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Discussion Starter · #1 ·
I have a 351W in my Fairlane. I have the stock cruise-o-matic transmission in it and I feel like the power of my 351W isn’t as it should be. I was told to put in a C4 and that would "wake" my motor up. Is that true? Can I just put in a higher stall in the cruise-o-matic. The motor is .40 over, Thumper Cam, Edelbrock intake and Holley street avenger carb. It is very sluggish starting out but once it gets going it drives wonderful. Any thoughts :confused:
 

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I have a 351W in my Fairlane. I have the stock cruise-o-matic transmission in it and I feel like the power of my 351W isn’t as it should be. I was told to put in a C4 and that would "wake" my motor up. Is that true? Can I just put in a higher stall in the cruise-o-matic. The motor is .40 over, Thumper Cam, Edelbrock intake and Holley street avenger carb. It is very sluggish starting out but once it gets going it drives wonderful. Any thoughts :confused:
what cruise o matic will you be removing ?

brand names of parts with out specs is useless info

That a Super Vic with a 600 cfm carb plus 38 cc .040" dish pistons ? that would make for snail

Change the Rear Gear ratio
 

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As Dan indicates, there are likely other reasons for you lack of performance. The Cruise-O-Matic series are good trannies, though heavy and harder to find performance parts for. The C4 will absorb less HP to the wheels (less parasitic HP losses), but it wouldn't be enough to "wake it up". Listing your engine build parts, tuning specs, and driveline parts (be specific) would help in finding any mis-matches that would make for a dog.

David
 

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Plenty of cars (mine included) run quite well with a cruise o matic\FMX trans.

One thing I can think of is to make sure your shift linkage is adjusted right. If it's shifted into 2nd then it will start out in 2nd and seem like a dog.

Unless it's slipping badly, starting out in 2nd gear, skipping gears or some other drastic failure then your problem lies elsewhere.
 

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CRUISEOMATIC was basically a marketing term and could have been used to describe an FX/MX, C4/C6 or the later FMX.

You need to know exactly what you have.
 

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CRUISEOMATIC was basically a marketing term and could have been used to describe an FX/MX, C4/C6 or the later FMX.

You need to know exactly what you have.
I was thinking the same thing about the term Cruise-o-matic. Without know exactly what your current set up or plans are it's really hard to give out good answers. With that said, a set of lower gears will help a lot and if your cam is designed to make power up higher a looser converter will work great too. I was shocked when I swapped out a 2,400 stall for my 3,000 TCI Street Fighter. Night and day performance increase, even on the old 300 HP 289 I was running before.

If the rearend is stock original you could be running 2.80 or 3.00 gears. I'd go with a 3.50 for better highway manners and you'll still get some off-the-line performance. If it's just a cruiser you could go 3.70 or 3.91 and really wake it up. Not as much fun on the highway though.

Again, the more info you supply, the better answer you'll get.

John
 

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Discussion Starter · #7 ·
My apologies. I should have listed my engine.

1983 351W bored .40
Edelbrock Performer RPM Air Gap intake
670 Holley Street Avenger Carb
Thumper Cam with the intake duration at 279 and exhaust 297 (@ .050 227/241)
Stock Heads
Cheap Headers
MSD eletronic ignition, MSD distrib., MSD coil
Timing set at 16 when vac. hose undone and light on balancer.
2400 stall
stock rearend gears (apologize I don't know the exact number).

Hope this helps.
 

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My apologies. I should have listed my engine.

1983 351W bored .40
Edelbrock Performer RPM Air Gap intake
670 Holley Street Avenger Carb
Thumper Cam with the intake duration at 279 and exhaust 297 (@ .050 227/241)
Stock Heads
Cheap Headers
MSD eletronic ignition, MSD distrib., MSD coil
Timing set at 16 when vac. hose undone and light on balancer.
2400 stall
stock rearend gears (apologize I don't know the exact number).

Hope this helps.
I ask which c-o-m , . higher stall will help .

unkown rear gears ....good chance a change is in order

see why you say ...down on (low end) power
 

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Stock heads are not good for power.
 

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Discussion Starter · #10 ·
Stock heads are not good for power.
I am thinking about adding some AFR's to it. I have done some research and will probably order the 3.50 Richmond Gears for it and probably a TCI 3000 stall. Hopefully that will address my initial problem and the addition of the heads will be the "icing on the cake."
 

