P-51 heads

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Re: P-51 heads

Post  Dave De on June 7th 2015, 10:09 pm

I got a game plan.  I need more data so another trip to test without the Flowmisers or Slowmasters is in order. I am going to reset the valve clearance at the track to .030 to see if it picks up. Im at .015  now.

I didnt pick the mufflers they came with the car as a roller and the entire system is jet hot coated. It looks great but it all weighs about 50 pounds. I may change the mufflers to another straight thru design if I can find something that fits.

Any other suggestions for test please speak up.
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Re: P-51 heads

Post  bbf-falcon on June 7th 2015, 10:12 pm

Also,1/10 is sometimes hard to pickup when you are already in the low 9's. The faster you are, the harder to make big gains. Smile

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Re: P-51 heads

Post  BOSS 429 on June 7th 2015, 11:12 pm

Dave De wrote:I got a game plan.  I need more data so another trip to test without the Flowmisers or Slowmasters is in order. I am going to reset the valve clearance at the track to .030 to see if it picks up. Im at .015  now.

I didnt pick the mufflers they came with the car as a roller and the entire system is jet hot coated. It looks great but it all weighs about 50 pounds. I may change the mufflers to another straight thru design if I can find something that fits.

Any other suggestions for test please speak up.

I wouldnt put them at .030
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Re: P-51 heads

Post  BOSS 429 on June 7th 2015, 11:31 pm

Dave De wrote:The SCJs were to flow over 385 and the P-51s have data sheets that show 425. When I first ran the P-51s I used 1.8 rockers and the car slowed down a little or there was no change over the SCJs. I went back to 1.73 rockers and it picked up. This cam is  intentionally compromised to be small for reliability. Could my full 4" exhaust with Flowmaster 44s be an issue? The mufflers have the second baffle knocked out.
I thought that with 580 cubes it would pick up more because these heads are ideally suited for less displacement. Then with 10 percent more flow it would like to run higher and it really doesnt. I think that if I were to have dyno'd each setup there wouldnt be much difference in power.

Well at least ive got the SCJs for the other motor now.


Ive tried a lot of diff mufflers since about 1987,and flowmasters were always the fastest.
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Re: P-51 heads

Post  butterbean on June 8th 2015, 12:57 am

its not the flowmasters, I would adjust the valves to .025, I thought the same thing the P-51 are not that much better than the SCJ"s, there is a guy on this forum that made over 950 hp with SCJ"s. JMO!!!!!!!!
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Re: P-51 heads

Post  maverick on June 8th 2015, 8:22 am

I'm not saying the Flowmasters are his problem either....just that I wouldn't use them.  A chambered muffler will NEVER flow as well as a straight through design, inlet/outlet sizes being equal.
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Re: P-51 heads

Post  68galaxie on June 8th 2015, 9:53 am

What intake manifold was used on the engine (cylinder head comparison) test?
Was the intake attached to the heads for the flow test comparisons?

Just a thought - I agree with Randy M here- something else is holding back the combo.

Cheers
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Re: P-51 heads

Post  IDT-572 on June 8th 2015, 3:28 pm

P-51's require less timing with a flat top, where is your timing now?
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Re: P-51 heads

Post  IDT-572 on June 8th 2015, 3:37 pm

Give us the info on the engine from carb to pan, something is amiss Rolling Eyes

Mine has a little more flow and compression and cam, but it is a ton faster. There is a piece of the puzzle we are missing.

My 557 ran 5.67 with a set of TFS Streets and the same cam as yours at 3200 lb., and I pulled them off and sold them, put on my old Dooe-r's and ran a 5.71 at 100 lbs heavier.

46 more cfm = hp when everything is right.
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Re: P-51 heads

Post  Lem Evans on June 8th 2015, 7:52 pm


"580 cubes, 13.4 comp, 3100 pound car, both heads were ported and the SCJ heads have 2.25 valves"

I agree that there may be other issues but, your SCJ heads having the 2.250" intake valves have removed one of the advantages that the P51 have over the typical 2.200" scj frpp head.

