Motor rebuild advice
08-20-2014, 01:22 PM
#1
Burning Brakes
Thread Starter
Motor rebuild advice
Hi all,
I have a 1970 small block (350/350). The previous owner did some mods to race it including exhaust headers, different cam, Edelbrock Torker intake and Holley 650 DP carb. The last time I took the car to my mechanic for a tune-up he said the motor was "shot." He said the compression was quite low and it either needs to be rebuilt or replaced. Since it is a #s matching car, I would like to rebuild it rather than replace it (although I'm not going to keep it 100% stock). I want it to be a reliable and strong performing driver that I can take to "informal car shows"...that is, it will be nice enough to take to a car show, but would never expect to win...make sense? I would be interested in putting the original Qjet back in based on a lot of what I have read, but I'm not sure if it's enough carb based on the modified intake and cam that has been done??
From some of this forum's recommendations I reached out to a performance shop and asked for some budgetary costs to do a rebuild and I was floored by the response (may just be my lack of knowledge), but it came in around $7k - $10k (including pulling the motor out and putting it back in).
I hope you can all tolerate my lack of knowledge and many questions on this!
Based on a motor that has "lost compression" what work would you think I NEED to do in a "rebuild" to bring it basically up to par for performance? I realize we might find other things wrong with it along the way...but what are the must-dos? Change piston rings? New pistons? Machine the block? Machine the heads? New crank? New cam? And any rough idea of what these things cost (for either an outside shop to do it, or I try it myself (obviously I won't machine anything))?
Then, what are the "as long as you are in there, it would be very wise to also do the following" items? Again - any ideas of what these sorts of items might cost?
Then, what are the..."if you did this, you would see a nice little pick-up in performance as well" type of things? In my mind, this would be enlarging the cylinders, etc??? Again, costs???
I'm trying to find a light somewhere...otherwise I'm depressed about the car. I figured it would be ~$7-$10k to paint it, but not to do motor work. So now I'm looking at ~$20k for motor and paint, and I still have interior and others...starting to wonder if it's worth it?
Last - what are your comments about doing it myself? Ideally I would do this work myself...as I would love to learn about it and it would give me a great sense of accomplishment...but I really don't know what I'm doing and would be forever worried that I did something wrong or whatever. So, my abilities/experience are things like oil change, plugs and wires, I just did my first brake job and outer tie rods (different cars), I took the carb off the Vette once, etc. But I've never pulled a motor out of a car and never pulled a motor out. If I take my time and study and ask lots of questions, can I do it? Would I save a significant amount of money?
Any comments would be greatly appreciated!!!!
I have a 1970 small block (350/350). The previous owner did some mods to race it including exhaust headers, different cam, Edelbrock Torker intake and Holley 650 DP carb. The last time I took the car to my mechanic for a tune-up he said the motor was "shot." He said the compression was quite low and it either needs to be rebuilt or replaced. Since it is a #s matching car, I would like to rebuild it rather than replace it (although I'm not going to keep it 100% stock). I want it to be a reliable and strong performing driver that I can take to "informal car shows"...that is, it will be nice enough to take to a car show, but would never expect to win...make sense? I would be interested in putting the original Qjet back in based on a lot of what I have read, but I'm not sure if it's enough carb based on the modified intake and cam that has been done??
From some of this forum's recommendations I reached out to a performance shop and asked for some budgetary costs to do a rebuild and I was floored by the response (may just be my lack of knowledge), but it came in around $7k - $10k (including pulling the motor out and putting it back in).
I hope you can all tolerate my lack of knowledge and many questions on this!
Based on a motor that has "lost compression" what work would you think I NEED to do in a "rebuild" to bring it basically up to par for performance? I realize we might find other things wrong with it along the way...but what are the must-dos? Change piston rings? New pistons? Machine the block? Machine the heads? New crank? New cam? And any rough idea of what these things cost (for either an outside shop to do it, or I try it myself (obviously I won't machine anything))?
