Little Mouse - The 1994 - 4.3l TBI engine blueprint and tuning
#21
08-02-2017, 09:33 AM
Some parts restored
I'm a nerd when it comes to do things correctly. So a lot of time goes into details even some details that will never be seen once assembled.
I have several parts which needed restoring such as the timing chain cover or the aluminium support for the HVAC compressor. Some of this stuff will be put together in a different manner such as using studs instead of bolts. E.g. the stupid bolts on the climate compressor where you have to take the pulley off to get them out. I'll try a similar approach as for a racing engine with ease of access and servicing in mind.
Pictures of some of the repairs and changes. Timing cover has been in paint remover, straightened in two places where it was dented, sanded a scratch (not from me) and had it galvanized.
Also had both my TBI's rebuilt with a complete gasket kit and one put into my running Blazer. Had some issues and changed all the sensors on the engine and got a complete set of new ones for the build. Now I start to hope that the engine is not running too good or develop too many HP, else I have to switch injectors on the TBI and retune the whole thing. We'll see once it runs and hangs on the dyno.
The pics show:
- timing gear cover rust-free and repaired
- timing gear cover and the oil pan rails after black galvanizing.
- A/C compressor support disassembled
- TBI 220 disassembly
- TBI taken apart and laid out
- TBI re-assembly
- A/C compressor support after grinding the casting parting lines
- The support wile priming
- The support getting it's final aluminium silver color. A special paint we use in restoration of cars to paint the aluminium blocks of old italian sportscars. They did that in the 50 - end of 70's on the cast aluminium blocks to prevent the bare aluminium from corroding.
I have several parts which needed restoring such as the timing chain cover or the aluminium support for the HVAC compressor. Some of this stuff will be put together in a different manner such as using studs instead of bolts. E.g. the stupid bolts on the climate compressor where you have to take the pulley off to get them out. I'll try a similar approach as for a racing engine with ease of access and servicing in mind.
Pictures of some of the repairs and changes. Timing cover has been in paint remover, straightened in two places where it was dented, sanded a scratch (not from me) and had it galvanized.
Also had both my TBI's rebuilt with a complete gasket kit and one put into my running Blazer. Had some issues and changed all the sensors on the engine and got a complete set of new ones for the build. Now I start to hope that the engine is not running too good or develop too many HP, else I have to switch injectors on the TBI and retune the whole thing. We'll see once it runs and hangs on the dyno.
The pics show:
- timing gear cover rust-free and repaired
- timing gear cover and the oil pan rails after black galvanizing.
- A/C compressor support disassembled
- TBI 220 disassembly
- TBI taken apart and laid out
- TBI re-assembly
- A/C compressor support after grinding the casting parting lines
- The support wile priming
- The support getting it's final aluminium silver color. A special paint we use in restoration of cars to paint the aluminium blocks of old italian sportscars. They did that in the 50 - end of 70's on the cast aluminium blocks to prevent the bare aluminium from corroding.
Last edited by error_401; 11-19-2017 at 05:23 AM. Reason: update in text and images
#22
08-02-2017, 09:47 AM
Working the heads
I do not plan on porting the heads. The flow up to 4'500 rpm should be enough and the engine being built for low end torque will hardly ever see above 4'500 rpm. Nevertheless I will do a "clean up" in all the runners and especially the bowls. The OEM casting and the cutting leaves a lot of irregular protrusions in the bowl area. Also the valve guides are sitting on a boss in the runners. All the cut edges will be smoothed out and the surface smoothed. Still working on the geometry to put on the straight edge towards the heads flat surface but a minimal radius might be best there to avoid hot spots.
Have to search for the good pictures. These are from the beginning of the work. Put about 2 hours into each head, doing runners and bowls so far.
Once I have another day to spend with them I have to cc the runners, make gauges from sheet metal to insert into the runners and cut them as close as possible to even out differences. The EGR port in the heads is still a problem and I'll see what happens there but again it is a street build and of minor concern.
Have put a nice smooth radius onto the intakes from begin of the bowl to about 1/8" to the seat. The rest will be done after cutting the seats for the final valve set. The exhaust ports have been smoothed and quite a bit of casting stuff, flesh and irregular ridges removed. The short bend radius has been left untouched except for smoothing it. The next step will be to match the ports to the gauges i'll make and then match them to the OEM headers.
