Ansel Marrow Posted August 25, 2006 Share Posted August 25, 2006 Hey all, Turns out it was a timing issue, with my previous thread. So finally I have all 300 ish horses under the hood of the datsun. It peels out in every gear, and its a 3 speed auto! Such an awesome car to drive, its louder than most of the rice burners I drive past. I have to thank this site, reading every night and constantly learning about how to work on these engines and the difficulties and challenges of dealing with these hybrids. On a side note, I was getting roughly 3-5mpg. I was just cruising in the z, watching my gas meter drop like crazy. I told myself "these cars are astoundingly cool, but if people actually got 3mpg from them, I doubt half the people on the board would have them". So this morning, after having my car back for 3 days, I noticed the gas leak this morning. So, if I can get this car to 12-15mpg, Ill keep it till I die. I dont think thats impossible for a 305? Any reccomendations as to how to treat it will be appreciated (I did a search already, didnt find much). A pal reccomended a spread bore carburetor. Does that help gas mileage a lot? Quote Link to comment Share on other sites More sharing options...
COZY Z COLE Posted August 25, 2006 Share Posted August 25, 2006 It peels out in every gear, and its a 3 speed auto! There's your gas mileage answer.... LARRY Quote Link to comment Share on other sites More sharing options...
Nealio240z Posted August 25, 2006 Share Posted August 25, 2006 Im using the same set up... almost. 350 w/ TH350. about 300 horses... What diffential are you using? What carb are you using? Im using a 750 cfm Q-jet and Im getting in the range of 16mpg when im on it. 18-20 when im just putting around... What is your top end, and freeway speed? Im having a problem with that. It runs about 2800 rpm at 55mph... Quote Link to comment Share on other sites More sharing options...
Bartman Posted August 25, 2006 Share Posted August 25, 2006 I'd be surprised if you couldn't get into the high teens or even into the 20 mpg range if you can keep your foot out of it. Of course there are many factors that can affect your mileage including the state of tune and various installed components. If your going to be doing any high speed cruising an overdrive will help a great deal. Upgrading to fuel injection could help as well. Congrats on getting her running well, and good luck with her in the future. Quote Link to comment Share on other sites More sharing options...
Pyro Posted August 25, 2006 Share Posted August 25, 2006 Should get 14 to 15 easily in the city with a mildly cammed 305 and over 20 mpg on the highway, even with 3.54 gears and a 3 spd auto. What is your set up: gears, cam, heads, exhaust, carb, ect??? Quote Link to comment Share on other sites More sharing options...
getZ Posted August 25, 2006 Share Posted August 25, 2006 I get about 20 mpg with a four speed auto and 3.9 gears. Keep your foot out of it and you get reasonably good gas mileage. Quote Link to comment Share on other sites More sharing options...
Ansel Marrow Posted August 25, 2006 Author Share Posted August 25, 2006 This is where I am sort of lost, on answering these technical questions. I know how a car works and all the basics, but its a learning experience. Heres what I know... gears: dont know cam: unknown (i asked seller, he said some mild cam, plans to replace it in the future) heads: dont know (cast iron) exhaust: headers with 2.25-2.5" dual all the way to the back, with glasspacks. Going to go sidepipes real soon. carb: 650 holley, i think im having issues with it, likes to backfire rear end: r200 The trans has a shift kit, with a B&M shifter that I can bump to change gears. I was considering a tremec 5 speed, because I miss manual. I was thinking also that the 3 speed was causing me bad gas mileage, it revs really high on the freeway (4-5k ish). Maybe overdrive kit (if they make them? I dont know). If Im puttering around, it does have a nice note to it, just cruising, so Ill try to drive it slowly when Im short for gas. The leak is the main culprit, Ill have to fix that before I can realistically expect to measure gas mileage. Quote Link to comment Share on other sites More sharing options...
deja Posted August 25, 2006 Share Posted August 25, 2006 The leak is the main culprit, Ill have to fix that before I can realistically expect to measure gas mileage. Before you "can realistically expect to measure gas mileage"????? I'd be more worried about fire than I would be gas mileage. Gas leaks are not something to ignore. A gas leak and a backfiring engine are a recipe for major disaster. Take it from someone who's been there, watching your hotrod go up in smoke is not fun. About the idea of side pipes. I put them on my AMX way back in 1970. They look cool, and sound awesome, but if you're going to use the car for city driving be prepared in inhale a ton of exhaust at every stop light. And be sure to tell your passengers to watch their step when they get out, your friends will not be happy with the burned calves that are inevitable. BTW your car looks very cool. Quote Link to comment Share on other sites More sharing options...
piston Posted August 26, 2006 Share Posted August 26, 2006 3-5 miles a gallon? i better be running 10s with that. im wondering if your not sure about cams and stuff, how did you figure the 305 putting down 300hp? Quote Link to comment Share on other sites More sharing options...