Then, what are the "as long as you are in there, it would be very wise to also do the following" items? Again - any ideas of what these sorts of items might cost?
Then, what are the..."if you did this, you would see a nice little pick-up in performance as well" type of things? In my mind, this would be enlarging the cylinders, etc??? Again, costs???
I'm trying to find a light somewhere...otherwise I'm depressed about the car. I figured it would be ~$7-$10k to paint it, but not to do motor work. So now I'm looking at ~$20k for motor and paint, and I still have interior and others...starting to wonder if it's worth it?
Last - what are your comments about doing it myself? Ideally I would do this work myself...as I would love to learn about it and it would give me a great sense of accomplishment...but I really don't know what I'm doing and would be forever worried that I did something wrong or whatever. So, my abilities/experience are things like oil change, plugs and wires, I just did my first brake job and outer tie rods (different cars), I took the carb off the Vette once, etc. But I've never pulled a motor out of a car and never pulled a motor out. If I take my time and study and ask lots of questions, can I do it? Would I save a significant amount of money?
Any comments would be greatly appreciated!!!!
Last edited by Mpls Funk; 08-20-2014 at 01:37 PM.
08-20-2014, 03:29 PM
#2
Le Mans Master
Member Since: May 2002
Location: Lebanon Township New Jersey
Posts: 5,005
Received 706 Likes
on
401 Posts
Assuming you ask for help here as you go along, I'd say you could remove and disassemble the engine yourself. Other than removing the hood, its a one man job. As for assembly, installation and (particularly) start up, help from someone with experience would be very valuable.
As for the engine, if you have the block boiled, bored .030 and honed, replaced the pistons with hypereutectics, used your crank and rods, new rings, bearings, gaskets and seals of course, balance the bottom end and put in a new hydraulic flat tappet cam, lifters and springs add a valve job to the heads you will spend a fraction of that $7K. A good Quadrajet with a stock manifold will work fine. Maybe convert your distributor to an HEI type, you'll have a much better running car than now considering your low compression test results now.
As for the engine, if you have the block boiled, bored .030 and honed, replaced the pistons with hypereutectics, used your crank and rods, new rings, bearings, gaskets and seals of course, balance the bottom end and put in a new hydraulic flat tappet cam, lifters and springs add a valve job to the heads you will spend a fraction of that $7K. A good Quadrajet with a stock manifold will work fine. Maybe convert your distributor to an HEI type, you'll have a much better running car than now considering your low compression test results now.
08-20-2014, 04:37 PM
#3
Melting Slicks
What are the bad symptoms the engine shows now? Smoke, knocking, leaks, etc??? Low compression could be caused by sticky rings or bad valves...
If it runs fair for now maybe you could crutch it along for a while...maybe get a more info of what root cause is or get somebody else to do the test.
If it runs fair for now maybe you could crutch it along for a while...maybe get a more info of what root cause is or get somebody else to do the test.
08-20-2014, 05:14 PM
#4
Le Mans Master
Assuming you ask for help here as you go along, I'd say you could remove and disassemble the engine yourself. Other than removing the hood, its a one man job. As for assembly, installation and (particularly) start up, help from someone with experience would be very valuable.
As for the engine, if you have the block boiled, bored .030 and honed, replaced the pistons with hypereutectics, used your crank and rods, new rings, bearings, gaskets and seals of course, balance the bottom end and put in a new hydraulic flat tappet cam, lifters and springs add a valve job to the heads you will spend a fraction of that $7K. A good Quadrajet with a stock manifold will work fine. Maybe convert your distributor to an HEI type, you'll have a much better running car than now considering your low compression test results now.
As for the engine, if you have the block boiled, bored .030 and honed, replaced the pistons with hypereutectics, used your crank and rods, new rings, bearings, gaskets and seals of course, balance the bottom end and put in a new hydraulic flat tappet cam, lifters and springs add a valve job to the heads you will spend a fraction of that $7K. A good Quadrajet with a stock manifold will work fine. Maybe convert your distributor to an HEI type, you'll have a much better running car than now considering your low compression test results now.
