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Author Topic: Pushrod length and gt40 heads (newbie questions)  (Read 8257 times)
FourtyOneFord
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« on: December 03, 2010, 04:31:15 pm »

Hey,   Welcome I'm new to this forum and glad to be here, lots of good reading. 
Let me start by saying I'm building a 347 stroker this winter for my '41 coupe.
I'd like to make good power from 1500-6000, car is for the street w/ AOD transmission.

I'm new to engine building, but have been tooling with cars for years.

I'm starting with a .030 over block from the machine shop (full roller block).
Scat cast steel 28oz crank 3.4in stroke.  ARP main bolts.
Floated style 5.4 SIR rods and ARP bolts.

I bought a Ford racing E303 roller cam kit from Jegs (M-6250-E303K) which came with
some gaskets, hyd roller lifters and pushrods (I don't know what length). 

I also bought some GT40 cobra heads off EBay from Promar;
  1.84 intake and 1.54 exhaust valves
  62.5 cc combustion chamber (I think a final compression ratio 10:1)
  Spring Pressure Closed 60lbs Open 230lbs
  Valve Springs are for Hydraulic Roller cams and can handle up to .510 valve lift.

  I plan to measure for the correct push rod length but I haven't bought any
rockers yet.  I like the idea of roller rockers and they may be in the budget.
I want to stay with the 1.6 ratio as the E303 cam already has .498 lift already
but as I understand the Cobra heads had 1.7 rockers stock.  My heads don't
have any rockers on them now, or even the studs to mount them.  I read that
these heads stock used a pedestal type of mounting system for the rockers.

Finally my question;

  Could someone please point me at some part numbers for the rockers and
hardware necessary?

Thanks.
  Chris




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'41 Ford business coupe 347 scat crank, GT40 heads, E303 cam, FRPP Victor Jr, Holley 750 dp

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The author is a fairly well known idiot, who hasn't built anything.  So whatever
advice he gives is in question...
FourtyOneFord
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« Reply #1 on: December 03, 2010, 05:02:21 pm »

Suppose I should read up on this here first  ;

http://www.mustang50magazine.com/techarticles/18679_roller_rocker_arms/index.html

I wonder if it's worthwhile getting a pedistal to stud conversion like this;

http://www.summitracing.com/parts/CRN-36655-16/?rtype=10
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'41 Ford business coupe 347 scat crank, GT40 heads, E303 cam, FRPP Victor Jr, Holley 750 dp

Quote
The author is a fairly well known idiot, who hasn't built anything.  So whatever
advice he gives is in question...
mighty mouse
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« Reply #2 on: December 03, 2010, 05:12:13 pm »

Roller rockers for a bolt down Ford head are made by quite a few companies (or at least sold through them).  Ford Racing/Crane has the "famous" 1.7 Cobra rockers that will bolt to your P heads just fine.

Talk to your cam grinder about what ratio will work best for your application.
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« Reply #3 on: December 03, 2010, 05:17:43 pm »

Thanks Mista !  
  Any opinion on what point is it worth going to a stud mount kit?  I'm using the stock springs.  The heads are the non-P variety and the cam grind is from Ford (E303)
  Suppose I'm also curious about opinions on the 1.7 ratio rockers, I'd probably need new spring as the lift goes to like 5.23
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'41 Ford business coupe 347 scat crank, GT40 heads, E303 cam, FRPP Victor Jr, Holley 750 dp

Quote
The author is a fairly well known idiot, who hasn't built anything.  So whatever
advice he gives is in question...
mighty mouse
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« Reply #4 on: December 03, 2010, 05:22:47 pm »

The stock springs will not work for that cam.  Just letting you know.

I would never waste y money on that kit.  If you are thinking studs, machine the heads for the right ones and guideplates.
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1986 Mustang GT Convertible
Suspension and Differential by Team Z Motorsports
8.2 Deck Forged Shortblock by FordStrokers

With a Novi2000...

I'd rather be a fool who is loyal to his friends than a POS that jumps ship to save face. We were wrong in the end, but nobody can ever call us disloyal. I can live with that.
FourtyOneFord
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« Reply #5 on: December 03, 2010, 05:43:18 pm »

 Thanx!
  When I bought the heads the machine shop had this to say about them

"Spring Pressure Closed 60lbs Open 230lbs
  Valve Springs are for Hydraulic Roller cams and can handle up to .510 valve lift. "

  Since the E303 cam is a hydraulic roller cam with only .498 lift I just assumed it would be ok. 

I would have had valve float all over the place  .  So in need some stronger springs for sure. 
Will the pedistal rockers be ok with the E303 cam and new springs, or do I need to get the head work done so I can use some adjustable stud rockers?

