High Altitude Camshaft Selection

[SBM4theW!n]

Hi all,

So last year after taking my car to Bandimere (5800ft) and running 17s with a stock rebuilt 360LA I decided to pull the engine, throw in some SpeedPro 10-1 pistons, 2.02 IV ported J heads, and a 230 duration camshaft (Comp 280H). As I was putting everything together, with the pistons still .04 in the hole and 69CC chambers, I was measuring about 9.3-1 Static Compression Ratio, which should have been fine based on Comp's requirements. After all this, I picked up 1 second, and no real noticable seat of pants difference other than it revved up a bit higher (6000rpm vs 5200rpm).

Long story short, the engine is back out of the car and after some internet schooling with the long duration (230 @50/ Inlet Valve Closes at 66 degrees ABDC) cam and high altitude, my Dynamic Compression Ratio was way down (like 6.31:1 per Wallace Racing's DCR calculator at 5200ft).

So I replaced the stock intake valves with some manley's which reduced the head chambers to 65cc, got a mopar thin head gasket (.026 compressed), and the heads are at the machine shop getting milled 20 thousands, all of which should put me at 10.4:1 scr. That being said, even with the increase my dcr is still only 7.15:1 at 5200ft.

From what I've read, with these open chamber Iron heads and 91 octane, I should be shooting for between 7.5 and 8 to 1 dcr for maximum efficiency?

So is my next step to get a lower duration camshaft, or should I be ok?

 

[T56MaxTorq]

I run a 224/230 cam in my 360 at 6200ft and it runs very strong. But that's In a truck...

This high up there isn't much we can do. It sounds like you've already built the high compression engine you need. No matter what cam you have, you still have 20% less air pressure than sea level. Fortunately, everybody else has the same disadvantage. I don't think you'd benefit much from less cam.

 

[yellow rose]

Hi all,

So last year after taking my car to Bandimere (5800ft) and running 17s with a stock rebuilt 360LA I decided to pull the engine, throw in some SpeedPro 10-1 pistons, 2.02 IV ported J heads, and a 230 duration camshaft (Comp 280H). As I was putting everything together, with the pistons still .04 in the hole and 69CC chambers, I was measuring about 9.3-1 Static Compression Ratio, which should have been fine based on Comp's requirements. After all this, I picked up 1 second, and no real noticable seat of pants difference other than it revved up a bit higher (6000rpm vs 5200rpm).

Long story short, the engine is back out of the car and after some internet schooling with the long duration (230 @50/ Inlet Valve Closes at 66 degrees ABDC) cam and high altitude, my Dynamic Compression Ratio was way down (like 6.31:1 per Wallace Racing's DCR calculator at 5200ft).

So I replaced the stock intake valves with some manley's which reduced the head chambers to 65cc, got a mopar thin head gasket (.026 compressed), and the heads are at the machine shop getting milled 20 thousands, all of which should put me at 10.4:1 scr. That being said, even with the increase my dcr is still only 7.15:1 at 5200ft.

From what I've read, with these open chamber Iron heads and 91 octane, I should be shooting for between 7.5 and 8 to 1 dcr for maximum efficiency?

So is my next step to get a lower duration camshaft, or should I be ok?

You still don't have enough compression. You need to get the piston at zero deck.

I run 11:1 on iron heads at almost sea level

 

[nm9stheham]

As above: No reason to not shave and deck. (Just retard the ignition timing when you drive to Death Valley.) Are you just using this engine at the strip? What rear gear and TC stall speed?

Advance that cam by 4 degrees and pick up about 0.25 in DCR.

The Magnum cam profile is not very aggressive. If you went to the XE274 cam, you would get the same 230@.050" duration with a tiny bit more lift, and 6 degrees earlier intake closure. Add 4 degrees advance to that XE274 cam, and your DCR goes up by around 0.45 in DCR. Lunati Voodoo cams have a similar steeper cam profile.

Comp XE Hi Lift 275 cams would give you 231@.050" duration and a similar intake closing angle as the XE274, with more lift for better breathing with those 2.02" valves. Or just use 1.6 rockers with the Xe274. But keep in mind that the higher you go with lift to duration raito, the higher the lifter-to-lobe pressures and the more careful you need to be with cam break-in and lubrication.