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Re: P-51 heads

Post  quick 52 on June 8th 2015, 8:03 pm

Lem Evans wrote:
"580 cubes, 13.4 comp, 3100 pound car, both heads were ported and the SCJ heads have 2.25 valves"

I agree that there may be other issues but, your SCJ heads having the 2.250" intake valves have removed one of the advantages that the P51 have over the typical 2.200" scj frpp head.
Now they tell you $$$$$$$$$$ later






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Re: P-51 heads

Post  Lem Evans on June 8th 2015, 8:13 pm

[quote="quick 52"]
Lem Evans wrote:
"580 cubes, 13.4 comp, 3100 pound car, both heads were ported and the SCJ heads have 2.25 valves"

I agree that there may be other issues but, your SCJ heads having the 2.250" intake valves have removed one of the advantages that the P51 have over the typical 2.200" scj frpp head.
Now they tell you $$$$$$$$$$ later





I'm not sure the issue[s] are the engine's ......just saying that a ported set of scj would like the 2.250" intake valve.

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Re: P-51 heads

Post  Dave De on June 8th 2015, 11:32 pm

Lems got it right that the heads were brought closer together by using 2.25 intakes on the SCJs.
I see Blakes numbers and he is in another league from me but our parts are close.
I spent 30 minutes looking for my cam card to no avail.
Here are the stats anyway.
A460 block, Diamond flat tops with small dish to go 13.4 compression, 4.530 bore, 4.5 stroke. Scat forged crank, Scat H beam 6.70 rods. Rings are standard package 1/16 thick. TFS track heat, 1250 dominator built for E85. Cam is .700 lift 278/290 @.050 solid roller 111LSA on 108 CL. Fuel system is Aeromotive that has good pressure at the end of the track. Timing is best at 33 degrees.
MSD locked out, intake is port matched, carb has 1/4" spacer.
Car has 9.5 converter with stall to 4600 rpm and C6 with 2.40 first gear. 3.82 9" with 31 tall tires. Leaving off the brake at 3800.
Shifting at 6500 to 6800 doesnt change the ET. Ladder rear, M2 front.
60 ft is 1.30 to 1.33
1/8th mile is 5.80 to 5.85 at 117
1/4 mile is 9.20 to9.25 at 146

This car is driven on the street and is compromised for that. Converter slip at the big end calculates to be 12% and at the 1/8th it is 23%. Is this normal? I might have a lame converter.  The car seemed to run better when it had 32" tall tires and I will be goimg back to them. Also there is no vacuum pump onthis engine.


Last edited by Dave De on June 9th 2015, 6:51 am; edited 1 time in total
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Re: P-51 heads

Post  FalconEh on June 9th 2015, 12:08 am

Dave,
I wouldn't tighten to .030 though you could offset int/exh a few thou... have you tried a taller spacer 1". Get on the plugs lean/fatten it a little and try to get a few more degrees into it. The tune seems a little conservative N/A, and the converter a little loose, have you hit it at 4200+ yet...this is a new motor now and the baseline is gone...time for a new one.
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Re: P-51 heads

Post  Dave De on June 9th 2015, 6:49 am

FalconEh wrote:Dave,
I wouldn't tighten to .030 though you could offset int/exh a few thou... have you tried a taller spacer 1". Get on the plugs lean/fatten it a little and try to get a few more degrees into it. The tune seems a little conservative N/A, and the converter a little loose, have you hit it at 4200+ yet...this is a new motor now and the baseline is gone...time for a new one.
No room for the 1" spacer. I will try a hit at 4,000. Timing has been optimized. The carb is 2 circuit and is jetted best for WOT.
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Re: P-51 heads

Post  Gary Blair on June 9th 2015, 7:42 am

Dave De wrote:Lems got it right that the heads were brought closer together by using 2.25 intakes on the SCJs.
I see Blakes numbers and he is in another league from me but our parts are close.
I spent 30 minutes looking for my cam card to no avail.
Here are the stats anyway.
A460 block, Diamond flat tops with small dish to go 13.4 compression, 4.530 bore, 4.5 stroke. Scat forged crank, Scat H beam 6.70 rods. Rings are standard package 1/16 thick. TFS track heat, 1250 dominator built for E85. Cam is .700 lift 278/290 @.050 solid roller 111LSA on 108 CL. Fuel system is Aeromotive that has good pressure at the end of the track. Timing is best at 33 degrees.
MSD locked out, intake is port matched, carb has 1/4" spacer.
Car has 9.5 converter with stall to 4600 rpm and C6 with 2.40 first gear. 3.82 9" with 31 tall tires. Leaving off the brake at 3800.
Shifting at 6500 to 6800 doesnt change the ET. Ladder rear, M2 front.
60 ft is 1.30 to 1.33
1/8th mile is 5.80 to 5.85 at 117
1/4 mile is 9.20 to9.25 at 146

This car is driven on the street and is compromised for that. Converter slip at the big end calculates to be 12% and at the 1/8th it is 23%. Is this normal? I might have a lame converter.  The car seemed to run better when it had 32" tall tires and I will be goimg back to them. Also there is no vacuum pump onthis engine.

