best bang for buck gearing or exhaust?

[darksider1911]

sorry if this is in the wrong area, I thought this was the best place. so for my 71 cutlass with a 350 olds, I'm trying to figure out what would be the best bang for my buck power wise and drivability wise. My rear end has 3.08s in it and I'm thinking of going to 3.42s for better acceleration and still remain daily drivable over 3.73s. then on the other hand I'm already replacing my mufflers with moroso spiral flows but was also thinking of putting in a pypes x-pipe kit. my issue is which will be the best upgrade over all and what will be the easiest to install as this will be my first time doing either. I'm assuming the gears but I just want to make sure. I would do both just don't have enough funds to go for both. thanks for the help.

[67TXStang]

The gears would provide a greater performance increase. They would obviously negatively impact gas mileage if that is a concern. I would not expect an incredible difference in performance as the rear gear ratio is not changing all that much (3.08 to 3.42).

Gears require special work to get the alignment correct. This would be something you would need to research well if you are trying to do it yourself. If not aligned correctly, you can get whine and/or wear out the new gears quickly.

[darksider1911]

that right there is why I wanted to ask this. thanks 67txstang, I have read a bit about doing the gears but never came across anything about need to be shimmed or anything until you had mentioned it. I would love to get rid of the gears I have now but it looks like I may just have to hold off until I have better knowledge of the rear axle.

[badazz81z28]

The gears would provide a greater performance increase. They would obviously negatively impact gas mileage if that is a concern. I would not expect an incredible difference in performance as the rear gear ratio is not changing all that much (3.08 to 3.42).

Gears require special work to get the alignment correct. This would be something you would need to research well if you are trying to do it yourself. If not aligned correctly, you can get whine and/or wear out the new gears quickly.

Why are the options "Gears or Exhaust"?

Gears will give you no horsepower gain, but will improve acceleration. They are not hard to set-up, but takes time, tools, and some knowledge. Exhaust is just a bolt in and go.

Have you considered an intake swap? Cam swap? Head Swap? Headers?

What are you after? and your overall goal?

[darksider1911]

basically I'm working with a mostly stock 350 olds, it has a mild cam unknown specs 600 edelbrock carb and an old edelbrock ol4b intake and headers with dual out into old thrush 2 chambers. The biggest reason I'm looking at just those two options is because I figured its the cheapest fastest option for a little more low end or what feels like low end. As well as I honestly only have an extra $200 to put toward something for that car. The only other thing performance wise that the car has is MSD ignition box and coil. honestly my biggest goal at this point until I can put more money into her is to be able to hold my own on the road if I need to.

maybe there is something else someone can chime in that might help me come closer to my goals?

[Mr Nick]

$200 won't be enough to purchase new gears and have them installed. You'd have to do the labor yourself, which may mean buying the correct tools, which could also blow the budget. Do you have a friend that could do the install? (properly)

That being said, I do agree that gears is a better gain then an X pipe. If you had a single exhaust, then I'd suggest dual pipes... but you have that already.

[badazz81z28]

$200 won't be enough to purchase new gears and have them installed. You'd have to do the labor yourself, which may mean buying the correct tools, which could also blow the budget. Do you have a friend that could do the install? (properly)

That being said, I do agree that gears is a better gain then an X pipe. If you had a single exhaust, then I'd suggest dual pipes... but you have that already.


Even having a friend install the gears will be more than $200. $200 will only cover the gears, let alone a quality install kit and lube. If you are going through the trouble to swap gears, might as well do it all (Axles, seals, Posi)

Why not buy a NOS Cheater Kit?? That will be the best bang for the buck and you will pick up 100+hp!. Unless you put these mods on a solid foundation, I feel you are wasting $$...You need a solid engine first that is capable of making good power before a good exhaust will make a significant difference.

[darksider1911]

The motor would handle the power I know all the internals are forged it was rebuilt 92k miles ago. the only problem is its (according to the PO) got 10.5:1 compression and to my understanding its not a good idea to run nos with that high of compression, though I could be wrong. Ya I looked at the full gear kit and it alone is around $400.

according to the PO it was dynoed at 375 fpt and 346 hp but I have yet to see the paper work. I intend on dynoing it when I get a few extra bucks to find for sure where I'm at. Its got tons of power but I really thing the 3.08 is really holding it back. It doesn't have any issue breaking it loose at the drop of a hat.

