Gmanuel

Thanks for the advice every one. Normally, I would only be driving it around town on the weekends, but who knows, I might want to take it down to Austin, or San Antonio and I'm a little east of Dallas, in rockwall.

Gun Jam

The numbers I quoted are rear wheel horse power (rwhp). If you decide to switch heads later All that might need to be changed is cam, pushrods and lifters. I almost certain you could use your intake over Im pretty sure it uses the same bolt pattern the carb would work fine too.

Im not sure if the exploder heads are designed for roller cam or flat tappet cam.

-Gun

rbowmar

I like the rear end change. It is the quickest way to increase your performance and it will continue to contribute to additional power increases you make in the future.
I am running a 72 Mach1 with a C4 and a 3.73 rear end ratio (at least that's my reading of the mfgr's tag). The engine turns 3000 rpm at 70. It's acceptable. You can determine how far to go on rear end ratio by picking your maximum desirable RPM at a given speed.

My car came with this setup so I can't tell you what the change would be.

One thing I can tell you is that the need for speed doesn't stop with one upgrade. I try to do upgrades in stages because I know that once I've gotten used to a particular level of performance, I will want more. Of course, if you have it apart to put in a cam, that's the time to do the rest of the top-end so that's one stage. Still, the guys running 8's are still fighting and spending to get more power....

Enjoy your project..

Gun Jam

Thats quite a feat...your rear tire height from pavement to the top of the tread doesn't happen to measure 30 inches tall does it?...if not how tall is it?

-Gun

toybreaker

The exploder parts bin is quite nice.... explorer heads were on a roller 5.0 short block so spring swap to beehives, screw in studs and guideplates and a mild hydraulic cam swap (no more than 220 @.050 on a 289 I'd think) and some summit or jegs brand roller rockers in 1.6:1 ratio, intake, ignition (pertronix conversion and new coil at least) and carb and that would be around 300 hp at the crank.

Doing a cam and head swap is not that hard. get a chiltons or haynes manual (rebuild not maintenance, there is a difference) and follow the procedure. It will go step by step on what to do.

Your 289 is worlds easier than your sisters Honda 4 cylinder....

OCHOHILL

Other than a rebuilt 289 and a C4 can you further describe your engine or post some photos?

What rear gears do you have? Is the diff an open diff or do you have a traction device?
What work can you handle yourself? As stated before $2000 doesn't go far in a shop.

rbowmar

My best guess for my tires: 27-28" range. Stock tires are are roughly in the 24.5"-25" inch range.

Thanks, Gun, I learned a couple of lessons.

My point remains the same: Changing your rear end ratio for the sake of acceleration is a relatively quick and easy. Driving at 3k+/- RPM is tolerable for the sake of good acceleration, but if your car is a highway driver I'd go for something less.

As Gun pointed out, without large diameter tires my 3.73 rear end would give much higher RPMs at 70 so my previous recommendation for a 3.73 rear end ratio is incorrect for stock-sized tires.

There is a nice tire size vs RPM calculator here:
http://www.tacomaworld.com/forum/tir...0r14-235-45r17


The other lesson is to check my basic information. I posted misleading information based on a couple of errors 1:I assumed what I had been told about the 3.73 was fact without verifying it. 2:I never checked to see if my wheels/tires were stock. The mix worked fine so I didn't check my figures.

The final Lesson? If you are thinking about changing your rear end, decide on your ideal tires in advance, then verify the final ratio that's already in place.


I hope this is useful.

Gun Jam

-rbomar
I guess what I was eluding to for the sake of the OP's pending decision is you have encountered 1 or more of 3 possible issues.

1) you arent going 70mph the speedometer gear was never changed to properly accommodate the rear end ratio change you are actually going 63 mph assuming 26" tall tire

2) you dont have a 3.75 rear end you have a 3.25 and 26" tall tire

3) your tach is wrong.

so to the OP if you wish to go the rearend route carefully decide future plans and how you plan to drive the car (freeway vs city and how often) and try not to exceed 2900 rpm for extended periods as that cuts into fuel mileage. Also make careful measurements of tire height as you can see it doesn't take much to change things a lot.

Finally gears are relatively inexpensive so if later on you get a t5 with an overdrive the gears can be swapped pretty easy and rear end ratio plays a pretty big roll in choosing a cam for your engine. Cams are not as easy to swap as gears so technically you should be doing gears first but that just leads to t5 swaps which technically should be done at the same time as gears....

so much easy decisions right??

-Gun

rbowmar

Consider this: Because my car was not as fast as I thought, did I actually have great time driving it? Should I stop enjoying it now that I know? <LOL!> Should I tell my son, or let him continue in a state of blissful ignorance?

Gun has my curiosity going...I will check out 1, 2, 3 above when the car is back in town.

I look forward to seeing how you spend your speed fund!
All the best,