M1 Single Plane Question

I have been playing around with my combo and have noticed something very disturbing. My M1 Single Plane is a spreadbore design. I'm running a QF 950 DP on my Eddy headed 408. I've been playing around with spacers as well. Don't know why I didn't pay any attention before, but dam it seems like a bad mismatch between the spreadbore intake and a square spacer. Am I missing something here? Trying to improve 60 ft. times and it looks like a poor air/fuel flow match between the manifold, spacer and carb. Is there a different M1 with a square bore carb flange that I need? Thanks for listening.

Darren

Oh well, I guess it was a pretty dumb question. Ordered a Wilson Super Sucker 2" spacer and will reinstall the 750 now that I have learned to tune a little better now.

Darren, I'm surprised a motor head didn't see and answer this.

While there are mods that you can do to the M-1 single for better fuel distribution and add HP when it's done. once you have a spacer on top of it, it won't really matter. Although if the wilson spacer is a super sucker with the contored hollowed bottom, I'd wonder about it.

The intake was first designed to work and compete in a super stock arena since it was big back in the day. They never re-did the intake since, theres no real need. The class rules said, "Stock carb to be used only."

Thanks for the reply rumblefish. I'm hoping to see some improvement with the 2" Wilson spacer. That explains the spreadbore flange. Is there anything else that I should do or try, or would I be better off with another intake?

If its really rubbing you the wrong way, pick up some good 2-part epoxy putty, make sure its REALLY clean(cant emphasize CLEAN enough here), put your spacer on, and fill the gaps between the spacer & the top of the manifold, then go in with a die grinder and smooth out the transition. This used to be a standard part of prepping an intake. Nowadays everyone figures you just bolt it on & run it. If you are using the Wilson four-hole this wont work as the joint wont be easily acessible.

Just by the tone of your post, I think you also need bigger shooters, but I might be stating the obvious here.

I put in a 50cc squirter on the primary side. We'll see after I run at the Mopar Nationals at Ennis, Tx in April. I had a 950 DP, and was told it was too big. So I put the 750 back on. It seems as if the 950 had more "seat of the pants" pull, but I will give the 750 another try. Thanks for the reply.

Are you only worried because it looks bad, or because it is showing problems with cylinder to cylinder tuning? The reason it has the T quad flange but both patterns is because bolting the carb to it does little to hurt performance on it and means those of us who do like the Tquads dont need the adaptor which hurst hood clearance on some cars. If you were really doing the intake modifying bit, there's a lot you can do to make gains. None of them would include filling the "wings" on the secondary side. I don't know the combo, so I can't really say if the 950 helps or hurts the combo. But in terms of intakes, the M1 is a good piece that does work on a large variety of packages well. If you are concerned with the pad and you're racing the car and are not concerned with hood clearance, try the Edlebrock Victor before you spend $300 on various special spacers. In most cases, major gains with a spacer mean either the wrong intake choice (possibly just the wrong tweaking of an intake), or the wrong carb, or both..

edit: I think this might do better in engines or MP section. That's why I didnt see it...lol

69Chrgr said:

I put in a 50cc squirter on the primary side. We'll see after I run at the Mopar Nationals at Ennis, Tx in April. I had a 950 DP, and was told it was too big. So I put the 750 back on. It seems as if the 950 had more "seat of the pants" pull, but I will give the 750 another try. Thanks for the reply.

Click to expand...

Yea, but what size are the shooters themselves? Have you played with the shooter size? I may be stating the obvious here, but if you increase the size of the pump, but use the same size of shooter, you are increasing the duration of pump shot, not the initial amount. Not sure if I am explaining this well. Get my drift?

Yes sir I do. Sounds like I need to check the size on the nozzle and go up to the next size?

Heres the traditional method for setting shooter size. Snap the throttle wide open from a flat idle with no load. Keep going up in shooter till theres instant throttle response, then test drive the car. The right size is usually a size or two bigger than the one that works with no load. Might be 3-4 sizes bigger if the car is heavy or doesnt have enough converter. Its possible you may not have even needed the bigger pump, but it doesnt hurt to have it. If you can get the 950 to respond crisply off the starting line, which you should be able to do with tuning, it should out-perform the 750. I dont know much about your combination, so its POSSIBLE ( but not likely, unless its REALLY mild) that it doesnt need any more than 750 cfm. Smaller carbs are more forgiving of shoddy tuning, as the smaller venturi size will increase booster signal, so the car will pull fuel through the booster sooner.

