1986 3.2 Engine rebuild best practices

[PandA]

Howdy all!
It is that time, starting to collect parts for a total engine rebuild.

Do we have a sort of best practices for going through a motor? Is it worthwhile going to larger piston size? How about the individual throttle bodies? Can you still run heat with the Individual throttle bodies? Already have a Fabspeed exhaust but their heat kit was cobbled together at the last minute ("it fits a variety of cars") and fits poorly and looks terrible, is there a better exhaust system out there? Do we have a favorite cam?

The car is mostly an occasional commuter car that would benefit from more low end power but also who doesn't enjoy 6krpm shifts? Those running the individual throttle bodies, how is the reliability? I see some talk on need cam timing, but can we not just keep the flywheel timing?

So many questions and so many more I am not thinking of. Any other words of wisdom?

Thanks!!

Andrew

[Cairo94507]

Unless you want to build it yourself, I would recommend Bruce Abbott, (flat6pac) on this site. He built my 3.2 and it is a wonderful motor. If you have to replace pistons and cylinders, I would bump up to a 3.4. Cheers.

[Neil Harvey]

Originally Posted by PandA

Howdy all!
It is that time, starting to collect parts for a total engine rebuild.

Do we have a sort of best practices for going through a motor? Is it worthwhile going to larger piston size? How about the individual throttle bodies? Can you still run heat with the Individual throttle bodies? Already have a Fabspeed exhaust but their heat kit was cobbled together at the last minute ("it fits a variety of cars") and fits poorly and looks terrible, is there a better exhaust system out there? Do we have a favorite cam?

The car is mostly an occasional commuter car that would benefit from more low end power but also who doesn't enjoy 6krpm shifts? Those running the individual throttle bodies, how is the reliability? I see some talk on need cam timing, but can we not just keep the flywheel timing?

So many questions and so many more I am not thinking of. Any other words of wisdom?

Thanks!!

Andrew

"""It is that time, starting to collect parts for a total engine rebuild."""

My advice, do not buy anything until you have set a performance goal and an engine budget. I guarantee both will be miles apart.

When reality sets in and you get over the shock, start making compromises that have the least effect on the performance.

If you have never done this before, ask plenty of questions. Be careful who you listen too as well. Everyone on this forum will want you to build "their" engine.

Create a full list of all parts required, all outside labor required, and any other misc parts and costs before you buy anything. This way, you will know the engine you will build, and the costs. Otherwise you will end up with a mixed bag of parts, and runaway costs.

I do this for a living and give this same advice everyday to many. Go slow, be methodical and make sure you understand every step.

To find out what is required, you will need to disassemble your engine, clean it and measure.

If you are married, now is the time to cosy up to your wife and do all those promised chores you have neglected.

[PeteKz]

Listen to Neil. What's your budget?

[PandA]

Thanks for the replies. I will reach out to Bruce and see what he has to say.

So much data and I am having a problem putting it all together into a coherent reply that will enable the most help; so here it goes in no particular order:
While I brought the car into our marriage, she does the majority of miles on it commuting. I recognize that to do the motor justice we are 20k for a rebuild 30k if we are doing different ECU (manifold, etc)
Big pictured is that I rekon what I am after is a more reliable setup. The motoronic, even with the SW chip, seems to just be fighting me every step of the way. The temp sensor is bad, no it is the wiring, no it is the MAF, no, it is not reading the AC switch, nope it is a vacuum leak....

And yes, I do all the promised chores, (expand the car port, make it a garage, build a wood and welding shop out back, get full HVAC in both of them, re-do the kitchen, then I can have the car I really want. A Ford Model A. But until then we press forward with what we have.

So, to that end. What would you all recommend for better reliability? (other than a model A) I like the 3.4 idea, wife and I are big believers in bang for the buck. Also from what I am reading the individual throttle bodies seem to give you about 50% more power, which seems pretty awesome bang for buck, plus better throttle response...

[mepstein]

If you want better reliability, fix all the stock Carrera parts. ITB’s certainly aren’t more reliable than stock motronic and you don’t get a 30% power increase just dropping them on the engine. A good set of itb’s and an engine management system will cost $10-15k.