Ansel Marrow Posted August 26, 2006 Author Share Posted August 26, 2006 I didnt drive it much after I found the gas leak, its in the garage till I fix it. I know its a HUGE issue, and I dont want to blow up the car Ive wanted since I was 6. So thats being fixed tomorrow (its a loose rubber hose, I checked). I had a mechanic realistically guess with all the stuff thats on it, and after he took it around the block he guessed that it was pushing that, maybe a little less. I have no idea what these engines are stock hp wise, I suppose I still have more reading to do. The seller also told me he estimated above 300hp, maybe 320hp. I suppose Ill need to get it dynoed before I go throwing figures around. I know its faster than a friends stock 92 camaro with a 302, and hes got his to 350hp, and I can smoke him. That doesnt tell me what my hp is, I know. Thanks deja, its got 9 different things in the mail coming to make it look even better, and then Ill update a pic of it. The thing looks like its moving when its standing still! Its such an awesome feeling to own such a cool car when you see hondas with fart pipes and stickers all over them, when the datsun doesnt have to try to look cool, it just IS. It makes me feel like a little kid when I get in it, I cant stand riding in sedans or SUVs compared to the z. Quote Link to comment Share on other sites More sharing options...
deja Posted August 26, 2006 Share Posted August 26, 2006 the datsun doesnt have to try to look cool, it just IS. It makes me feel like a little kid when I get in it, I cant stand riding in sedans or SUVs compared to the z. That's for sure. One of my friends said about my 280Z when I got it last year. "That design still works after all these years". My other vehicle is a Ford Ranger so I know exactly what you mean about riding in other cars. I'm taking the Z off the road soon to upgrade to an LT1, gonna be hard not driving it for months! Quote Link to comment Share on other sites More sharing options...
Nealio240z Posted August 28, 2006 Share Posted August 28, 2006 Up grade your rear tires to 225/70/r14. They are 26" tall and 7-1/2" wide. They will increase you top end and gas economy alot, and give your car a raked look... They WILL fit without rubbing. (and it looks awesome) Quote Link to comment Share on other sites More sharing options...
Pyro Posted August 28, 2006 Share Posted August 28, 2006 I don't want to bust your bubble but 305's aren't know for making that much hp. Especially with stock cylinder heads. So, it is always better to guess low to not disappoint your-self on dyno day. Stock heads, mild cam, holley and some headers will make about a 250hp (200rwhp) 305cid, if you are lucky. The good news is with some better cylinder heads this can be increased to 250hp. Then add a 350 short block for another 50 hp. Back firing out the carb indicates retarded timing and/or a lean mixture. If your diff gear is stock, it should be a 3.54. A 25 inch tire with a 3.54 will make the engine rev 1000rpms for every 21.0 mph in 3rd gear (1:1 in a th350). So, 70 mph will make the engine rev to 3,333 rpms. Sound about right? What tach are you using? Right now you should be able to run a low 14 at 98 mph. I'm trying to be positive here. In JTR V8 manual they say a stock 350 with a 5 spd in a 240 will run 14.5 at 95mph. So, do except much more from a mild 305. Quote Link to comment Share on other sites More sharing options...
Ansel Marrow Posted August 29, 2006 Author Share Posted August 29, 2006 Thanks for the info, I feel like I know a little more about my car. Can I just buy bigger tires or should I get new wheels? Would removing 2 feet of exhaust pipe give horsepower? Or make no difference at all? Quote Link to comment Share on other sites More sharing options...
Phantom Posted August 29, 2006 Share Posted August 29, 2006 Going from a 25" diameter tire to a 26" diameter tire will only reduce your engine RPM's at cruise by 4% or about 125 rpm. Likewise, going from a 3.54:1 differential to a 3.36:1 will reduce it again by about 5%. The only way you're going to serioiously affect your cruise RPM's is to get an overdirve transmission. Oh - and unless the 2' of exhaust pipe is about 1/2" in diameter you'll never notice the difference and I doubt if a dyno would even be able to tell the difference. You have a higher probablility of asphyxiating yourself than gaining HP. Quote Link to comment Share on other sites More sharing options...
rubin Posted August 30, 2006 Share Posted August 30, 2006 I know its faster than a friends stock 92 camaro with a 302, and hes got his to 350hp, and I can smoke him. Either hes got a stock 67-69 with a 302 (the only years 302's were available) and hes got somewhere above 350hp stock or its a 92 with either a 305 or 350 and had between 230-245 hp stock and was at low to high 15's 1/4 mile Quote Link to comment Share on other sites More sharing options...
Lewis Maudlin Posted August 30, 2006 Share Posted August 30, 2006 I used to get 12 mpg from my 355 w/400 hp mated to 700R4 and 3.54. Of course, I have a heavy foot. With a 305 and a 3 speed, you should be able to get similar mileage. Quote Link to comment Share on other sites More sharing options...
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