Edelbrock Performer vs Thermoquad...

[Dr. Righteous]

Wish I found this forum earlier. \nI have run the gamut of Carters and Edelbrock carbs over the years.\n\nThe FIRST thing I would tell you is a Edelbrock 1406 is the WRONG carb for your application. First it is jetted LEAN and intended for smallish V8s in it's stock form. \nIf you ran a spreadbore to square flange adapter then likely you defeated the split plenum design of the intake. This gives you a weaker vacuum signal to the left and right sides of the carb respectively. That is going to give you poor throttle response. \n Secondly I would advise to get the Thermoquad rebuilt. It is a myth that parts are scarce for these. The Thermoquad is probably the BEST all around 4BBL carb ever made but they are easily screwed up by people that are not very familiar with how Carters work. \nWalker make complete build kits and sell individual parts including the plastic bowl sections. Look at your version number on the base plate of the carb and search by that.\n(Mine is a 6460)\n\nhttps://buy.walkerproducts.com/carburetor/components/carter/carter-4bbl-tq-1-carburetor-components.html\n\nO'rileys Auto Part carries walker kits; you can order it from them probably cheaper than anywhere else.

[Acesneights]

Yeah, the 1406 was not a good fit. The Holley works really nice but the heatsoak. I may still rebuild the TQ bt for now I found a nice Edelbrock performer Aluminum Intake on the Bay for 90$. I also ordered Felpro Intake gasket 1215 which blocks the heatrisers to the intake. They are not needed on this as I only use it in warmer weather and from what I gathered from a few mopar perforamne forums it may even add a slight improvement in performance.\nWill see. Intake should hopefully be here this week.\nRight now I don't dare shut it off hot or idle too long or it runs like crap for a good 5 minutes or so until cooler fuel reaches the bowls and they cool off.\nI can't wait t put a Cummins in it.

[Acesneights]

On a side note my TQ was rebuilt once already by Holley. I was lead to believe that was a good version.

[Dr. Righteous]

\nI can't wait t put a Cummins in it.

\n\nA 6BT swaps into winnies and other Dodge chassis motor homes is a popular swap.\nFor me I did the math and because of the high gear ratio in my MH, it isn't ideal. \nThe Rockwell 130 rear is geared at 4.88:1. \nA cummins diesel swap is really only worth the expense if you can target the "sweet spot" RPM range at highway cruise.\nThat is 1800-1900 RPM. Above or below that the cummins will not deliver it's best fuel economy. \nWith my gear ratio and an over drive it puts me running 45-50 MPH highway to maintain the sweet spot and that includes running an OD. That is way too slow.\nHowever most dodge chassis MH less than 30' are equipped with a Dana rear with a more reasonable 4:11 ratio.\n\nSo doing the math:\nSay your tire height is 32" (size on mine)\nIdeal cruise due to aerodynamic drag is 60-65. \nGear ratio is 4.11:1\n3spd auto is a 1:1 high gear ratio will give you:\n2589 RPM for 60 mph cruise speed\n2805 RPM for 65 mph cruise speed\nOut of range. A cummins 6BT swap must include a OD to pay for itself in mileage gains. \n\nIf you are running a Dodge AOD tranny (.69:1 OD ratio) you can expect a engine RPM of \n1787 RPM for 60 mph cruise speed\n1935 RPM for 65 mph cruise speed\nThis setup is ideal.\n\nNow if you have a GEAR VENDORS OD unit install that has a different OD ratio of .73:1\n1890 RPM at 60 MPH cruise speed\n2048 RPM at 65 MPH cruise speed\nNot ideal but still pretty close. \n\nSo it looks like finding a good 6BT with the AOD tranny from a defunct Dodge 2500/3500 truck is the way to go. \nI see this combination for sale quite a bit in the $2000-3000 range. Installing it is a major job but worth it of you can hit the sweet spot.\nAlso you would be money ahead if you paid for a overhaul of the engine and transmission before doing the conversion.\nThe swaps I have read about have all been $5000+ just to get it installed.\n\nCheck your tire height and plug the number into this engine RPM calculator:\nhttp://www.crawlpedia.com/rpm_gear_calculator.htm\n\nDoing all the math before hands can really open your eyes on this kind of project.\nI have read several blogs on "diesel swaps" where the person gets less than ideal or worse end results considering the increase in fuel cost because they didn't do the math before hand.