[PandA]

Originally Posted by mepstein

If you want better reliability, fix all the stock Carrera parts. ITB’s certainly aren’t more reliable than stock motronic and you don’t get a 30% power increase just dropping them on the engine. A good set of itb’s and an engine management system will cost $10-15k.

Because I do not know any better: stock motor has ~200hp. So many of the guys that are touting their ITB builds are closing in to 300? Or am I making things up? Or am I missing something else?

Not being difficult, just trying to understand.

Thanks!

Andrew

[mepstein]

Originally Posted by PandA

Because I do not know any better: stock motor has ~200hp. So many of the guys that are touting their ITB builds are closing in to 300? Or am I making things up? Or am I missing something else?

Not being difficult, just trying to understand.

Thanks!

Andrew

On those 300hp engines, ITB’s are just part of the equation. They help all the other modifications, changes and upgrades reach full potential. A 300hp 3.2 is also a $50k+ engine. We are building one for a customer right now. The build sheet isn’t in front of me but it was around $5k to add bigger valves and twin plug the heads. As you modify an engine, all the costs increase in multiples. I’m not saying not to do it, I’m just saying you need to plan it out and not just throw fancy parts on the engine without understanding what they do. We also like to think from the bottom up, not the top down. Start with the short block, then long block, then valve train, etc.
and listen to any advice from guys like Neil. We are lucky enough to have Peter Dawe on speed dial so we can get good advice from an expert. The guys on pelican are great but you have to be careful about trying to build by committee.
A good running 3.2 is a beautiful thing.

[PeteKz]

Why do you think you need a complete engine rebuild, espeically on a 3.2, which last a long time?

[Cairo94507]

Of course, you could always buy my fully rebuilt ;87 3.2 rebuilt by Bruce Abbott (flat6pac) which now has 9K miles on it. Minimum down time to pull your motor and put this one in and enjoy driving a fresh motor. https://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/1146189-fs-87-3-2-carrera-motor-9k-miles.html

[mepstein]

Originally Posted by Cairo94507

Of course, you could always buy my fully rebuilt ;87 3.2 rebuilt by Bruce Abbott (flat6pac) which now has 9K miles on it. Minimum down time to pull your motor and put this one in and enjoy driving a fresh motor. https://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/1146189-fs-87-3-2-carrera-motor-9k-miles.html

Buy Michael’s engine for $30, sell yours for $12-15. You’d be way ahead.
Not to mention the engine switch can be done in a weekend or 2 compared to months for a top end.

[Neil Harvey]

Originally Posted by PandA

Howdy all!
It is that time, starting to collect parts for a total engine rebuild.

Do we have a sort of best practices for going through a motor? Is it worthwhile going to larger piston size? How about the individual throttle bodies? Can you still run heat with the Individual throttle bodies? Already have a Fabspeed exhaust but their heat kit was cobbled together at the last minute ("it fits a variety of cars") and fits poorly and looks terrible, is there a better exhaust system out there? Do we have a favorite cam?

The car is mostly an occasional commuter car that would benefit from more low end power but also who doesn't enjoy 6krpm shifts? Those running the individual throttle bodies, how is the reliability? I see some talk on need cam timing, but can we not just keep the flywheel timing?

So many questions and so many more I am not thinking of. Any other words of wisdom?

Thanks!!

Andrew

I found two papers I wrote several years ago, addressing your questions. They are long and I have to break them up into 5 posts.

Part 1.

Rebuilding an engine.

Its all about the planning.

The most important task in rebuilding and engine needs to be completed before you even remove the first nut or bolt.

What is the objective? What is my maximum budget and what are my performance requirements? Is the engine going to remain stock or is it going to tickle my back side some more?

Remember, most if not all air-cooled engines need a restoration not just rebuilding.
Take pen to paper and plan!! I cannot stress the importance of this!

To remove the engine from the car, do I have the room to do this safely. Can I leave the car in the same place while the engine is been rebuilt? Do I have all the right equipment? If not, what will this cost? Can I borrow it? Will I make a mess (yes), and be able to keep the workplace clean? What am I going to do with all the disposal oil and trash?

