xHighOctanex Posted October 26, 2014 Report Share Posted October 26, 2014 Hello, I have had my 86 720 for quite a few months now. I actually bought it off a friends neighbor for basically -$495, since he paid $497 in backfees before giving it to me and the bill of sale was for $2. Anyways I have a cheap $40 tach and I keep the shift needle set at 4k. This got me wondering how high are these motors (Z24 carbureted) actually safe to rev too? Do they have a limiter? I read on a few things online they stop making power a little after 4. This thing runs so nice I don't wanna just mash it and stupidly blow the thing up. Quote Link to comment
Guest Rick-rat Posted October 26, 2014 Report Share Posted October 26, 2014 Welcome to Ratsun, great price on your 720. We like pics here of your truck. Nice to hear you don't want to beat it til it dies. My rev limiter is my right foot on my 620 B) Quote Link to comment
JoeCool Posted October 26, 2014 Report Share Posted October 26, 2014 I don't know about the Nap-Z motors, but the L20B in my 80 720 has no rev limiter. I have gone to 7500 (end of numbers on dial) with it just to test it once. Redline is 6000, so I don't go past it, most of the time under hard acceleration I shift around 5000, as power drops off afterwards. Quote Link to comment
datzenmike Posted October 26, 2014 Report Share Posted October 26, 2014 You won't hurt it. If it helps the factory tach is red lined at 5,500. From 4,000 to 5,500 is about two sips of coffee long. 1 Quote Link to comment
_chiefjt Posted October 26, 2014 Report Share Posted October 26, 2014 I've taken mine to 8k lol. But it pretty much stops right there. After that it's useless cause there's no more power/pull. When I ran it at the drag strip I was taking it to 7k. Stock z24 with weber 38 and a 4.38 rear end. The only thing is I'm dreading when the head gaskets gonna blow. Untouched z24 with 188k miles. 1 Quote Link to comment
datzenmike Posted October 26, 2014 Report Share Posted October 26, 2014 When the engine is dead cold, loosen one bolt and torque to 60 ft lbs. Go to the next bolt, looses and torque to 60 ft lbs. Do all head bolts ONE AT A TIME and any order. That's it. Do this once a year. This will keep the head firmly clamped to the block and the gasket compressed. 1 Quote Link to comment
xHighOctanex Posted October 26, 2014 Author Report Share Posted October 26, 2014 I was going to add pictures when I posted this but they were still all on my phone at the time. It's a great truck that to be honest I had never even heard of before I got it. Got it with about 133000 on it and have put about 3k on it since. We got the truck and it wouldn't pass smog, so egr valve, o2 sensor, lots of vacuum rerouting, pulling apart the carb, 3 failed smog tests, and a new tvv later and it finally passed. Put all 4 new tires on it, chopped off the exhaust after the cat and put a glasspack on it, lowered it 2 inches, pulled off the back bumper, had some cheap airhorns on it just because why not but until I find a better place for them I have taken them off. Right now am in the process of sanding it down piece by piece and priming it, put the seats from my 63 in it so I could fit a little box with 2 8 inch subs in it. Anyways haha I think the highest I have ever brought it was around 6 or so normal driving I shift about 2500 and getting on it I shift about 4. 3 Quote Link to comment
_chiefjt Posted October 26, 2014 Report Share Posted October 26, 2014 Yeah, I know about the whole head gasket thing it's just I don't wanna touch it or mess with it and then something happen. But then again it could happen if I don't touch it so that's why I'm on the fence about it. lol And nice looking truck. You could probably try and straighten out that bumper with a rubber mallet. Or at least so it looks better.Mine was worse and got it decent looking. At least yours isnt creased anywhere, it's just wavy at the top. Quote Link to comment
xHighOctanex Posted October 26, 2014 Author Report Share Posted October 26, 2014 Yeah, I know about the whole head gasket thing it's just I don't wanna touch it or mess with it and then something happen. But then again it could happen if I don't touch it so that's why I'm on the fence about it. lol And nice looking truck. You could probably try and straighten out that bumper with a rubber mallet. Or at least so it looks better.Mine was worse and got it decent looking. At least yours isnt creased anywhere, it's just wavy at the top. I plan on taking it off eventually to work on getting it a little straighter. I made the mistake of letting someone drive my truck and they went around a corner right into an oncoming car. Now have a pick n pull fender on that side. Quote Link to comment
datzenmike Posted October 26, 2014 Report Share Posted October 26, 2014 Make sure you have some horns, even stock, it can prevent an accident. At 133K you are well within the 100K head gasket blowing risk. It's simple, easy and at most, will cost you a valve cover gasket. Failure of the gasket, beside leaving you stranded for a ride home, can also incur a tow bill and can happen at the worst possible time. Then there's the repair.... do you have the time or have it fixed. Price out having a mechanic do the work. This will have you running to your tool box. Additionally, blowing the HG will lead to over heating and that should always be avoided on an aluminum head vehicle. A half hour once a year, on your terms, is cheap insurance. Quote Link to comment
xHighOctanex Posted October 26, 2014 Author Report Share Posted October 26, 2014 Make sure you have some horns, even stock, it can prevent an accident. At 133K you are well within the 100K head gasket blowing risk. It's simple, easy and at most, will cost you a valve cover gasket. Failure of the gasket, beside leaving you stranded for a ride home, can also incur a tow bill and can happen at the worst possible time. Then there's the repair.... do you have the time or have it fixed. Price out having a mechanic do the work. This will have you running to your tool box. Additionally, blowing the HG will lead to over heating and that should always be avoided on an aluminum head vehicle. A half hour once a year, on your terms, is cheap insurance. I still have the stock horns I just also had a switch to the air horns. Also I'll do what you said with the head bolts tomorrow. I have auto twice a day in school and my dad owns a shop in town. Quote Link to comment
datzenmike Posted October 26, 2014 Report Share Posted October 26, 2014 Engine must be absolutely cold so the metal is not expanded from the heat or you won't be applying the torque properly to the gasket. When it cools the metal will shrink. Quote Link to comment
xHighOctanex Posted October 28, 2014 Author Report Share Posted October 28, 2014 Engine must be absolutely cold so the metal is not expanded from the heat or you won't be applying the torque properly to the gasket. When it cools the metal will shrink. Retorqued my head bolts one at a time to 60lbs today. Quote Link to comment
datzenmike Posted October 28, 2014 Report Share Posted October 28, 2014 Just curious.... Were any bolts easier to loosen than the others??? Quote Link to comment
xHighOctanex Posted October 29, 2014 Author Report Share Posted October 29, 2014 Just curious.... Were any bolts easier to loosen than the others??? Don't think so, at least nothing drastic enough for me to notice. Quote Link to comment
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