Which leads right into roller cams, with their superior lift to duration profiles. Seems like your situation is a good candidate for this. I'd be very seriously looking at this option.

I gotta admit being at 5200' is distinctly 'sub-optimum'!

 

[AJ/FormS]

I agree; you need more compression and a faster cam.The 230 is a good size. My 367 at 900 ft makes gobs of power with it. I am at 10.7Scr,8.7Dcr and aluminum heads, and 87E10. I milled the block to get KB107s .005 out of the hole and run .039 gaskets, for about .034 squish. I have run .020 at one time with no problems.From what I have Seen, CompCams are pretty lazy ramps. I would suggest a custom fast rate of lift,grind.These are sometimes called HighIntensity
But here's the deal, you already spent the money on the pistons and cam. I can't see you being anxious to do it again. At .004 plus .026 =.030Squish, you are pretty good there. So at this point your best bets are; fresh cold air, optimizing the TC and rear gear, and putting her on a diet.
If you are running an Auto, They have a pretty wide powerband requirement. Running a higher stall than you might think appropriate, can help with that, and your gears will have to be on the money to MPH well.
The Hughes Engine Site has a very nice Tech section on cylinder pressure.
Hughes Engines
Go to camshaft articles, and #11
My Wallace says 11.5 is needed for a 66*ICA, which could be a 276/286/112 cam.The 112* will reduce specific power output, but widen the powerband to accommodate the powerband requirement of the auto. So perhaps more average HP putdown in first and second, at the slight expense of power through the traps.

 

[MopaR&D]

another +1 for the 'quicker' cam and more CR, I used to live in Lakewood only like 10 minutes from Bandimere and went to the T&T nights a lot. The best I did was a 14.91 at 96 mph and my car is around 3400 lbs. with me in it, 3/4 tank of gas, some tools etc. I am running a 360 LA with Magnum heads (factory 1.6 rockers) and I put in the KB flat-tops, the block was already decked and bored .060" over (I know that's a lot ) so I just had the bores honed. Stock iron Magnum heads, Air Gap intake, shorty Hedman headers, and the smaller Lunati Voodoo cam (213/220* duration at .050"). Also 625 cfm Carter AFB carb. It's a torque monster and those numbers I ran were with a stock converter, 4.10 gears and 28" tall street tires that spun like I was on ice; the gears I borrowed from a fellow FABO member in the area and were actually too much I think it would have been better with 3.55's which I plan to put in in the near future.

This thread is really useful to me because I am planning to put in a bigger cam since mine feels like a rocket from right off idle but I can feel the torque falling off past 4500 RPM and usually shift around 5000. I'm planning to get a custom-grind cam FWIW, the more I learn about cams the more I see how important it is to have them spec'd exactly to the rest of your combo and intended usage and our high altitude is a big factor to consider. Also it's like, the more I learn the more I realize how much I don't know LOL. It is basically the same price after all.

 

[AJ/FormS]

