mopardude318
Well-Known Member
Can you do a quick test and add a 1” spacer? Maybe that would cure that idle down??
Dual Plane vs Single Plane Manifold with TBI
- Thread starter 65 Dartman
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Would like to see Any and all comments from the guys and gals in the know on this subject. (OP original quote ^^^)
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Just a few questions to help understand your final goal.
What is the starting point of your '66 273 engine? Stock build, stock cam, 2 bbl single plane with 2 bbl carb like this intake below?
Or being a Commando is it a factory 4 bbl.
If an improved 4bbl carb setup can be achieved on your existing intake and it starts and performs nicely would you be happy with that?
Just a thought for a 2 bbl intake so you don't have to open up the engine for a manifold change.
Or do you have your heart set on doing the 100% conversion over to a Sniper TBI setup with onboard computer, and higher pressure in the tank fuel pump . . for the fuel injection systems?
Just Curious . . .
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Just a few questions to help understand your final goal.
What is the starting point of your '66 273 engine? Stock build, stock cam, 2 bbl single plane with 2 bbl carb like this intake below?
Or being a Commando is it a factory 4 bbl.
If an improved 4bbl carb setup can be achieved on your existing intake and it starts and performs nicely would you be happy with that?
Just a thought for a 2 bbl intake so you don't have to open up the engine for a manifold change.
Or do you have your heart set on doing the 100% conversion over to a Sniper TBI setup with onboard computer, and higher pressure in the tank fuel pump . . for the fuel injection systems?
Just Curious . . .
Right from the gitgo it was a complete 66 Commando motor right to the stock single plane cast iron 4 barrel Commando intake using the AFB carb down to the oil pan. It’s been to the machine shop and now ready to be assembled. Racer Brown supplied the cam which is based on an OEM Commando cam with a few minor upgrades based on his recommendations. When ready to be assembled, the only deviation will be swapping out another forged 273 crank with the larger crank pocket allowing me to run a later transmission (A500)
I will only use a Carb to break the cam in on a run stand, then add the Sniper when I install the motor in the chassis. I would like the use the best manifold based on using the TBI right from the start after motor break in.
Right from the day the wagon got delivered, it’s been my intention to run FI. I have pulled the trigger on the Sniper as well as the Holley A Body in tank pump system with sending unit. I could use the OEM Commando intake with an adapter hence this discussion. I know people use adapters quite frequently. I really don’t want to go that route.
I was discussing with @oldkimmer the subject of intake manifolds and his recommandation was to use a Holley Street Dominator or an Edlebrock Streetmaster rather than the LD Or commandow/adapter that I have. I am open to any comments on anything I have mentioned
67 gt
A Wog boy who loves his Mopars !
I use a 1/2 inch open wood spacer on my air gap with the sniper . Didn’t touch the divider no need .
I was contemplating using my LD4B with either a spacer or milling the divider - no problem. I was also reviewing the instruction manual for the Sniper and discovered it uses a larger temp sensor rather than the stock Mopar sensor which is also what the Dakota Digital system uses. The LD4 only has the small Mopar-style opening for the temp sensor. I suppose I could drill and tap for the larger sensor but that that kinda ruins the manifold for someone else down the road. So the single plane manifold seems to be the choice of many to run with TBI. I found and bought a Holley Street Dominator which takes care of the intake design AND features several plugs in the water passage that will take care of the 2 sensor issue. Many thanks to oldkimmer for his thoughts on single plane manifolds as well as everyone who commented on this thread
i expect I will be liquidating both my LD4 and stock 66 Commando intake sometime in the future.
i expect I will be liquidating both my LD4 and stock 66 Commando intake sometime in the future.
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AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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I used a Weand Excellerator on my lo-Compression 318, with an old Holley lo-pressure TBI System. I think it was 23psi or something.
The Excellerator is a small-plenum single-plain with the runners transitioned to the smallports . It seemed to work well enough until winter. Then I had icing problems. So I put a Thermoquad on it. And you guessed it, I sold the Holley, and the TQ stayed on.
Not long afterward, I found a small-port cast-iron dualplain, and that was even better.
So the take-away for me was the small-plenum, and small ports. And of course at my power level with the stock cam, the dualplane was the way to go.
But in all fairness, I never ran the TBI on the dual-plain.
I think the dual-plains are for working within the limitations of carbs at low rpms. I don't see them needed for EFI even TBI. However, Ima thinking a stock lo-compression 273 may have problems with a large plenum, at low-rpm, so if it was me,
I would find a single-plain with a tiny plenum, like the one posted by George in #27. Decades and decades ago, I had a 71Demon with a 318 and one of those; and it was a pretty sharp combo..... altho, it was the last of the hi-compression 318s,lol.
If the pad is too small for your Sniper, I would not bolt an adapter on tho; I would modify the pad.
But surely, some aftermarket company must have a small-plenum, small-port, single plain? Surely.......
The Excellerator is a small-plenum single-plain with the runners transitioned to the smallports . It seemed to work well enough until winter. Then I had icing problems. So I put a Thermoquad on it. And you guessed it, I sold the Holley, and the TQ stayed on.
Not long afterward, I found a small-port cast-iron dualplain, and that was even better.
So the take-away for me was the small-plenum, and small ports. And of course at my power level with the stock cam, the dualplane was the way to go.
But in all fairness, I never ran the TBI on the dual-plain.
I think the dual-plains are for working within the limitations of carbs at low rpms. I don't see them needed for EFI even TBI. However, Ima thinking a stock lo-compression 273 may have problems with a large plenum, at low-rpm, so if it was me,
I would find a single-plain with a tiny plenum, like the one posted by George in #27. Decades and decades ago, I had a 71Demon with a 318 and one of those; and it was a pretty sharp combo..... altho, it was the last of the hi-compression 318s,lol.
If the pad is too small for your Sniper, I would not bolt an adapter on tho; I would modify the pad.
But surely, some aftermarket company must have a small-plenum, small-port, single plain? Surely.......
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Don’t think my Commando 273 will qualify as low compression since I estimate it will have at least high 9’s to 10 to 1. Whatever it is, i will have to live with it and the intake and Sniper I bought for it.
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