Replacing FAST EFI on HP 383, with what?

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I have a '73 Space Duster with a 383 (.030 over) dropped in it. I am old school and hate the FAST efi. I am going back to carbs. Don't know how many cfm I really need and how many carbs to feed it. The 383 (400hp) has HP purple cam, roller rockers, Edelbrock alum heads, MSD, Edelbrock Al DP4B intake, 70 440 magnum exh. manifold w/ 2 1/2" exh pipes. Trans is HD727 with full go kit, TCI clutch and seals and Hughes performance converter and aux cooler. 355 rear end. I have read so many articles on the web and in both A and B Bodies forums that now I am totally confused and frustrated. This site focuses on 340s and 318 and a 360s. As expected. Please help me to decide on 3x2, 2x4, dp, straight 4?? 670cfm, 750, 850 1050?? Don't know cfm on 3x2, 2x4. I have a 850 4150 DP on my 440 (600hp) and know how it performs, but don't know how multi carbs would run on it either. Should probably stay with what I know, but need to explore the multi carb set ups. Any recommendations as to manifolds and carbs for the 383 would be greatly appreciated. Oh, one more thing. There is metal in the pan of the trans. Any recommendation on what level of 727 I need with this set up? I know this is not the thread for this, but I figure that anyone knowing what to put on the 383 in carbs, will know the answer to the level of 727 I would need. Than you
 
For the street
You need a single 4bbl intake and a 700 to 750cfm carb.
you don't need anything fancy when it comes to the 727; just a basic HD unit and I like a TF-II kit.
You didn't say which purple( there's like 4 of 'em), But none of 'em are real friendly towards 3.55s unless you have a TC matched to the cam and lots of compression.
Those heads wouldda really liked a fast-rate of lift Voodoo cam, but then it wouldda wanted headers.
 
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Find a Big block High Performance TQ and be done. Ran one on a 383, 727, 68 Formula S daily driver for years. Factory everything but a 72 400 intake and TQ. Decent mpg and enough get up and gone to satisfy. You can always try what you have also. As for the 727, replace the fluid, filter, and adjust the bands. Try that first.
 
For the street
You need a single 4bbl intake and a 700 to 750cfm carb.
you don't need anything fancy when it comes to the 727; just a basic HD unit and I like a TF-II kit.
You didn't say which purple( there's like 4 of 'em), But none of 'em are real friendly towards 3.55s unless you have a TC matched to the cam and lots of compression.
Those heads wouldda really liked a fast-rate of lift Voodoo cam, but then it wouldda wanted headers.

The purple cam has 484 lift. I will need to look up the rest of the numbers. Thanks for your advise. This where my mind took me to begin with. The compression of engine is 9.7 to 1. I am still reading and trying to learn about TCs. How do you find out what you need without having chosen one to begin with? If I try to find the point at which the drive shaft starts to move as a result of WOT, how do I do it without having put in a TC to begin with? If my trans is "crashing" won't that give me an erroneous result? Forget about headers, there is no space left (as I see it) with out doing some cutting, pounding and cussing. I have looked at them and will look some more after I fix what I got. Again, thanks for help.
 
That cam is too big for the amount of compression ratio you have. The heads are far more than you need for your combo.That cam wants headers to take advantage of the overlap period. And also to pull up the bottom-end torque. Consequently, your off-the-line performance will be soft, and so you will need about a 3000 TC to get moving with any kind of dignity.
I'm guessing your cylinder pressure is around 150 or less. Those heads will easily support 185.The low cylinder pressure, leads to a very low for your combo, VP, of about 128 which is less than a 1969 318 musters, but more than an 8/1 teener. The best part of your compression ratio is you can burn 87E10 all dayeveryday.
As it is 3.55s will be fine once you hit 25mph.However, they will keep your engine operating at rpms where there is very little power.
For a fun combo, you will need to pump the compression way up, and for street, loose that cam.
Where did you get the 400 hp number from?
 
