What is acceptible Engine Mileage?
Thread Starter
Joined: Dec 2004
Posts: 1,458
Likes: 6
From: Olivehurst, CA
What is acceptible Engine Mileage? I am considering a swap into my '53 Studebaker (it has a 350 SBC now)and have started looking around for engines and automatic transmissions. I understand that the Gen III smallblocks are designed and expected to last a lot of miles. Some how I still have problems accepting claims that 79k is low mileage 
The mileage obviously affects the price, so how much weight do I give to engine mileage? The car this motor will be swapped into is only driven about 3000 miles a year. The motor may see some performance mods, but not for serious racing. I will take the car on some trips so reliability is important to me.
All that being asked, what are the weak points and parts that show wear? Are there motors that are more desirable or ones to be avoided? How about the Automatic transmissions? Do they last as well as the motors? Do they perform well stock or do they need to be modified for performance street use?
I have got books coming to help with my education so I won't have to be asking everything, I really appreciate your sharing experience and knowledge
Pat
The mileage obviously affects the price, so how much weight do I give to engine mileage? The car this motor will be swapped into is only driven about 3000 miles a year. The motor may see some performance mods, but not for serious racing. I will take the car on some trips so reliability is important to me.
All that being asked, what are the weak points and parts that show wear? Are there motors that are more desirable or ones to be avoided? How about the Automatic transmissions? Do they last as well as the motors? Do they perform well stock or do they need to be modified for performance street use?
I have got books coming to help with my education so I won't have to be asking everything, I really appreciate your sharing experience and knowledge
Pat
its not so much mileage as it is the type of mileage and the conditions they were in. would you rather have a 70k mile motor thats been babied, oil changed regularly, still has good compression and no blow by. or a 20k mile thats been beat to ****, not serviced, had tanks of n2o run through it, and burns oil?
click the FAQ in my sig, its got all the basic ls1 info you want/need (engine wise). the 4l60e is a pretty stout tranny, i'd wager you'd have no problems with basic bolt on mods. what rear end are you going to use?
click the FAQ in my sig, its got all the basic ls1 info you want/need (engine wise). the 4l60e is a pretty stout tranny, i'd wager you'd have no problems with basic bolt on mods. what rear end are you going to use?
Thread Starter
Joined: Dec 2004
Posts: 1,458
Likes: 6
From: Olivehurst, CA
WOW!! What a FAQ! That is really some great stuff, read most of the ones that are of interest to me now, kept me busy for a hour or two. I understand the concept of how a motor was treated and maintained. Where I'm coming from is given similar conditions, how worn out is a 70, 90, 110k motor? Again I realize these things are in factory high performance cars and people are going to drive them, also the ones available have probably been wrecked. Let me simplify my question. For my car and application would a 80-90k motor with good compression be a safe bet? Also what usually goes first in these motors? Valves, rings, bearings, or whatever? How many miles do some of you folks have on your rides?
Now for my rear-end, it currently has an 8 inch Ford, 28 spline axles from a Maverick. Chosen for its stock narrow width. It has 2.79 gears, non-posi at the moment. One of my upgrades will be lower gears and a limited slip. My pre-LS1 plan was to go to 3.80 gears with an overdrive automatic. My tires are pretty tall by your standards, 29", so the 3.80s would be comparable to 3.55 or 3.42 with shorter tires. Given the overdrive and the limited miles I drive I could even go to 4.11. While the 8" Ford is not bullet proof I believe it to be at least as strong as the stock Z-28 rear-end. Given my intended use it should hold up. If I start breaking it, well then hello 9 inch.
Thanks again for the good info and for your work on that FAQ
Pat
Now for my rear-end, it currently has an 8 inch Ford, 28 spline axles from a Maverick. Chosen for its stock narrow width. It has 2.79 gears, non-posi at the moment. One of my upgrades will be lower gears and a limited slip. My pre-LS1 plan was to go to 3.80 gears with an overdrive automatic. My tires are pretty tall by your standards, 29", so the 3.80s would be comparable to 3.55 or 3.42 with shorter tires. Given the overdrive and the limited miles I drive I could even go to 4.11. While the 8" Ford is not bullet proof I believe it to be at least as strong as the stock Z-28 rear-end. Given my intended use it should hold up. If I start breaking it, well then hello 9 inch.