1. Disconnect the battery.
2. Drain the coolant (but don't be surprised if more comes out later on...)
3. Drain the oil and put fender covers on both fenders.
4. Remove the air cleaner.
5. Disconnect the alternator wires and remove the alternator and it's brackets, take pics and bag and tag the bolts
6. Take the fan off. Hold the fan, while removing the four bolts on the front of the fan.
7. Remove the power steering pump and bracket (no need to disconnect the power steering hoses, just lay the p/s pump to the driver's side
8. Remove the ground wire on the drivers side of the radiator support and mark it with a piece of tape.
9. Remove the A/C compressor and lay it off to the side.
10. Drain the radiator and remove the upper radiator hose, lower radiator hose and heater hoses, mop up any coolant with soapy water, it's slippery stuff!
11. Remove the radiator support and note the four bolts that come out from inside the fenders.
12. Disconnect the throttle cable from the carb and any vacuum lines.
13. Disconnect the fuel line and clamp it tight.
14. Remove the distributor and the spark plug wires.
15. Remove all the manifold bolts and knock or gently pry loose the intake manifold
16. Remove the entire radiator and shroud, completely out of the car (I did it as one piece).
17. Unbolt all the exhaust manifold or header bolts from the head.
18. If you have a manual trans, remove the Z-bar so that you can drop the headers if you have them. But first, disconnect the header collector from the exhaust system, so you can drop them free from the heads. Best to remove them and sometimes, easier from underneath.
19. Jack up the car safely and put jackstands behind the front wheels.
20. Disconnect the starter wires and remove the starter and then pull the inspection plate from the front of the trans. For an automatic, there are three bolts around the torque converter. You can put a large screw driver in the flanges that hold the torque converter to turn it, so that you can remove the three bolts or have a friend turn the engine for you.
21. Disconnect the fuel line from the fuel pump and clamp it shut, so that no fuel leaks out. Remove the fuel pump from the block (two bolts)
22. Remove the two long bolts that go front to back on the motor mounts (one on each side).
23. Put a jack on the transmission and jack it up, just enough to get a jackstand under the front edge of the casing.
24. Get an engine hoist and if it's a modern 'short one' you're going to be stuck doing it from the side. If it's an older American made hoist, that has a long reach, you can do it from the side.
25. Use a couple of the bolts to attach a chain to the intake sides of the heads in a diagonal from one corner of the block to the other, across the empty valley, where the intake used to sit.
26. Put the entire chain link into the hoist hook sideways, not the inside hole of the chain link through the hook!
27. Start slowly jacking it up and watch to see if it's hung up on something or something is not unbolted. Wiggle it and shake it, until the engine block breaks free of the transmission. Slowly pull it, straight up and out.
It was easy to remember, because we pulled two engines this week at the shop! If I left out anything, add it in here, but I think I got it all.
08-20-2014, 06:54 PM
#5
Le Mans Master
I just did this exercise on my 78 L-82 4 speed. I pulled the motor myself, disassembled most of it but not the bottom end, upgraded the heads (AFR) and roller cam. I had the bottom end professionally redone-new pistons/rings (JE Forged), new bearings, hot tank the block, recondition L-82 rods, polish L-82 crank, bored .030, balanced, new clutch kit, degreed cam etc. I assembled the top end. The cost was $3,500. To have everything done by the builder would be $8-10K in my area.
If you do much of the work, not machine shop stuff, and reuse much of the LT-1, you should be able to rebuild that engine for $2,500-3,000 easy.
If you do much of the work, not machine shop stuff, and reuse much of the LT-1, you should be able to rebuild that engine for $2,500-3,000 easy.
Last edited by jb78L-82; 08-20-2014 at 06:56 PM.
08-20-2014, 08:38 PM
#6
Burning Brakes
Thread Starter
What are the bad symptoms the engine shows now? Smoke, knocking, leaks, etc??? Low compression could be caused by sticky rings or bad valves...
If it runs fair for now maybe you could crutch it along for a while...maybe get a more info of what root cause is or get somebody else to do the test.
