 05:05 AM -------------------- Helping smart-arses look like dumb-arses since August '85
Me on TripleJ and smashin it! 72 Ford Galaxie (557 stroker in build) 73 XB Falcon (351/toploader/9") 80 CM Chrysler (265/4spd) 94 XG Falcon Ute (4.0/5spd) 93 EB Fairmont (302/BTR) WANTED: poor condition 2nd hand alloy wheels and tyres. Want some alloys repaired and refinished? PM me |
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mxmad
Post #2
a mate of mine had a hr holden 202 bored and stroked to 208 big cam big head tripple 48ml webbers a few other bits and pieces used to run constant low to mid 13's,ful street trim no semi slicks i think it had ta's or kelly chargers,full exhaust.he used to drive it from mt druitt to castlereagh race it all night and drive back home.yes it was a long time ago and them times for a hr back then were pretty quick especially one that was full street legal.the same bloke now owns or i think he still owns a pink ek ute has mock up number plates dog 308 black 304 vk v8 not street legal just drag but its all andra approved runs low 10's the whole car was built in his backyard including all the engine machining very cluey bloke when it comes to cars.some of the oldskool drag people out there might know him. |
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lil_bobby_260
Post #3
Very cool. Any other straight 6 weapons out there? I'm thinking these p-plate laws which have been in for a few years now really are a good thing- if it pushes people to get back in touch with old school cars and modifications. |
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lil_bobby_260
Post #7
QUOTE (176OES @ Sep 28 2011, 03:12 PM)  Brothers Torana Thats what we're talking about - very cool. Thats decent RWHP for a 3.3L carby-fed inline 6!!! Id be stoked to pull that figure, its about where we are aiming. I think where i will come up short is the lack of cash im throwing at headwork. Im really limiting myself to upping compression and a quick polish of ports to match them closer to the aftermarket inlet manifold. Also, i really dont want to be pulling the bottom end apart yet. . And err... yes, 300cui ford motors are more than welcome. Dont see a lot of them getting around tho. Chrysler Aus were going to build a tall deck 265 for trucks etc which displaced 300cui also but abandoned the idea as projected sales werent enough to make it economically feasible. |
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the_random_hero
Post #8
New pistons are always the best way to raise compression. If you have the option of a bolt-on EFI setup and have the knowledge to do it, you'd be silly not too - it is by far the easiest way to get more power, fuel economy and driveability. |
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lil_bobby_260
Post #9
QUOTE (the_random_hero @ Oct 1 2011, 07:09 PM) New pistons are always the best way to raise compression. If you have the option of a bolt-on EFI setup and have the knowledge to do it, you'd be silly not too - it is by far the easiest way to get more power, fuel economy and driveability. Hey buddy I was really trying to avoid pulling the bottom end apart hey... Purely because the missus isnt keen on anyhting too crazy and im trying to get away with what i can haha... Hence the idea of decking the head to raise the CR. If the head work method isnt going to do the job i will keep the CR standard. I wasnt aware of an EFI system for these? Or are you talking purely aftermarket? Again tho, not really sure if id want to go that level. Fuel economy isnt a real issue, and never should be with a car like this. A few extra cents per KM is really the last thing to worry about. |
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the_random_hero
Post #10
QUOTE (lil_bobby_260 @ Oct 1 2011, 07:47 PM) Hey buddy I was really trying to avoid pulling the bottom end apart hey... Purely because the missus isnt keen on anyhting too crazy and im trying to get away with what i can haha... Hence the idea of decking the head to raise the CR. If the head work method isnt going to do the job i will keep the CR standard. I wasnt aware of an EFI system for these? Or are you talking purely aftermarket? Again tho, not really sure if id want to go that level. Fuel economy isnt a real issue, and never should be with a car like this. A few extra cents per KM is really the last thing to worry about. Basic rebuild shouldn't set you back -too- much, plus always a good idea to check the bores/bearings before you start spending money on getting more power out of a car. As you're not exactly pushing the limits of the engine, it's something you can definitely do at home if you have a good eye for detail and a lot of patience. As for EFI, if you can get a manifold to suit Webers you can run EFI with an injector adaptor plate - however unless you're spending big, I'd only play around with OEM bolt-on kits (which are available for some engines but not all obviously). A friend went with the adaptor plate setup on his Cortina (250 xflow), made around 250rwhp with plenty of compression and decent sized cams. One of the angriest engines I've heard ha. |
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lil_bobby_260
Post #11
Yeah thats the other reason i want the compression - sounds amazing. But i think EFI/triples is a bit much for it. Its the missus car, and im REALLY trying to keep it basic for her so she can do most of the work herself. |
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arturokemp128
Post #12
Every car owner is always checking their bearings always as all updates of the car so it wont be ragged. |
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lil_bobby_260
Post #13
Just had the joy of finding out that the valiant was optioned from factory with a D34 code "premium performance' motor. This means it is the same 265 from Pacers, 770's, and R/T Chargers - 203HP (151kW). |
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lil_bobby_260
Post #14
QUOTE (arturokemp128 @ Oct 3 2011, 03:44 PM) Every car owner is always checking their bearings always as all updates of the car so it wont be ragged. Errmmm.... Watermelon. Yes. What? . Anyway - does anyone have some input on the pro's and concs of Long runner inlet manifolds vs short runner, for street driven vehicles? What are the benefits and draw-backs of each type? Is it similar to dual and single plane manifolds on V8s? Im after a decent torque curve, not so much just top end power. Any feedback would be great. |
