347 and T5 in my 65 convertible first impressions - Vintage Mustang Forums
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post #1 of 19 (permalink) Old 05-20-2019, 01:14 AM Thread Starter
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347 and T5 in my 65 convertible first impressions

a few weeks ago I was able to finally get the 347 and t5 in my 65 mustang convertible and wanted to share some fist impressions and some stuff I have learned.
Here are some details:
71 Mustang 302 block
Scat forged rotating assembly
AFR 185 heads, 8019 springs
custom grind Bullet Racing cam:
Lift .588/.585 (1.6)
109 LSA
Duration 230/235
Dougs Tri Y headers
Magnaflow 2.5 in SS exhaust with x-pipe
reused the Mallory Unilite my dad bought for the car in the 80's
Quickfuel Brawler Race 750 carb
t5/t5 bell/reused the 3 speed toploader yoke and driveshaft
3.73 gears
215 60 15 tires
wideband a/f guage

At first I was a bit worried that the carb was going to be too big, but with some tuning using the a/f gauge I have been able to dial it in pretty well and it drives better now that the car did with the 600 vac secondary and 289. It needed larger accelerator cams on both, and larger squirters on both (blue cam, #35 squirters). I battled a lean stumble when I would barely give it gas and got that out mostly with the above changes, and by going one size up on the idle jets, and a size or two down on the idle air bleeds. I really don't know how I would have tuned the carb without the meter-probably one of the most useful things I could have done. For the jets, it came 74/84 and now it is 72/78.
I killed the really bad drone with a couple of 26 inch U shaped pipes (1/4 wave resonators) in back right in front of the gas tank. Absolutely no drone now, very deep rumble and mellow sound. Could be too quiet for some even.
I can break traction very easily in 1st-it is almost useless with my 215 street tires, but from a rolling start/2000 rpm after shifting I can't break traction in second-which is good I guess, but does this seem normal for a 65/347 with 3.73 gears? Could it be the largish cam and 750 carb? At WOT my a/f is around 12 (was lower before jet change). It screams through the gears and feels very torquey even in 5th.
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post #2 of 19 (permalink) Old 05-20-2019, 10:29 AM
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I can break traction very easily in 1st-it is almost useless with my 215 street tires, but from a rolling start/2000 rpm after shifting I can't break traction in second-which is good I guess, but does this seem normal for a 65/347 with 3.73 gears? Could it be the largish cam and 750 carb? At WOT my a/f is around 12 (was lower before jet change). It screams through the gears and feels very torquey even in 5th.
I'd expect that you would be able to break those skinny tires loose with a healthy 347 and 3.73 gears.

Would probably help for you to get it on a dyno and see what your torque numbers are throughout the entire RPM range. Could be that your motor is setup to make torque higher in the RPM range...that might be what you want, but for street cars, guys usually like torque down low because the motor spends more time in the lower RPMs.

Dan
Chapel Hill, NC
***PM me if you're close by and can lend a hand with my 65 Fastback project***
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post #3 of 19 (permalink) Old 05-20-2019, 11:09 AM
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Hmmm.....I used to get a bark in 2nd and 3rd with a t5 in my bone stock 1983 trans am...which was factory rated at 140 HP on almost those exact same tires (215 65 15 IIRC).

You should have what, 300 HPs at the rear wheels and 300 ft pounds, easy.

What is the condition of the clutch? I just think it has to be slipping some.

That being said...I broke that trans am's t5 AND the diff with that 140 HP and my habit of barking through the gears. So....keep that in mind. Your 347 will make enough power to destroy everything behind it if you drive like a teenager.

I know, because I used to be that teenager.

