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Discussion Starter #1
Last year I put an A headed stroker in my car in place of my 466 CJ headed engine. Then I fought tractions issues till the end of the season. I swapped 3.73's in and sold my 4.33's. The car ran 6.10 @ 117.5 with the 4.33's and 6.10 @117.3 with the 3.73. However the 4.33 made the car nearly undrivable. The 3.73's calmed it down quite a bit however it was still spinning and not running like it should for the mph it has.

Over the winter I worked with Mike Duffy and others to help get the suspension closer to where it should have been. I also hammered the fenders a little more and some other changes to fit a little taller tire under the car. Now this year it has stopped blowing the tires off and it isn't spinning but yet isn't going any faster than it was.

So far the best it has run this year is 116.7. I understand the slightly taller tire killed a little gear ratio but overall I expected it still to pick up knowing it isn't blowing the tires off at the starting line or spinning till 400' down the track.

I'm using my old NOS convertor (Lenny's @ Ultimate) which will stall to 6K on the brake which is where he said it should be. I was launching at 3000 to 3200 but stepped it up to 4400 this last weekend. The added launch RPM improved my 60' times to a 1.439 from a best of 1.455 with the 3.73 or 1.511 with the 4.33's. Anyway the car was still only running 6.teens @ nearly 115 with horrible air (~4200) that we just had this last weekend.

Regardless I'm expecting this thing to run 5.70's to 5.80 and it just won't. I know the engine is making around 900 HP and runs like a top. I've double checked everything with the engine and rearend and nothing seems to be going away. Is it possible the tranny is robbing this much from my car or is something that far off with my combo. I have a PG with a 1.76 first.

Anyway sorry for the long post but does anyone have any thoughts on this? :?
 

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I heard you say what the convertor stalled to against the trans-brake, but what does it flash to on the launch?

I'm suspicious of the "nitrous convertor" and I'd like to see you borrow some buddie's convertor and put it and see how it does. That's where I'd be looking first.

Hope this helps,
 

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well, You have one of the best converter guys and chassis guys helping you. That 60' should be low 1.30's easy.

What size converter, and is it a spragless or not?

The gear and tire size you went to more or less just works the converter different, is Lenny aware of whats going on with it now?
 

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Are you two stepping down at the starting line or foot braking??

Either way seems to me you are giving up a lot by dragging the motor so far down its power curve. Not to mention the amount of time the converter is going to cost you while it slips when you first take off. A 6k stall converter is not going to be very efficient at even 4400 rpm.

Is it just that you have to run a small tire due to rules and you are trying not to overpower the rubber??

dkp
 

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The converter sounds too loose to me. Does it load the motor well going down the track? Does the engine drop RPM's real good during the shifts? You might be powering your way through the converter. Judging by the 6K you can brake it to I'd say it needs to be tightened.

Maybe now since the chassis is sorted a little better you could try stepping up with a 3.90 or 4.10 gear.
 

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Discussion Starter #6
Charlie I'm not exactly sure what the convertor will flash to off of the line. To be honest I have never looked because I have always been more concerned with trying to keep the nose pointed in the right direction. Now that the suspension is working better I'll have to try and watch. I am just guessing but I would say upper 5's or so, it doesn't seem that far off to me just by the seat of the pants.

Jon, yes Lenny knows I swapped the tire. I talked with him 2 weeks ago right after our first race. That's the first thing I thought too. I also agree that the 60' times should be in the 1.30's that's what I was expecting. The convertor is a 9" and has a sprag. I'm pretty sure the sprag is fine. I blew one of those up a couple years ago when I tried a friends spare superstock convertor with my last engine. He thought the convertor should be pretty close but wanted me to get the engine dynoed before we change anything.

Boss, I am two stepping at the starting line. Started with 3600 last year with the bigger gears and had to go down to 3000 otherwise it would just completely blow the tires off. Then the 3.73's helped and I could go to 3200. This year is completely different with the suspension help and different tire. I'm up to 4400 and it didn't really change much at all.

I was trying to be conservative with the launch RPM primarily just to try and get the thing off the line. The heads up race that I want to run in limits the tire size (30*13.5 DOT). Right now I have 29*11.5 Hoosiers. I used to run a 28*12.5 M/T. The new hoosiers are a 94.25" circ. vs. the M/T 91.25. both are about 10.5" wide at the tread and the section width of the hoosier is 1/4" wider that the M/T.

JBoz, The engine seems to be pulling good down the track. I am shifting at 6700 and it drops to 58-5900 at the shift and climbs to around 6200 at the 1/8 mile stripe. Once the car is rolling it moves out great. Even the Chevy guys have commented on how the car comes on once its out of the hole.

It just seems getting it to leave it tough. I double checked the brakes, suspension etc. Nothing is froze, or not releasing etc.

