cny first gen 71 Posted January 26, 2021 Share Posted January 26, 2021 Another thing to think about with changing the stock manifolds on a big block isnt there some other mods that have to happen? I dont really know so I'm asking. Dont the headers interfere with the perportioning valve, starter and oil filter stuff like that??? Also would have to replace exhaust pipes and possibly the rest of exhaust? Just something else to think about. Stock factory look is a good look on an SS just another thought. So much to think about lol Quote Link to comment Share on other sites More sharing options...
Canuck Posted January 26, 2021 Share Posted January 26, 2021 Do what you want with it but just keep all the parts. 🙂 Quote Link to comment Share on other sites More sharing options...
Skifoggy Posted January 26, 2021 Author Share Posted January 26, 2021 You guys rock. I guess being an old hot rodder I am still missing a light cam lope with a nice header tint sound. Being a 365 HP engine, how far did they drop the compression in '71? I will drive it hopefully soon after the rain stops this week and make some decisions. I am just excited to get rolling on making it mine. Quote Link to comment Share on other sites More sharing options...
Skifoggy Posted January 26, 2021 Author Share Posted January 26, 2021 2 hours ago, DragCat said: I'll X3 do what you want, its your car enjoy it. And save all the parts you remove. Use the "search" function to do your research (like for headers), a bunch of people have been down that road and have very good advice and experiences. Looking at the one pic of the car tire wise they look kinda close on clearances, what size tires on it now? There is also a couple of threads with tire options, backspace and such 235 60 15. front and back. Standard vette rally wheels with no offset. Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted January 26, 2021 Share Posted January 26, 2021 The 15x8 Corvette rally wheel has a 4inch back spacing. 235/60r15 is about the widest tire you can fit with that combo. Quote Link to comment Share on other sites More sharing options...
MCfan Posted January 26, 2021 Share Posted January 26, 2021 2 hours ago, Skifoggy said: 235 60 15. front and back. Standard vette rally wheels with no offset. IF the 15x8 "Standard Vette rally wheel" has a 4" backspace, then it absolutely does have offset. In fact, it is a -12mm offset which pushes the rim outboard an additional 1/2" from a zero offset which is a 4 1/2" backspace. That's why you can only safely mount 235/60s to keep sufficient clearance between the sidewall and the wheel well lip. Now, if you want to trim the lip, you can go with a bigger tire on the rear but only up to a point because lip trimming will almost always be less than one inch. A 235/60 on a 15x8 rim with a 4" backspace will give you right at 1" of clearance between the sidewall and an untrimmed wheel well lip. A 245/60 on the same rim will reduce that clearance to .4" which is very risky under some conditions (unless the lip is trimmed, of course). Offset is measured (usually in millimeters) from the dead center of the rim which is known as zero offset. Negative offset pushes the rim outward, positive offset pulls it inward toward the frame. Backspace is measured (usually in inches) from the outer edge of the inboard rim lip (not the tire mounting edge) to the wheel mounting surface. Since the backspace measurement ALWAYS includes the rim lip thickness (almost always 1/2"), the dead center (zero offset) of any rim will equate to a backspace that is one half of the tire mounting width (i.e. 7, 8, 10" etc.) PLUS 1/2" for the rim lip thickness. So, for a 15x8 rim to have zero offset, it must have a backspace of 4.5 inches. If it only has a 4" backspace, then it also has a -12mm offset. There is an excellent table at the bottom of the page on the wheel-offset-calculator on the tiresize.com site (https://tiresize.com/wheel-offset-calculator/) that shows all of these offset-to-backspace conversions for a wide range of rim widths. Quote Link to comment Share on other sites More sharing options...