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For the street
You need a single 4bbl intake and a 700 to 750cfm carb.
you don't need anything fancy when it comes to the 727; just a basic HD unit and I like a TF-II kit.
You didn't say which purple( there's like 40 of 'em)
Made the correction for ya!:lol:
I agree with AJ on cfm.
Maker and style of carb are really your call and then just take the time to tune the carb from there.
If I was to do an Edelbrock carb, I would actually do a 800 AVS II. (On top of the RPM intake.)
The new 750 Street Demon with the phenolic middle would be a very good street strip carb that tunes like the Edelbrock/TQ.
 
That cam is too big for the amount of compression ratio you have. The heads are far more than you need for your combo.

OMG! What are you talking about!?!?!?!?!
Oh hell no and no way!
Consequently, your off-the-line performance will be soft, and so you will need about a 3000 TC to get moving with any kind of dignity. That cam wants headers to take advantage of the overlap period. And also to pull up the bottom-end torque.
Oh hell yea!
As it is 3.55s will be fine once you hit 25mph.
Where did you get the 400 hp number from?
A lot would be in tire diameter. Along with the converters stall.
Tha combo is an easy go north of 400hp level.
 
Holley 3310 750 vacuum secondary carburetor. No need to over think it. OR like rumblefish recommended, the new 750 Street Demon is another fine choice.
 
I like it! A 3310, simple easy, BAMM! Not a hard carb to work with.

Yes sir! They really broke the mold when they made that carburetor. Or.......maybe it's the old farts in us that still like it so much. LOL
 
Yes sir! They really broke the mold when they made that carburetor. Or.......maybe it's the old farts in us that still like it so much. LOL

Lot of good advise and input, however, it still leaves me with more questions than I started with. I hear you loud and clear about the cam being oversized, but, what is the recommendation if I keep the heads? What VooDoo cam would you recommend for these heads? I can swap out cams pretty easy, but there seems to be more to making this car run like I am used to. You hit it on the head when you said that the car would not react for crap up until 25 mph or so. It does have an approx. 2200 - 2800, maybe 3000 TC in it. That alone, I am not used to and don't want. Actually, don't know why I bought an automatic to begin with. We are in agreement on the carb choice. The 750 Street Demon was my choice, but I have this Holley 4150 dp 850 sitting here. Is that too much carb. I saw dino tests on a 383 hp and between the 670, 750, 850, and 1050 the 850 was slightly better than the 750 in torque and in hp, neither carb was a dp. The 850dp runs great in my 440 but took both physics and chemistry to get it that way. It concerns me that the 383 will be even more critical with that size DP. Any experience with a HP 383 running a 850 dp? AJ, the 400 HP came from the builder, who I now have doubts about. I inherited (at auction) the machine as is where is. As for headers, I'll repeat, I don't know how they will fit. I would think that the 440 exh manifolds go into 2 1/2" pipes would help. Am I wrong on this?
 
Space Duster, your over Analyzing the whole issue. That cam is also not too big for the heads you have. To be honest as a matter fact, it is a bit small, for the heads.

To effectively use what you have with minimal change, swap to a smaller cam.

TTI has headers that will fit. Schumacher creative services also has tri- Y headers that fit very well.
 
Space Duster, your over Analyzing the whole issue. That cam is also not too big for the heads you have. To be honest as a matter fact, it is a bit small, for the heads.

To effectively use what you have with minimal change, swap to a smaller cam.

TTI has headers that will fit. Schumacher creative services also has tri- Y headers that fit very well.
I have always matched my convertors to the camshaft, it aint rocket science to me. A set of lower rear gears would make a lot of diff. in ur case. Not arguing w/ the other posts, they sound good too, but headers and gears would make a big diff.. A 750 holley or quickfuel would be my choice in carbs. What don`t u like about the fast f.i. ?
 
Space Duster, your over Analyzing the whole issue. That cam is also not too big for the heads you have. To be honest as a matter fact, it is a bit small, for the heads.

To effectively use what you have with minimal change, swap to a smaller cam.

TTI has headers that will fit. Schumacher creative services also has tri- Y headers that fit very well.