Once the engine is apart, what am I going to do myself, what am I going to send out to have done, etc. Getting a base line cost for any machine repairs ahead of time, the lead time to receive back, is very important. This is a huge part of the budget planning. Am I going to have the parts powder coated, CAD plated, painted etc.? All this needs to be decided before doing anything. These costs are well known as they are a common restoration upgrade. If you have a magnesium engine case, plan on head stud inserts, oil by-pass mod, line bore, cylinder decks skimmed parallel, some thread repairs, and some additional cleaning. Plan on having to rebuild the heads, new guides, maybe seat inserts, broken Exhaust stud removal, new valve springs and some or all, new valves. Plan for the worse, hope for the best. Remember to include parts like, new Clutch assy, oil hoses, filters, fuel lines and maybe some electrical upgrades and or repairs. The Alternator may need rebuilding, at the vey least, checking, the wiring probably needs some repair work as well. A lot of this can be established by a close inspection before the engine is even removed.

[Neil Harvey]

Part 2

What basic rebuilding parts and consumables will I need? Will I replace all the standard hardware and fasteners? I will need new bearing shells, timing chains, chain support rails etc. Where am I going to buy these from? Will I go cheap and buy from the aftermarket and risk buying out of spec parts or will I buy direct from Porsche agencies. My advice is to do both. Buy the most critical parts like bearing shells from the dealer and the less critical parts like chain guide rails from the aftermarket.

Get answers to all of this before you even start. Planning is so important. Make up a schedule of work to be done and in what order. I am going to remove the engine on day X. I will remove the gearbox and clean it on the same day. Another day I will disassemble the exhaust system and intake. I will inspect each part and note any repairs required and add these to my rebuild plan and make sure these are covered in my budget. Included in the preplanning should be, what can I do to help lower the outside labor costs? Once I have the parts back and the assembly starts, do I know what I am doing? Do I understand how to measure the case main housing, can I measure bearing clearances, do I understand how to check the piston to valve clearances, do I understand how to time the cams? Now is the time to understand all of this. Too many “jump” into this with excitement about rebuilding their engines without any clue of what they are doing or about to embark on.

Now, the engine and gearbox are removed from the chassis, the disassembly part begins. What tools are required, and do I have all the tools required? Can I store the gearbox somewhere? Do I have the correct engine stand? Do I have an area to store all the Intake, sheet metal, exhaust system? Do I have a clean work bench space?

Keep the workplace clean. Clean after yourself especially after removing the exhaust system and Intake. Keep the floor clean. Keep the tools clean. As you make a mess, clean it. You will feel so much better working in a clean environment. I have seen pictures of tools left lying over the floor, an oiling mess on the floor, such a toxic place to work. Keep it clean and clean as you go. Only have the tools required to perform each job out, clean and put them away as you finish each job.

Now you have the top end apart, inspect the parts. Now is the time to collate the schedule and budget you have made to see if you are under or above what you have planned for. Do as much cleaning as you can yourself and do it as you remove the parts. Storing clean parts is way easier than dirty oily parts. In your planned budget you will have some timeline on when you will send out parts for cleaning and any finishing.

The major parts now under inspection will be the Camshafts, rockers, and cylinder heads. Probably most DIY’s will send out the heads for repair. The camshafts should be carefully inspected now for pitting on the lobes. If they are to be reused, and in great shape, clean them, oil them and put away in a safe place. Do not drop them as they will break into two pieces very easily. Inspect the rocker arms for wear. The bushings will probably show wear, especially on the thrust side of the rocker arm. Do the rocker arm pads show signs of wear? How do the timing chain gears look? Often these shows signs of chain misalignment and need replacing. Now is the time to check your budget for these parts or add to it. A running total will be easier to budget than a hefty unknown amount at the end.

[Neil Harvey]

Part 3

You should know what camshaft you are going to replace your’ s with before starting this rebuild. This is part of the performance planning. Making sure your cam can either be reground with the new profile or are you buying new billets.