SBM4
But you have an automatic,so don't suffer from time-lapse downshifts. When you floor it, it's ba-bam! downshift. And 35 with 3.55s is in the neighborhood of 3800,or a bit more. That is near perfect, to blast off with.
At your altitude, you are gonna some airflow.And for sure;fresh cold air. Hot underhood air will really slow things down. I had earlier tried a 292/508/108 cam. I didn't much like it as a street cam. The power was way up there. I think IIRC it didn't even start until past 5000rpm. Terrible for street. I had to run 4.30s, to take advantage of her. I even tried 4.88s.They say that cam is 249@050. I measured mine at less, around 241,IIRC. And I am convinced that that is too big,for street. Too many sacrifices.
So my final cam is 230@050/110, also a fast-rate Hughes.This cam does well with a starter gear of 3.55 x 3.09 =10.97, and with the GV unit cruises in 3.55 x .78 =2.77...This makes 2236 with my 27s at 65mph. This cam can't make the gas-mileage numbers anymore.
The Dcr calculator shows a Scr of 11.5 is needed to make a Dcr of 8.0 at 5200. This is a Total Chamber Volume of 71.27@ 4.03 bore.
At 10.4Scr, you currently need 79.6cc TCV. So you need to lose about 8cc.
So if you can't get down to 71.27, your 230* will need some torque multiplication to get off the line.
To mph well, you are gonna need 4.30s to 4.56s, and to get off the line well, the 4.30s are about right.And to ET well, you are gonna need some TC...2800 is not gonna be enough.If you could get a Superfast 230cam that slams the intake closed real early, you would be set.
So there are the sacrifices. Daily driving, and fuel economy, for MPH and ET.
With a SBM at your elevation, it is impossible to have both.
As a streeter, I feel that my 230* is more than enough for a 360. Actually I loved that earlier 223* cam and often miss it. But I'm at 900ft. At your elevation, I would suggest a minimum cam of between those two, leaning towards the highside if track is important to you, and leaning towards the low side if street fun is more important. But never lose track of your Dcr. If it gets too low, the street fun goes away.
If I was you I would give Dave a call at Hughes. He seems to know his stuff. He will ask you a bazzilion questions. You will need to have all the specs handy for your build, and including the current cylinder pressure, and including exact race-weight and gearing and TC, and tire size etc.He will also ask you what you are willing to sacrifice.
But I gotta tell you, if you start chasing Mph/ET it gets expensive in a hurry. Especially ET. And even more so,at high elevation.It is my humble opinion that it would probably be cheaper in the long run to either supercharge your 360, or go to a bigger engine, or get a second car for track-days.. Again, especially if street fun not to be sacrificed. It's hard enough here at 900ft to do both. I'm staying a streeter.And For me, 230/237/110 is as big as I care to go.To harness that is/was expensive enough.I would guess that, between; the tranny, theGV, the narrowed and relocated rear, the 325/50-15s, the 1350 D/S conversion, the gears,and the clutch; harnessing that little 367 to be safe,reliable, and fun cost me in the neighborhood (no labor!) of 8 to 10Gs. NO Labor included.That was stepping up from a 223* cam to a 230* cam..... And it's still slow, and it is no longer a DD....
I might as well swap shocks, put on slapper bars and call it a dragcar. Or
put the 223* back in.
Hmmmmmmmmmmmmmmmmmmmmmmmmmmm

Short answer is more compression. Lots more. Pulling 8cc out will be no fun at this stage!But not impossible.If your pistons are really down .040, going to Zero deck will get you what you need; 8.36cc at 4.03 bore.Of course that will require re-maching costs to get the intake ports to match up.Add-up all your machining costs, it might be cheaper to swap out the pistons to something like the KB190s with a .050Quench-domes. These might get you 6.2cc with no machining costs. That would get you 11.2 and a Dcr of 7.85@5200ft;pretty close..And it will be gang-busters right off idle, with a small TC. I would run it with a TQ. a BIG TQ.
OOOOO I am feeling the fun
Another option might be to fill the 5cc eyebrows if you don't need them.This will get you 11.0/7.7@5200. The only good thing about 7.7, is it will run on anything.

 

[AJ/FormS]

Mope
I like your combo!
I had a Hughes 223/230/110 cam in mine for a couple of years, so I know what you mean about it being a torque monster.Mine went 12.9 @900ft and 3650 pounds.The Hughes cam with their springing, reved to the moon. I felt the power nose over at about 5400, so it probably peaked a bit lower.With the Hughes and Aluminum heads, it was hard to tell where exactly to shift.I revved her mercilessly. I run a 4 spd, so it has a pretty narrow powerband requirement, and of course an adjustable "stall". This is about the smallest cam I would put in a 360. This combo can get incredible fuel mileage with O/D gears. And at a 700/650 rpm idle, I could just barely tell it had a cam.
With 3.55 x 2.66, the starter gear was 9.44, just right for a one-gear romp to 60mph.Well 3.23s wouldabin better.It was a little lazy at 35 in second(2963rpm), so I tried a bunch of other gears.Which of course, led to ridiculous hiway rpms. At the time the car was a DD, cuz it was getting incredible fuel mileage, and also cuz it was so much fun to drive.
SO it wasn't long and then I bought a GearVendor O/D.
And then a bigger cam.

