Anyhow, here’s where it gets exciting...placed an order with Mark (VortecPro) for a stock-appearing stroker. He’s confident it will still go over 600 hp with headers, even with the cast iron intake and QuadraJet carb.

Talk about burying the lede!! Congrats on your purchase!!

That motor gonna be happy running around on a 2.56 gear? I'm assuming you talked it all through with Mark. I think I see what you're trying to do -- make your torque with a MJ big block instead of via gearing. Be careful with torque converter selection.

-Dave

 

Thanks Dave.

There are a few things which will make this engine a little different from Mark's typical 650 hp, 496, things to broaden the power band (as if it really needs it lol) to work with the factory converter, and eventually manifolds.

Hopefully, the lack of real traction prevents driveline catastrophes. I’m imagining a smooth roll-on start and a long, steady thrust back into the seat.

A TH350 with 2.56 gears, in this case, acts like a power glide with 3.90 gears at the stripe, more or less. I’m hoping the shallow combined first gear and extended time in the upper rpms allows the engine to apply enough average power to run the number.

 

A smooth start doesn't make for a good ET. The most important part of a pass down the track is the first 330'. After that, not much will change the resulting ET unless you're Top Fuel or the like!

 

Thats what makes this idea intriguing, can it be done? My best guesstimate is that I need a 60’ in the low 1.7s to get in the high 11s. So, the whole idea boils down to is there 0.3 of a second improvement in the 60’ between what I have now and what Mark delivers (and I can put down in the first 60’). After 60’, Mark’s hp will do what it will do, and that’s add mph.

I can tell you there’s about 0.3 of a second difference in the 60’ between 14.1 and 13.0, with both passes applying the same hp after 60’. If the 60’ improves by 0.3, the rest should take care of itself.

 

You will achieve your goal and then some. I ran a 12.99@102.33 mph with 2.56 gears in my 70 SS454 many years ago. I did have 1 3/4" primary headers,2.5" exhaust and a B&M 2400 Holeshot convertor. 60 ft. was 1.83 using a 235/60/15 BFG drag radial.

 

Your Chevelle gives me hope that running well into the 11s on street tires with a mild gear is doable. You have a few advantages though; converter (4K) and gear (3.31) jump out as major differences. You have a better intake (square port) and carb arrangement (Holley), too. I’m also thinking you’re slightly lighter (3925) going down the track as well.

You’re probably several tenths slow running exhaust manifolds compared to headers, and obviously, I’ll have that same challenge soon enough.

Are these things enough to keep me out of the 11s? I don’t know...but we will see soon enough.

 

You'll certainly have enough engine. I'm looking forward to the results. Big fan of the MC's too. Post pictures along the way if you can.

 

I like the way your thinking. Using the th350 as a power glide and having third gear as an overdrive. I’ll be interested in whats learned with this. Are you thinking high stall to get off the line? Or stock tight to maximum your power band ? Seems like an ideal street strip set up if you can get it done. Drive on the highway at low rpm to the track and click off 11’s then drive it home, all while being able to hear your self think. I’d say that’s just about ideal.

 

I’m planning on giving it an honest effort with the cast iron intake, QuadraJet, and headers with the original converter. In any case, this will be done on hard tires with a possible attempt on a 255/60 ET Street R if the hard tires spin in vain.

We’ll see where this ends up with headers, then swap to manifolds and 2.5” exhaust to get closer to FAST class legal. Hopefully, it’ll still run 11s with manifolds, on FAST class legal tires.

 

Sounds like fun...I think it will be tough to pick up .3 in the 60’. Thats alot of weight to get going. You are good at getting the car off the line now, I think you will get your 11’s.

 

You probably have enough engine to pull it off, but that just seems like it's gonna be such a lazy start, even if you get your 1.7 60' -- I just noticed you said you're keeping the stock converter?? I wish you the best, but I predict that will be your Achilles heel.

-Dave

 

Dave, honestly, I’m not sure if the original converter is an asset or liability.

On one hand, it’ll help keep the engine out of the highest torque peak before the chassis has reacted, and that’s good for traction in the first 3’. However, before adding the locker, I found that taking off from a stop light without partially spinning a tire was nearly impossible on smooth blacktop surfaces. The engine had a slight part-throttle stumble that translated into a sudden-but-small climb in rpm which would spin a tire.

This leads me to believe a tight converter might actually be worse in traction-challenged applications, because it causes the tires to respond too quickly to engine input, i.e., almost a direct drive of the wheels before the chassis can react.

This could make driving it out of the hole with hard rubber a major challenge, especially when you have an engine bringing major sauce. I guess what I’m saying is, a high stall convert can act somewhat like a shock absorber, or accumulator, allowing you to better modulate the launch.