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Mongrel
Post #16
QUOTE (lil_bobby_260 @ Oct 3 2011, 11:32 PM) Errmmm.... Watermelon. Yes. What? . Anyway - does anyone have some input on the pro's and concs of Long runner inlet manifolds vs short runner, for street driven vehicles? What are the benefits and draw-backs of each type? Is it similar to dual and single plane manifolds on V8s? Im after a decent torque curve, not so much just top end power. Any feedback would be great. QUOTE (pipster11 @ Oct 4 2011, 07:33 AM) pretty sure longer runners give more torque but short gives better high rpm power two things to research, pulse ram theory and helmholtz resonation. As you'd know air doesn't flow smoothly through a inlet tract, at 5000rpm the air in a runner stops approx. every .015sec and causes a high pressure ripple back through the inlet tract. If you can catch this ripple on the next intake(ie .015 seconds later) you can charge the cylinder. This is pulse ram and it only occurs at +/-500rpm of the tuned frequency but resonation tuning(of the over all volume) can broaden this. |
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lil_bobby_260
Post #17
I'm not talking tuned length trumpets, just whether a 4bbl manifold with long runners is a better option than one with short runners. From what I can gather, short runners are good for torque like a dual plane v8 manifold, and the long runner ones are good for top end power like a single plane. |
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WideFTW
Post #18
short will give you better response, thats about it. cause less distance between butterfly and inlet valve. id go triple SU or if you got the money, triple web. more barrels the better, good tuning qualities, and you will get better low end, as you will have a higher air velocity. a good drivable cam with a noticable hot spot i find is around 274 |
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pipster11
Post #19
QUOTE (lil_bobby_260 @ Oct 5 2011, 08:40 PM) I'm not talking tuned length trumpets, just whether a 4bbl manifold with long runners is a better option than one with short runners. From what I can gather, short runners are good for torque like a dual plane v8 manifold, and the long runner ones are good for top end power like a single plane. other way i think, long runners get the air velocity up maximising cylinder filling or something like that |
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lil_bobby_260
Post #20
QUOTE (pipster11 @ Oct 5 2011, 09:36 PM) other way i think, long runners get the air velocity up maximising cylinder filling or something like that Haha i keep getting told opposite everytime i ask someone!!! In which case i should be aiming for a long runner inlet manifold - just aiming for a good torque curve. |
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Mongrel
Post #21
QUOTE (lil_bobby_260 @ Oct 5 2011, 08:40 PM) I'm not talking tuned length trumpets, just whether a 4bbl manifold with long runners is a better option than one with short runners. From what I can gather, short runners are good for torque like a dual plane v8 manifold, and the long runner ones are good for top end power like a single plane. It's not for trumpets it's for overall intake tract, changing trumpets on a ITB/IC is just one way of changing the overall inlet tract because the throttle plate is close to the head.....on a single carb the throttle plate is at the start of the inlet tract so you're benefits come from changing the manifold runner length, diameter, overall volume, etc. Smaller diameter runners improve air speed which increases mixing/turbulence=more power...but a smaller diameter runner also limits the overall airflow=limiting power. If you want to run on that principle alone, You are not going to get very far in finding a good manifold, short runners don't = more power/long runners don't = more torque, it's a generalization from proper development/research that is based around intake pulse and resonance frequency tuning. A dual plane manifold separates a engines inlet into two separate systems. two separate individual plenum's that have relatively long runners and are usually designed for good idle and progression response. that's not to say you can't make a dual plane manifold designed for high rpm, it's just that in high rpm/hp applications the low to mid range drivability with a big carb and cam is going to be pretty piss poor...why bother making a dual plane with good mid range air speed and tunning if you can't use it any way. Use a single plane (single large plenum chamber and usually sits higher with relatively shot inlet runners) and have a manifold that makes it's performance in the high rpm area where the cam and carb come in to play as well. |
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gutless
Post #22
This should turn out to be a very good read as i already love straight 6s and am gaining an interest in oldschool cars ontop of my apparent love for Skylines |
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lil_bobby_260
Post #23
QUOTE (Mongrel @ Oct 5 2011, 10:55 PM) It's not for trumpets it's for overall intake tract, changing trumpets on a ITB/IC is just one way of changing the overall inlet tract because the throttle plate is close to the head.....on a single carb the throttle plate is at the start of the inlet tract so you're benefits come from changing the manifold runner length, diameter, overall volume, etc. Smaller diameter runners improve air speed which increases mixing/turbulence=more power...but a smaller diameter runner also limits the overall airflow=limiting power. If you want to run on that principle alone, You are not going to get very far in finding a good manifold, short runners don't = more power/long runners don't = more torque, it's a generalization from proper development/research that is based around intake pulse and resonance frequency tuning. A dual plane manifold separates a engines inlet into two separate systems. two separate individual plenum's that have relatively long runners and are usually designed for good idle and progression response. that's not to say you can't make a dual plane manifold designed for high rpm, it's just that in high rpm/hp applications