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Discussion Starter #1
Hey all, new member here. Not a Mustang guy, rather a '92 5.0 Thunderbird. Recently done some mods to the car & have some cam questions for y'all.

1st, here's what's been done to the car-

1) Cleaned up/smoothed E7s w/1.9" intake valve & 3 angle valve job
2) Trick Flow Stage 1 cam
3) 'Cobra' rockers (stamped steel) unsure if 1.6s or 1.7s. How can I tell?
4) U/D pullies on crank & water pump only
5) K&N flat panel in stock air box
6) 2.25" duals (no cats) w/X-pipe & Flowmaster 40s

Otherwise, she's all stock- AOD & 3.08 Trac-Lok. When I return from a deployment in mid-Aug, the stock lower will be ported/cleaned/smoothed.

The car pulls hard from 2500 rpm, BUT getting up to 2500, she's a dog- much softer than stock. Mechanic/local 5.0 guru recommended the cam based on it's similarities to the 'E', which is 'sposed to be good in autos, but apparently it's too much duration for a 4000lb pig w/AOD & 3.08s.

Current options are more gear, looser T/C, or milder cam. To me, adding gear only masks the cams shortcomings & is more expensive (I don't know how to do rear ends) & involved (overcoming the factory rev limiter) than I'm ready for just yet. I like the T/C idea, but good ones aren't cheap & I'm tranny-phobic when it comes to wrenching. I'm leaning toward a milder cam that's an improvement over the stocker from off-idle to 5000 or so, as the car rarely sees the strip & I want a fun, torquey street car.

I've looked at a bunch of cams & I'm thinking one of the 3 would be what I need:

Comp XE258HR: 208/[email protected], .533/.544, 112 LSA
Comp XE264HR: 212/[email protected], .512/.512, 114 LSA
Comp XE266HR: 210/[email protected], .533/.533, 114 LSA
vs.
current TFS1 w/ 221/[email protected], .499/.510, 112 LSA

I want low end torque & throttle response with power that doesn't run out of breath till after at least 5000 rpm. What do you guys think? Again, I'm after a torquey, fun street car, not a strip terror. Thanks.
 

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Your stamped steel rockers are just standard 1.6 rockers. The "Cobra" rockers are aluminum roller rockers with a 1.7 ratio. Given the weight of that car, the stock gear/AOD/stall and your driveability desires I'd take the stage one cam out (very poor match for what you're trying to do - may want to seek out another mechanic/guru) and replace it with either a stock HO cam or a stock Cobra cam. In 93 the Cobra cam was put in the T'birds because it makes better torque down low than the stock HO cam did. The XE258 or the 264 might also be a good choice, but you'll need to be sure you've got enough valve spring to handle the ramp rates and lift. Any of those 4 cams I think would be a big improvement over the Stage 1 that's in there. Biggest thing though to move the heavy bird with authority is getting rid of the 3.08's. It's a must. A set of 3.73's would liven things up. 4.10's would be preferred, but may wind things a bit too tight for your liking. Lastly, if you've got the stock headers on it, you really need a set of shorties or something to further help the exhaust side. The E7 heads are intake biased as it is, and it sounds like you've might have made them even more intake biased with your larger intake valve and stock exhaust valve. I'm gonna guess anything you can do to help the exhaust side the engine will really like. It might really like the extra exhaust lift and duration of the 258. The safe bet is either the HO cam or the Cobra cam - they were designed with the kind of low end and driving manners you're after. Throw a set of 1.7's on it if you just can't stand having the stock specs - but swap the gear. That'll make a huge difference.
 

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...And, if you want to be much more certain about the results you're gonna get, contact a custom cam designer and have them design one specifically for your desires. Only way to go for me from now on. There are a number of folks out there - do a search. Buddy Rawls did mine - and my requirements were much like yours - low/mid range focus with good idle and power peak not above 5000. He did a fabulous job with it. Link below:

http://www.wighat.com/fcr3/
 

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...oh, and I'm not sure about your perceived link between rear gear and factory rev limiter. The limit's set at 6250, and with the power band you want, you'll be shifting well below that anyway. Can't see that there's a problem - but perhaps I'm missing something.
 

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I agree that the first thing you need to do is steeper rear gears. This will improve the performance of your heavier car more than anything else you can do for the investment. 3.73 is a good compromise between performance and highway economy. Probably a good, conservative choice for what you are trying to do. Even without the torque converter, this will provide a significant improvement. Settle on your "final" (at least for a while) engine combination before shopping for a torque converter; the converter needs to be selected to match the torque curve of the motor.

One reason why your engine feels "soft" with the Stage I cam is that you didn't increase your static compression along with the increase in cam timing. This results in lower cylinder pressures and lower torque...the opposite of what you're looking for.

For an off-the-shelf cam, the Comp XE258 that you mentioned might be a good choice. The timing looks good, although I doubt that the extra wear generated in the valve train by the high lift is going to rewarded with more performance...the stock type heads just don't flow significantly better up in those high lift ranges. I'd vote for a custom cam...it's worth it. Again, though, think through what you want your final combo to be so your cam expert can match the cam exactly to your needs. That's the whole point of the custom, so make your decisions first and receive full benefit. With ANY cam, be certain that you get the appropriate, matching springs; they are just as important to performance as the cam itself.