Phil



"Two barks means faster!" Enzo
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post #4 of 19 (permalink) Old 05-20-2019, 11:45 AM
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Quote:
Originally Posted by Chip Phillips View Post
a few weeks ago I was able to finally get the 347 and t5 in my 65 mustang convertible and wanted to share some fist impressions and some stuff I have learned.
Here are some details:
71 Mustang 302 block
Scat forged rotating assembly
AFR 185 heads, 8019 springs
custom grind Bullet Racing cam:
Lift .588/.585 (1.6)
109 LSA
Duration 230/235
Dougs Tri Y headers
Magnaflow 2.5 in SS exhaust with x-pipe
reused the Mallory Unilite my dad bought for the car in the 80's
Quickfuel Brawler Race 750 carb
t5/t5 bell/reused the 3 speed toploader yoke and driveshaft
3.73 gears
215 60 15 tires
wideband a/f guage

At first I was a bit worried that the carb was going to be too big, but with some tuning using the a/f gauge I have been able to dial it in pretty well and it drives better now that the car did with the 600 vac secondary and 289. It needed larger accelerator cams on both, and larger squirters on both (blue cam, #35 squirters). I battled a lean stumble when I would barely give it gas and got that out mostly with the above changes, and by going one size up on the idle jets, and a size or two down on the idle air bleeds. I really don't know how I would have tuned the carb without the meter-probably one of the most useful things I could have done. For the jets, it came 74/84 and now it is 72/78.
I killed the really bad drone with a couple of 26 inch U shaped pipes (1/4 wave resonators) in back right in front of the gas tank. Absolutely no drone now, very deep rumble and mellow sound. Could be too quiet for some even.
I can break traction very easily in 1st-it is almost useless with my 215 street tires, but from a rolling start/2000 rpm after shifting I can't break traction in second-which is good I guess, but does this seem normal for a 65/347 with 3.73 gears? Could it be the largish cam and 750 carb? At WOT my a/f is around 12 (was lower before jet change). It screams through the gears and feels very torquey even in 5th.

Sorry this is off topic from your question, but I’m getting ready to install a 2.5” magnaflow kit with x-pipe in my 64.5 vert and would love to see some pics of your exhaust install, particularly from the collectors into the x-pipe if you have any.

Also wondering if you had to relocate the bracket near the cross member that holds the e-brake cable?

Thanks!

Last edited by Chaplin; 05-20-2019 at 11:53 AM.
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post #5 of 19 (permalink) Old 05-20-2019, 12:00 PM
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You should have what, 300 HPs at the rear wheels and 300 ft pounds, easy.
I'd hope more. My 306 has 324rwhp.

Maybe it's just carb tuning, could be squirters.

2000 is also pretty low RPM. Will it break traction flooring it rolling at 3000-4000?

1965 Mustang
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post #6 of 19 (permalink) Old 05-20-2019, 12:51 PM
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Quote:
Originally Posted by HoosierBuddy View Post
You should have what, 300 HPs at the rear wheels and 300 ft pounds, easy.
I'd hope more. My 306 has 324rwhp.

Maybe it's just carb tuning, could be squirters.

2000 is also pretty low RPM. Will it break traction flooring it rolling at 3000-4000?
Agreed, and same question. I would also look into that distributor tuning, aka, timing advance. Lack of timing will create a sluggish motor.
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post #7 of 19 (permalink) Old 05-20-2019, 12:56 PM
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You've got kind of a case of the "bigs" with your cam/head/carb combo. Although you can dump more fuel in and make it run okay, I am sure it's blowing a lot of gas out the exhaust at low RPMs.

Your large exhaust contributes as well. While adding some power on the top end, you have no scavenging going on at lower RPMs, so again, you lose out on torque below 3k.

By winging the throttle and getting up around 3-4k, I am sure your car runs hard! That combination probably has a LOT of power on the top end, but just mashing the gas from a rolling start at modest RPMs would likely fail to impress.

So - bottom line? Your car would probably be pretty wicked on a drag strip (if your transmission and clutch can stand up to the abuse!) but as a street car? Unless you have a lot of wide-open roads there, I'm betting it doesn't get to stretch its legs very often. In-town driving is going to be pretty ho-hum except for a lot of stops at gas stations, unless you're not afraid to buy new clutches and tires. I'm guessing this behaves a lot like the old Boss Nine setups; people who tried to drive them 'normally' were usually not that impressed. It's not what they were made for though.

If your intent is more street than track, going to a cam with a wider LSA (I'm thinking around 112) would greatly broaden your torque curve, and give you a much harder punch at low to mid RPMs. The carb you've got would not hurt wide-open-throttle, but is probably too big to give you very good tip-in or low-rpm performance. I don't think the Brawlers have annular boosters, so you're likely getting poor atomization even at WOT at low RPMs. Not enough velocity to smash apart the tiny droplets of gas. What intake are you running?