[Acesneights]

Actually I think I'm running 4:56.\nThe swap is along way off unless one falls into my lap real cheap or the 440 blows up but after the swap I may consider even swapping the ring and pinion to something more diesel friendly.\nPretty easy to swap a R&P in a Dana.

[77Travco]

I also have the factory 4:56's. I am still trying to work 4 wheel drive into the mix as well. I am always on the lookout for a diesel 4x4 Mitsubishi 2.5 ton delivery truck as a donor vehicle. I have seen a few around as well as a big 4x4 UPS van. One of these days something will come along.

[Acesneights]

I'll do ome pics later but put an Edelbrock performer on that I scored of eBay for 125$.\nThe engine was hot when I pulled the intake because I had been working on the dash air. I put the hot intake on the ground and 30 mins later is was still 180f OFF THE ENGINE. That is why cast Iron is no good. The Edelbrock sat a bit higher so I had to mess with the linkage a little and re drill the bracket for the servo for the Cruise. Had to move the vac line too for the brakes. Seems alot better though.

[Dr. Righteous]

I'll do ome pics later but put an Edelbrock performer on that I scored of eBay for 125$.\nThe engine was hot when I pulled the intake because I had been working on the dash air. I put the hot intake on the ground and 30 mins later is was still 180f OFF THE ENGINE. That is why cast Iron is no good. The Edelbrock sat a bit higher so I had to mess with the linkage a little and re drill the bracket for the servo for the Cruise. Had to move the vac line too for the brakes. Seems alot better though.

\n\nThink you are looking though the wrong end of the telescope on this one. \nThe cast iron stayed hot because it tends to hold in heat. NOT wick it away. In other words cast iron is a poor thermal conductor compared to aluminum. \nAn aluminum intake will wick the engine heat straight to the carb because it is relatively cool in comparison. Not good because the carb will quit working when the gasoline starts to vaporize. Thus the need for thermal barriers etc to try to keep this from happening. This also can have a negative effect because a more "open" plenum often causes a weaker vacuum signal thus, a sluggish throttle response. \nKeep in mind Chrysler utilized a heat riser system to facilitate a quick warm up for years with excellent results. This is because the cast iron intake was very efficient at keeping the heat in the manifold and not getting the carb too hot. The same system would not work with an aluminum intake because it would roast the carb. \n\nNow another point to consider is the only real advantage to swapping to a aluminum intake is to increase air flow and thus better performance. But this advantage is only seen in the upper RPM ranges. A large runner intake is a disadvantage at low RPM because you have lower port velocities, and here again this hurts throttle response and acceleration. In our applications we are interested in best efficiency cruise speed. For this the stock cast iron intake is fine.

[77Travco]

He installed an Edelbrock PERFORMER intake. It is a dual plane intake meant for use from idle to about 5000 RPM. It actually should work great for trucks, tow vehicles, etc.\nI am curious how it works out as I may also install one for better performance now that I have my heat issue solved.

[Dr. Righteous]

He installed an Edelbrock PERFORMER intake. It is a dual plane intake meant for use from idle to about 5000 RPM. It actually should work great for trucks, tow vehicles, etc.\nI am curious how it works out as I may also install one for better performance now that I have my heat issue solved.

\nYeah, I understand the difference between dual and single plane. \n\nBut the point I'm making is the problems that arise when going from a cast iron intake to an aluminum one. And for this application the advantages will be minimal.