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Highway cruising
b_hill_86:
I’ll just reiterate, I drove mine about 2 hours one way last year with 27” tall tires (just a little taller than yours) and a 3.08. I’m around 2700ish at 70. No issue.
FormTA:
Ya, my car was fine but I had 273 gears and th350 but now with ls and 4L60E I'm like 1500. For me it's the rest of the car seems no quite up to it. I'm talking about 70+. I think my problem is more precise wheel alignment and maybe driveline angle. (I have a slight vibration over 60). I know these may not apply to you but the wheel alignment may. Just how stable/comfortable is the car at the speeds you'll be diving? Like others said, 3k is really normal rpm hwy driving. But if it wanders, pulls or darts now that will get old trying to maintain a lane. Also lose steering can be exaggerated at higher speeds. Just a few other things to consider.
N PRGRES:
Honestly it’s actually a very good driving car, only to be better with the new gear box I just got. The whole suspension is new
stros:
--- Quote from: FormTA on March 27, 2024, 03:29:05 PM ---Ya, my car was fine but I had 273 gears and th350 but now with ls and 4L60E I'm like 1500. For me it's the rest of the car seems no quite up to it. I'm talking about 70+. I think my problem is more precise wheel alignment and maybe driveline angle. (I have a slight vibration over 60). I know these may not apply to you but the wheel alignment may. Just how stable/comfortable is the car at the speeds you'll be diving? Like others said, 3k is really normal rpm hwy driving. But if it wanders, pulls or darts now that will get old trying to maintain a lane. Also lose steering can be exaggerated at higher speeds. Just a few other things to consider.
--- End quote ---
My LS3 and 4L70E is around the same rpms with 3.08 gears. It actually seems to drive pretty well up to 75mph with the PTFB suspension bits. I am just paranoid that some crazy person is going to hit me staring at it on the freeway, plus zero safety features doesn’t add to the confidence level. I’ve been taking it out for a few 3-4 mile highway runs of late just to stretch the engine a bit. The traffic here sucks anyways so it’s just more fun to drive the back roads into work once in a while.
I was also at about 3000 rpms with the original Pontiac 400, at least up until it overheated and then died😀.
nUcLeArEnVoY:
--- Quote from: stros on March 28, 2024, 10:01:58 PM ---
--- Quote from: FormTA on March 27, 2024, 03:29:05 PM ---Ya, my car was fine but I had 273 gears and th350 but now with ls and 4L60E I'm like 1500. For me it's the rest of the car seems no quite up to it. I'm talking about 70+. I think my problem is more precise wheel alignment and maybe driveline angle. (I have a slight vibration over 60). I know these may not apply to you but the wheel alignment may. Just how stable/comfortable is the car at the speeds you'll be diving? Like others said, 3k is really normal rpm hwy driving. But if it wanders, pulls or darts now that will get old trying to maintain a lane. Also lose steering can be exaggerated at higher speeds. Just a few other things to consider.
--- End quote ---
My LS3 and 4L70E is around the same rpms with 3.08 gears. It actually seems to drive pretty well up to 75mph with the PTFB suspension bits. I am just paranoid that some crazy person is going to hit me staring at it on the freeway, plus zero safety features doesn’t add to the confidence level. I’ve been taking it out for a few 3-4 mile highway runs of late just to stretch the engine a bit. The traffic here sucks anyways so it’s just more fun to drive the back roads into work once in a while.
I was also at about 3000 rpms with the original Pontiac 400, at least up until it overheated and then died😀.
--- End quote ---
Why do you suspect it overheated? The cooling system in my '79 400/4-Speed is completely overhauled and it barely reaches operating temp around town if I'm not using AC. Getting onto the freeway at 55+ MPH is the only time the temp will creep up to the first tick on the temp gauge or past it. I've never been on the highway long enough to see how high it'll go mostly because of a vibration I get at 60+, at least during the daytime but I'm wondering if my car is at risk of doing the same thing as your's.
I'm running around 2300 RPMs at 55 MPH with the original BW ST-10 4-Speed and stock 3.23's, so figure 70 would be like 2900 or so.
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