Before you rush out and buy a cam, put a real carb on it. Something closer to 800 or better. 360s love bigger carbs. A bigger carb will allow a slightly higher nose-over, and the fall off after the peak is also extended several hundred rpm. My 223 cam with a 750, kept on pulling til way past what I expected.I often didn't shift until 6800.For you I am imagining a spread-bore. I seem to recall Rochester big-bores making a come back. You might want to check those out. I love how spread-bores tune with automatics and smaller gears.
Let her buck!
5000 is totally short-shifting.
Especially if you have an automatic.
Shifting at just 5000, makes second (59% split) have to pull from the basement at 2950.Climbing out of that hole at high altitude will take forever. Better it would be, to rev to say 5800, to come in at 3422. The torque peak with that 223 cam will be much more interested in pulling from that rpm. The slight power loss at 5800 will be more than made up for by what you gain at the bottom, for a net average hp gain during the time spent in that gear. More average hp means quicker through the gear.And shifting at 5800 puts the center of the powerband at 4600, which better matches what you are feeling; the noseover past 4500.
With a bigger carb I think you will find that shifting even higher will get you through second quickest. Shift loops will find the magic shift rpm, which will be different from the 2-3 shift. The TFs actually have a pretty nice 2-3 split of 69%.
Just borrow somebodies 750, and rev it UP! ;see what you think. I would sell that 625 in a heartbeat; that's an um, shhhh, teener, ptouiii, carb!LoL
And I'm a thinking you will want to do something about traction. More rubber might not be the answer. 295s over 245s didn't help me that much in straight-line traction. They do however, keep the back, in the back,around the turns, as they are screaming for mercy.I am thinking slapper bars are pretty good value, and you can build them yourself pretty cheap.Of course the search for traction often leads to springs and shocks, so you may need to make more sacrifices.It never ends......................................................................................
And as always, fresh cold air at altitude is paramount. It is worth whatever it takes.

 

[MopaR&D]

AJ I remember PM'ing you back and forth about my combo a few months back definitely learned a lot... About a month ago I bought a 750 Street Demon and sold my AFB to a guy with a 318 '71 Challenger. It does pull a bit better in the higher RPMs but it still doesn't feel any quicker if I shift at 5500 as opposed to 5000; you say 2900 RPM is "in the basement" but with my engine that's literally right about where PEAK torque is lol. Cam Spec Card :: Lunati Power that's the cam card for my cam; note the wide 112* LSA and short duration for the lift, this cam is intended for stock-ish smaller cube low-comp street engines and I'm running it in a 10.5:1 370 c.i. mill.

To the OP I think the larger Voodoo (Voodoo Hydraulic Flat Tappet Cam - Chrysler 273-360 268/276 - Lunati Power) would work great, that 280H is an old-school grind and won't build cylinder pressure like a modern fast-ramp cam. One very important point as well, at high altitude you NEED a split-pattern cam to take advantage of exhaust scavenging since the intake pressure is lower. I learned that straight from Gary DeWerth at Colorado Custom Cylinder Head in Englewood, definitely knows his stuff I think he's been a machinist for like 50 years?

 

[AJ/FormS]

Oh dear, I thought you had a 224 in there. Well then yeah thats pretty small. I take back everything in the last post

Peak torque don't mean much in terms of mph.If it did we'd all be short-shifting. If you want to be quick you will concentrate on putting down the max average hp in each gear. With a 59% 1-2 split,You may have to rev quite high to find the outgoing power equal to the incoming power. In there somewhere is the max average power. The 2-3 is a little tighter at 69%, so you need to find a new, different,shift rpm for that one.Shift loops, or dyno chart, or best guess. Seat of the pants never told me much, but then, I'm a streeter.
A 213/220/112 cam has a real flat curve. It is really hard to feel the peak power. Over the nose,it might be nearly the same for 600 or 800 or more rpm. My 223/230/110 cam was like that too, I think there was like 800 rpm where the hp was nearly flat.I bought one of those stick-on-the-window accelerometers to help me zero in on the right shift rpm.Then I totally ignore it and shift at 7200! lol. I can't help it; dual 3 inch dynomaxers just scream up there.And if the tires are on fire, it don't matter where I shift.
This is probably why Chrysler, back in 68, spec'd different cams for 340 autos to 340 stick cars; different powerband requirements.And probably why they spec'd a 114 LDA for the auto.
The 266 low box has 72/73 percent splits;quite a bit narrower.With a 6000rpm shift-speed the M/T will drop just 1620 rpm, in every gear(more or less); while the auto drops 2460 and 1860. Totally different powerband requirements.And totally different shift-rpms. As the Rs go up, it gets worse.