Glen Posted January 26, 2021 Share Posted January 26, 2021 5 hours ago, Skifoggy said: You guys rock. I guess being an old hot rodder I am still missing a light cam lope with a nice header tint sound. Being a 365 HP engine, how far did they drop the compression in '71? I will drive it hopefully soon after the rain stops this week and make some decisions. I am just excited to get rolling on making it mine. The compression dropped to 8.5 if memory serves me correctly. Who doesn’t love a lopey cam? But I err on the side of purists... a real SS needs to stay as stock as possible with the exception of mods that are easily REVERSIBLE. Upgrade or change what you need to make the car more reliable to drive and enjoy without permanently hurting originality. And YES, save all original parts. That said, you’ve scored an absolutely beautiful car that appears pretty much original and complete. Throw us drooling guys lots more pix when you have the time. If the seller was the original owner, I’d imagine he probably had/included lots of documentation with the car also. Welcome to the club, Skifoggy... my FGMCC seniority now moves up another spot! Quote Link to comment Share on other sites More sharing options...
Skifoggy Posted January 26, 2021 Author Share Posted January 26, 2021 9 hours ago, MCfan said: IF the 15x8 "Standard Vette rally wheel" has a 4" backspace, then it absolutely does have offset. In fact, it is a -12mm offset which pushes the rim outboard an additional 1/2" from a zero offset which is a 4 1/2" backspace. That's why you can only safely mount 235/60s to keep sufficient clearance between the sidewall and the wheel well lip. Now, if you want to trim the lip, you can go with a bigger tire on the rear but only up to a point because lip trimming will almost always be less than one inch. A 235/60 on a 15x8 rim with a 4" backspace will give you right at 1" of clearance between the sidewall and an untrimmed wheel well lip. A 245/60 on the same rim will reduce that clearance to .4" which is very risky under some conditions (unless the lip is trimmed, of course). Offset is measured (usually in millimeters) from the dead center of the rim which is known as zero offset. Negative offset pushes the rim outward, positive offset pulls it inward toward the frame. Backspace is measured (usually in inches) from the outer edge of the inboard rim lip (not the tire mounting edge) to the wheel mounting surface. Since the backspace measurement ALWAYS includes the rim lip thickness (almost always 1/2"), the dead center (zero offset) of any rim will equate to a backspace that is one half of the tire mounting width (i.e. 7, 8, 10" etc.) PLUS 1/2" for the rim lip thickness. So, for a 15x8 rim to have zero offset, it must have a backspace of 4.5 inches. If it only has a 4" backspace, then it also has a -12mm offset. There is an excellent table at the bottom of the page on the wheel-offset-calculator on the tiresize.com site (https://tiresize.com/wheel-offset-calculator/) that shows all of these offset-to-backspace conversions for a wide range of rim widths. I used the incorrect lingo when I said that they had no offset. I meant standard offset. Thanks for the info! Quote Link to comment Share on other sites More sharing options...
Andy's Auto Posted January 26, 2021 Share Posted January 26, 2021 You did good. Great car, great condition. Great colors, great options. If it was mine, and it is not, but if it was..... Pop that engine out, go through it, add a small hydraulic roller cam, and let her eat. Thirty years ago my room mate had a 71 SS. Mulsanne blue, cloth black buckets, and a black hat. Early in ownership he broke a rocker and I pulled the engine. Simple stuff, just a light rebuild and added nothing more than a cam. Damn that thing sounded good. 2 Quote Link to comment Share on other sites More sharing options...
stangeba Posted January 26, 2021 Share Posted January 26, 2021 I prefer rare vehicles stay stock. As many have said, keep ALL stock parts that you may (I hope not) remove. I always suggest you have things repaired vs replaced like starter mtr, alternator and master cylinder. Tires, that's a tough one because radial's are so much better but single thin white stripe (hard to find) is the best look (IMO) for your car. Enjoy it. Quote Link to comment Share on other sites More sharing options...
Michael Boyte Posted January 26, 2021 Share Posted January 26, 2021 Keep all original parts, Then build it the way you want it. Take a good look at Steve Lavante's SS( Monteman71) or Dan's '70 Z20 . Two fine examples , As nice as they come and built to have a lot of fun with. Definitely go with a hydraulic roller cam and never look back !! 2 Quote Link to comment Share on other sites More sharing options...
