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post #1 of 17 (permalink) Old 4 Weeks Ago Thread Starter
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347 Build

Hello all,

It has been a while since I was last on this forum, but I am back in the states now and I am ready to get back to work on this 1995 Cobra. Here is a little background on the car:

Engine: Stock block, Eagle 347 rotating assembly, crankshaft, and rods along with flat top pistons. Top end is stock with the exception of a comp cam (Magnum 270HR if I remember correctly).

Goals for the car: I want a car that will be fun to drive, has plenty of torque, and will be reliable. If I had to put numbers down 400rwhp and 400rwtq would be a good ballpark. Seeing as I am running a stock block I do not want to push high rpms, nor do I care to go north of 400rwhp. This will not be a daily driver, but I drive the car often and therefore reliability is important to me. I do not plan to take the car to the track.

As far as H/C/I goes, my plan is to purchase AFR 185 Renegade 58cc heads, have my Cobra intake ported by Tmoss, and have a custom cam made by the guys over at FlowTech Induction Systems. My current heads have 1.7 roller rockers and upgraded springs. Would you guys recommend running 1.6 or 1.7’s with the new heads?

I am currently using the stock 3.08 gears and have considered upgrading to 3.55’s or 3.73’s. For the cars intended use, what would you recommend?

The exhaust system also needs an upgrade. Ideally, I would like to switch to ceramic coated long tube headers, O/R H pipe, and spintech mufflers. Seeing as this will be a fairly moderate build would you recommend using 1 5/8” or 1 3/4” long tubes? Also, any brands you would recommend?

Any recommendations you guys can make, to include H/C/I choice, will be greatly appreciated.

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post #2 of 17 (permalink) Old 4 Weeks Ago
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With what you described, your choices are excellent. I'd go with 1.6 RR's, to reduce stress on the valvetrain and keep it nice and quiet, except that you already *have* 1.7's, and there's nothing wrong with that. Rear gear choice will obviously depend on what gearbox you're running. With overdrive, you'll have fun with either gear ratio. I'd probably go with 3.73's, just for the fun of it.

Headers are all about tuning. Longtubes give your top end and peak HP a big shot in the arm, but they don't improve scavenging until you're at or near the peak RPMs your engine will handle. Shorties fit the easiest, but offer no actual 'boost' to the engine. Tri-Y headers offer a mild boost at midrange, and at the top end, but somewhat lower RPMs than long-tubes, so they're ideal for street. (scavenging's all about harmonics, so your experience may vary). Your displacement and stated horsepower goals are right about at the edge of where 1 3/4" headers become practical, but since you're more likely to spend your time really driving and not just WOT on the track, I think I'd go with good ceramic 1 5/8". If you go with shorties, you get no real scavenging boost, so just let out the steam as fast as you can with some 1 3/4".

Sounds like your ride is going to be a lot of fun!

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post #3 of 17 (permalink) Old 4 Weeks Ago
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I’ve tried 2.73, 3.73, and now 3.31 I’m my ‘95. I didn’t find 3.73’s to be all that fun. To me they were more of a headache and they didn’t increase acceleration enough to justify that headache. I was just shifting sooner.
During normal driving I was shifting into 2nd with in the first few feet of taking off and it’d be in 5th gear between stop lights. It would engine brake fairly hard if I let off the gas in 5th on the hwy. RPM’s were over 2k at 60+ mph in 5th. It wasn’t just the rpm and the noise that got old. It was the fact that it wouldn’t ever “settle down and cruise.” It was always right at the beginning of the powerband in 5th and it felt like it needed a 6th gear. It took until third gear to do 60 mph and 110 or so is all it would do in 4th.
I dig the 3.31’s though.

Last edited by 90lxwhite; 4 Weeks Ago at 09:04 PM.
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post #4 of 17 (permalink) Old 4 Weeks Ago Thread Starter
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Thank you for the replies.