Here is my combo

68 Cuda Notch
275/60 M/T
4.11 Locker
Dynamic 3200 stall
A999 w/2.74 1st gear
408 Magnum(Formerly 380 Crate)
4.00 Eagle Crank
175-185 PSI Cyl. Pressure
Forged Pistons
OOTB Eddy Heads
M-1
MSD Ready to Run w/MSD 6AL-2(one silver, one blue spring, w/black bushin)
Electric Fan
Underdrive March Pulleys
Hughes Roller Cam, 238 and 242 @ .050, .555 int. and .585 exh.
Crane 1.6 Roller Rockers
Trying to figure out which carb(750 QF and a 950 QF, both D.P.'s) and messing with spacers

What does the 750 actually flow? What do you trap at rpm wise?

This sounds like a very well matched combo. Is the converter a 10"? What is the 60' time? What is the present et & mph? Is it hooked and leaving soft, or is it spinning the tires? Personally, if it was my car, I would work with the 950, as I think it could possibly pay a small performance dividend over the 750 on this combo, but its close. This is just a guess, but I think if you run the 750, it will probably like a 2" open spacer, the 950 will probably like no spacer, or the Wilson super sucker. The cam is what I would honestly consider to be on the small side, but it sounds like its very well matched to the compression ratio you are running. I usually shoot for 190-200 psi cranking compression but I probably have better pump gas than you do. We have Chevron 94 up here, its pretty good. Whats the lobe separation, 110? Just a guess. Measured compression ratio is around 10/1?
Whatever carb you use, I'm thinking this combo is going to like a fairly large shooter, as the converter sounds fairly tight, and the intake has a failr amount of plenum area. If both carbs have dogleg boosters, I would figure you are probably gonna end up somewhere around a 40 on the primary side, and a 42 on the secondary, but this is just a guess, and the best way to go is use the method I suggested earlier. Annular discharge boosters will be ok with slightly less shooter, as they are more responsive.
I always prefer to have people understand what they are doing rather than just try to tell them what will work.
Basically, when you whack the throttle-plates open on the starting line, there is a bog, or lean spot, until the vaccum in the venturi gets strong enough to start pulling fuel through the main jets. The booster venturi is a smaller venturi within the main venturi that helps to amplify the vaccum & start the fuel flowing through the main jets sooner, but there is still a considerable lag between the time the throttle plates whack open, and the time fuel actually starts being pulled through the main jets. The job of the accelerator pump is to add extra fuel into the system until fuel starts pulling through the main jets. It really helps to think about the process in these terms. If the pump shot is not instantaneous, or does not deliver enough fuel quickly enough, the engine will bog due to a lack of fuel. ANY throttle movement should result in fuel coming out of the shooters.
Hope this helps. of course there is FAR more to carb tuning than main jets & pump shooters, but working with these two will get the car pretty close at the track. Now if you REALLY wanna open a can of worms, try to optimize WOT, and part throttle cruise at the same time, but I'll stop here for now.

Dick Landy does M-1 mods on the intake. Goggle him up and look for his shop on line. Hugesengines as well.

Dick Landy died feb 11, 2007...

dont know if his brother mike is still in business

As far as manifold mods, I havent worked on an M1, but most intakes respond well to a nice fat radius where the roof of the runners enter the plenum, and they usually need a little help in that area as they come out of the box. Nice fat radius on the leading edge of the runner dividers too although that usually involves adding material, which most guys dont want to get into. But for sure, you can probably gain something by cleaning up the radius where the roof of the runners enters the plenum.

Hey Darren. If I remember my carb stuff correct, the cfm wont really matter untill you are really cranking out the RPM. Not to mention running open headers. A 600 to 650 cfm carb should be plenty depending on what RPM you want to max out at is. As for the adapter or spacer I was told once that the higher up you get your carb off the intake the better your top end. Maybe I heard wrong. Try messing with the settings on the accelerator pump especially since you already changed the shooters. If I am wrong on these ideas folks please let me know. I hate going through life with the wrong ideas coming out my yap.

