P-51 heads

IDT-572 wrote: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.

Blake,
I started playing with numbers but also ratio'd our tire sizes. For me to get the same 7.21 I would need a 3.35 gear instead of my 3.82, that's a big change. I may drop down to a 3.67 or a 3.50 because I got them on the shelf.  The gear and tire height now are great for cruising at 50 mph if I go smaller I may not be using 3rd gear much.
How high did you spin your 580 P51 motor?

Dave De wrote:

IDT-572 wrote: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.

Blake,
I started playing with numbers but also ratio'd our tire sizes. For me to get the same 7.21 I would need a 3.35 gear instead of my 3.82, that's a big change. I may drop down to a 3.67 or a 3.50 because I got them on the shelf.  The gear and tire height now are great for cruising at 50 mph if I go smaller I may not be using 3rd gear much.
How high did you spin your 580 P51 motor?

What BLAKE is probably recommending, in his round-about way,  is to put a glide in your car ...

Probly an excellent idea...... Its got the wheelspeed of a 2 ton haytruck in granny low as it is

Good one Jon. I will look at going up to 32" tall and a 3.50 gear. I like shifting twice and I'm comitted for that UCC converter.

Dave I have a 3.50 gear if you need it

quick 52 wrote:Dave I have a 3.50 gear if you need it

Thanks I got 2 of them.
32" tall, 5000 stall and 3.50 gear should mph at around 153. I just hope I can do it without bars. That combination just sounds wrong.

Hmmm, not a gear change but a throttle stop on a street car

Dave, I shift at 7100 through the 1/8th at almost 7000

3.55 C 6 = 2 speed at the track and you will have an extra gear for the street, best of both worlds.

IDT-572 wrote:3.55 C 6 = 2 speed at the track and you will have an extra gear for the street, best of both worlds.

Well, in the 1/8 mile anyway ... all the tracks up around here are a 1/4 mile long.

Dave De wrote:

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.

Looks like you have a good working C-6 as well. I used to run one in a 2700 lb 67 Mustang years ago. I found no matter what combo I had in the car it liked to be short shifted so to speak at 5800-6000 1-2. It liked to get out of low as soon as you could. I like to think you would want it to drop back into the grunt zone and let it accelerate to 7200 or so. Looks like you have plenty of grunt too.

Gary Blair wrote:

Looks like you have a good working C-6 as well. I used to run one in a 2700 lb 67 Mustang years ago. I found no matter what combo I had in the car it liked to be short shifted so to speak at 5800-6000 1-2. It liked to get out of low as soon as you could. I like to think you would want it to drop back into the grunt zone and let it accelerate to 7200 or so. Looks like you have plenty of grunt too.

Launch at 3800 off the brake with 4500 stall. Notice the 1-2 time shifting at 6200. This was 1/8th mile with a 1.32 60ft. It doesn't matter that I was early .012
Skip the last 2.5 minutes. I see just under 2 seconds in first gear.

https://youtu.be/IMqaFtlSV4o

Dave De wrote:

Gary Blair wrote:

Looks like you have a good working C-6 as well. I used to run one in a 2700 lb 67 Mustang years ago. I found no matter what combo I had in the car it liked to be short shifted so to speak at 5800-6000 1-2. It liked to get out of low as soon as you could. I like to think you would want it to drop back into the grunt zone and let it accelerate to 7200 or so. Looks like you have plenty of grunt too.

Launch at 3800 off the brake with 4500 stall. Notice the 1-2 time shifting at 6200. This was 1/8th mile with a 1.32 60ft. It doesn't matter that I was early .012
Skip the last 2.5 minutes. I see just under 2 seconds in first gear.

https://youtu.be/IMqaFtlSV4o

I see, goes nice and straight. Maybe change just the convertor and leave at your 3800 and then try 5000. Is it a ladder bar or a 4 link?

Ladder

Very nice looking car you have

I've seen these movies before.

An engine that had a converter and other things that was marginal and things did not go well when the power curve changed.

Lem Evans wrote:I've seen these movies before.

An engine that had a converter and other things that was marginal and things did not go well when the power curve changed.

.

X2

Lem Evans wrote:I've seen these movies before.

An engine that had a converter and other things that was marginal and things did not go well when the power curve changed.

Okay Lem, we know the converter is crap so now Im going with a UCC 9" to stall at 5k and then the gear will be down to a 3.63
What else falls under the other things category?

I think the new convertor can pick it up. Of course it's possible that it could have picked it up with the SCJ's too. If you were to retune the P-51 with more cam I can't see any reason why it wouldn't help the SCJ's as well.

Dave De wrote:Ladder

It leaves with the right attitude. It's just right I think.

Dave,
That is one Very classic kick azz Stang, like bowling... rack em and knock em down.

Gary Blair wrote:

Dave De wrote:Ladder

It leaves with the right attitude. It's just right I think.

FalconEh wrote:Dave,
  That is one Very classic kick azz Stang, like bowling... rack em and knock em down.

Thanks for the compliments. UCCs converter should be here Friday and slid in the car Saturday for a TnT event at Milan on Sunday. I will post results for the converter and a tire test.

Update? I know we had monsoons on Saturday

bigblockfox468 wrote:Update? I know we had monsoons on Saturday

Milan was wet but the track was dry. There was a 15 to 20 mph head wind that would also go from side to side. Air was 2200 to 2500. My new converter didnt change anything and I actually was a little slower. My friends Firebird ran like clockwork at 9.06 and 151 mph same as without a headwind.
I played around with the setup and started running the 2 step at 4400. 60s were all 1.32 to 1.36
Changed the 31x14 GY slicks to my old MT 31x13 ET Drags, added one psi (9 cold) and the car pulled a 2 footer at an angle towards the wall, left in the left lane. I lifted and slammed the front end hard enough to mess up the camber and toe on the passenger side.
In spite of that it did the best 60ft for the day. I did gain one mph on the top end over the previous time out.
Im looking to replace the GoodYears with 32 talls that have more rollout and stay with 13 wide if I can find them. Probably Hoosiers or 14" MT's.
I'll straighten out the front and be back up to Ubly on the 4th.
After that a gear change.

Gary Blair wrote:

Looks like you have a good working C-6 as well. I used to run one in a 2700 lb 67 Mustang years ago. I found no matter what combo I had in the car it liked to be short shifted so to speak at 5800-6000 1-2. It liked to get out of low as soon as you could. I like to think you would want it to drop back into the grunt zone and let it accelerate to 7200 or so. Looks like you have plenty of grunt too.

^^^Did you try the short shift, could help the wheelie, and gain more through top.