I don't mind swapping out cams, but what is the recommendation with the heads and rear end, the 750 cfm and assuming headers that many believe I need. Will I have to pull the engine to put the headers on and drop it all back in together? Had to do that with 2" headers on the '67 Satellite's 440. That's a big job for me with what I have to work with. I will definitely check with Schumacher and TTI. Thanks for the guidance.
 
I have always matched my convertors to the camshaft, it aint rocket science to me. A set of lower rear gears would make a lot of diff. in ur case. Not arguing w/ the other posts, they sound good too, but headers and gears would make a big diff.. A 750 holley or quickfuel would be my choice in carbs. What don`t u like about the fast f.i. ?

FAST has the worse service techs I've ever tried to talk to. This is a common complaint on blogs. My problem with FAST is inconsistency in driving conditions. Seems to take the computer a long time to adjust. Any changes you make effects other driving conditions. Maybe I am not giving it a chance. Maybe the race mechanic I have taken it to can set it up. If so, I'll run it for awhile, but remember, I am old school and I understand carbs. I don't like wiring I am not familiar with. And, it looks like crap sitting on top of the machine. Not a real good answer, I just like carbs more.
I am most interested in matching the convertor to the camshaft. I am waiting for a recommendation and affirmation on the choice of cams to match up with the Edelbrock Al heads. I like mid range acceleration and like a 373, but will keep the 355 in the rear end for now. Would you recommend a TC and with what 727 to go with it? Thanks.
 
If you keep that cam that powerpeaks at like 5600, and you run the shift rpm up to 6600 or better, and you keep that wussy 9.7 compression ratio you're gonna need a 3500TC and 3.91s.
That cam needs 11/11.5 to make take proper advantage of those heads. Otherwise a well engineered teener is gonna make mince-meat out of you.
But what do I know. My 367 only goes 93 in the 1/8th. With a little tiny wiener cam

9.7 Scr, that cam,3.55s and a lo-stall TC will hold your engine back until about35 mph before it wakes up then it will scream thru the top of first gear. If you choke it by short shifting it at 6000 or 52 mph, then the Rs will fall back into the basement, like 3600 and you get to climb out of that hole again. So the heads just started working and then you pulled the rug our from under them. My guess is the heads were working for about 1 or 1.5 seconds so far. So now you're in second at 52 mph and 3540. And you're on your way to 88pmh@6000. So the heads are gonna pull from 5000(73mph) to 6000(88mph) Or another 2.5 seconds. (And in a speed zone you are very seldom gonna be in, I might add).

Without headers, your overlap period means pretty much nothing, so you can ditch those 68 overlap* and get a much smaller cam that has way more midrange power. Then pump up the cylinder pressure, and crank in some decent lift, and make those heads work all the time.I mean you paid for'em, you might as well make use of 'em.
But the 3.55s are still gonna be a bit of a handicap. But now you are gonna blow the tires away, so a bit less so.
If you you get the combo hot enough, you may not need any extra stall, cuz firstly the 185 psi is gonna push the stall speed up a little higher, and secondly, the 185 psi is gonna build more torque than the tires can stand anyway.
185 is waaaaay more than 150. different world.200 is something!
Here's my opinion
I bought aluminum heads to run the psi, cuz if I was stuck with 150psi, I'd have to pretend I had power. 150 is a waste of aluminum, and that's my opinion.150 is almost a waste period. Shoot I've built lawnmowers to beat that.
 
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FAST has the worse service techs I've ever tried to talk to. This is a common complaint on blogs. My problem with FAST is inconsistency in driving conditions. Seems to take the computer a long time to adjust. Any changes you make effects other driving conditions. Maybe I am not giving it a chance. Maybe the race mechanic I have taken it to can set it up. If so, I'll run it for awhile, but remember, I am old school and I understand carbs. I don't like wiring I am not familiar with. And, it looks like crap sitting on top of the machine. Not a real good answer, I just like carbs more.
I am most interested in matching the convertor to the camshaft. I am waiting for a recommendation and affirmation on the choice of cams to match up with the Edelbrock Al heads. I like mid range acceleration and like a 373, but will keep the 355 in the rear end for now. Would you recommend a TC and with what 727 to go with it? Thanks.
I have never had any problem w/ the service techs at fast, contrary, it`s been among the best I`ve dealt with! They are busy, but have called me back when I couldn`t get ahold of them. I`m no wiring expert by any means, but their directions and a "little" common sense worked for me. I only have about 350 miles on my fast 2.0, but it has already smoothed out and running fine. I have changed the fuel ratio, and timing some tho. Pricy, but comes w/ everything, no need to go order other parts, or scrape up fuel pumps , or somebody elses regulators and such ! Very nice to tune, in the drivers seat ! Have heard that a lot of systems need about 500 miles on them to clean up .
 
