Thread: 351 Cleveland needs more hp

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Hello to all, this is my first post after joing the group just a few minutes ago. I would like to beef up my 72 cougar convertible's h.p. It has a 351 Cleveland, all stock, all original. The tranny is an FMX. I would suppose one of the first things I could do is to get rid of the points/condensor and replace with electronic ignition + a super coil. I'm not a mechanic by any means, but I can hire it done once I now what to do, ha! I would appreciate any guidance offered. Thanks,

Wyatt

Ok just got done rebuilding a 550hp 351C.
The easiest things would be carb and intake, maybe some headers.
Are you gonna rebuild it or just pump it up a little.
Kurt

By 1972 Ford was dropping the compression and hp of this engine considerably over what the 1970 engines had been, so it will never produce the same numbers without a fair amount of work. We had a 1970 Cleveland in a lightened '68 coupe. We had Gapp and Roush reworked heads, a crane cam, edelbrock intake, holley 800, mallory ignition, headers, and all running through a toploader 4 speed and 4:88 Nodular rear axle. It ran mid 11's, so these can be built to run.

The '72 will need an aluminum intake, an edelbrock or holley carb, vacuum advance aftermarket electronic distributor, headers, a cam sort of like an RV grind, and some better gears (lower by a few numbers) and it should wake up to be a pretty presentable performer.


Don

Thanks for the info. I don't want to have to rebuild (right now, perhaps later) I just wanna juice it up with whatever I can bolt on. A question on the electronic dist. - there is a shop here in Okla. that sells a Pertronix Ignitor module. It comes with the correct molded ends and hides neatly under the dist. cap. Would that be the same as buying an elec. dist.? They also offer a Pertronix flamethrower coil (40,000v), and I would guess that would be another addition to go with the module? As far as the aluminum intake and carb, where can a guy shop for stuff like that? On line, or what? Now, I need a little education on why I would need vaccum advance and lower gears.

Nothing will give you more seat of the pants feeling of improved power like a change to deeper (lower numerically) rear end gears. You may have something like high 2's now (2:79, etc) and if you go to 3:50's it will make a big difference in take off power.

Pertronix is an excellent way to convert a stock point type dist to electronic. I can't remember, does your '72 have points or is it electronic already?

Reason I mention vacuum advance is that a mechanical advance can cause a street driven engine to overheat. You need the vacuum to cure that. Your stock dist is vacuum already.

As for parts, like intake etc. Get some catalogs from Summit, Jegs, Performance Auto Warehouse, etc. and start comparing. Edelbrock makes a performer series of intake and matched carb that will be perfect for your car. Dual exhaust or headers and duals will help the power also. About a 600 cfm carb would be right for a mild street 351.

You are asking some good questions.
Don

Don, okay, that's first on my list. To do the Petronix, then the intake and carb. To answer your question, my 72 has points and condensor. Do I need the Flamethrower coil to go with the Pertronix dist. module? As far as the rear end gears, what does that take? The car currently has a 2.75 (non locking) rear end. If I would replace the gears, does that mean having to replace the axle also? I don't have a clue as I am not that mechanically inclined. With that in mind, if my stock dist. is vacuum already, why would I need a vaccuum advace? There are no stupid questions are there? thanks,
T.Wyatt

No man, your questions are very sensible.

Ok, you've got points........get the appropriate Pertronix kit, and sure, step up to a hotter coil. It will fire your plugs better. Talk to Pertronix for their recommendations. You may want to step up to better plug wires at the same time to take advantage of the new spark.

As for vacuum advance distributors versus mechanical advance.......here is all you will really need to know about that subject. Most cars come from the factory with distributors that have both mechanical and vacuum advance to advance the timing as needed. Race cars generally use only mechanical advance, and some guys try to run them on the street, but quite often the car will overheat because it isn't getting advanced properly at low speeds, and a retarded condition occurs. This makes the car run hot. You have vacuum advance, so don't mess with anything there.

Your Cougar most likely has what is called a 9 inch rear end. That number refers to the diameter of the ring gear. (you can't see the ring gear, it's inside, so don't sweat that piece of info) You could also have an 8 inch rear axle.....also refers to the diameter of the ring gear. Of the two, the 9 inch is stronger and more desirable, but even if you have an 8 inch, you will be fine in the hp you are putting out.

Here is how you tell which one you have: Take a 9/16 inch deepwell socket and try to put it on the two or three (I forget) bottom nuts on the very bottom of the rear end center section. This part is called the pumpkin in common terms by car people. If the socket will go on those nuts straight on, you have an 8 inch. If it will not go on, and you need a box end or open end wrench to remove those nuts, you have a 9 inch.