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The answer to your question is probably gears. Jack up the rearend and put it on jack stands, Mark both the rear tire(s) and the driveshaft with a piece of tape or whatever. Have someone rotate the tire and count the number of revolutions the driveshaft turns for one turn of the tire. Keeping in mind that the shaft probably won't make a complete revolution on the last time around, unless you happen to have a 3.00 or something like that. I'm guessing you're running the 2.80 rearend gear so it might be close to 3 turns.

If I'm correct and you are running a tall gear like that you'll see a MAJOR improvement in performance by swapping in some 3.50-3.70 gears. It's not a cheap modification unless you can do it yourself but in the end that $300-500 (or more) hop-up will without a doubt be your best one to date.

My brother has a '66 Fairlane hardtop with a very similar set-up (351W, C4 and 9-inch) and is running 3.70's and loves it. It's not a daily driver but it's been on some long cruises and so far he's okay with it.

Check it out and I'm sure you're next step is going to be a gear swap! :tup:

I was just posting this and saw your added comment about the heads. I'm also running AFR's on my 347 and love them! I went with the 185's and feel that I made a good choice. Mine are the pedestal mount rockers, not the stud type. I don't plan on high RPM stuff (much over 6000) so that's not a real concern to me. I found them on eBay a few years ago and was able to get them for $1,101.00 shipped to my front door so I couldn't pass them up. They were new in the box and complete, not stripped down. A private party deal, not a dealer. They make great power right out of the box and haven't been touched.


John
 

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Discussion Starter · #12 ·
The answer to your question is probably gears. Jack up the rearend and put it on jack stands, Mark both the rear tire(s) and the driveshaft with a piece of tape or whatever. Have someone rotate the tire and count the number of revolutions the driveshaft turns for one turn of the tire. Keeping in mind that the shaft probably won't make a complete revolution on the last time around, unless you happen to have a 3.00 or something like that. I'm guessing you're running the 2.80 rearend gear so it might be close to 3 turns.

If I'm correct and you are running a tall gear like that you'll see a MAJOR improvement in performance by swapping in some 3.50-3.70 gears. It's not a cheap modification unless you can do it yourself but in the end that $300-500 (or more) hop-up will without a doubt be your best one to date.

My brother has a '66 Fairlane hardtop with a very similar set-up (351W, C4 and 9-inch) and is running 3.70's and loves it. It's not a daily driver but it's been on some long cruises and so far he's okay with it.

Check it out and I'm sure you're next step is going to be a gear swap! :tup:

I was just posting this and saw your added comment about the heads. I'm also running AFR's on my 347 and love them! I went with the 185's and feel that I made a good choice. Mine are the pedestal mount rockers, not the stud type. I don't plan on high RPM stuff (much over 6000) so that's not a real concern to me. I found them on eBay a few years ago and was able to get them for $1,101.00 shipped to my front door so I couldn't pass them up. They were new in the box and complete, not stripped down. A private party deal, not a dealer. They make great power right out of the box and haven't been touched.


John
Thanks for the input. I will do that tonight. I am thinking that I am running stock gears but will double check. I was wondering, is there a major difference in the 3.50 and 3.70. I want it to be a daily driver but of course want the most performance I can get out of it. Would you also rec. that I do that stall upgrade to 3000 or just wait and see what the gear change does?

The AFR 185's are on my list and I think those will be soon. However, with that upgrade and the gears, if I don't do the 3000 stall with the gear upgrade will I need to with the AFR upgrade?

Also, love the pic of your car. It looks fantastic. Mine is almost done and once it is I will post it.
 

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I'm not sure if there's much of a difference but the closer you get to 4.11 or something like that, the less daily driver it becomes, if that makes sense. If you don't need to do a lot of highway driving you could probably get away with the 3.70's. If you do some highway driving regulary I'd stick with the 3.50's. A good compromise of performance and cruising.

Would I swap my 3.50's for 3.70's? Nope, only because I think it wouldn't make enough of a difference. I'd go to a 3.89 or something close but my car only sees the freeway a couple times a year on out of town car shows, etc. For the cost and hassle of doing a gear swap I'd want one that really made a difference.

I was a little confused on your second question(s) but I'll say this; everything needs to be a "package" a term I've stolen from another member here. Some parts complement others, some not so much. With your cam I can tell you that if your gears are what I expect them to be, you'll be way happier with a lower ratio. Personally, I would fix the gear thing first. If by chance they are already low enough then the converter change is in order.

The heads are going to make a huge difference in performance I'm guessing. I've heard people and read articals on them and most agree that a 40-80 HP increase is normal, depending on the build specs. They are expensive though. Get your gearing issue right and then decide.

Hope this helps!

John

PS: You can check out my "Garage" photos if you want to see more.

John
 
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