I have never had any problem w/ the service techs at fast, contrary, it`s been among the best I`ve dealt with! They are busy, but have called me back when I couldn`t get ahold of them. I`m no wiring expert by any means, but their directions and a "little" common sense worked for me. I only have about 350 miles on my fast 2.0, but it has already smoothed out and running fine. I have changed the fuel ratio, and timing some tho. Pricy, but comes w/ everything, no need to go order other parts, or scrape up fuel pumps , or somebody elses regulators and such ! Very nice to tune, in the drivers seat ! Have heard that a lot of systems need about 500 miles on them to clean up .
I'm going t give the FAST sys a chance. It is being properly "tuned" with a new MSD disy. My race mechanic believes that the spark was the culprit all along. We will see next week. I will give the tech staff at FAST the benefit of the doubt. I may have caught them at bad times and talked to a tech that had little or no patience. For reasons mention before, I am still looking to go with carbs. Thanks for your support and your experience.
 
If you keep that cam that powerpeaks at like 5600, and you run the shift rpm up to 6600 or better, and you keep that wussy 9.7 compression ratio you're gonna need a 3500TC and 3.91s.
That cam needs 11/11.5 to make take proper advantage of those heads. Otherwise a well engineered teener is gonna make mince-meat out of you.
But what do I know. My 367 only goes 93 in the 1/8th. With a little tiny wiener cam

9.7 Scr, that cam,3.55s and a lo-stall TC will hold your engine back until about35 mph before it wakes up then it will scream thru the top of first gear. If you choke it by short shifting it at 6000 or 52 mph, then the Rs will fall back into the basement, like 3600 and you get to climb out of that hole again. So the heads just started working and then you pulled the rug our from under them. My guess is the heads were working for about 1 or 1.5 seconds so far. So now you're in second at 52 mph and 3540. And you're on your way to 88pmh@6000. So the heads are gonna pull from 5000(73mph) to 6000(88mph) Or another 2.5 seconds. (And in a speed zone you are very seldom gonna be in, I might add).

Without headers, your overlap period means pretty much nothing, so you can ditch those 68 overlap* and get a much smaller cam that has way more midrange power. Then pump up the cylinder pressure, and crank in some decent lift, and make those heads work all the time.I mean you paid for'em, you might as well make use of 'em.
But the 3.55s are still gonna be a bit of a handicap. But now you are gonna blow the tires away, so a bit less so.
If you you get the combo hot enough, you may not need any extra stall, cuz firstly the 185 psi is gonna push the stall speed up a little higher, and secondly, the 185 psi is gonna build more torque than the tires can stand anyway.
185 is waaaaay more than 150. different world.200 is something!
Here's my opinion
I bought aluminum heads to run the psi, cuz if I was stuck with 150psi, I'd have to pretend I had power. 150 is a waste of aluminum, and that's my opinion.150 is almost a waste period. Shoot I've built lawnmowers to beat that.
Bottom line is I have to figure out how to get more compression ratio and I need a new cam and TC to match up to the heads. If that is what you are saying, then what cam do you recommend and what TC would go with it. You might tell me what carbs you would put on it to replace the efi (assuming I replace it).
 
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Bottom line is I have to figure out how to get more compression ratio and I need a new cam and TC to match up to the heads. If that is what you are saying, then what cam do you recommend and what TC would go with it. You might tell me what carbs you would put on it to replace the efi (assuming I replace it).

