Rebuild bottom end end vs. save $$$

Rock777 · Oct 8, 2004

Rebuild bottom end vs. save $$$

My car has 130,000 and I am going to do a complete H/C/I install soon. I was wondering how many people have done this swap on high mileage cars without rebuilding the bottom end. My car uses very little oil, probably about a quart between every oil change. I know I am going to be broke after the H/C/I, but don't want to do all that work and drop a piston or something on the bottom half. If I do the bottom end, should I rebuild the one I have or buy a new block. I am by no means on an unlimited budget, but do live by the "do it right" motto.

1992blkGT · Oct 8, 2004

Rock777 said:
My car has 130,000 and I am going to do a complete H/C/I install soon. I was wondering how many people have done this swap on high mileage cars without rebuilding the bottom end. My car uses very little oil, probably about a quart between every oil change. I know I am going to be broke after the H/C/I, but don't want to do all that work and drop a piston or something on the bottom half. If I do the bottom end, should I rebuild the one I have or buy a new block. I am by no means on an unlimited budget, but do live by the "do it right" motto.

My car had over 143k miles on it when I did my H/C/I install. If it runs well, doesn't burn a lot of oil, and doesn't smoke too much, I don't see what the problem would be. As long as you do not have future plans to supercharge it or run nitrous I wouldn't worry about it. Go for it!!

TIMMY2734 · Oct 8, 2004

Do a leakdown dest and compression test. If all is good, go for it..

Rock777 · Oct 8, 2004

1992blkGT, you have the exact combo I would like the to, and I mean everything. How do you like it so far, do you burn any oil, have you taken it to the track, any major problems? Thanks for the input, it's definitely taken into consideration.

Rock777 · Oct 8, 2004

What is a leakdown test exactly?

90mustangGT · Oct 8, 2004

Rock777 said:
What is a leakdown test exactly?

Measures how much air leaks from the combustion chamber durring a cycle. Say your complete cylinder holds a volume of 50 cubic inches of air, and after the piston moving up and down once you only had 45 cubic inches of air, you would have 10% leakdown. I'm not good at explaining this, am I thinking of a different test? Correct me if I am wrong.

I would take the above advise. If your motor isn't burning too much oil, and has good compression and low leakdown, don't worry about it. Some guys here have H/C/I and spraying 200 shots on 200+K stock bottom ends.
Borrowed time? Probally but it tells you something.

FiveLtrRiceEatr · Oct 9, 2004

if you read any engine rebuild book it says to rebuild the bottom end first. Because adding more power to something that hasnt been rebuilt inst the best idea. I agree with dont supercharge, nitrous, or turbo it. But if you stroke it along with your ideas it will be stronger and produce my hp and trq. But as I know everyone is on a budget including me. Thats why im waiting til next winter to rebuild my engine.

Rock777 · Oct 9, 2004

I wasn't planning on building up my engine right now, I just decided to after I blew a head gasket. I figured I don't want to tear it all down now, replace a gasket, and then tear it down when I'm ready to do the H/C/I. I have absolutely not intentions of turbo, nitrous, or s/c. I know to do everything right, I should rebuild the boittom, but my bank account says not. I still don't know for sure though, I'm trying to figure out exactly what combo to go with and figure out how much it'll all tally up to. I'm probably goin to do like the other guys said and do a compression test, if it is good then I will leave it as it is, if there are a couple weak cylinders then I will most likely do everything.

5.0Droptop · Oct 9, 2004

I did HCI on my 87 vert with 125k on it. It was using some oil before the swap.

After about 3-5k more miles it was using more oil had develpoed more blow by and it started to lose oil pressure.

This is in no way to discourage you,because I know several guys who have added HCI to high milage motors and had no issues.
My old motor had been mistreated alot before I got it.

I would suggest performing a compression test and see how the rings are doing. If it makes good compression and all the cyclinders are within 10% of each other I would do it.
My old motor had good compression and was with in 10% of each other even after it was ready to be removed. But it didnt hold compression, it would start leaking down immediatly. Thats where the oil went and the blowby came from. The rings were just worn out.

90mustangGT · Oct 9, 2004

Rebuilding the motor doesn't cost that much, depending on what you do. Some get away with just rehoning the cylinders, pollishing the crank, and replacing the rings and berrings. That wouldn't cost that much at all but then again you might want/need to overbore the cylinders and put some better pistons in there. Align honing the mains and getting the assembly balanced is also a very good option.

1992blkGT · Oct 9, 2004

Rock777 said:
1992blkGT, you have the exact combo I would like the to, and I mean everything. How do you like it so far, do you burn any oil, have you taken it to the track, any major problems? Thanks for the input, it's definitely taken into consideration.

I only burn oil when I first start the car up after it's been sitting for awhile. I think that is because I'm using fully synthetic Mobil 1 when I should be using normal motor oil. Other than that no motor-related problems. Had some problems with the TFI module but that is known to go out. Right after I did the H/C/I install it leaked oil like crazy. Turned out I didn't use enough RTV on the lower intake. Took it off and fixed that prob though. I am going to get a new short block or do a rebuild next summer, but that's because I want to supercharge it. Hope this helps!

bln92cpe · Oct 9, 2004

i bought my 92 LX for $5500 with a blown head gasket and a vortech s trim..I was thinking all right i am gettin new TFS heads a cam and everything i need to get it running again..Then the bug hit me and I said screw it I am gettin a brand new 306 Street Fighter from CHP...Since I plan on keeping this car forever or till it scares me, I went this route..Do it right the first time if you can afford it..It took me 2 years to save and work on my project..Now its together and I couldnt be happier.

Rebuild bottom end end vs. save $$$

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