OK but I just gotta ask; why the stump-puller cam?

 

[MopaR&D]

OK but I just gotta ask; why the stump-puller cam?

Basically, I already had it lol. I put about 5000 miles on it in my old oil-burning stock 318 and was curious to see how it would act in my high-comp 360 as in the 318 it had a noticeably lazy bottom end. The AFB carb was reused from the 318 as well. Also I was at first still running my 2.76 7 1/4 which I swapped to my current 2.94 8 3/4 (with a clutch-style SG) which I have been running for the past 2 years. I really like highway cruising in this car and I've driven it all over the state of Colorado like that. I know it will be a lot quicker with a bigger cam and 3.55s but I'm still hesitant to give up that 3000 rpm @ 80 mph cruise. And no I don't have the $$$ for an overdrive at the moment but some day it will get some form of 5-speed overdrive stick.

 

[AJ/FormS]

Hah! I'm at 2750@80. But I totally agree, that part is nice. And I loved my 223/230/110. I would still have it if it hadn't dropped 2 lobes
Thx for the response.

 

[nm9stheham]

I really like highway cruising in this car and I've driven it all over the state of Colorado like that. I know it will be a lot quicker with a bigger cam and 3.55s but I'm still hesitant to give up that 3000 rpm @ 80 mph cruise.

Not to mention the fuel mileage drop...

 

[Cudafever]

keep the 355 gears, talk to a cam company, and be total honest with him, with exactly what you have and what you do with it most. High altitude cams are NOT an off the shelf cam!
NOW, as far as quench or piston to head clearance, FORGET ABOUT IT. When you build your next eng and you buy some closed chamber head, THEN you can get a good quench(more efficient burn/power/) You can deck you head until you have 0 deck with your current pistons(don't do it, you will destroy your block) and have a close piston to head and still have 0 yes 0 quench capability.
A cam company can adj your valve open and close events to take better advantage of you lack of air. Aka dynamic compression ratio.
Brian at IMM and comp cams put together a roller camshaft for my 408. ( I race a 6600 feet)
I have a stock converter that has been tweaked to around 3000 rpm.(aka not efficient)
They spec'd the cam out, all i did was install it and then advance it 2 degree (Per their suggestion)

Love it, runs like a top, has the bottom end power i was looking for. It runs out of steam about 5800 rpm has run a best of 8.14(1/8 mile) in a car that weigh 3860 (just weigh it ) and i'm still tuning on it!

Have a cam, made for the eng package that you have built, and the way you drive it.
Off the shelf cams were never designed for High altitude.
Most of the cam bought will be install in cars that never see above 2500-3500 feet.

 

[Cudafever]

Sorry i missed the post were you said you had 2.94. When i had that tall of a gear, 2.76. i was running 90 mph at 3000 rpm. but i had 27" tall skinny on it at that time. Heading to the Mile High Nationals no less.

 

[MOPAROFFICIAL]

"High altitude cam" never heard of one....but i have heard of thin air....so raise the compression and get some gears.
Aim for a dynamic/cranking of 8.2-8.4 which is around 165-170 ish psi roughly. There's my opinion.

 

[Cudafever]

"High altitude cam" never heard of one....but i have heard of thin air....so raise the compression and get some gears.
Aim for a dynamic/cranking of 8.2-8.4 which is around 165-170 ish psi roughly. There's my opinion.

I think both describe it well. Have the "Cam" designed for High Altitude. or thin air. that better.............
We can all throw out dynamic numbers, intake and exhaust, open and close ### but even with all that. The cam designer will understand all that much better. And make a better combo for You.