Pack the heads ready for shipping. Inspect the cam housings for wear and plan on removing the oiling spray tubes for cleaning. Now you can turn the engine over and visually inspect the cylinder bores for wear and any damage. It’s a good idea to do this before you remove so you at least have an idea of what is ahead of you. Again, this can add to the budget, so now is the time to make additions. Removing the cylinders and pistons can now be done with careful attention not to damage or beak anything. Be patient here. Expect the pin clips to go into space, Use some eye protection here. Don’t worry about losing any clips, these will be replaced with new ones. Be careful not to break any Piston rings either. You want to know if they were broken before so any oil consumption issues can be confirmed.

The bottom end of this engine is now in front of you. The rods are sticking out of the case. They can be removed now with care, or after the case is split. Its your choice. I suggest, if you can, to remove the rods while the case is together hanging on the engine stand. Undo the nuts and before you remove the nuts fully from the rod bolts, tap on the nut with a soft drift or use the socket to push the caps off the beams. Remove the beam and carefully slide the cap around the crank pin and out. Now inspect the rod bearings. The two bearings to really take note of are the number two and number five rod bearings as these are the last to get oil. If they look great, you can almost be sure the main bearings are in great shape. No oiling issues to be concerned about within the engine case. You will be replacing the rod fasteners, so don’t be concerned about mixing any up. Note here, before you measure or have the rods rebuilt, replace the fasteners that will be reused in the final assembly first. Do not measure or rebuild the rods with the old fasteners. Expect the rods to need repair. Magnaflux crack check, straight check, Pin bushing replaced, fasteners replaced, BE’s resized, CCL’s checked and rebalanced. It is also a good idea to plan in the costs to have them re shot peened.

A large part of the rebuild cost is in front of you. The Pistons and cylinders. The first parts to check are the cylinders. Any damage and or big scratches? Don’t worry about the cross hatching. If they visually look good, now is the time to measure the bores. I would expect them to have an amount of ovality and taper to them. If you are staying with the same bore size, these can be repaired. Just be careful who you send them to. A third-party parts house offers this service but unfortunately, they have no clue of the repair work required nor do they have clue about what finish is required etc. I have re done the specs for so many customers who were given poor replacements. I won’t name who they are, but just be careful and before you send them anything, ask them for the specs that your cylinders will be repaired to.

[Neil Harvey]

Part 4

Some things to know about re plating cylinders. Typically, Nikasil or a derivative (silicon carbide) of this is used. This stuff is super hard. Its used as it’s wearing surface is very good. The rings cannot be chromed faced as you cannot run two super hard surfaces against one another. The break in period is often talked about. Bedding in the rings. This is so misunderstood with Nikasil coated cylinders. Under a microscope, the surface will be full if high peaks and low valleys. The surface is extremely hard and does not wear, when compared to the ring faces that are a lot softer. So, when you have very rough surface finish, with lots of high peaks, you will wear away the ring faces and destroy the ring seal. Therefore, the surface finish must be of a certain number. The lower the number on most scales is a finer finish. The 3rd party company I have mentioned here have no clue on what the surface finish should be. So be careful. My advice is to ask an engine builder or the actual repair place for their advice, not a parts salesman.

You need to also check the cylinder heights to make sure they all match. If they dont’, they can be equaled by removing some material off the base. Also, now is the time to decide on any sealing system to be performed. This should have been included in your preplanning.

Pistons. These are easy to inspect for wear; the skirts should be unmarked and show no signs of trash sliding down the sides. If they do, they need replacing. If they look good, the next is to clean them. Removing all the carbon and dirt will show any signs of valve contact or head contact. Expect the pin bosses to need some help. Probably removing the burr made when you removed the clips. The pistons once cleaned need to be measured to make sure they are within spec. If they have a lot of time on them, it’s a good idea to have them checked for hardness. They do go soft over time with all the heat cycles. Most of the time these are replaced with a larger bore version. Ring lands need to be checked for wear as these become larger over time and the side clearance of the ring is an important dimension to hold otherwise you will have ring control issues especially when the piston is not under load. Pins sometimes show wear, and these should be carefully inspected as well. If new pistons are to be use, they will come with new pins and clips.

Next is the engine case assy. Before disassembly, and with the Cylinders removed, now can be a good time to have a general look over. Typically, this is the part that is covered with years of dirt and will require a lot of time to clean. You need to remove the chain housings and the rails. The rails are held in place by the bolts, on both sides, in the front of the engine case.