What are the 330 and 1/8 for the SCJ and P-51?
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Re: P-51 heads

Post  butterbean on June 9th 2015, 9:05 am

Dave 2 things, I think you are loosing some ET through the converter, 1.30's 60' is kinda slow for your ET's my last car only ran 6.60's@102-103 1/8th and it had 1.38-1.39 60' times, so maybe??? and the cam only being .700 lift BUT I'm not a fan of a lot of lift either because I bracket race and do not want to be changing valve train parts all the time, I want to go laps without failure and or adjusting my shiite all the time, I think it runs good as is but we all always want to go faster.
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Re: P-51 heads

Post  Dave De on June 9th 2015, 5:21 pm

Well I talked with Lenny at UCC and ordered a converter to fix my slip condition. If I could come closer to Blakes numbers it would be money well spent.
Its probably 4 weeks out before I'll know anything.
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Re: P-51 heads

Post  FalconEh on June 9th 2015, 8:17 pm

Dave,
Maybe a dumb question, but were the SCJ heads milled, and did you check the pushrod length?
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Re: P-51 heads

Post  Lem Evans on June 9th 2015, 8:21 pm

FalconEh wrote:Dave,
    Maybe a dumb question, but were the SCJ heads milled, and did you check the pushrod length?

SCJ FRPP and P51 do not use the same p. rod lengths.

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Re: P-51 heads

Post  Dave De on June 9th 2015, 9:31 pm

Lem Evans wrote:
FalconEh wrote:Dave,
    Maybe a dumb question, but were the SCJ heads milled, and did you check the pushrod length?

SCJ FRPP and P51 do not use the same p. rod lengths.

Yes the pushrods are longer for the P51s. I bought the heads as a package with pushrods. The geometry is great with Scorpion rockers and not so good with the Ford 1.8 rockers. The pushrods are Kaase .080 wall. I dont remember the lengths but the 1.8 rockers need a shorter length.
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SCJ

Post  Gary Blair on June 10th 2015, 12:30 pm

Lem Evans wrote:
"580 cubes, 13.4 comp, 3100 pound car, both heads were ported and the SCJ heads have 2.25 valves"

I agree that there may be other issues but, your SCJ heads having the 2.250" intake valves have removed one of the advantages that the P51 have over the typical 2.200" scj frpp head.

Lem,
Is this SCJ one of your builds? Runs real nice.
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Re: P-51 heads

Post  Lem Evans on June 10th 2015, 1:03 pm

No sir, it's not.

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Re: P-51 heads

Post  IDT-572 on June 10th 2015, 6:18 pm

One thing I see is the converter, I would think from the builds I have had control over should be flashing up around 5000-5200 for that cam to leave the best.

And also your first final gear ratio is at 9.56:1, I think when you get the converter up to tq peak and getting the tq to the rear end it will be spinning.

I ran the same cam in my 557 TFS STREET headed engine @ 3200 LB and ran a glide with a 7.21 ratio, 4.10 ratio rear and 28 inch tires.

I think when its said and done you will want less gear in the rear. Especially if your street driving it.
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Re: P-51 heads

Post  Dave De on June 10th 2015, 8:10 pm

Gary Blair wrote:
Lem Evans wrote:
"580 cubes, 13.4 comp, 3100 pound car, both heads were ported and the SCJ heads have 2.25 valves"

I agree that there may be other issues but, your SCJ heads having the 2.250" intake valves have removed one of the advantages that the P51 have over the typical 2.200" scj frpp head.

Lem,
Is this SCJ one of your builds? Runs real nice.

Gary,
Thanks for the compliment. Lem helped me with my first build a 547 and had the heads done at Oaklys shop. The 547 was running 9.45 until an oiling problem got away from me. When I went 580 he wanted me to go A head and I said no. We all know Id be well into the 8s with that setup. I could almost see how quickly Lem typed " No sir, its not". I tell you what a guy and he didnt even say I told you so.
So here I am with this Frankenstein set of parts but my limits are no power adders, no chute and no bars (I hope). So the limit is 150ish mph. And its knocking on the door right now.
Lem has been very good to me almost like a coach or a mentor. I never consulted him about P51s over SCJs. I think he would have said there is much on that change but then he did afterwards. I was going to buy another set of heads anyway for my street car and the P51s came up FS used. Better to have the P51s on the race car even if they are only worth a 10th over my SCJs.
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