I wouldn't spend any money on your stock intake manifold; they just don't flow much. If you have extra time on your hands and want to try to improve it yourself, you have little to lose by cleaning it up, but also probably little to gain. For the cost of any modification that will significantly improve the stock manifold, you can replace it with something like the Performer 5.0 and get better performance.

Steve A.
 

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Discussion Starter #6
Cool guys. Thanks.

I considered the custom cam route, but my eventual goal is a healthy 331 & I can't imagine the same cam working for both motors. No, I'm not cheap, just poor & trying to do this as cheaply as possible.

Re- rev limiter, I've read/heard that the basis for the MN12's limiter has to do with driveshaft rpm. Not sure if swapping in the appropriate speedo drive gear would correct the reading the computer gets or not.

As far as the heads go, the cleanup/porting was on both the intake and exhaust & were built with the TFS Stage 1 cam in mind. The heads & cam were hand me down's from a bud's 'Stang running a 73mm Maf, 65mm TB, shorties, T-5 & 3.73s. Killer combo in his car, but we all forgot to account for the extra weight of my 'Bird & the vagaries of a stock AOD w/tall rear end.

I do eventually plan to go with 3.73s, it's just that I currently also need rear shocks & new springs all round & have only a finite amount of money. Plus, my wife's about to kill me for the money I've already spent on the 'Bird :D It's easier to get her to approve a cam purchase & a few evenings in the garage than the cost of gears & install.

Anywho, I do appreciate your advice. Anyone else?
 

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Another thought Carl, given budgets/wives/issues (I know the feeling) -- there are a number of folks out there who've given stock cams away. They're not that hard to come by free or for a very small fee. Go with a stocker, and save the $250-300 that the Comp or custom cam is gonna cost and put it towards gears. The gears make such a BIG difference in a heavy car - it's really one of the first steps. May even actually help around town mileage as it will be easier to get things moving.
 

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I did the same thing (actually sold my stock upper end - cam, heads, intake, alternator, starter, t/b, maf - etc.) right after I got mine together. Was just glad to have it out of the garage. And then I couldn't make an E cam work the way I wanted it to - like yours, too soft on the bottom for me. And I wanted my stocker to put back in. Oh well. But post around - you'll be able to find one free or real cheap. You may want to post a wanted ad here in the classifieds. The Cobra cam would work even better - as I mentioned, it was put in the bird in 93 because it produces even better bottom end than the HO does.
 

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HO cam from 89-95
Intake duration at .006" 276, Exh. duration 266, peak lift .278"

Cobra cam

Intake and exhaust duration at .006" 270, peak lift .282"

You can multiply the cam lift by your rocker ratio to get valve lift. The intake valve timing on the Cobra opens almost at same time as the HO, but closes earlier. And Exhaust valve opens and closes sooner. According to Ford's data sheet footnote, the cam was phased into use in the Thunderbird because it produced slightly less HP but more torque than the HO grind.
 

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Discussion Starter #13
Heh heh. Wouldn't you know my guy at the shop has a few HO cams on the shelf in the back room & will just give me one. Cool, huh? And offering me a decent deal on set up & install 3.73s w/a re-build of my tired Trac-Lok. Things are looking up.

Would love to add a set of shorty headers, but the MN12 chassis is a very odd duck & only MAC & JBA make shorties for it. MAC has discontinued them & the JBAs are too spendy.
 

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Split a set of 1.7's with somebody - put the 1.7's on the exhaust side only - give the stock headers a bit more time to empty things. Just a thought...
 

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Just a thought, if the car is a pig below 2500rpm ,why not get rid of the stock converter that prolly only stalls to 1500-1600 rpm and put a 10" 2500 rpm stall converter in it and skip right over the weak spot in the rpm range? Might even make the 3.08's not so bad.I have heard of guys picking up as much as five tenths in a stock AOD car from a good converter swap.And mike is right the stock "headers" on the birds are a joke,swap em! Good luck!
 

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Read the whole post though - he's not trying to build a drag strip terror. Knocking 1/2 a second off in the quarter isn't as important to him as building a fun, torquey, relatively low rpm street car - that is what he's after. While the converter works as you described, I'm guessing with the 3.08's 95% of his drive time (including highway cruising) would be below the 2500 stall speed of the converter which makes for lots of tranny heat and slippage and it will likely hurt what's already tough around town fuel economy. Granted, the converter would probably make it quicker, but I think there are ways to make it quicker which are better suited to what he's trying to accomplish.
 

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Discussion Starter #19
I think yer right on that one, Mike. I do plan on doing the tranny, but not till I have the money to do the enging I want- an evil bastard, torque-monster of a 331. In the interim, I'm just trying to wake 'er up as cheaply as possible. Hell, that's why I used that TFS1 cam in the 1st place- it was a freebie, along with the heads, from a friend.

I'm goin back to a stock HO cam & putting in 3.73s when I get back from this deployment (State Dept stuff in Africa, ugghh!), along with getting the stock lower cleaned up & port matched.

Then, I've got fresh springs & shocks to do, '93 up spindles w/ '99 up Stang 2-pot calipers, sub-frame connectors & strut tower brace.

Never ends, does it......
 
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