69Chrgr said:

Here is my combo

68 Cuda Notch
275/60 M/T
4.11 Locker
Dynamic 3200 stall
A999 w/2.74 1st gear
408 Magnum(Formerly 380 Crate)
4.00 Eagle Crank
175-185 PSI Cyl. Pressure
Forged Pistons
OOTB Eddy Heads
M-1
MSD Ready to Run w/MSD 6AL-2(one silver, one blue spring, w/black bushin)
Electric Fan
Underdrive March Pulleys
Hughes Roller Cam, 238 and 242 @ .050, .555 int. and .585 exh.
Crane 1.6 Roller Rockers
Trying to figure out which carb(750 QF and a 950 QF, both D.P.'s) and messing with spacers

Click to expand...

Whats that combo running for times??..are the Edelbrocks just as they came out of the box??have you tried the air gap intake,thats what i run on my 416 with a quickfuel 850 and 1" wood spacer..results were great 11.0's at 120...

Thanks for all the informative replies guys. The Eddy's are OOTB untouched. Last year I went 12.1 @ 113 in the quarter @ the Ennis Motorplex. My 60' was 2.1. That was with the 750 QF double pumper and no spacer. I have since added a 6 pack hood, playing with spacers, added an MSD 6AL-2, removed the big heavy coil springs from the distributor and replaced with one silver, one blue, and contemplating running the 950 QF. To be honest, the 950 was much more street friendly than the 750. I just can't figure that one out. The 950 should be the worst out of the 2, at least for street manners, but it was the opposite. My tuning skills have improved exponentially since last year(no, I'm not that good now, I was just that stupid last year lol). I will now try to increase the discharge nozzle size, I just need to find out what I have on both the 750 and 950 QF's stock.

How much initial timing are you running? 60' sounds pretty soft. Is it spinning a bit, or is the car weak out of the hole?

Last year it was just totally weak. I have since replaced the 72 Buick sized coil springs from the MSD Ready to Run distributor and run about 35 degrees total timing. Now, when I power brake, and slam the throttle, there is a bad hesitation, then BAM, it takes off. I'm really beginning to think the discharge nozzles are too small.

ABSOLUTELY. Yes, now that you tell me that, you NEED bigger shooters. I suspect you could probably stand a little more initial, would probably help throttle response, but I think the shooters are gonna be about 90%, more initial will get you the last 10%. Do you have a timing tape/degreed balancer on the motor?

Yes sir, I have an ATI degreed balancer. But every since I read the directions about my MSD 6AL-2, it said not to use a dial back to 0 light, so I will need to find a non digital conventional timing light. But by gauging the strap on the plugs, I'm pretty darn close. I will reset the timing and then try the new boosters I just ordered from Summit.

Your total is probably about right, Again, just a stab in the dark, I would try the initial around 14 degrees. Might even be right around there now, depending on how the distributor was set up out of the box.

69Chrgr said:

Thanks for all the informative replies guys. The Eddy's are OOTB untouched. Last year I went 12.1 @ 113 in the quarter @ the Ennis Motorplex. My 60' was 2.1. That was with the 750 QF double pumper and no spacer. I have since added a 6 pack hood, playing with spacers, added an MSD 6AL-2, removed the big heavy coil springs from the distributor and replaced with one silver, one blue, and contemplating running the 950 QF. To be honest, the 950 was much more street friendly than the 750. I just can't figure that one out. The 950 should be the worst out of the 2, at least for street manners, but it was the opposite. My tuning skills have improved exponentially since last year(no, I'm not that good now, I was just that stupid last year lol). I will now try to increase the discharge nozzle size, I just need to find out what I have on both the 750 and 950 QF's stock.

Click to expand...

12.1 something is off..my duster was running those 11.0's with less cam and less gear then you,and 60' in the 1.40's...and my current 360 is running 11.70's 60' in the 1.60's..your combo should be well into the 11's...