Grimbrand: As far as rockers go, ideally I would like to run the 1.7s mainly because I already have them but Iím not sure what would be better for the engine in terms of longevity and performance. I am not averse to buying 1.6ís if they will be better overall.

1 5/8Ē long tubes seem to be the way to go in terms of the performance I am looking for. I am more concerned about losing torque with bigger tubes than gaining some horsepower up top. Havenít heard of the Tri Y headers, I will have to look them up.

90lxwhite: I appreciate your comments on the gears. It seems like a lot of people go with 3.73s or 4.10s but I donít see those being all that practical for this build. Iíve even considered leaving the 3.08ís in. The way the car sits I have enough traction problems with 555rís.
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post #5 of 17 (permalink) Old 4 Weeks Ago
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Run the 1.7's with that cam. I appreciate Grimbrand's VERY wise caution statement but in this case the ramp velocity is not too great to cause a problem. A solid roller would have ME cautioning you too! It will give you .030+ additional lift at the retainer over the 1.6 rocker. I have a Cobra ( Crane bolt down) on a Ford "F" cam so my lift increases fro .512 to .545 and there are no ill effects after 25,000 street/race miles. Using them will get the 270HR more in line with your power goals. Ford used the 282HR with a 1.6 rocker in thier 385HP 351 and 430 HP 392 crate engines. You will probably make 430-440 flywheel HP with the superior AFR head if your EFI manifold is as good as you say. A Vic Jr manifold and 750 carb would do it for sure. I found a good all around power gain on a similar '90 LX auto trans Mustang when I went to the 1-3/4 long tube set from Hooker over the previous 1-5/8ths mac long tubes and before that Doug Thorley tri y long tubes. Shorties were "almost" a waste of money , especially if I had bought them new. Luckily they were junk yard finds. Resold them for more than I paid for them LOL
Good luck,
Randy
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post #6 of 17 (permalink) Old 4 Weeks Ago Thread Starter
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Good to know. I am planning on upgrading the cam to a custom grind either way so the difference between the 1.6/1.7 rockers should be accounted for (unless I am missing something).

I have considered upgrading the intake however, it seems like all of the aftermarket stuff makes sense for high rpm applications. While I would love to go this route, I am hesitant due to the fact I am running a stock block. I think the ported cobra can get me to my goals, granted it will certainly make less horsepower than others out there.

On another note, I am assuming my stock 24lb injectors will be inadequate for a ~400hp engine. What size injectors should I be looking for and any recommendations on a fuel pump?

I really appreciate the input so far!
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post #7 of 17 (permalink) Old 4 Weeks Ago
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I had my 347 stroker built last year and i've been very pleased with the custom roller grind my builder went with. Perhaps i can indulge you on it since you are still deciding on what to get. Getting in touch with CompCams will always be wise but i dont see any harm getting inputs here and there. I was looking for a street warrior engine since i don't really hit the track big cams were out of the question. Before having the engine shipped to me i had it broken in and dynoed with my little 600 cfm Edelbrock carb and the numbers were really promising at the flywheel. Max HP was 429 @ 6000 rpm , max torque was 406 lbft @ 5200 rpm but the real beauty about the camshaft is its low end torque. 393 lbft @ 3600 rpm is plenty of pep for these lightweight cars and with my LSD and 3:80 gear she gets out of the hole pretty fast and yes it gets noisy over 70 MPH. Engine runs at 2800 RPM @ 70 MPH not too shabby at all. I'm happy with the shorties if i could i would've gone a different way but there are limitations with the AOD and i didn't feel like spending a fortune on custom made tri-y headers..


Intake Exhaust

Duration @ 50 216 224

valve lift .545 .556


LSA 114


Engine idles beautifully around 950 rpm and has great vacuum, i can definitively see the advantages of the 114 lobe separation angle. I also wanted something that could be compatible with EFI in the future. I was told with a bigger carb say a 650 cfm i could've seen even bigger numbers but i'm pretty content with my carb. Sometime around next year i'd like to take the car to a dyno and see those rear wheel numbers. Adding the MSD box has done wonders to the engine as well.. BTW, i used 1.6 RR on this engine.