If it runs fair for now maybe you could crutch it along for a while...maybe get a more info of what root cause is or get somebody else to do the test.
08-20-2014, 11:15 PM
#7
Racer
I have certainly noticed that it bogs down when I accelerate. The exhaust is a bit stinky and you can see a bit of white smoke. It seems to really be drinking gas as well. Now, realize that much if this could be poor carb tuning??? You had a good suggestion about having someone else look at it and do a compression test....
08-21-2014, 07:52 AM
#8
Safety Car
That torker intake is the wrong type for your application and its certainly not helping the street driving performance.... a dual plane intake would perform much better than the one you have now which is more for wot racing.
08-21-2014, 08:15 AM
#9
Le Mans Master
Member Since: Jul 2006
Location: charlotte north carolina
Posts: 8,117
Likes: 0
Received 100 Likes
on
92 Posts
This "performance shop" is ripping you off. It's a corvette, so a normal $2500 engine rebuild triples in price. Any proficient machine shop can clean, fully machine and rebuild with new internals a SBC for a third of what you were quoted.
08-21-2014, 08:32 AM
#10
Le Mans Master
And God knows, what kind of carb is sitting on there! Wouldn't be surprised if it was oversized and overcarbed. A client brought in a rough running '74 Chevy p/u and it had a carb, that was designed to barely be able to drive it to a local drag strip. We replaced it with a Holley 670 Street Avenger, vac secondaries and it ran like a happy kitty, right out of the box! Idled smooth and was well-behaved, but still had plenty of punch, right now. The intake manifold and carb choices are critical in how ancar runs!
08-21-2014, 02:39 PM
#11
Burning Brakes
Thread Starter
And God knows, what kind of carb is sitting on there! Wouldn't be surprised if it was oversized and overcarbed. A client brought in a rough running '74 Chevy p/u and it had a carb, that was designed to barely be able to drive it to a local drag strip. We replaced it with a Holley 670 Street Avenger, vac secondaries and it ran like a happy kitty, right out of the box! Idled smooth and was well-behaved, but still had plenty of punch, right now. The intake manifold and carb choices are critical in how ancar runs!
08-21-2014, 02:41 PM
#12
Burning Brakes
Thread Starter
I will strongly consider this...thank you so much. What burb do you live in? I am down in the southern suburbs.
08-21-2014, 02:46 PM
#13
Burning Brakes
Thread Starter
"The only way I do a rebuild is with new bushed rods, forged pistons and moly rings. I also do a complete cylinder head restoration with new valves, viton seals and hardened exhaust seats as required. The valve springs are replaced, so are the pushrods, rod/main bearings, cam bearings and timing chain set. The crank is turned and mag checked and then micro polished. The full rotating assembly is balance to within 1 gram. The block will either be jet washed, cleaned and painted or it will first be put in the oven and then shot blasted to remove all rust, scale and paint. We do all of the engine and machine work in house. We also have an engine dyno if you want to break in the engine before it goes in the car. The camshaft is always a custom and new lifters are used. I am very careful about the numbers on the block and heads, they will not be harmed in any way.
Basic numbers
Rebuild engine with stock style components $4000
Add $500 for fully ported stock heads
Add $500 for engine dyno testing
Add $1500 for R and R of engine in car.
Add $800 to switch to a roller camshaft
Hardened valve seats and guide replacement, if required, is extra
Fluids, filters and extra parts would be extra"
08-21-2014, 02:47 PM
#14
Burning Brakes
Thread Starter
I just did this exercise on my 78 L-82 4 speed. I pulled the motor myself, disassembled most of it but not the bottom end, upgraded the heads (AFR) and roller cam. I had the bottom end professionally redone-new pistons/rings (JE Forged), new bearings, hot tank the block, recondition L-82 rods, polish L-82 crank, bored .030, balanced, new clutch kit, degreed cam etc. I assembled the top end. The cost was $3,500. To have everything done by the builder would be $8-10K in my area.