Here is a top end video from the first weekend. I launched at 3200 shifted at 6700.

http://s104.photobucket.com/albums/m167/BrendenHowe/?action=view&current=Brendendftpass.flv

Thanks
 

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Brenden,

Do you really need that much stall? I know your A headed engine is making some MAD power but your peak torque shouldn't be peaking in the high 5k's should it? i.e. my 8" converter that stalls 4600-4800 is about perfect for my 534. With your A-headed engine, I'm sure you are running more cam but I would think that you wouldn't need more than say 5400 taking into consideration that you are running a glide as well. Maybe you are passing your peak torque? Just some food for tought.

Watching the video, you are making a LOT of power on top!

Good Luck!



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Discussion Starter #8
Damon,

I'm sceptical of that as well. Since I didn't dyno the engine I really don't know where the peak tq. is occurring. From seeing dyno sheets from similar engines it might be the case. However Lenny didn't really think it was out of line.

Maybe Charlie or Boss would have a good idea.

572 c.i.
4.5*4.5 Ablock/heads, ported by charlie flowing 424 and 315. Lem's cam 284/300 .764I, .761E on a 114, 1250 dominator, 2.25 headers 4" collectors with 4" exhaust.

I'm guessing around [email protected] 6500+/- HP and 750 Tq +/- @5500.
 

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Brenden,

Agree that some of the A-headed guys need to chime in on this one but IMO your converter is too loose and you need to move it down where your peak torque is.

Rule of thumb is to put a little more stall in with a glide but with 572CI's and a 4.5" crank your making a TON of torque! Now if your converter is flashing to 6K on the brake then it's way too loose... Now I'm no converter expert but that just my opinion :wink:

IMO, try a tighter converter. Hell, if the converter gets TOO tight just spray it with a 150 shot :p



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Thanx Brenden for posting your combo, couldnt remember it...something is definately off....like everybody suspects...I think you have to try another converter from someone else....it could be so inefficient that its killing your power.....also have you tried shifting higher?.....you have a difficult problem here to figure out for sure........I'm still thinking...lol.....D
 

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Brenden said:
Damon,

I'm sceptical of that as well. Since I didn't dyno the engine I really don't know where the peak tq. is occurring. From seeing dyno sheets from similar engines it might be the case. However Lenny didn't really think it was out of line.

Maybe Charlie or Boss would have a good idea.

572 c.i.
4.5*4.5 Ablock/heads, ported by charlie flowing 424 and 315. Lem's cam 284/300 .764I, .761E on a 114, 1250 dominator, 2.25 headers 4" collectors with 4" exhaust.

I'm guessing around [email protected] 6500+/- HP and 750 Tq +/- @5500.
Where do you have the cam set in at?
 

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Discussion Starter #12
I haven't really tried messing with the shift point much as it seems the first 60' have been the biggest hold up so far.

Lem I know your going to give me hell but I just installed it straight up. I was running out of time and was planning on experimenting with it on the dyno. Next thing you know I was out of days even to do that so that's where I'm at now. We have a few weeks off in July. I'm planning on pulling it out, dynoing it and checking the bottom end then also. I've checked the lash, springs, compression, etc. Everything else looks good. Where would you like to see it?
 

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Discussion Starter #14
OK Lem I remember that for the dyno.

Do you think I'm too far off with my guestimate for HP and TQ and where it should be occuring at?
 

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Discussion Starter #16
What is anybody's thoughts on my starting line ratio?

4.33 * 1.76 = 7.62,
3.73 * 1.76 = 6.56

I know this isn't much starting line ratio compared to most. Do you think I need to look at a 1.96 1st or something like that?

3.73 * 1.96 = 7.31

Maybe the 3300 lbs. is just too much for my first gear.
 

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Discussion Starter #18
Damon, yes and no. The bracket races where I'm usually at are 1/8 mile. But I want to give the 1/4 a try once it gets sorted out further. I just don't want to spend the money on the drive to find out I needed to change something else anyway. The heads up races are 2x/year and they are 1/4.
 

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Brenden........I agree with some of the other guys here, in that I think you've got a little too much converter.....and not enough gear. I fought your problem for most of a season a few years back. In my case, trying to tame things down in order to keep it hooked up was my downfall. I finally dedicated myelf to hooking it up, then letting her eat. I now know that a great engine will look like a pig if it's in a lousy chassis......but a good chassis can make a so-so engine look great.

My combination now uses 4.86 gears with a 5500 J.W's converter and 'glide. It'll go 1.23 in 60', wheels up.....that's in a steel 2700 lb. Ranger (high 5.80's) with a LOT less motor than you have. I think you've got a ton of power just begging to be used. I'd sort out the traction issues, then smack it with the A-head power. :wink:
 

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somthing thats real easy to do and very cheap just to get an idea is to drain the atf and put the John Deere Hyguard in it. It will snug the converter a good 300 rpm, if nothing you will see if it responds to a tighter converter with little money and little work.

Be sure the filter in the trans is a screen type.
 
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