 

[SBM4theW!n]

That all makes sense.
Curently the car is just a toy that I drive around town and take to the occasional test and tune at bandimere. I've had it since I was 15, and I just tinker as I go. The thing is, I want it to feel fast and put down some respectable numbers. I'm afraid to zero deck it as I've got non-adjustable rockers, so 10.4 CR is about as high as I can go without jumping to adjustable rockers or custom pushrods. I'm also not in a huge rush to throw a new cam in it after just installing this one last year.

It's got a 4 speed, but it is the overdrive unit, so gear splits suck. Next year I'm throwing in the steepest gears I can find and a stronger rear diff once I can save up.

So it sounds like the next project is a dual pattern cam with higher lift and earlier intake closing to increase cylinder pressure, possibly roller for more aggressive ramp.

AJ- I couldn't agree more with these things getting expensive. The car always felt quick and fun, but after I took it to the track and embarrassed myself I pulled a perfectly good engine and just started throwing money at it. Still slow, back to the drawing board and a lot more $$.

 

[AJ/FormS]

Until you get it on the pipe, you will continue to be disappointed. That wide ratio tranny is a killer at sea-level, never mind at 5200.

Here's a little math for you;
Let's say you target 100 mph(for now).And let's say you are gonna use 27 inch tires.
To trap well, you will want to hit that at about 5% over your peak power. So let's say that 230 peaks at 5700@5200ft, so you are looking at trapping around 6000.
So 100 x 1056/(6000 x 27 x 3.1416) = the required gear = 1/.2075 = 4.82, so 4.86s it is.
The gear ratios are 3.09-1.67-1.00-.71/.73 and the splits are .54 and .60
So;Your optimum 1-2 shift rpm with that cam and a 54% split is gonna be 7300rpm to drop into second at 3942,for a powerband requirement of 3358rpm, centered at about 5621.Your 2-3 shift with that cam and a 60% split, will need to be about 7000rpm to drop into third at 4200, for a powerband requirement of 2800rpm, centered around 5600.With these gears and upshifting at the correct Rs, you would be putting down the maximum average hp in each gear to get the maximum mph through the traps.The shift rpm is a requirement of that wide-ratio box. Of course, I don't know what your HP curve looks like so it is an estimate. If your power drops off faster, then the shift would have to occur earlier, and the holes would be deeper
I bet you didn't wind it out that far did you?
No you probably shifted it at 6400....in which case the Rs would drop into 2nd at 3456 and into 3rd at 3640. And I bet you were barely into 3rd(direct with 3.55s) and then it was all over.Those are some deep holes to climb up out of. The 230 has a pretty good powerband here at 900ft, but it ain't 2800 to 3358 wide. And at 5200 ft, it has probably lost all hope.So over the course of the 3 gear run, with the rear gearing you have(3.55s I'm assuming?).Your average horsepower put down during the run, will have been very low,indeed.
So let's look at a regular 2.66 low 4 speed
The ratios are 2.66-1.92-1.40-1.00, and the splits are .722-.729-.714
The ideal gear for 100mph might be 4.86s again.
So, the 1-2 shift rpm might be 6550, to drop into 2nd at 4729, for a powerband requirement of 1821, centered at 5640. The 2-3 shift rpm might be 6550, to drop into 3rd at 4782,for a powerband requirement of 1768, centered around 5666. And the 3-4 shift might be the same 6550 to drop in at 4677, for a powerband requirement of 1873, centered around 5613.
So now you are using the same engine,but 4 gears. The starter gear is 4.86 x 2.66 = 12.93;pretty good. The powerband requirement is about1788. And the shift rpm is 6550 across the board. And with these new numbers you will be putting down some very good average hp numbers from 26 mph(4200 rpm)to 100 mph(6038rpm) which is 6% over the estimated 5700 rpm peak.Now I'll go out on a limb and say with this closer ratio tranny, you might trap even higher, so the 4.86s will end up in the scrap heap, and 4.57s might be better. These will get you 106 at the same 6038 rpm.Nothing else changes. The shift rpm is governed by the tranny splits, and matching the outgoing hp to the incoming hp, to put down the maximum average hp, in each gear.