If you do much of the work, not machine shop stuff, and reuse much of the LT-1, you should be able to rebuild that engine for $2,500-3,000 easy.
If you do much of the work, not machine shop stuff, and reuse much of the LT-1, you should be able to rebuild that engine for $2,500-3,000 easy.
08-21-2014, 02:54 PM
#15
Le Mans Master
Thanks...that's what I'm wondering. I mean, I sure when they were done with it it would be a hot ride...but are they doing more than they need, and/or are they just over-charging. Here is what he replied with:
"The only way I do a rebuild is with new bushed rods, forged pistons and moly rings. I also do a complete cylinder head restoration with new valves, viton seals and hardened exhaust seats as required. The valve springs are replaced, so are the pushrods, rod/main bearings, cam bearings and timing chain set. The crank is turned and mag checked and then micro polished. The full rotating assembly is balance to within 1 gram. The block will either be jet washed, cleaned and painted or it will first be put in the oven and then shot blasted to remove all rust, scale and paint. We do all of the engine and machine work in house. We also have an engine dyno if you want to break in the engine before it goes in the car. The camshaft is always a custom and new lifters are used. I am very careful about the numbers on the block and heads, they will not be harmed in any way.
Basic numbers
Rebuild engine with stock style components $4000
Add $500 for fully ported stock heads
Add $500 for engine dyno testing
Add $1500 for R and R of engine in car.
Add $800 to switch to a roller camshaft
Hardened valve seats and guide replacement, if required, is extra
Fluids, filters and extra parts would be extra"
"The only way I do a rebuild is with new bushed rods, forged pistons and moly rings. I also do a complete cylinder head restoration with new valves, viton seals and hardened exhaust seats as required. The valve springs are replaced, so are the pushrods, rod/main bearings, cam bearings and timing chain set. The crank is turned and mag checked and then micro polished. The full rotating assembly is balance to within 1 gram. The block will either be jet washed, cleaned and painted or it will first be put in the oven and then shot blasted to remove all rust, scale and paint. We do all of the engine and machine work in house. We also have an engine dyno if you want to break in the engine before it goes in the car. The camshaft is always a custom and new lifters are used. I am very careful about the numbers on the block and heads, they will not be harmed in any way.
Basic numbers
Rebuild engine with stock style components $4000
Add $500 for fully ported stock heads
Add $500 for engine dyno testing
Add $1500 for R and R of engine in car.
Add $800 to switch to a roller camshaft
Hardened valve seats and guide replacement, if required, is extra
Fluids, filters and extra parts would be extra"
Rebuild engine with stock style components $4000 (That's friggin' outrageous! For $4K, you'd better be getting something with 400-500 hp and no other additional costs!)
Add $500 for fully ported stock heads (Cough, BS! Do they own a flowbench??? I've seen a Z28 with stock LT1 run 10.8 seconds on Car Hoarders!)
Add $500 for engine dyno testing (UNNECESSARY!)
Add $1500 for R and R of engine in car. (!!! We charge $150!!! to pull it It ain't that friggin hard! You're getting *** raped here!)
Add $800 to switch to a roller camshaft ($150 to $200 gets you a set of roller rocker arms from Comp Cams, why do you need a 'roller camshaft', any flat tappet camshaft will work just fine!)
I'd be seriously looking for somebody else!
08-21-2014, 06:36 PM
#17
Pro
I was quoted $4500 for a complete rebuild and 12 hours shop labor last year, so it seems your numbers are high. Perhaps you should shop for an aftermarket engine and keep the original, it's hardly worth rebuilding existing engines unless you are a purist.
08-21-2014, 08:28 PM
#19
Le Mans Master
I have been working on cars as a hobby for 35 years-and have worked on my 78 for 30 years-just about everything-engine, suspension, electrical. I just put Chrysler 300 Hemi front brakes on my 300 limited and 2001 Impala Police Struts/Springs on my 2001 Grand Prix. I would say advanced.
08-21-2014, 11:07 PM
#20
Burning Brakes
Thread Starter