Thanks for the education on this topic. There is an awful lot more that goes into "matching up" components to achieve the best results. Everyone wants to see their classic perform the best it is capable of doing. The main difference is whether you are going to run the strip, run only to/from/in town, or both. I will not be going to strip. I will however race myself on the way to and from home from the town. It is there I want the maximum performance. After running in town the engine usually wants to load up and needs to have an "Italian Tune-up" on the way home. (I used to restore Alfas, sorry about that) So, If I take what everyone on the forum has said in reply to this forum thread, and taking into consideration the numerous articles I have read, let me see if I am getting closer to what the 383 needs.

1) If the existing FAST efi does not respond as it should, I already have a 850 dp Holley I can convert to. A bit much, but with headers and a proper cam and TC, it should work, I believe. In either case, I will keep the Edelbrock DP4B on the engine. I find it hard to pass up on going with a 6 pack or two quads down the road, if for nothing more than putting on what is popular to buyers. I lean toward the 3x2s because of being able to run on the center one when not showing off.
2) I did order a set of headers from Schumaker as recommended.
3) I am going to stay with the Mopar 484 lift cam, for now. Once I am satisfied with the performance of the other components, I can always put in a recommended cam based on results.
4) I will either have the 727 rebuilt in accordance with street/strip options, or, purchase a newly rebuilt one. The cost is not that much different. The key is to get the best builder in the area.
If the existing trans is a boat anchor, I will purchase one from the likes of Summit, Monstertrans, B&M, Hughes.......
5) You all have taught me that the TC is a very important component to making this set up perform. I never thought it was that big of deal unless you were at a the drag strip. I have never owned a classic with an automatic. My guess is that this set up will need a 2800-3000 range TC, however, I believe I will leave the decision up to the recommendations of the trans rebuilder and the race shop technician putting it all together for me, while I take the input I get here and apply it to the same.
6) There was a lot of talk and recommendations for going with a different gear in the rear. I will change the 3.55 and go to a 3.73. or 3.91. Probably after I get the items above corrected. Any strong recommendation?
7) I did order, and am installing, a new MSD Billet disy to go with the mopar 6AL unit.

I ask all of you to please tell me if I am on the right track......have I missed something? I have tried to find ways to increase the compression ratio. It was raised up to 9.7:1, but I believe I understand more would be better. With out changing the head or tearing the engine down, I don't know how that would be accomplished. This is something I will most likely live with. I want to keep the Edelbrock Aluminum heads and build around them. The question is, am I going in the right direction to accomplish this? Am I? Any fine tuning? Thanks for listening to me trying to get smarter about this 383 +.030 set up for the Duster. A Happy New Year to all.
 
I got the duster 383 back from the first shop. Put in a MSD Billet with new plug wires and wiring. Changed all the fluids, plugs, filters, etc. We wanted to see what we would get with the 383 getting good spark and timing more precise so that we could really find out how the FAST efi was going to perform. It sat up and laid down like a dog. Started great, idled great, sounded super. Took it home and called it a "sack-of 'em (bunch of cuss words). I know I can't blame it on the FAST, yet, but I may never know how good or bad it will be. It is in my garage now and will get the 3.91, a rebuilt 727 to match the motor, TC to match, and a cam kit (or piece one together). Lunati seemed anxious to match it up. I'm going to try the 850 DP I have. It sure wouldn't work with the set up it has now.
I had a new '64 Fury and traded it for a new '65 Sport Fury, both had 383 hps in them. Both 4 speed and only change made was a high riser on the '64. That was over 50 years ago, but I remember the feeling both, especially the '64, gave me. This Duster is a "feather duster" to them. So, I'll spend the bucks and do it right. Too late to turn back now. Hey, I thank all those that replied to the post and if you have any other feelings about the direction I am going, please let me know. I am very confused about one aspect and that's the 727 and the TC I think the set up will dictate the TC, but if anyone has a recommendation or experience with having supplying a trans that would help get me to the end, I'd appreciate it. There's plenty of re-builders around, even here in the Ozarks, but I'm not taking it to, or buying one from someone that others on this board won't recommend.
 
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