Even is you kept the 3.55s, and made it a 3 full-gear race, you would hit 100 at 6174 in 3rd. that would still leave you a nice 3.55cruiser gear. If you were to go this way, I highly recommend the 3.09 low box as the starter gear will be required. 3.09 x 3.55 =10.97, about the minimum for a 230* cam.
So If I was in your shoes right now, the 3.09/direct 4th box and 3.55s will make a world of a difference.Oh, wait, I am in your shoes!
AJ's Quest for the Funnest Street 360-4spd Combo;short version

 

[SBM4theW!n]

Yeah, the OD box stinks except for cruising.
I actually never realized how bad until I took it to the strip, and really felt those splits. Just using it as a daily driver I wouldn't be banging gears, so I never really noticed. Currently it's got 3.23s so the last time I took it on the 1/4 it was faster to stay out of third gear. Think I was going through the traps at like 95mph and like 6500rpm in second, hence why I was thinking of going to 4.11s.

I've looked at the non-OD units, but it's not cheap for both the box and a new bellhousing with the smaller bearing hole. I also have an open 8 1/4 which isn't helping anything. So right now I've got 4.11s and a suregrip unit priced out at $1,300, or around the same price to throw in a non-OD 4spd and new bellhouse. Figured I'd knock out two birds with one stone with the gear ratio and posi to start, and see how I liked it before swapping the trans.

 

[AJ/FormS]

You'll still have the wide ratios. You'll have a teensy bit better holeshot, and 96 will be 8166/4890 in 3rd/4th, neither of which is any good.
So forgettabout the 4.10s, go straight to the 3.09/direct 4th box.You will not be sorry, even with 3.23s.And 96 will be 5400 in 3rd,coming right up on the powerpeak, so between the extra gear, and being on the pipe through the traps I bet you break a hundred no sweat. And 100mph is 5618rpm in 3rd. Leaving you 300/400rpm for improvements.
These boxes come up all the time for reasonable money, and you can reuse your bellhouse by installing an adapter ring. You will spend less money on a tranny and a suregrip than that 1300 bills. And you will be waaaaaaaaaay happier
Stay away from the 2.66 box, unless you have your heart set on a 4.xx rear gearset. The 3.09low works well with gears up to 3.91, but after that first gear is like 100ft and then it's time to shift.It works great with 3.55s or less

 

[MopaR&D]

You know, my cousin has an 18-spline A-833 he bought to put in his '71 Satellite project but it turned out to need a rebuild so he just wants to sell it. I know the direct-drive 4-speeds are hard to come by and I'm just up in Fort Collins, let me know if that might be of interest to you...

 

[AJ/FormS]

Satellite means it has the long B-body tail,right?The tail from the O/D box will not fit in the Satellite box.Well the tail might but the O/D mainshaft will not accept the Satellite 3rd gear.Do you have an idea what low gear is in it?
The brass and synchronizer sliders from the O/D box will fit right into the Satellite box
I put a complete longshaft B tranny into my 68 FormulaS with the 64/65, 3.09 low gearset, and I like it a lot.
I have seen that 3.09 low box come up for sale here on FABO several times in the last 6 or 8 months. One was very affordable at IIRC $250?

 

[MopaR&D]

Satellite means it has the long B-body tail,right?The tail from the O/D box will not fit in the Satellite box.
But I put a longshaft B tranny into my 68, and I like it a lot.
Do you have an idea what low gear is in it?
The brass and synchronizer sliders from the O/D box will fit right into the Satellite box.

I'm not sure of the low gear I know it's either 2.66 or 2.47 depending on the year, but yes it's the B/E-body long tailshaft one. I don't know how bad of shape it's in anyway my cousin just briefly mentioned it needed to be gone through and he just wanted to put the money towards a modern 5- or 6-speed transmission. I know for sure it is an 18-spline box though I counted myself.

 

[SBM4theW!n]

That's the first I've heard of the bearing adapter ring, but sure enough Passon sells one to adapt a 4.8 to a 5.125 OD bearing hole. Well that's a couple hundred bucks I thought I had to spend.

MOPE- I'm pretty sure I have a 23 spline currently, so I'll probably try to find a 23 spline to avoid messing with my clutch which is almost brand new.

AJ- sounds like you've swapped these back and forth a couple times. I'm assuming my current linkage won't swap completely over to a non-OD unit?