Now, how do you go to a deeper gear ratio? Two ways. You either remove your axles then remove the pumpkin (by removing all of the nuts around the perimeter) and you either replace the entire pumpkin with one that has already been fitted with the desired gear ratio, or.......you take your old pumpkin to a shop that does hi performance work and you have them remove your old ring and pinion and put in the new set. I like keeping the old pumpkin and buying one already set up, as you may want to go back to the 2:75's some day for gas milage reasons.

Your old axles do not get replaced in this switchover. You mention not being mechanically inclined, so for the first several steps you may want to seek out a small garage that has a good reputation in your area to do things like the rear axle swap.

Not trying to steer you into any particular direction, but gears are a great place to start, and you will feel the difference immediately. However, gas milage will suffer, but hey, we have to keep those guys in ski lodges, don't we???



If it were me, I would put in either 3:50 or 3:70 gears. Both are tame enough to be ok on the street, but will still give you a noticable kick off the line, especially with the automatic. My roadster runs 3:90's and it is perfect for me, as I am running 30 inch tall tires which drop the ratio to maybe 3:70 or so.

Next point. Ford used either 28 spline or 31 spline axles on these units. 28 is considered weaker, but still fine for your application. When you pull out the axles, count how many splines are one one of them. That will be the same type you need to buy to replace the old pumpkin.

I see guys on ebay selling rebuilt rear ends, ready to install, all the time. If you pay attention to their feedback rating, you should be able to buy with some degree of confidence from them.

I'm with Don, after you get the ignition squared awy, switch to a set of 3.50's or 3.73's in the rear end... There's a lot of companies selling them, probably run around $700 to $800 to get a set of gears and a posi new... Maybe a bit less if you do some careful shopping... Usually a hungry hot rodder around someplace to do the work for you, check with some of the locals and see who is a well respected wrench in the area that does a bit of side work. A lot of the repair shops and dealerships have personnel who are totally lost on fixing things that aren't diagnosed on their scanners... Find a hot rodder with his own shop, check out his work and his rep, make friends!!!! I have numerous customers who couldn't change their own oil, but still drive some of the slickest cars around....

Thought I would post a pic so you all can see the car. Feel free to send me comments. Good or ?

T.W.

Howdy, since it's been 10 days since I last posted and haven't received a reply to my last post with picture, thought I would check and see if all is well with my computer. If so, another question about the pertronix electronic ignition and ignitor super coil I plan putting on the 351C first. Will I have to increase my plug gap as soon as I install or? The selling pitch is of course first, no more points/condensor, then ability for wider plug gap, better milage and more power.
BTW, I looked for intakes on Summit and the only thing I could find was an Ofenhauser (sic) intake, no Holley for a 351 C. Next, are the 3.73 gears for the rear end. Any guidance as to where a guy can look for those? Last, are you able to see the pic of the Cougar? If not let me know and I might try something different. Regards,

Wyatt

Yeah, it's the biggest picture I've ever seen in my life.


Really a very nice, clean car. Maybe it is just me, but I wouldn't screw around with the outside too much. It is a classy ride and you don't see these every day, particularly a convertible. You mentioned 18 inch wheels in your one post. I don't know about that one. The image of a pimp-mobile comes to mind. Not trying to insult you, just can't see this car with 18's. That big of a tire/wheel is also going to wipe out any gain you make in going to lower gears. Perhaps some of the younger guys on here will tell me I'm just an old fogey, and that is ok. But when I see a car this nice with outsized wheels it just seems wrong.

As for the intake, if you have a 2 barrel 351 C I think you are going to be a little limited on choices, so the one you found is fine. Be sure if you have 2 barrel or 4 barrel before you plunk down your cash, they are not the same.

This really is a very very nice car.


Don


Look at the picture below, and see if you agree with me about big wheels.

Yo, Yo, Yo Bro. Gotcha some 20's on that ride???


Don

Here is a pic of the 18" wheels. Sorry, not quite as bad as the superimposed 20's on the front. As with the wheels, if the pic is too big, oh well. Need more pc skills to go along with mechinical aquired skills, ha! In fact, will I have to regap the plugs when I install the pertronix? Thanks guys (and girls) comments are welcome. Good or otherwise. BTW, personally I like the 14's that came on the car. Peace,

Wyatt

Having trouble attaching pics. Try and click on the camera by my user id and see if that works.

Sorry to say it Wyatt, but the wheels just do not fit the look of the car.

Just my opinion, but I had to be honest with you.


Don