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'41 Ford business coupe 347 scat crank, GT40 heads, E303 cam, FRPP Victor Jr, Holley 750 dp

Quote
The author is a fairly well known idiot, who hasn't built anything.  So whatever
advice he gives is in question...
Joel5.0
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« Reply #6 on: December 03, 2010, 07:54:04 pm »

FYI.... that "good to .510" lift" spec you are getting is at coil bind for those springs. IOW... they are junk for the E303 or any OTS cam, they need to be replaced regardless of that "lift based spec".

#1. A 347 setup with those heads, regardless of the camshaft used, will be begging for airflow.

#2. E303 cam and a 347 stroker is a mismatch. Again, that 347 will be begging for airflow.

#3. If you still need/cannot do anything else but use those heads and cam on that stroker, keep the pedestal rockers.... don't throw money away by making upgrades that will not net you any performance results and use 1.7 rockers.

#4. The single w/dampers valve springs upgrade kit from Trickflow will do the trick (NPI) w/out having you spend more money on machine work on those heads, other than the "drop-on" valve springs kit.

#5. Better option?.... TFS TW 190 FAC heads and a different OTS or custom cam with stud mount 1.72 roller rockers.

 Welcome
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« Reply #7 on: December 03, 2010, 08:14:29 pm »

FYI.... that "good to .510" lift" spec you are getting is at coil bind for those springs. IOW... they are junk for the E303 or any OTS cam, they need to be replaced regardless of that "lift based spec".

#1. A 347 setup with those heads, regardless of the camshaft used, will be begging for airflow.

#2. E303 cam and a 347 stroker is a mismatch. Again, that 347 will be begging for airflow.

#3. If you still need/cannot do anything else but use those heads and cam on that stroker, keep the pedestal rockers.... don't throw money away by making upgrades that will not net you any performance results and use 1.7 rockers.

#4. The single w/dampers valve springs upgrade kit from Trickflow will do the trick (NPI) w/out having you spend more money on machine work on those heads, other than the "drop-on" valve springs kit.

#5. Better option?.... TFS TW 190 FAC heads and a different OTS or custom cam with stud mount 1.72 roller rockers.

 Welcome



 What He Said         AHMEN
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FourtyOneFord
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« Reply #8 on: December 03, 2010, 08:41:37 pm »

Ugh!
  Not totaly unexpected response  

  I'd like to understand why and not just take your word for it.

Wonder, Ponder

  o)  So for a street car 347 that shifts at 4000-5000 what cam / heads would you recommend?
  o)  At what RPM will I run out of air?
  o)  What pound springs for this cam before I loose power just pushing the springs?
  o)  Will the valves really float with those springs under 5000 RPM?


  Maybe I don't need a stroker in my street car, but I don't race...

I found this (below) about the '93 cobra 302...
  so with a bigger duration / lift cam and more displacement, 4bbl RPM manifold I'm looking at a measily ~275hp?  Dissapointed

"  The powertrain  was driven by a 302 CID V8 (5.0L) motor, producing 235 hp (175 kW) and 280 ft·lbs (380 N·m) of torque. According to Road & Track, this could send a Cobra through the 1/4 mile  in 14.5 seconds at a trap speed of 98 mph (158 km/h). Acceleration  from zero to 60 mph (97 km/h) took 5.9 seconds.  "
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'41 Ford business coupe 347 scat crank, GT40 heads, E303 cam, FRPP Victor Jr, Holley 750 dp

Quote
The author is a fairly well known idiot, who hasn't built anything.  So whatever
advice he gives is in question...
Joel5.0
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« Reply #9 on: December 03, 2010, 10:05:42 pm »

Ugh!
  Not totaly unexpected response 

  I'd like to understand why and not just take your word for it.

Wonder, Ponder

  o)  So for a street car 347 that shifts at 4000-5000 what cam / heads would you recommend?
  o)  At what RPM will I run out of air?
  o)  What pound springs for this cam before I loose power just pushing the springs?
  o)  Will the valves really float with those springs under 5000 RPM?


  Maybe I don't need a stroker in my street car, but I don't race...

I found this (below) about the '93 cobra 302...
  so with a bigger duration / lift cam and more displacement, 4bbl RPM manifold I'm looking at a measily ~275hp?  Dissapointed

"  The powertrain  was driven by a 302 CID V8 (5.0L) motor, producing 235 hp (175 kW) and 280 ft·lbs (380 N·m) of torque. According to Road & Track, this could send a Cobra through the 1/4 mile  in 14.5 seconds at a trap speed of 98 mph (158 km/h). Acceleration  from zero to 60 mph (97 km/h) took 5.9 seconds.  "


Thumper Cool?......

o) A  street car 347 that shifts at 4000-5000 = a  street car 302/306 that shifts at 4480-5600. Isn't the E303 a 302 stroke based cam? Aren't the GT40 heads 302 based heads? It will depend on the actual heads you choose to use.... but 302 parts make 302 performance.

o) Quiet early.... but that is subjective to what is acceptable on your criteria, not mine.

o) That was answered when the TFS upgrade got posted,

o) Yup....... or cause other type of damage.

