460 Ford Forum banner

Help Needed on 557 BBF

18K views 26 replies 9 participants last post by  hotrodder 
#1 ·
I run a 125" Fiat altered, the motor is a 460 block from a 1971 Thunderbird, the heads are TFS standard Cobra Jet style, I use alcohal for fuel, the cam is a Clay Smith solid roller (280 deg @ .050 with .745 lift at the valve) the crank was a Scat 4.300 stroker lite weight with 6.700 Scat rods, Maule flat top pistons, zero deck, 4.440" bore.
With this motor I was consistantly running 8.50 ET @ 154 MPH with the car and myself weighing 2150 pounds.

I scattered the motor in Sacramento last month and replaced it with an identical set up except it went to a Ohio Crankshaft 4.500" stroke 4340 crank that is NOT a lite weight version (about 4.6 pounds heavier) and 6.800" rods, Diamond flat top 4.440" pistons The cam is the same cam that was in the other motor, the rockers, valves, springs, EVERY thing else is the same! The old motor came out at 13.12 CR and the new motor is 13.19 CR due to the extra .200" storke. Every thing else is identical, even the timing! Its just 557" now as opposed to 530" it was before.

Now I struggle to make 8.75 et and 149 MPH with the car!

Could the extra weight of the crank really eat that much et? over two tenths?

Any one got any ideas? I need to find those two tents before the final ANRA race in Bakersfield in three weeks!

Thanks for reading and thinking about this, I am sure someone way more knowledgable than I am will come up with the answer!

Thanks Guys,

Kim Lee
ANRA NE II 2011 Points Leader (hope to stay that way if I can)
 
See less See more
#2 · (Edited)
Kim, I'm thinking that with the extra stroke/cubes that you have now you're making more torque at a lower RPM, now your converter may be wrong. Maybe it wants more cam now. What do your 60's look like? What type of induction do you have? What do the plugs say? Fat, lean? It would take 200 LBS to slow you down 2 tenths. Same type pistons? It might want different timing.
Rob
 
#3 ·
With that much difference I would look at the timing.

I have seen major differences in the same brand and part # timing sets. You did use a new timing set, correct? The cam may be advanced or retarded over the prior deal.
 
#4 ·
the 60 foots are from 1.19 to 1.21 to 1.30's now, I use a 1050 PRO Systems 4500 with 200 jets all around. Plug reading has never been my thing, they look just like they came out of the box after two runs. no color even on the ground strap. With the old motor, I could run 220 jets and 192 jets and see no difference in the plugs, but thats probably just me not knowing what to look for.Same type pistons, but the dome/dish is -7CC now as opposed to -5CC before. I went from 32 degrees up through 37 degrees and it slowed down every change. so I went back to 30 and it ran the same as 32.
your convertor idea makes a lot of sense, the car just seems flat now, it doesnt carry the front wheels like it used to either. do you think I am over the torque RPM from the begining of the run? The convertor will let the motor go to 5500 on the trans break.
Thanks for taking the time to respond to my dilema.
 
#6 · (Edited)
Sounds to me like you need to get some quick dyno time and tuning done then pick a converter and tail gears for your torque curv.....Ya got time for that? As far as the plugs go....you're running alcohol, they'll look clean right up to the time they melt! lol you might see some ground strap discoloration if it was too hot or lean....
Rob
 
#7 ·
I have scheduled some wheel dyno time for next week, how to find some more HP with that process, and yes, your advice sounds like the best thing to do, but the race is Oct 8th and 9th. I will probably do a gear change this winter between seasons.
(If I can get my wife to open her purse)
I have attached (I think) a few pictures of the plugs, bu the camera is not much for close ups.
 

Attachments

This post has been deleted
#9 ·
You might just try swapping the rear gears, it can be done in about an hour if its a 9" inch rearend!!

Of course the high heat and humidity we've been having lately could also be affecting it too. Its not uncommon for some vehicles to slow down a couple tenths in the outrageous heat.
 
#13 ·
The one hour is pretty accurate, IF I didnt have to remove the floor pan, the driveshaft tunnel and remove the entire housing from the chasses, there is a cross member that prevents the pumpkin from comming out far enough to drop down! Its a disaster to change the gears on this heap!
What gears are your thinking would help? 3.91?
 
#23 ·
The Dyno Results

Made six pulls, the best one was with .176" jets, down from .200" at the last race and at 30* Timing.
first pull was just at 600 HP at the wheels and the final was 647 HP at the wheels.
The increase was with jets and timing only, the number are very dissapointing to me but now I know where Im comming from when we make a cam change.
Here is a video of pull number five.

 
#26 ·
converter

Mr. Evens is very good about cam selection from what I have witnessed so I would look into his advice there, but with the drop in your 60t foot I would think maybe when you broke your engine you also broke your torque converter. I have almost the same setup in my dragster at 2050 lbs and it will run 790sin in the heat at 168mph
 
#27 ·
I run a similar combination in a slingshot - mine's a 552 with a 4.5 stroke scat forged crank, with steel rods, probe flat tops, stock unported SCJ heads, a rons flying toilet on methanol and a lem evans cam (278*/288* 110 LSA and a 0.727 lift on both valves), running through a powerglide with a 1.80 first gear ,5500 stall convertor, a 9 inch with a 3.89 gear, and 33.5 x 15 x 15 rear slicks. She's mild steel and id guess she weights in around 2000-2100lbs with me in her (but that could be an under estimate).

Our PB is a 8.443 @ 157.55 mph, with me shifting at around 6000rpms. On that run the 60ft was a 1.269 (but that was probably on the rear wheels as the fronts are usually in the air past 60 ft) - 1/8th mile was 5.36733 at 129.49mph. The 60s tend to be consistantly in the high 1.26's or low 1.27 - best was a 1.22.

bdkfs - are your heads ported on stock? Id love to run 7.9 so im looking to see what i need to do to get there.

nevadabandit - were those wheel horsepower figures? If so then based on 15% losses between the engine and the rollers (so driveline / tyres) then that would be around 750 hp yeah?
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top