Last edited by Grimbrand; 05-20-2019 at 01:08 PM.
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post #8 of 19 (permalink) Old 05-20-2019, 01:12 PM
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I disagree with a lot the above. This engine should make peak power at 6500 RPM which makes for a good SBF street engine. It's not a stump puller but if you build an SBF to be one of these so called stump pullers you'll end up with a dog. Guys like happystang and myself have proven this on the dyno with lots of power per CI and flat torque curves.

The 109 LSA is pretty narrow but it's not crazy. 110 would be what I'd normally expect. Mine is 112 but it's actually a blower cam.

I disagree with the exhaust being too big too. These aren't F1 cars. Usually our headers are so poorly designed that nothing after the collector really matters. No amount of money spent or exhaust tuning after the collector is going to matter much. We're talking <5hp on the top end and almost no difference on the low end no mater what you do. If anything his TRI-Y headers and 185cc heads are holding him back. I'd have put 205s on it and at least 1-3/4" longtubes.

There's so much conjecture about what is too big and almost no dyno results. People rarely dyno their car with "too big" stuff and then switch to smaller stuff, go back to the dyno and see if they make more torque at 2500 RPM. Engine Masters debunks a lot of the "too big" stuff we all read in magazines thirty years ago or heard from our uncles who built cars in the 1960s with no CNC ported aluminum heads, no roller cams, etc.
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post #9 of 19 (permalink) Old 05-20-2019, 01:24 PM Thread Starter
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Intake is Air Gap with 1 inch spacer
It actually gets decent gas mileage, a little over 20 hwy?
I have the a/f values dialed in prettt good so I know it isn’t dumping gas (12/13 wot, 13.5 cruise, 13/14 idle)
The cam was discussed at length with the cam maker (Mark at Bullet Racing) and we went for something good for the street but makes power up to 6500 with 7000 redline.
Idle is rough but I like it 🙂
Yes, it feels quite nice at 3/4K and has broken traction a little a few times in 2nd and maybe even 3rd. If I use the clutch and shift hard I can surely spin through 1st 2nd and into 3rd.
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post #10 of 19 (permalink) Old 05-20-2019, 01:29 PM Thread Starter
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I had a 54 Studabaker in highschool that looked awesome but drove like a tractor. I always preferred the Mustang with the 289 so with this build I wanted to keep it with some upper RPM power. And yes, there are lots of open roads out here in Eastern Wa
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post #11 of 19 (permalink) Old 05-20-2019, 01:45 PM
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I have the a/f values dialed in prettt good so I know it isnít dumping gas (12/13 wot, 13.5 cruise, 13/14 idle)
Throttle response is something you can't measure with an A/F gauge or dyno, only test driving, and I'd say if your car isn't doing what you think it should, then there's room for improvement. If you don't have bog then I'd say you have it pretty close, but maybe it could be better. Getting the A/F right at wot, cruise and idle with a gauge- that's the straightforward stuff. Accelerator pump cams, squirters, secondary springs (if applicable)- that's more by Braille.

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post #12 of 19 (permalink) Old 05-20-2019, 05:36 PM
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Just to be clear, it doesn't sound like your engine is hurting for power, as it is. I am surprised you're getting 20 mpg on the highway, but honestly , those AFR heads are amazing.

It does sound like you're looking for more low-end grunt and streetability. The changes I suggested would offer that. I'm not saying to make it a tractor!

"big heads, mild cam" is actually a thing, and it's a recipe for a really hot street engine. It would also ruin your rumpity idle, though. Engineering's always about compromises, so finding the set of characteristics that's best for you is important. You made a lot of awesome choices for your motor, and as a package, it sounds really good.

