But shark, that only 66mph at 3 grand. You can't take a fast highway cruise for too long a time like that. Ever try 75 mph for 2 or 3 hours? I have and it sucks. Not knocking you, just my opinion.

Sorry Fellas', I thought that you were looking to come out of the hole well and have a good friendly cruising rpm at real highway speeds.

 

M22 is the "rock crusher" and has same ratios as the M21. As far as the rear end goes, just drain it and refill with new lube and a bottle of GM's posi additive.

 

"But shark, that only 66mph at 3 grand. You can't take a fast highway cruise for too long a time like that. Ever try 75 mph for 2 or 3 hours?"

That's why I mentioned that we don't take this one on any longcruises. We haven't had it on thefreeway over65mph for more than 25 minutes since wegot it. It's just not a travelin' car between the race gas and thetendency to heat up even with a big block radiator (which oddly enough came with the car from the factory even though it is a number matching 350/350 small block. I think ithas something to do with it being an A/C carordered in Texas). And yes, I know what you're thinking. But, It's a fresh 3 core rebuilld with all the proper seals and shrouds. I know an Aluminum radiator will cure the overheatingbut it's really not an issue since I don't drive it long distances at high speeds.

So that being said. Has anyone had any experienceswitching from a 3.38 (or 3.36, I can't read my tank sticker all that well) to a 3.55 rear end? Will I notice a difference? Most of the comments seem to be related to 3.08 rear end to 3.55 or 3.73 which is a more substantial jump.

And yes, A/C cars did come from the factory with other than 3.08 gears.

Thanks again for all of your comments.

 

Hi there,
I have your same problem.
I still have to check my rear end gear ratio , but it seems 3.73 or 4.1 . I'll know this later today , when I'll lift the car at my mech and check underside.

Anyway , I think that such a type of ratio is closer to my driving attitudes.
Just to give you an idea of the roads here in south Italy , please have a look at these youtube clips. No drag strips here but , just 10 miles from here , there's the "Fasano Selva race" .
Anyway all the roads here are about likethose in the clips. We have flat , straight roads too , closer to the sea ( 5 miles from here: my town is at the top of a hill , about 100 m above sea level)
http://www.youtube.com/watch?v=cByaKOxT-Ps
http://www.youtube.com/watch?v=t9q39fX5ElA

I look forward to have myCorvette with new tires and new suspensions to test these roads

I attach a pic of my car , just to remember to you allwho I am
Aldo


[IMG]local://upfiles/6949/F9CAC8ACEF214814957B0E5E0220C88D.jpg[/IMG]

 

I struggled with overheating issues for a long time - had a fresh 4 row copper/brass radiator in it too. Long story short - I replaced everything and finally broke down and got a universal fit aluminum radiator (2 row) for under $200.00. Now the temps never go up past 200*.

If you plan on keeping your car I would strongly suggest an aluminum radiator. It will prolong the life of your engine and also help keep you more comfortable in the cockpit. The universal radiator was almost a direct fit, all I did was modify the upper radiator bracket on the drivers side ( I ground it down a little on a grinding wheel) and substitute a stainless steel flex hose (eye candy) for the lower radiator hose.

As far as gearing choices? Lower RPM's extend engine life and keep the heat down too, as well as increase fuel economy.

What else do you know about this engine? 350 engine with 11:1 compression ratio - what else? this doggy performance off the line and engine pinging bother me, something's not right and I don't think it's the gearing. Inquiring minds want to know....

[sm=icon_cheers.gif]

 

hey rick,
You did open this topic by saying that you didn't want to go 70mph and feel that the motor was SCREAMING. Seems like you've contradicted yourself and/or asked for two contradicting happenings. I suggested the best of both worlds and then bowed out as what you wanted seemed to change. My comment about 3 grand at a chump-*** highway speed of 66mph was, like I said, what yousaid that youdidn't want, but, you say thatyou don't go that far to worry about that...WTF...and you quote me like I'm not understanding what you're asking for...Well, you're right.

Oh, or is 3500 rpm @ 77 mph a comfortable cruising combination for you? That's right, you don't make those kind of trips...Yes, I read the whole topic again.

 

Jim,

Like I said, I am thinking about changing the gear ratios, thus I'm weighing my options. If improving out of the hole performance isn't possible (at least a noticeable improvement over what I have with 3.38's) without the engine screaming at 60mph then I know that changing the rear end ratio is not going to accomplish what I want it to, and thus isn't worth doing. In regards to the comments on this threadabout living with higher gear ratio on trips that involve hours at70-75mph, there is a big difference between living with an engine/trans combination for hours at a time versus 20 minutes on the freeway. What is not tolerable for 2 hoursmay be acceptable for 20 minutes. What I'm trying to avoid is turning the kind of rpms that make me think I'm driving on the freeway in 2nd gear.

Your advice about changing to a 5 or 6 speed is on the money but for a lot of us that isn't what its all about. In a lot of ways these cars deserve to be preserved for what they are. And if the driving experience is rougher than modern carsthen that is part of the vintage corvette experience.Bottom line, if your focus is performance than I recommend selling your C3 and buying a C6 since the average Altima will smoke most of these cars at a stop light and burn half the gas doing it.

I don't mean to be short but don't tell me I'm contradicting myself. To me its a contradiction to put a modern 6 speed in a 30 year old chasis with a carbuerated motor, I just didn't feel the need to say WTF when the thread strayed outside of the original question.

Thanks to everyone that weighed in with their experiences.

Rick.