Can you spin your tires with non-stock cam and stock stall?

K

kerb12

Well-known member
I've been constantly swapping parts on my engine over the past few years, trying to get more power, and have never been able to break my rear wheels loose... but I've seen people with completely stock 200's do it with no problem. Unfortunately I never drove it stock since it needed a complete rebuild when I got the car, and one of the first things I did was throw a COMP CAMS 260h cam in.

Could it be that it's shifting my power band up too high and I need a higher stall torque converter in my C4 to do it now?

Anyone else able to do it with an aftermarket cam?

-Nick
 
what sz rear tire and rear gear?
do U know the current tq converter?

"...constantly swapping parts…"
what R those?
what carb currently?

May B give it more advance?
 
Howdy Back Nick:

If all you want to do is to spin your rear tire(s) try this; remove all the junk in the trunk, air up the rear tires to 45 PSI and pre-load the torque converter to the max. If that doesn't get your tires spinning, something else is wrong.

You don't say in your signature what CR your engine has? IF it is at least 9:1 or higher and the spark advance curve is dialed in you should be good to go.

Personally, I prefer balanced traction to tire spin.

Adios, David
 
Tires are 205/70 on 14x7 rims, and rear is the 7.25" so I think that's 2.83:1? Torque converter is a rebuild of the stock. If I hold the brakes and floor it, it levels off around 1,500rpm.

Engine is a rebuilt 200, with the COMP 280h cam, and large log head with direct mount Autolite 2100 1.08. Mild porting and polishing, with larger valves. Duraspark distributor with MSD 6a control box. Long tube headers. I think that's about it?

Static compression might be low, should be around 8.7:1 with the gasket I'm using. I think in '66 it was 9.1:1 stock? Not sure if that's taking away some low end power too.

I've tried more initial advance - I usually have it at 14 degrees, but I think I might have even put it at 18 the last time I was playing with it.

I've been thinking about trying a bigger carb.. either an Autolite 1.21 or 1.23, or the Holley 350... but that would take away low end power right?
 
Howdy Back Nick:

Is the cam a 260 or a 280? You've mentioned both.

I don't know your locale (elevation), but 8.7:1 is on the low side for use with a performance cam. The increase in duration will lower your dynamic CR, which is why higher CR and more duration goes hand-in-hand.

Also your wheel tire combination are ideal for maximizing traction- not for tire spin.

Check you door frame code of the differential tag for iding you rear axle ratio. If it is a 2.83:1 ratio, that will also make tire spin on take-off less likely. a 3.20 ratio would be better all around. And, given your lower CR and longer duration it is unlikely that more carb cfm will help with lower rpm performance. The 1.08 is just about ideal for an engine like yours.

Did you get any knock with the initial advance at 16 before? If not, more might be better with your combination? What is your elevation?

Did emptying your trunk and airing up your tires help? Oh, and a gas tank no more then 1/4 full.

Yes, more stall speed in the converter, lower gear ratio and more CR will also help you spin your tires. Oh, and mount up some 14x1.85x75 tires and air them up to 45 psi.

Keep it coming.

Adios, David
 
if it's all about burn outs ( and not quick 1/8 mi) a gear change would be the real ticket - but - not good for the rest of ur driving…
I have 2 B careful in the bronk cuz I got 411 in my rear but U would not hafta go that hi I don't imagine.
8-0
I think $120 - 200 for ring/pinion change if U can do the wrk your self.
 
"...rear is the 7.25" so I think that's 2.83:1?…"
I got "a truck" so don't know the 'stang but that's a MPG rear end, no? (2.81:1).

Never heard of a Ford ratio @ that number.
Do U know how to get the ratio offa da tags (door, rear end) or calculate it w/a jack up & count?
 
Oops, typo... 260h. It has a .44 lift.

I'm at low elevation (maybe 500 feet?)... I was going for lower compression because I was planning on going the turbo route, but not sure if that's actually going to happen. If I'm doing the calculation right, a .025 steel shim (if I can find one) would raise my compression to about 9:1... so maybe that's the way to go, this way I don't have to mill the head more.

Ok, checked the code on the door against the shop manual and it's definitely a 2.83 rear. Unfortunately I'm almost positive the gears are not replaceable on it... so I'd have to find an 8" or 9" to change the gearing, and that will probably turn into a major project.

Thanks for all the advice though. It just snowed again today, so might be a few days before I can take the car out again, but I'll try boosting the psi in the tires first and see what happens.

To be honest, it's not that I really WANT to do a burnout... it's more that I'm worried that the fact that I can't might mean there's something off with the engine build.
 
