I have a stock 1969 W31 turbo 350 trans, it has a 4.33 gear now but would a 3.90 be better with the stock F70 tires, they are 26" tall. Has anyone run their W 31 in the pure stock drags? Thanks.

 

A guy named Casey races a pure stock blueprinted 70 W31 automatic and runs a 4.66 gear was its best ET in the 12's BTW on stock tire, he could tell the difference of a 4.33 to 4.66 he likely tested that

 

The W-31s are among the best-revving hydraulic lifter engines produced back in the day. My guess is 3.91 would be a step backwards.

 

Several have run at the event. Casey Marks sold his several years ago. The owners of Inline Tube have it now.

 

If you cross the traps at 110 like this guy's W31 - 3.90 gears may be perfect with the 26.2" tire. But that's a big MPH for a stock appearing W31. Not sure if this car meets the pure stock requirements or not. If it's more like 103ish the 4.33 gears may be perfect. I would think you would want to cross the traps at or around 6000 RPM. My vote is to run it with the 4.33s and see where you are, then decide.

-Joe

 

Thank you, I think that's the way I will go.

 

You'll want to turn it well past 6000 if the valvetrain and bottom end can take it. Pending the cam profile, you end up increasing the valve spring pressure for stability, then pushrods like to go through stock rocker arms. Anyways, small blocks like gear, so I'd start with the 4.33's. There's been at least one '68 ram rod than ran, two '69 W-31s, can't remember on '70s beyond the green one.

 

Have you worked on your suspension, transmission and converter or are they completely stock?

 

It is 100 percent stock, frame off resto and all was replace with NOS parts.Motor rebuilt to factory specs, with forged pistons, OEM cam.

 

From reading his other threads, I'm under the impression that OP's car is a factory original 100 point show car. My advice would be for him to make some runs with absolutely no changes (that aren't mandatory to pass tech) in order to establish a baseline and determine weak areas that might be improved. Then go from there.

 

I am doing nothing except new plug wires, a better set of points, and plugs.A good quality oil,trans service. I am coming from Colorado so this might be the only one I will take part in. We have zero of these out west I know of.

 

Agreed !

Keep in mind "pure stock" drag racing is a misnomer/lie. Sure some cars are truly factory stock such as yours but some are heavily tweaked and run several seconds quicker than they ever could truly factory stock, but fly under the radar ...

CarLife tested your exact same automatic version with its original 3.91 rear. And saw a 14.9 @ 96 with a 3935 lb test weight. Shifting at 6200 rpm.
If you've never done this or its been a while I would aim for duplicating those specs. Potentially you should be quicker because of the 4.33s and possibly less test weight. And in case you are worried about over revving they also ran a top speed test on the then new 1969 W31 as well, seeing 128 mph at 6600 rpm.

96 mph is good for a 13.8 so they had some serious traction issues. My understanding of pure stock drags is bias ply slicks are allowed. That would probably help a whole lot more than any gear change for now. In any case here below is what a truly factory stock stick W31 ran vs a "pure stock" (fantasy) 1974 Malibu 454.

W31 14.3 @ 97 mph vs Malibu 14.5 @ 94 mph. In reality a true stock 74 Malibu 454 is a 17 second car. This video perfectly illustrates what you will come across at pure stock drags. In reality the W31 would obliterate the Malibu not just barely pull ahead.

 

Pure Stock actually has fairly strict rules and inspections, certainly with regard to things like cam profiles and displacement. All equipment on a contestant's car has to have been available on the model originally, although not necessarily on that specific car. Last time I looked, drag radials were permissible, though. Significantly improved times over magazine road tests from back in the day are usually due to painstaking engine building and tuning, suspension tweaks and other racers' tricks.

You may be thinking of FAST racing which is considerably looser.

 

A couple of questions…

Have you ever raced before? I highly recommend getting some seat time at your local track. Eeking out a respectable time in a car you’re not familiar with racing is very difficult. The 4.33’s are going to equate to massive tire spin if you don’t know what you’re doing. The bias-plys are only going to exacerbate the problem.

Was the engine dyno’d or have you had it on a chassis dyno? Even one of the hand held units that calculate your 0-60 and 1/4 might help you tune it up for performance a little bit.

Sounds like a fun adventure…but do as much prep work as possible before you go. A track even isn’t where you want to figure out your program or you’ll just get frustrated.
Good luck!

 

Stage as shallow as possible!