Jdub's recipe for the longtubes WOULD add more power... on the top end. Long-tube headers have only one harmonic where they start helping your exhaust, and that's pretty high - usually around 5500-6500 RPMs.
Try-Y headers have two frequency ranges in which they improve scavenging. One of them in the midrange, and another on the top, around 5500 RPMs. Which is great for a street motor! All the other exhaust setups basically do nothing except get the burnt gases out. On the top end, your engine is making enough power that the 2 1/2" exhaust is well-matched; it's not holding back anything, and probably helps peak HP. So - simply said - Longtubes = big boost, but only at the very top. Tri-Y headers = modest boost at mid AND top end. And shorties/cast iron manifolds? Nothing.

However, on the bottom end, it's also big enough that you get very little scavenging at low RPMs - that requires velocity, and the bigger pipes don't help with that. Smaller pipes create more of an effect, despite being 'too small' to make max power on the top end. Again, this is another tradeoff. This is not something I'd change, since it's already done. Your exhaust, as-is, is probably pretty close. I don't think you'd see big power gains OR losses if you mess with it. We're talking about 5 horsepower for hundreds of bucks.

Where I think you WOULD see pretty dramatic changes is cam. With your setup, I would not be surprised to see 400 lb-ft of torque from 2000 rpms all the way to 6500, with a more modest cam selection. Right now, I think your powerband is probably a little narrower and peakier, kicking in more around 3000 and doing great right until around 6500 where you'd be valve-limited by your (presumably hydraulic) setup. If you pulled that down and widened it out a little, you would lose some on the top end, but gain a LOT throughout the rest of your powerband. Again, this would be dumb if you were racing your car, but for something you just want to drive, it would make a lot of sense.
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post #13 of 19 (permalink) Old 05-20-2019, 06:47 PM
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Your carb is not too big by any means. A 347 and 7000 rpm needs a 750...a dual plane is more forgiving with a larger carb. I like your setup and would like to see what it makes with a tune.



I have 255s on the back of my 65 FB. With a 331 160cc ported 351w heads and a 750 HP with single plane Vic Jr and 3.50 rear gears, traction thru 1st more or less non existent thru 1st and partly thru 2nd until I hit about 60 mph where it would finally hook up. With 3.89s traction starts becoming a reality somewhere north of 65 mph. I like my Dougs headers a lot and they seem to be up to the task to 7000 rpm.



Don't be too quick to judge. First impressions can be a biotch. Get a tune and I think you'll be needing wider tires. Did you mention compression ratio?

Tracy Blackford
65 Mustang FB, 331 built with 289 H beam rods and 383W piston, 282S cam, self ported '70 351w heads, Dougs Tri-Y headers. 1.7 shaft rockers and beehives. Hurricane Single Plane and custom 750 HP. T5z and 3.89 9" TL rear. PTP Engineering front suspension and 25540R17s all around
430 HP @ 6500...not too shabby for old school heads!

Daily Driver - 2013 Corvette 427 Convertible Collectors Edition

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post #14 of 19 (permalink) Old 05-20-2019, 08:54 PM
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Even at 100% volumetric efficiency, a 347 only pulls about 700 CFM at 7k. Going 'oversize' means you'll never pull vacuum at WOT on the top end - or less vacuum anyway, so you have (theoretically) more peak power. But it also means that you are creating larger droplets of fuel that don't stay in suspension well, when you're at part throttle and lower RPMs. That reduces *average* power a bit.

But you already have your carb! It seems to be working pretty well. I wouldn't mess with it. =)
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post #15 of 19 (permalink) Old 05-21-2019, 12:53 AM Thread Starter
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About the bracket (cross brace for convertibles) and exhaust, I had planned to weld some square tubing to the bracket and re-install, but the shop put the exhaust way too low to do that-it looks like it would have interfered with the e brake setup if it weren't so low. So, no bracket on there for now and I don't quite know what I'll do about it.
Also, compression ratio is 10.2, and valve train was selected to spin up to 7000 rpm (8019 springs, Morel Link bar lifters). I figured the block was the weak point in the setup as far as rpm-it is a Mexican block but that was just by chance ($100 Craigslist purchase). I also played it safe and went with a billet flywheel and sfi balancer. The power band does feel like 3000 to 6500+ from what I can tell, and I do like it so far. I think if I were to start out in first I wouldn't have traction until close to 3rd, I just can't brake the tires loose cruising in second and stomping on it.
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Last edited by Chip Phillips; 05-21-2019 at 01:09 AM.
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