J
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1965 Mustang Resto-Modded with a classic charm
347 ci stroker 10:1 CR ( street warrior engine with a very mild custom ROLLER cam for torque) Weiand Stealth intake ported to AFR 185 cc ,CompCams GOLD 1.6 Roller rockers ,Wiseco ProSreet Forged Pistons,Manton custom pushrods, Hedman ceramic shorties
AOD stage 1( good up to 450 HP)
Rear End 3.80 gears, Monkey Grip Trac Lock posi unit
Tires 15" all around 225's in the back
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post #8 of 17 (permalink) Old 4 Weeks Ago
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Quote:
Originally Posted by 347cobra View Post
Good to know. I am planning on upgrading the cam to a custom grind either way so the difference between the 1.6/1.7 rockers should be accounted for (unless I am missing something).

I have considered upgrading the intake however, it seems like all of the aftermarket stuff makes sense for high rpm applications. While I would love to go this route, I am hesitant due to the fact I am running a stock block. I think the ported cobra can get me to my goals, granted it will certainly make less horsepower than others out there.

On another note, I am assuming my stock 24lb injectors will be inadequate for a ~400hp engine. What size injectors should I be looking for and any recommendations on a fuel pump?

I really appreciate the input so far!
Injectors- I’m only making 332 at the wheels via forced induction and I’m using 19#’ers and an fmu. The tuner said that if I wanted to not use the fmu I would need 42# injectors. So this is just a guess but you might need as large as 60’s. Maybe get with the a tuner and see what they think.
Moss did my lower HO intake and it was a decent bang for buck for around $300. Moss says a ported cobra flows around 250cfm. Here’s an article with high revving intakes vs a ported cobra. The cobra does ok. The Holley Systemax made more power at 5,250 than the Cobra did though and that’s not all that high of an rpm. A tfs track heat (not the high revving R) might out due the cobra at all rpms. Seems like even a ported cobra would choke down a 347.
http://www.mustangandfords.com/how-t...173-0101-super
*edit*
Here Moss says the tfs track heat flows 265 cfm https://www.google.com/amp/s/forums....m.html%3famp=1
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JustAnotherRuki,
The cam you have is ( I believe) the type Grimbrand was warning about, Short duration and high lift. Using a 1.7 rocker would bump the lift at the valve to .580 I and .590 E. This combined with the short duration would cause high acceleration of the steel valve and "possibly" cause a valve float condition unless heavy springs or lighter valves were used. At 429hp it's working well.
Randy
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post #10 of 17 (permalink) Old 4 Weeks Ago
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347cobra
The 24s might be at max duty cycle. Making 460 hp , I ran Ford 30 lb injectors and didn't work them as hard. 255L pump was good without a power adder.

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post #11 of 17 (permalink) Old 4 Weeks Ago Thread Starter
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Thanks for all of the good info. Iíve been thinking stepping up to 30# or 36# injectors would be a good idea. Would I have any issues running 36# injectors?

90lxwhite: Thanks for passing along that article. I have been debating on whether or not to upgrade my intake or not and the Systemax is a pretty good candidate. What rpm can I realistically push this engine to safely? My initial impressions are I should keep this thing around 6000.
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post #12 of 17 (permalink) Old 4 Weeks Ago
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Quote:
Originally Posted by 347cobra View Post
Thanks for all of the good info. I’ve been thinking stepping up to 30# or 36# injectors would be a good idea. Would I have any issues running 36# injectors?