 

Yes I race all the time all over the country. I race a 8 second 2010 Ford Cobra jet mustang, and a 2019 Mustang Gt that runs 9's on the motor. I ask all the questions I have because this car was bought a show car and has set for the last 6 years., Maybe 200 miles since it was restored in the early 2000's. I will go through everything before I hit the track. As I said, this may be a one time thing or who knows? We don't have these pure stock drags out west although I could take it to a local track for bracket racing. You could visit my Facebook page to see my racing if interested . But thank you for your insight, I am planning some changes for the car this summer and this will kick things off for me,

 

When you get a baseline, post it here. Very curious!

 

OK, gotcha...that changes a lot!
I pictured a newbie to racing taking a 4.33 geared car down a track on bad tires and winding up in the wall.

Sounds like you know what you need to do. If they give you a few test passes I'm sure you'll learn the car.

 

https://www.psmcdr.com/

 

Well you have the driving covered. I think the fuel pump might hold you back and the tight front suspension.

 

To what Bernhard said, make sure it will run all the way up clean through high gear, fuel delivery with a mechanical pump and a Q-jet is typically a challenge. It will only get worse because you'll drop several thousand feet in elevation at PSMCDR and need the fuel even more.

Track prep for the event is marginal, so practicing on the street is probably a good match. You can do a lot tuning the timing curve and Q-jet secondary door release and spring tension for how the car leaves. Getting it all in as fast as possible doesn't typically work, though you're on the low end of the torque scale, so it could help, too. Sometimes we do the opposite of the prevailing "hot rod knowledge" to make the cars work.

Looking forward to seeing the car in September!

 

I thought about changing the fuel pump since it is getting old, any suggestions for those? I have played with Q Jets many years,so I need to read up on mods for sure.

 

What about the race at Milan Mich in May?

 

https://www.robbmcperformance.com/
https://cliffshighperformance.com/

 

Thank you.

 

The RobbMc pump does not fit easily. I'll have to try to get a pic of mine but it's easier on a big block. Holley made high performance mechanical pumps decades ago that were known for dumping fuel into the crankcase when the diaphragm, I think someone started knocking that same design off a few years ago.

Cliff is great, only sells parts now.

 

How did these cars manage to run back in the day? I could see upgrading if the motor has mods even in pure stock form.

 

Back in the Day when they ran stock they were allowed a single electric fuel pump. The mechanical pump had to be used as well in conjunction with the electrical pump. Some racers did not use a cool can because they felt it restricted fuel flow. Today they run 1/2 fuel line and expensive fuel systems.

 

A good one would run mid-14s in the mid 90s off the showroom floor.

See post #12.

 

I’ve seen a few older (mostly original) cars have an electric fuel pump pulling the gas up to the mechanical pump.

 

I run 3/8" line and a $150 Carter mech pump on my Mopar that goes 115 mph without laying over, just don't have that option for an Olds.

 

It is hard to believe that these cars would come from the factory with a fuel system that could not get them through the quarter mile without running out of fuel. I am not going to invest a lot of money in fuel system parts when I am going to put fuel injection on the car. If I was going to run pure stock drag races on a regular basis then I would. Out west where I am at we don't have these, so may make one or two back east but the would be it.

 

It may be time to sell that car and get what you really want.

 

I have race cars, the idea to run it 100% stock sounds like fun. But I am keeping it and changing it up to what I want it to be at this time. I could not find a better finished car than this. Whatever I do can be reversed down the road whoever gets the car later. I will not sell any of the hard to get parts that I remove,

 

I guess I'm just having a hard time getting my head around what the point is of having a W-31 that runs 11s if you've changed most of the things that make it a W-31. You might as well just buy one of those new electric Dodge Chargers.

That said, your car to proceed with as you see fit. You do you, as the kids say. Have fun!

 

Well, at this point you have a bunch of aftermarket/reproduction components resembling a stock fuel system installed by non-factory humans. Sometimes it works, sometimes it doesn't, sounds like you'll find out in September. If 14s is the goal, you'll definitely achieve that, no need to spend needlessly.

 

Hell, if he's a decent driver and gets a little seat time in the car he should be able to achieve that without touching it.

 

I went out to the muscle car pure stock drags last year as a spectator, it was a blast, met a bunch of great people just out having fun with their cars and didn't give a damn what they ran. So this year weather permitting I am headed out to do the same. The Stanton venue is awesome, super clean and old school and relaxed, it was a great time.

 

Luke Is the Carter one of there NASCAR line of pumps? What carburetor does your Mopar run?

 

Street performance pump, M6903. six barrel, so 3 holleys.