Most likely you have too tall of gears and or to fat of tires. On my warn out stock 200 withe two cylinder s at 40 psi I could do a burn out but I have 3.20 rear gear and had 185 80 13 tires when I put on 195 75 14 I no longer could do it the tires having a better grip.
 
In a 50 y/o car the rear may have been changed (either the gear or whole axel) so a visual count (compaire # rotations of tire vs driveshaft) can give a true reading, but yes could change that for what U seek - & just ring/pinion could B done.

The tire suggestion mentioned would be a easy 1st try tho, no?
 
Ok, tried pumping up the tires to 35 psi (didn't want to go higher than that since it's the max marked on the sidewall of my BFG Radial T/A's).... no luck, still couldn't get the tires to spin.

It's definitely the original rear, I know the original owner... so with it being integral, I think gear swaps are out for now. In the future I might swap to an 8" or 9" rear and go with taller gears, but if I do that I would go to 5-lug so that would turn into a big project (front conversion, disc brakes, etc). Definitely not happening soon.

Do you guys think raising the compression to 9.1-9.2 would make a noticeable difference?

I came across a company that makes new .02" steel shims. With my 54.5 cc chambers and .030 overbore, that should give me a 9.14:1 compression ratio without having to mill the head more. This way if I decide to go turbo later, I can go back to a .045 Victor gasket and drop back to the current 8.64:1.
 
Yes raising the compression ratio 1/2 point should make a noticeable difference. Good luck :nod:
 
"...I came across a company that makes new .02" steel shims…."
I'd encourage you to share that for other members here…

I myself like to gather information and re3search reliability and reputation of companies we might utilize.
TIA ~
 
I have a 264h cam with 10.5-1 comp with a stock converter, it spins the tires very easily, I had my head milled to 48cc's and used tempo pistons, to get your comp up, i think the easy way would be to pull the head and mill it down a bit and add bronze washers to the head bolts to compensate for the amount that you mill unless you have studs. but if you are going to add a turbo the steel shim would help.
 
Ok, that's good to hear, thanks. I think I'm going to tackle the compression next and see how that goes. I was a little unsure because of this comment on the classicinlines head swap page-

"NOTE: On the typical wedge shaped combustion chamber, 1 point of compression, all else being equal, is worth a 4% increase or decrease in power."

That has to be a typo right? I can't imagine dropping from 9.2:1 to 8.2:1 would only lose you 4%.

The company is Silver Seal - http://www.silver-seal.com/category/sho ... hims.ford/ . I don't know anything about them other than they came up on a search and have 200 and 250 listed. I think I'll give em a try.
 
Sorry, one more question... if going to 9.1:1 is noticeable, would going from 9.1:1 to 9.4:1 be a noticeable jump too? According to the calculator, if I just mill another .010" off (for a total of .070"), I'd be at 52.5cc and with this steel shim I'd jump to 9.4:1. Then if I swap in the Felpro gasket later, I'd drop to 8.78:1, which might be in the acceptable turbo range again.
 
Howdy Back Nick:

The 4% increase/decrease is related to a stock engine with a stock cam. When you add a performance cam with more duration it, in effect decreases the dynamic compression, effecting low rpm performance. By increasing the static compression some of the dynamic compression is regained. So, in your case the 4% +/- will not apply.

That 4% figure is somewhat of a generality. Few, if any, will only increase the CR. It is increased along with other performance enhancements at the same time. Also few, if any, will invest in a before/after dyno test to empirically test. The 4%, IIRC, came from some baseline testing on a small block GM V8, in the Comp Cam dyno room. So, for our purposes, consider it a generality at best.

Is your distributor mechanical advance curve still stock? If so an advance recurve would also help. The DS II distributors stock advance curve is very slow making for lazy performance. That, and your cam, is why more initial advance is recommended. Did you get any knock at 15 BTC?

The sidewall rating of your tires is Max Load @ 35psi. You can safely go to 40 psi, but watch for unusual tread wear in the center.

Other vehicles (Mavericks, Comets and early FOX based Fords) used the 7.25 differentials also. 60s came with 3.20:1 in Mustangs with 200 3 spds. There was also a 3.25:1 in Rancheros. They are a code 4 or 5 on the door tag under "ax". Late 60s and 70s are coded as follows 3.20, 3.25:1, 3 and 4, open and limit slip. Most of these are 4 lug, drum brakes and the correct width. Keep an eye out for one of your V8 buddies who are swapping in an 8" or 9" rearend.

Lower gears, looser converter and smaller tires are your best bet to spinning your tires- but it all helps.

Adios, David
 
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