Thanks again for the good info and for your work on that FAQ
Pat
if its a modded motor and the trans hasn't been rebuilt expect problems if its had n2o tq pushed thru it... the 3-4 clutch is the weakpoint in the trans.. the ls1/ls6 motors imo are the stoutest ive ever seen to come off an assembly line compared to other new motors rolling off.. ive sprayed mine so many times i cant even guess... but it runs as strong or stronger then it ever has at 40k... but ive had 2 trans problems already out of it!
Originally Posted by Stu Cool
That is really some great stuff, read most of the ones that are of interest to me now, kept me busy for a hour or two. I understand the concept of how a motor was treated and maintained. Where I'm coming from is given similar conditions, how worn out is a 70, 90, 110k motor? Again I realize these things are in factory high performance cars and people are going to drive them, also the ones available have probably been wrecked. Let me simplify my question. For my car and application would a 80-90k motor with good compression be a safe bet? Also what usually goes first in these motors? Valves, rings, bearings, or whatever? How many miles do some of you folks have on your rides?
Now for my rear-end, it currently has an 8 inch Ford, 28 spline axles from a Maverick. Chosen for its stock narrow width. It has 2.79 gears, non-posi at the moment. One of my upgrades will be lower gears and a limited slip. My pre-LS1 plan was to go to 3.80 gears with an overdrive automatic. My tires are pretty tall by your standards, 29", so the 3.80s would be comparable to 3.55 or 3.42 with shorter tires. Given the overdrive and the limited miles I drive I could even go to 4.11. While the 8" Ford is not bullet proof I believe it to be at least as strong as the stock Z-28 rear-end. Given my intended use it should hold up. If I start breaking it, well then hello 9 inch.
Thanks again for the good info and for your work on that FAQ
Pat
Now for my rear-end, it currently has an 8 inch Ford, 28 spline axles from a Maverick. Chosen for its stock narrow width. It has 2.79 gears, non-posi at the moment. One of my upgrades will be lower gears and a limited slip. My pre-LS1 plan was to go to 3.80 gears with an overdrive automatic. My tires are pretty tall by your standards, 29", so the 3.80s would be comparable to 3.55 or 3.42 with shorter tires. Given the overdrive and the limited miles I drive I could even go to 4.11. While the 8" Ford is not bullet proof I believe it to be at least as strong as the stock Z-28 rear-end. Given my intended use it should hold up. If I start breaking it, well then hello 9 inch.
Thanks again for the good info and for your work on that FAQ
Pat
. rod bolts on the 98-99 and early 00's are a weak point but since you said you dont drag race or plan for big mods or RPM i dont see that being a problem. mechanical overreving and bending pushrods is also common (m6) but thats more of driver error 
and since your going with the auto i dont see that as a problem either. just about anything is better then the GM 10 bolt
, as you said, given your intention the 8" should hold up.Glad you liked the FAQ
i will be putting a cam in it this coming up week, i'm just gunna compression test it and then do a leak down and if all is good i will go ahead with my plans
Last edited by fast98; Aug 20, 2006 at 10:34 AM.
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My car has 117K miles on it now. No problems with it except for altenator and water pump. Mechanically its great, does'nt use any oil between changes. Runs very decent for the mods done and still gets 20 plus mpg.
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Launching!
Joined: Mar 2003
Posts: 240
Likes: 0
From: McKinney
I just put a heads and cam package in my 70k motor in the Vette and just got back from diving it 1600 miles. It got 27 to 30 MPG and no oil consumtion. Oh, on the stock tune as well and it screams!
Derek
Derek
Ive put 64K miles on my car in exactly 2 years, since I bought it new. The car runs as smooth at idle as it did when it was new, it still burns no oil, cold piston slap is the same as it was since new, which is normal. The engine has held up perfectly against all types of stupidity and the abuse of learning myself and teaching others to drive m6. I put alot of highway miles, But I would say that I get on her (~5-6K RPM) atleast once every 10 to 20 miles of highway. I dont speed much, but I do like to get on it in the low gears. You can probably gauge my driving style by my tires. I got 25K out of my last set of bfg kdws, worn down to the wear indicators. As long as the engine wasnt neglected, I wouldnt hesitate to buy a motor with 80K on it. Its the car around the motor that tends to fall apart.