90lxwhite: Thanks for passing along that article. I have been debating on whether or not to upgrade my intake or not and the Systemax is a pretty good candidate. What rpm can I realistically push this engine to safely? My initial impressions are I should keep this thing around 6000.
I’d go with the 36#. Corrections can made if they’re a little “big,” but I don’t think much can be done if they’re too small and you’re running out of fuel.
The rpm is going to be cam and valvetrain defendant. But I bet 6,500 is safe, and that power will probably start to fall off shortly after anyway. I run my E7’s to 6k, your big guy will be ok.
Get a good tune.
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post #13 of 17 (permalink) Old 4 Weeks Ago
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The AFR's happen to be really efficient heads, with pretty good BSFC, but even so, better to err on the side of caution when it comes to injectors. You're better off having "a little too much" injector than "Not enough". Running lean when you're at WOT is a really horrible way to test how good your engine is at resisting detonation. There are lots of good tools to figure out how much injector you need for a given power level. If it's really close between one or another, choose the bigger size. My Google skills tell me that 325 is nearing the limits for 24# injectors (N/A). 30# is good for just over 400, and 32# somewhere around 460. That's at 85% duty cycle.

These numbers sound a *little* optimistic, but close to the 'conventional wisdom' I've listened to from people I respect on injector selection too. Most people say that if you're over 300 hp, you want to get 30 lb injectors, for example. If you ever intend to go with forced induction or power adders, you'd want to go at least two steps larger for that. Keep in mind, going 'nutso' with the injector size is a bad idea too. You don't want 40# injectors for 400 hp on a N/A build for example. If for no other reason, the cost, but additionally it would be harder to tune, and I suspect there might be issues with fuel droplet size.

90lxwhite is dead on with needing a tune after you change them! Be sure to include some dyno time as part of your plans, or it will run like garbage. And unless you're running solid lifters, anything over 6500 is a bit dicey anyway.

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post #14 of 17 (permalink) Old 4 Weeks Ago Thread Starter
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Looks like my setup will be something along these lines:

AFR 185 renegade heads 58cc
Custom grind cam by FlowTech Industries (unless there are others you would recommend)
36# injectors and 255lph fuel pump
MAC ceramic coated 1 3/4Ē long tubes with 2.5Ē collectors
MAC Prochamber (still up in the air on this one)
Spintech Mufflers
3.55 gears
Dyno tune once everything is together

I am still debating on which intake to go with. It seems to me that a custom grind cam could potentially make up for some of the lost low/mid range torque when compared to the ported cobra. I really only see an aftermarket intake being beneficial if I can get my revs up to 6500, but I donít know how feasible/reliable that would be. Can a stock block handle that hp/tq at those rpms?
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post #15 of 17 (permalink) Old 4 Weeks Ago
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Quote:
Originally Posted by 347cobra View Post
Looks like my setup will be something along these lines:

AFR 185 renegade heads 58cc
Custom grind cam by FlowTech Industries (unless there are others you would recommend)
36# injectors and 255lph fuel pump
MAC ceramic coated 1 3/4” long tubes with 2.5” collectors
MAC Prochamber (still up in the air on this one)
Spintech Mufflers
3.55 gears
Dyno tune once everything is together

I am still debating on which intake to go with. It seems to me that a custom grind cam could potentially make up for some of the lost low/mid range torque when compared to the ported cobra. I really only see an aftermarket intake being beneficial if I can get my revs up to 6500, but I don’t know how feasible/reliable that would be. Can a stock block handle that hp/tq at those rpms?
With a good tune it’ll be safe up to (and probably a little past) where the power falls off. The top end will dictate where that is I suppose.
*Edit* It’s still going to be pulling at 6k I’m pretty sure. Let’s say the powerband starts around 3k. It won’t take but the blink of an eye to get there with 3.55’s. It won’t feel like an old Honda V-tec or 1980’s turbo lag where it’s riding flat for a long period with a big power spike once it finally gets there. It’ll be pulling from the jump. Even with the Systemax.

This guys “big head” 347 made 393 at the wheels.
https://www.google.com/amp/s/www.all...t.html%3famp=1


Last edited by 90lxwhite; 3 Weeks Ago at 10:27 AM.
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