Skifoggy Posted January 27, 2021 Author Share Posted January 27, 2021 I like the way you guys think. I've been doing some reading on the Big Blocks. Back in the day, I knew my way around a small block pretty well. The LS5 in '71 even with the drop in compression has way to little cam. I am looking for just a little bump in performance and a nice lope. Nothing radical but very drivable. Any suggestion's would be helpful. Thanks!!! Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted January 27, 2021 Share Posted January 27, 2021 And that's how it starts! Lolol 1 3 Quote Link to comment Share on other sites More sharing options...
DragCat Posted January 27, 2021 Share Posted January 27, 2021 ^^^^^^ That was funny ! Well since I think I see where your going i'll just say .........Pull the motor, bag it, and drop a new crate motor in there. Rebuild the trans and have a looksy at the rear gear scenario. No-one will ever know till you pop the hood and you'll still have a stock original 454 for later 😮 1 Quote Link to comment Share on other sites More sharing options...
Its Just Me Posted January 31, 2021 Share Posted January 31, 2021 Jeff, Welcome to the Club. Here's my story and thoughts and it's worth exactly what you paid for it, ha. When I had my '71 SS it didn't have the original engine, so I had no issues with diving in. The 454 it did have, was anemic. I pulled it out, bumped the compression to 9.4:1 with a piston change and installed a hydraulic roller cam from a ZZ502 crate engine. I also added an aluminum intake (painted orange to retain the original "look"). I tweaked the quadrajet (they are awesome carbs). My car came with headers so I left them on, but given the chance I would have preferred the stock exhaust manifolds for the original look and sooooo much easier to change plugs. The few HP you give up won't even be noticed as the big block makes plenty of torque, especially if you're accustomed to small blocks. My combo, with the original 3.31 rear gears knocked down 15 mpg, made about 450 HP on 87 octane, had a slight lope, was as reliable as my daily driver and was an absolute hoot to drive. Since you say you're an old hot rodder (me too), I highly recommend this route as you'll get a lot more enjoyment out of your car AND it retains the original look. I would discourage the thought of bagging the original engine and installing a crate engine. Storage of an engine is a tough road. Condensation and rust will find its way in no matter how well you prep and care for it. Unless you plan on making big power with high RPM, the chances of damaging the original block are nearly non existent. The best place to store an engine is in the car, the best way to care for that engine is to run it with regular maintenance. One of the greatest things about having a Monte is that everyone has a Monte Carlo story. You better have patience when fueling up as they all want to share their story with you. Nice car, ENJOY! Scott 2 Quote Link to comment Share on other sites More sharing options...
Skifoggy Posted January 31, 2021 Author Share Posted January 31, 2021 Thanks Scott and all of you who have chimed in. I finally had a chance to take a drive yesterday after we finally dried out from the week of rain. Went by a few buddies houses to show her off and turned heads everywhere. Looking down the long hood of the car took a little getting used to but I felt real comfortable by the time I got home. I noticed a few things that will need to be addressed and have seen the discussed in your forums. Fuel gauge is stuck showing full. Fan blower isn't working but these are all part of the game. My drive home down the expressway got a little hairy when the engine started sputtering and acting like it was running out of gas. Not I got it to a gas station and it took about 15 gallons of fuel so I know that I wasn't running out of gas. I will replace the fuel filter this am and go from there. I got the most of the history on this Monte and it is kinda interesting but and will add that to the story when I get a few more details. I did however get the original build sheet with the original keys. I will take a pic of it and add it later. I do know that the engine and tranny were gone thru back in '94 and it hasn't been driven a whole lot after. I will be adding a mild cam and headers just to make it mine. I also will be joining the club as a member. Thanks again! Jeff 5 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.