the low to mid range drivability with a big carb and cam is going to be pretty piss poor...why bother making a dual plane with good mid range air speed and tunning if you can't use it any way. Use a single plane (single large plenum chamber and usually sits higher with relatively shot inlet runners) and have a manifold that makes it's performance in the high rpm area where the cam and carb come in to play as well. Youre going over the top with the information - telling people to look for things and research things that are completely impossible to do... Manifolds for these cars dont come with this sort of information, and the gains performance wise on such basic motors being taken to only basic levels of modification, for the type of in depth manifold research and development etc, is simply not worth it. If i walked into a speed shop or hopped on the phone to someone chasing a 4bbl manifold for a 265 hemi and started sprouting what youre talking about, id get hung up on mate. ANy guys ive spoken to simply generalize on whether you want to buy a long or short runner, doesnt really go beyond that. WHen i ask why and whats best, they just sprout the high end power/low end torque story, and it changes everytime. Any R&D that was done on these manifolds was done 30+ years ago and hasnt been changed or improved upon since, and the R&D process has been lost in the sands of time. Might jump on hemi6pack or the charger forums and see if there are any real old school guys who have been fiddling with these for ages. Techno-babble is useless. |
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gutless
Post #24
QUOTE (lil_bobby_260 @ Oct 6 2011, 11:58 PM) Youre going over the top with the information - telling people to look for things and research things that are completely impossible to do... Manifolds for these cars dont come with this sort of information, and the gains performance wise on such basic motors being taken to only basic levels of modification, for the type of in depth manifold research and development etc, is simply not worth it. If i walked into a speed shop or hopped on the phone to someone chasing a 4bbl manifold for a 265 hemi and started sprouting what youre talking about, id get hung up on mate. ANy guys ive spoken to simply generalize on whether you want to buy a long or short runner, doesnt really go beyond that. WHen i ask why and whats best, they just sprout the high end power/low end torque story, and it changes everytime. Any R&D that was done on these manifolds was done 30+ years ago and hasnt been changed or improved upon since, and the R&D process has been lost in the sands of time. Might jump on hemi6pack or the charger forums and see if there are any real old school guys who have been fiddling with these for ages. Techno-babble is useless. Fair go mate, His information is valuable, interesting and may spark others interests. Thread is about modifying and tuning Carbie Straight 6s, no?  . As much as what he said may be too technical for the application you are intending, Let the man speak if not to inform anyone else interested in this sort of stuff. 
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pipster11
Post #25
QUOTE (lil_bobby_260 @ Oct 6 2011, 11:58 PM) Youre going over the top with the information - telling people to look for things and research things that are completely impossible to do... Manifolds for these cars dont come with this sort of information, and the gains performance wise on such basic motors being taken to only basic levels of modification, for the type of in depth manifold research and development etc, is simply not worth it. If i walked into a speed shop or hopped on the phone to someone chasing a 4bbl manifold for a 265 hemi and started sprouting what youre talking about, id get hung up on mate. ANy guys ive spoken to simply generalize on whether you want to buy a long or short runner, doesnt really go beyond that. WHen i ask why and whats best, they just sprout the high end power/low end torque story, and it changes everytime. Any R&D that was done on these manifolds was done 30+ years ago and hasnt been changed or improved upon since, and the R&D process has been lost in the sands of time. Might jump on hemi6pack or the charger forums and see if there are any real old school guys who have been fiddling with these for ages. Techno-babble is useless. bring it into the modern age and use science, not witchcraft  surely dyno sheets before and after the products are around somewhere, probably in some form of sales book |
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Mongrel
Post #26
You've got a good point Rob, I wouldn't expect anyone to try and calculate all that crap but as Tom said, it's not simple witchcraft any more. Information is everywhere on the net and I, like many other people now days, don't like being told it works just because... |
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lil_bobby_260
Post #27
Mongrel i was just trying to keep it simple is all. 90% of people on this site who would be building up a carbied 6cyl would be p-platers, so was kindof aiming it at that sort of group. And i have to have this chrylser finished by christmas haha... But hey - its not my thread, its the internets :-) all i did was post it haha... |
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gutless
Post #28
QUOTE (Mongrel @ Oct 7 2011, 10:08 AM) You've got a good point Rob, I wouldn't expect anyone to try and calculate all that crap but as Tom said, it's not simple witchcraft any more. Information is everywhere on the net and I, like many other people now days, don't like being told it works just because... Understanding some basic principles is good way understand how everything fits together. Just because it's basic modification on a basic engine doesn't mean you can't use a little 21st century know how to make your rig get power and still drive like a dream. I understand your topic is about tried/tested combo's that work, I just thought that introducing a little bit of info would help people understand the principles as to how and why different set-ups work, maybe even spark some interest into doing there own more indepth research, but it's your thread man. I'll keep quiet if you just want to keep to working combinations ;-)  please continue good sir
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