[Kenny]

It's probably a good time to do some salvage yard shopping. The x-pipe is okay, but don't hang your hat on ever increasing power with it to the point of feeling it in the seat of your pants...... it ain't gonna happen. I know you will feel the difference with the gear swap. A 10% gear ratio change does not equal a direct 10% gas mileage change. What I mean is that you are not changing the road hp needed to push the car at X speed, The change is purely what is required to run the engine and drivetrain the extra RPM, the down side is that the car may be so much more fun to drive that you drive more aggressively and lose more than 10%.

What trans do you have? TH 350? A stall converter makes another big improvement with the appropriate cooling. You are kind of stuck here. If this is your dd and mileage is important, a turbo 200-4r is a straight across swap that will give a lower first gear, overdrive, and a lock-up converter. It would open up the potential in every way, and definitely worth starting a loose change jar to fund it.

[Kenny]

Let me amend that last statement. The trans swap does require moving the x-member back for pan clearance

[darksider1911]

ya it has a rebuilt th350 with a stage 2 shift kit in it. as far as I know it has a 2400 stall in it. ya I'm thinking I'm going to have my heads done. I found a local shop that will do porting and polishing for 300, so I'm just going to save a little more money and have that done. even though this car is a dd I'm not worried about the mileage, I live 5 mins away from work.

[Kenny]

Head work is a really good option for the olds motor. The biggest gains are from putting in larger w-30 size valves, removing the EGR bumps in the exhaust ports, and a mild bowl blend/valve job. With the larger valves it is worth around 30-40 hp, but without the larger valves it is worth less than half that. Stock valve sizes are 1.875 int/1.562 ex, w-30 valves are 2.00 int/1.625 ex

[darksider1911]

I have the #6 heads from a '70 350. it has the 1.880 intake and the 1.567 exhaust valves with a 64 cc chamber. the shop I talked to mentioned doing a 3 angle on them as well for around an additional $50 -$100

[Kenny]

The biggest bang for the buck is gonna be the valve size increase for sure. They cannot do enough porting to a small valve head to make it flow as well as the bigger valves with a mild bowl blend. The valve job is an easy deal since it may not cost significantly more to install the larger valves except for the valve cost. You can get a good bowl shape by doing a 70-75° plunge cut with a "bowl hawg", and that will minimize any blending work . If they are a performance shop they should already have a cutter for this. You can save some of that money by removing the EGR humps yourself. You do not need to go with all out trick valves here. Cheap replacements will work great.

[Kenny]

Looks like Rockauto has Sealed Power valves in these sizes for about $9 ea.... If you search around for a discount code it could be even less.

[darksider1911]

ok Ya Ill do that thanks for the help. Now I just need to get the extra little bit of money so I can get these done and done right.

[Tom Welch]

changing tire diameter can also change the final drive ratio, cheaper than gear changes.

[Jim Nilsen]

Go with changing the trans. In the long run you will gain all across the whole seat of the pants feel and the overall drive ratio when you get O.D. and the search for a lower 1st gear in the trans at the same time would get you everything you want and if you look until you fing the right deal on the trans it could cost you a lot less labor and $$$$ than all the other things you are thinking.
Gears are everything these days and the trans is your best place to start for your future. So do your tranny research and save a few more dollars to get it because the $$$$$ will come back to you in performance and mileage.
4 gears are better than 3 any day of the week. You can find the trans you are looking for used and save along with being able to sell your TH350 to someone who still likes them for what they are doing.
Good luck

[MonzaRacer]

If doinjg heads also dont over look going to a slightly larger chamber to dump compression to a point,, or at least do research,,maybe a thicker copper shim head gasket or head saver shim if they still make one. If you can get compression down then you can get better performance cause over 10 to 1 makes it hard on current fuel.

[shizzy]

if you are talking about $200 budget, Don't spend your cash on the X pipe setup. Just go with a standard H pipe cross over. Pick up a piece of tubing, weld it in and keep the $200 in your pocket.

[vintageracer]

So the choice is to "Sound Faster" with new exhaust OR "Be Quicker" with a taller gear?

Since most everything in the modern world is mostly fake and cosmetic I vote for exhaust.

Be a poser and sound more bad than your bite!