Hey friends,

I am having a hard time deciding something for the car;) I plan to put one of these very nice tachometer that fits in lieu of the clock (that I don't have anyway). I love it because it looks original, fits perfectly and will be great now that I have the T5 (and I am reving a little :D)

Question is, should I go for the 6000 rpm or the 8000 rpm.

-> On one hand, I think that my rebuilt 289 can go higher than 6000 rpm
-> On the other hand, if I put the 6k it would somehow be a nice psychological limit and will be awesome to "rev it to the max"

Hope you got the point, let me know what you think:)

whoooo ... revving higher than 6000 has to be a proper rebuilt I believe
if it is revving higher than 6000, then def go for a 8000rpm tach. But if it's rather 5000max, get the 6000rpm
put it this way: if you have a 6k tach and can rev 6500, how would you know where to stop?! (i thought that was the whole point of a tach ;-)

Thanks ;)

I was seeing it this way, if I put the 6k, I will make me stop before 6k which will be better for the engine :D

It depends on what engine and components you have. A 302 could easily rev higher than 6k. I big block probably would not.

The stock redlines on the ford engines per piston speed are:
289 7300
302 7000
351 6000
390 5500
428 5200


With a stoke motor, you want to stay below 3500fpm piston speed. With heavy duty components, you want to stay below 4000fpm. With race components, you want to stay below 5000fpm. Now yes, valve float comes into play as well.

Given that, you should get the 8000 rpm if you are running a 289 or 302.

Thanks for the numbers!

Urban, there is no way a stock non-K code289 is going to hit 7300 safely. I wouldn't trust the stock rod bolts much past 5500.

Not only that, the valve springs wouldn't hold the valve train, the valves would float. Anyway, get a 8,000rpm tach in case you ever do a rebuild that's performance oriented, since most likely it will do 6,000rpm or more.

Hm, how many rpm's can a 289 with stock internals turn befor redlining then?

IIRC, the original 6K tach was for the 6 cylinder model.A V8 model had an 8K tach. So if it were me, I'd prefer the 8K tach.

If it has good rod bolts and a balance job, the block will usually crack first.If valve float isn't an issue with that. Seen guys take em to 7500 on a regular bassis, and then loose oil psi because of a broken block. But staryfury hit it, 5500 is pretty much it with the stock rods bolts.

I bought the 8000 RPM for my '67 coupe. I wish I had the 6000. At idle, the the thing is worthless. The gauge is too small for 8000 to be very accurate.

ORIGINAL: Scott H.

IIRC, the original 6K tach was for the 6 cylinder model.A V8 model had an 8K tach. So if it were me, I'd prefer the 8K tach.


i was convinced on the 65 models the tachs in the rally pac were all 6k. Only the Hipo was 8k tach.
And +1 to the redlines. I might be able to turn my stock 289 7000+, but I'm quite convinced not more than once

Please do not miss understand my numbers. Piston speed dictates how much load is put on the crank, pistons, rods, and rod bolts. Most stock motors are good upto 3500fpm if everything is not worn out. As I said above, the valve train is not taken into account on these numbers. The delimiting factor on the valve train is going to be rpms. Also not taken into account is can the motor pull enough air to get it to these levels. That is going to depend on your cam, intake, and heads. All I wanted to show is what a good condition low end will handle.

If you have a good lower end, with good valve springs, and your engine design will allow it, the 289 will turn 7000k without needing crazy nice parts. Maybe your tired engine will not do that safely, but there is no magic number or calculation to determine that. It may be good to 2000 or it may be good to 5000. That is going to depend on how worn out and stressed it is!;)

Regardless, the stock rod bolts are a severe weak point. There's a reason the K code motors got special rods/rod bolts; they needed to be able to spin up to 7k safely (and they do).The point is, astock non-hipo 289 bottom end is NOT good to 7k, even when it was brand new. Now, slap some ARP rod bolts in and I might feel safe taking it to 6500 with a solid top end setup.

351w = 7600rpms as registered on my 'new' 8k Shelby tach on a new rebuild[&o].

Got away with it though.

Man that thing revs fast & smooth.

Go with the 8K.

A6k tach will NOT stop you from revving it up higher.Installa rev limiter.

ORIGINAL: nassaubayman

I bought the 8000 RPM for my '67 coupe. I wish I had the 6000. At idle, the the thing is worthless. The gauge is too small for 8000 to be very accurate.


I was going to recommend the 6000 for the same reason. On the '65 Rally Pac, the 6k tach is easier to read than the 8k.