 

It will run 11.90's with the right converter and 2.56's, that part is the key to good times. Good luck, if I can run 11.20's with an 8:1 BBC and a 3.70 effective gear I think you can do it, especially with one of Mark's engines.

 

I tried to get a Qjet to run on one of Mark's mill; and it runs, but NOTHNG like a race Holley. I;ve yet to fiddle with all the tuning tricks Eric built into the Qjet.

They have a hard time handling this power level, FOR SURE!

 

Talk to Mark on a converter.My friend has one of Marks 496 in his 70. Mark will help you out getting the right one.

 

I would think a 600 hp motor would blow thru the stock converter. The 454 in the wagon would blow thru the stock 700r4’s converter...the upcoming 489 should annihilate it.

 

I've seen several people run 3.08 rear gears with some of Mark's 570-600 HP 468s....but I believe all had a custom converter....which is what I would do in this situation.
You really want to run a stock TH-350 converter (one that could otherwise work with a 160 HP 307) in front of one of Mark's big blocks?
That said, sincere congrats on getting a Vortec Pro Motor.....and no one can accuse you of not coming up with something cool to follow.
Best of luck....and keep us all updated!

 

I've seen several people run 3.08 rear gears with some of Mark's 570-600 HP 468s....but I believe all had a custom converter....which is what I would do in this situation.
You really want to run a stock TH-350 converter (one that could otherwise work with a 160 HP 307) in front of one of Mark's big blocks?
That said, sincere congrats on getting a Vortec Pro Motor.....and no one can accuse you of not coming up with something cool to follow.
Best of luck....and keep us all updated!

One of my concerns is driveline failure, and lunching the engine. I’m still pondering how I can slip a Rev limiter into a stock appearing distributor.

Whether or not a higher stall will help or hurt traction on stock rubber is not clear to me. Part of me thinks higher would be worse, another part of me thinks it could be better. I do know that my ‘81 Malibu wagon, with 3.42 gears and a 10” Hughes converter, took everything this same 467 had off the line (when fitted with exhaust manifolds and not enough timing) and was a dead hook on 15 year old, 275/60 Dunlop tires. The first 5’ was admirable, unfortunately the next 55’ were disappointing. The net result was a 1.84s, and me questioning giving up my 406 for a big block Chevy.

 

If you need one more dyno and drag test to look forward to...

1970 MC
4110 lbs
Original TH350 and converter
Locked, 2.56 12-bolt

Current 467 (estimated 450-460 hp) showing about 380 hp running 13.0 @ 108 mph, best 60’ 1.98.

FWIW, I think that if you had traction, your current motor would have run 12.3x to 12.5x with 3.31 rear gears and a custom converter.

Reason I say that (and I realize that it's pure speculation) is I still think you'll be leaving that much ET on the table with the same tranny, rear gears, and converter....assuming you don't destroy your TH-350.

I kind of dig what you're trying to do....but I think you have to be honest about what you're costing yourself ET wise.

Have you thought about chasing 10.90s instead?

 

My guess is that the current engine would run 12.40s with a 3.55 gear and good traction. A converter might put it in the 12.20s. It’s a fun driver for sure with the 2.56 gears.

My goal is to only give the combination enough of what it needs to run 11s, stock appearing. I may have to feed the beast with more gear and converter. We’ll see.

If I get the bug to open it up later, then 10.9 is only an intake, exhaust, converter, and gear change away (aside from any other supporting mods).

 

OK, here is some inspiration for going quick with highway gears...my memory is failing though, he had a 2.75 first gear, switch pitch converter, and was spraying 150 shot.

Anybody running decent times with cruising gears?

Just curious if anybody is running mid-12's or better with tall (3.23 & taller) gears? :cool:

www.v8buick.com

With 2.56 and radial tires
12.79@110 on engine 2.0 60'
11.65@118 (150 shot)
4300 lbs
About 15 MPG Highway

I keep preaching that numerically high gears are not the end-all-be-all that people think, at least for the 1/4 mile. You have to consider that Buicks have a fantastic amount of low-end torque, which can overcome the lack of gearing. In fact I have so much torque that I can't go full-throttle until about 20 MPH anyhow. Then, since I have a nice tall gear, I get to take advantage of the being in first gear all the way until about 55 MPH, but if I had 3.73s I would have to be in second gear by about 35 MPH.

Essentially, I get my torque multiplication from the transmission instead of the rear end. I don't run slicks, so more torque at the rear wheels would be converted to tire smoke anyhow.