If you don't race or care about performance.......  ... why ask performance oriented questions?

By The Way.... DO NOT misinterpret my reply above, but what is exactly that you expect from your setup? If the reply wasn't what you were expecting..... what is? 
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LUK  LMK  JIC  BTSTDTRT  YCYDYP  NFI-YTM  SPOBI, and the classic... DILLIGAS

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Quote from: Joel5.0
The right to be stupid is inalienable for sure however, there is no such thing as a right to impose stupidity onto others
Great Thoughts will Overwhelm a Feeble Mind
There is never money to do it right, but there's always money to do it over.
Knowledge based on external evidence is unreliable.
He, who doesn't ask, does not deserve an answer.
A mind is like a parachute it only works when it is open.  (oldmanjoe)
If you can't explain it simply, you don't understand it well enough. (Albert Einstein)
Tuning on a Dyno for the track, is like swim practice in a bathtub.
I can explain it for you, but I can't understand it for you. (90lxcoupe)
The proof of understanding is the ability to explain it. (H. Torruella)
Ignorance is bliss, but stupidity is orgasmic.
Fraud and falsehood only dread examination. Truth invites it. (Samuel Johnson)
The chaotic resistance of the opponents leads to the conclusion that they are not prepared to meet the challenge. The problem is already much more psychological then technological. [Bojidar Djordjev]
Individuals are rational and humane... Crowds are reactionary and barbaric. (Jason)
The person who says it cannot be done should not interrupt the person doing it. –Chinese Proverb
Nothing sways the stupid more than arguments they can't understand - Cardinal de Retz
FourtyOneFord
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« Reply #10 on: December 04, 2010, 11:59:38 am »

Thanks again for the advice Joel.

  So I took out the stock 302 motor (which was installed crooked) that came with my '41 (it was 27 years old).  I decided to use the stroker kit since the car is my hot rod.  Seemed like a good idea to get the short block and do some of the motor work myself even though I'll spend more money this way I'm having fun doing it.

  Main concern for me is that I do this assembly right and with the right (compatable) parts.  I really don't want it to just blow up this spring.  Beyond that it would be nice to make something like ~360 hp ~400 ftlb. seems like alot of folks are making that kind of power with the 302.  These guys made as much as 400hp with the stock ported heads;
http://www.mustangandfords.com/techarticles/engine/28898_400_hp_302_small_block/index.html

  Are these the springs from TFS? http://www.summitracing.com/parts/TFS-51400413/?rtype=10
 
  I expected those answers because everywhere I read most folks don't like the "alphabet cams" or cast iron heads.  It's not that I don't care about performance just that performance is not the most important item.  I don't think I've taken your advice wrong, I really appreciate you taking the time to help me understand.  Thanks again
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'41 Ford business coupe 347 scat crank, GT40 heads, E303 cam, FRPP Victor Jr, Holley 750 dp

Quote
The author is a fairly well known idiot, who hasn't built anything.  So whatever
advice he gives is in question...
Outlaw Bill
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« Reply #11 on: December 04, 2010, 12:42:15 pm »

GT-40 heads and intake will not make peak power past 5400-5500 rpms on a 347. Can it run good, of course, but you are leaving alot on the table.
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« Reply #12 on: December 04, 2010, 12:45:11 pm »

To the op, what is the most important thing out of this motor? driveability? Power? Sound? Honestly, if you were going for driveability, put some twisted wedge 190fac and the stock cam. It'll have driveability like a stocker, but more power. And it'll make more power than what you've got going on right now. Some where on the forms there is a thread about a stock head 347. I think they used gt40s. It wasn't impressive at all!
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« Reply #13 on: December 04, 2010, 02:28:45 pm »

Thanks Bill,
  I don't mind leaving a bit on the table, and especially where it's a street car daily driver I need a certain bit of reliability from it too.  If these 347 motors can make 550 fwhp and I leave %30 on the table and take away only 400 fwhp... sounds great...

also thanks '68 ,
  Most important thing right now is that I build it, and I do it right (ie runs good).  I'm having a blast with this old ford and really looking forward to getting the new motor in there.  Stuff like power and sound are pretty important to me, it's gotta have a lopey idle like a hot rod should, and of course I want to be able to do a nice burnout.

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'41 Ford business coupe 347 scat crank, GT40 heads, E303 cam, FRPP Victor Jr, Holley 750 dp

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The author is a fairly well known idiot, who hasn't built anything.  So whatever
advice he gives is in question...
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« Reply #14 on: December 04, 2010, 05:50:40 pm »

GT-40 heads and intake will not make peak power past 5400-5500 rpms on a 347. Can it run good, of course, but you are leaving alot on the table.

 What He Said  I have a article here in front of me with a GT40 headed 347. With ported heads, a big cam, 13:1 compression, and a Vic jr intake it was still finished by 6100 rpm. This was a engine built by a professional shop and still only made 400 hp. Not too impressive.
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