There are 13 Through bolts to undo. Two are hidden behind the Oil cooler, so be sure to remove this first. Be careful here, Oil will spill out all over the place. Undo all the 13 through bolts and all of the 8.00mm perimeter nuts. There are two nuts that need to be removed. The one on the outside of the 1/2/3 side of the case that clamps the case at the Intermediate shaft and the one down inside the chain housing on the same side of the case.

Splitting the case halves apart can be an issue. Glue, years of been together can make this hard. There is a tool that can be bought from a vendor that makes this easy I’m told. This needs to be added in your budget. Remember, tools like this may only have one time use. Go slow here and use gentle taps with a plastic mallet. Often the front of the case will split first as there are no dowel pins at that end. The rear Flywheel end has two dowel pins either side of the rear main bearing shells which makes the case harder to come apart. If you are doing this without any special tools, do not use a screwdriver to wedge the case apart. You will damage the sealing surfaces and increase the chance of an oil leak. Sometimes a piece of hard wood long enough to reach up through the arms of the engine stand can do the job. Position one end on the inside of the bell housing register and tap. It may take more than gentle tap but don’t go crazy here either. As soon as the case splits you may have to tap at each end to get the case to come apart front to back evenly. Lift off the case the 1/2/3 side and expose the Crank shaft and Oil pump assy.

[Neil Harvey]

Part 5

I have skipped a lot of the work involved here, as it becomes obvious what needs to be done and how. As you remove parts, inspect them for damage and wear. Intermediate shaft gears, crank journals, bearing shells, main housing bore. The Oil Pump will need to be disassembled to check its internals. The gears should always be crack checked as they are made from sintered steel and very brittle. A back lash check can be done before removing the Intermediate shaft to see if the gear is the correct one. Often these show wear and need to be replaced. If the gear look worn, there is no point in performing the back lash check.

I cannot stress enough about the pre rebuild planning. This is so important. If you know the total engine budget you can spend, this will dictate what upgrades you will be able to do. The most important decisions are, to make sure you have the engine funds available to rebuild the engine back into good working condition. There is no point in buying all these fancy upgrades if you must compromise on the repair work. Starting on something without having an end plan will turn this engine into your most hated thing and you will wish you never started it.

Go slow and be deliberate about this. Enjoy the journey. It should be a labor of love. The result will give you so much enjoyment once it’s all back together and running in the car.
In the assembly part there are many shortcuts, checks and “how to’s”, to help quicken up the assembly process. These are more unique to each assembler. These should be considered for what they are and not an absolute requirement. I will write up another paper on what we consider the “cheats” of assembly.

In this same paper, I will go into what to ask for when sending out parts for repair and what to expect when you receive them back. What to look for and what important repairs you need to be concerned about. Just because they look clean and shiny, doesn’t make them ok. Most of these engines make less than 350 BHP. So, any slight change in spec can have a huge affect on the final performance. Think of your engine as 6 individual single cylinder engines, all hopefully making the same performance. If your parts are hastily repaired to look good and you drop 5- 10 ft/lbs of torque per cylinder, overall you have lost upwards of 60 ft/lbs of torque, resulting in a drop in useable horsepower of approx. 77 BHP. It doesn’t take much.

Your engine does not make the same torque per cylinder due to air flow differences, cylinder heat and friction. The never-ending goal and pursuit is always trying to achieve this. So, why make it worse by assuming the repairs are correct, having a lack of understanding and making poor choices.

My hope is to dispel all the myths and fears many have about rebuilding these “simple” engines. They are one of the most uncomplicated engines you could rebuild.

[Neil Harvey]

I found another paper I wrote and will post this later.

This is my opinion and my way. Others will have theirs and probably better than mine. This was engrained into me during my F1 days and has guided me all these years later.

[zztot]

Great information….Thanks Neil!

[jess p]

Originally Posted by Cairo94507

Unless you want to build it yourself, I would recommend Bruce Abbott, (flat6pac) on this site. He built my 3.2 and it is a wonderful motor. If you have to replace pistons and cylinders, I would bump up to a 3.4. Cheers.

I think PandA would do a great job doing it himself and save a ton of money!