And since I have 2.56s, I can drive down the freeway at 80-90+ MPH and keep up with the other traffic. No trailer necessary! Sometimes I even wish I had 2.29s, or a GV overdrive with my 2.56s.

Anyhow, my combo is built for nitrous (as you can imagine). The time I mentioned is on a 150HP shot- my best without nitrous is 12.79@110 (still a very decent number) (2.0+ second 60'). My engine is built to handle a lot more nitrous even, but I've had some tuning issues when running 200 or 250HP shots so that I've never made a full run. But MAN does that thing pull hard!

My combo is not rocket-science either. My basic philosophy is to build strong components then pick items that will work well both on- and off-nitrous. Strength items: o-ring'd block, girdle, crower rods, head & lower-end studs, custom pistons from TA, etc. Performance items: TA Intake, decently ported heads (but not too much because that can hurt gas mileage), 9.6:1 compression, MSD/HEI, shorty headers (going back to full headers ASAP), 3" front pipes & 2.5" tailpipes, TH400 with 1st gear kit (2.75) & switch-pitch (also a tri-shield convertor, the 13").

I also have FI, but that is mostly for gas mileage because the car is used as a daily driver. I am not a fan of garage queens- if you want a showpiece then buy a marble sculpture IMO. If you want a racecar then buy a dragster IMO. This is a daily-driver that also happens to go fast. (no offense intended to the many others on here, that is just my personal opinion!) But I could go just as fast with a good carb, if not faster.

I'm glad your mind is open to tall gears. I think you'll like them. Leave the 4.11s to people who want to cross the finish line at the perfect RPM but don't ever drive their car on the street. If your daily driving is slower than mine (not many people go 80+ every day for any sort of distance), then maybe 2.56s are too tall. But don't be afraid of tall gears in general.

-Bob Cunningham

bobc455, Dec 15, 2005

 

That's exactly what I'm trying to build now .
Mountain of low engine torque with tall(er)
Gears

 

Dragginwagon definitely has a plan and is following what I call the "scientific process". Should be interesting to follow.
Best of luck. Look forward to hear how everything goes.

 

I am not sure of some here understand that big "torque" low RPM engines work different than the revved up high RPM engines. I suspected that my peanut port engine might be quicker and faster with less gear than the 4.10's I currently run and by running the 30" tall tires confirmed that. I ran 2 different converters with the 461 and even though the 10" worked good it was too loose, but my 8" converter worked better as it had a higher stall speed but was tighter on the top end. All Dragwagon needs to do is get that converter right and he will hit his goal of high 11's with the MJ engine. I have run a car with 2.56 gear and with my turbo 350 it's like using a power glide with a lower first gear, you only need the 1st and 2nd gear to get the job done.

 

Torque is a great thing! To be clear though, I’m trying to get this done with the original 1970 TH350 converter.

What I like about the 2.56 gear is how long the high output engine gets to eat before dropping back down under 4000 rpm (obviously, less of a concern with a “real” torque converter)...and it only does it once per quarter mile.

Look at the attached image, it’s obvious, why a 2.75 first gear set works very well when combined with a highway rear gear. But low first gear is high dollar, and we’re saving the money for an expertly crafted engine.

 

A bit similar experiment with 2.56 gears here also. 72 Chevelle 2 door with type o locker rear end. Basically very hard to find different gear sets, so the plan is to try how far the current set works with full weight iron headed bbc car.

Motor is a low compression mark 4 truck 454 with stock 4 bolt bottom end including stock pistons. Heads are changed to 781s and piston rings have extra gap for boost. Boost is provided as blow through carb configuration by Vortech YSI centri. Max boost will be quite low about 12 psi at 5500rpm. Exhaust is 3 inch with Hooker long tube comp headers.

Transmission is th400 beefed up little by a local race shop to take about 700hp. Driveshaft is a heavy duty crmoly one and converter is a beef custom 2200 stall and it should easily take everything this engine can throw to it. As type o rear end has bolt in axles the plan is to use about 10 inch wide radials for some traction.

The cam is a bit question mark if it works good enough at low rpms before ysi starts to make enough boost around 3000rpm. I did install 268 Comp extreme hyd flat tappet, but thinking now if it will be too much cam for about 7.5 compression to make any torque between 2000 and 3000rpm.

We'll see if it works and if the stock bottom end will take it. What do you think should I change the cam right away before running it in or could this combo work as a driver? Also hoping to be able to run at least to 12s at quarter mile.

 

One disadvantage of having 2-Series gearing is that the aftermarket does not support it well. Is anyone aware of any aftermarket carriers available for these thick gear sets?

I’m not too worried about the gear set. Even though it’s going to be taking the brunt of the torque, the 2.56 gear set is fairly robust compared to deeper gear sets. I’m a little more worried about the cross pin in my current Yukon Spartan Locker arrangement. I’m not too concerned about axles either, as they sit on the other side of the 2.56 gears

https://www.yukongear.com/downloads/productsheets/spartan locker.pdf

The driveshaft and joints, on the other hand, I’ll show them a little love.

 

seems like you need to make 525 HP from 5,000 thru 6,000 RPM with the smallest possible cam duration, if you could be making 275 HP at 3,000 you might get to 11.90 ET, a 505 cube stroker with one of those repro 163 intake manifolds would be my starting point

 

Must use factory iron intake and QuadraJet, the fuel system will be the challenge.

I’m guessing the current mill peaks about 450-460 and shows upper 300s for hp. Mark’s standard 496 would get it done too, but I’m looking for a smoother idle and a little cushion for when I hamstring it with manifolds and 2.5” exhaust.

To be clear, the extra stroke was not Mark’s idea, rather I convinced him to humor me. He’s a big fan of the 4.0” or 4.25” stroke, and if I understand his reasoning, it’s due to creating too much torque for the system. In my case, the system is a little different and the extra torque should be an asset.

 

Well I think you get it together and see what it does. Then if you don't make it change one thing at a time until you get to where you want to be. It may take a couple of things to get you there but some may be hp/tq related (like a manifold) others maybe be driveline like a new converter.

 

My guess it isn't with a stock converter.... lol
Love that bodystyle MC!

 

That’s what makes this such an interesting test. We’re still months away but it seems most are as interested in finding out as we are.

First the build and dyno test. I’m on the fence about asking Mark test both the Air Gap and iron intake. I’d like to know what’s being left on the table.

 

If the 60’ ends up in the mid-1.8x, the time slip might end up looking something like this?

For the record, I have no idea what was done to this car but I raced him. He’s running quite well in the FAST class, through manifolds.

My light was horrible since I didn’t know we were racing off a .400 tree.

The video is here.

 

It will be fun for sure! Converter makes a huge difference tho. Here's my lil guy with my 12yr old off the shelf tci streetfighter 10" converter 3.42's. I told him not to lift this time (he usually does and does lame ones) but it went WAY farther than I expected ! 10:1 355 vortec roller block with old tpi vette aluminum heads.
I know, I know, I really didn't think it would go that far!

 

I can relate to your video...even with highway gears and stock converter.

With the 511, it will be worse - I’d imagine it will easily boil them from a roll.

 

If you look at where your car is deficient it is in the 60ft and 1/8 mile from your time slips. Now if you were to put the 60ft in the 1.65 range it would get you even closer with the engine you have. Right not what I see is you need about to knock off 8 tenths in the 1/8 to try to hit the 11.99 number you are looking for. Here is what I would try if I were running 2.56 gears and a stock converter, I would put a powershot NOS kit on the car, set the jets for 100hp and hit it out of the hole and if it hooks then you would see what 100hp and 100lb ft. of torque would make you car run in the 1/8 then leg it out if you like, bet you hit that 11.99. Doing that, with a stock converter would be one heck of a lot cheaper that a new engine, you have enough power now. To run 11.99 you only need 113mph and you are at 108mph so you're close.

 

I probably could try spraying what I have now, the plate is already under the carb for a spacer. I do need to source a dedicated fuel supply for the plate though. Here’s a little better time slip from the video on that day (I also have a 1.98, 13.03 too, just need to find it.

My burnouts were far too large at this FAST Event, and I believe that led to traction issues). The balancing act is, I’m doing this on street tires - too much converter and it’s smoking the tires for an 1/8 mile, or until I hit the brakes.

It’s getting an engine this year, God willing.

 

NOOOOO.....not all TCI Streetfighter TH-350s have a 2.75 first gear:

Search results for: 'streetfighterr th350 transmission 69 79 6 tailshaft small big block chevy' - TCI® Auto

Leading provider of high performance automatic transmissions, torque converters and drivetrain components for race, street/strip, hot rod, street rod and towing

www.tciauto.com

StreetFighter TH350 1969-79 w/ 2.75 Low Gear 6" Tailshaft Non Lock-Up (Chevrolet V8 & 4.3L V6)

This TH350 transmission is equipped with TCI ® StreetFighter components to handle up to 575 HP from Chevrolet 4.3L V6 and V8 engines. Comes with 2.75 ratio first gear planetary installed, 6" tailshaft.

www.tciauto.com

 

Yeah I see that. 1700 for that tranny .
The planetary gear that makes it 2.75 first gear is 500 .
I wonder if theres anything else different in that tranny they're getting 1700 for other than the 500 dollar planetary gear