Some pics of the progress and a series of what I do to the intake bowl. Valve guide bosses will just get a radius on the edge, nothing fancy here except of basic aerodynamics. I'll not cut them back as the bowl opens quite quickly on these castings and also retain the "ski-jump-ramp" for swirl. Have yet to find evidence that cleaning out helps low end torque. A race engine would be a different story but then I'd probably go with a set of aluminium BRODIX heads.
Many think that removing as much material as they can will yield benefits but not so in a low end torque engine. One of the reasons I do not cut back on the valve guide bosses is the opening of the bowl in this area. A volume flow will keep it's speed as long as the area in any place is the same. As soon as I open the area (which would be the result of cutting back the guide) it slows down. From what I have found out talking to race engine builders all suggested for my particular build (truck engine in a truck) to leave the area small as long as possible towards the valve. All agreed that the low rpm will not be an issue with the rather generous short radius but the higher airflow will leave more inertia in the intake charge. Also they agreed on leaving the ski jump for swirl and see what the results are. Some even think that it could handle a more aggressive camshaft without problems as the downward spiral vortex has a lot of energy that will keep it from changing direction towards an open exhaust valve and keep a better filling in the cylinder without too much of the mixture being drawn out the exhaust during overlap.
The pictures show:
- Heads innards on the top side. Two rocker arm stud threads and the head bolt location with chamfered edges. Removed the casting lines on the oil return holes and deburred the edges of the pushrod holes.
- Intake before working on it.
- Same intake (upside down) with initial grinding in the depths of the bowl.
- Same intake when working on the step that had been left from cutting the valveseats into the casting.
- Same intake working from the bowl up to that parting
- And still the same intake with smoothed changes from the bowl to the seat. Final porting to be done after cutting the seats into the throat. (backcut at about 70 degrees)
Have to search for the good pictures. These are from the beginning of the work. Put about 2 hours into each head, doing runners and bowls so far.
Once I have another day to spend with them I have to cc the runners, make gauges from sheet metal to insert into the runners and cut them as close as possible to even out differences. The EGR port in the heads is still a problem and I'll see what happens there but again it is a street build and of minor concern.
Have put a nice smooth radius onto the intakes from begin of the bowl to about 1/8" to the seat. The rest will be done after cutting the seats for the final valve set. The exhaust ports have been smoothed and quite a bit of casting stuff, flesh and irregular ridges removed. The short bend radius has been left untouched except for smoothing it. The next step will be to match the ports to the gauges i'll make and then match them to the OEM headers.
Some pics of the progress and a series of what I do to the intake bowl. Valve guide bosses will just get a radius on the edge, nothing fancy here except of basic aerodynamics. I'll not cut them back as the bowl opens quite quickly on these castings and also retain the "ski-jump-ramp" for swirl. Have yet to find evidence that cleaning out helps low end torque. A race engine would be a different story but then I'd probably go with a set of aluminium BRODIX heads.
Many think that removing as much material as they can will yield benefits but not so in a low end torque engine. One of the reasons I do not cut back on the valve guide bosses is the opening of the bowl in this area. A volume flow will keep it's speed as long as the area in any place is the same. As soon as I open the area (which would be the result of cutting back the guide) it slows down. From what I have found out talking to race engine builders all suggested for my particular build (truck engine in a truck) to leave the area small as long as possible towards the valve. All agreed that the low rpm will not be an issue with the rather generous short radius but the higher airflow will leave more inertia in the intake charge. Also they agreed on leaving the ski jump for swirl and see what the results are. Some even think that it could handle a more aggressive camshaft without problems as the downward spiral vortex has a lot of energy that will keep it from changing direction towards an open exhaust valve and keep a better filling in the cylinder without too much of the mixture being drawn out the exhaust during overlap.
The pictures show:
- Heads innards on the top side. Two rocker arm stud threads and the head bolt location with chamfered edges. Removed the casting lines on the oil return holes and deburred the edges of the pushrod holes.
- Intake before working on it.
- Same intake (upside down) with initial grinding in the depths of the bowl.
- Same intake when working on the step that had been left from cutting the valveseats into the casting.
- Same intake working from the bowl up to that parting
- And still the same intake with smoothed changes from the bowl to the seat. Final porting to be done after cutting the seats into the throat. (backcut at about 70 degrees)
Last edited by error_401; 11-19-2017 at 05:26 AM.
#23
09-08-2017, 05:05 PM
Finished cc'ing all my combustion chambers. To my surprise found them to match within 0.3 ccm!
All within a range of 64.8 to 65.2 ccm. How nice!
With the flat tops and a .027 MLS gasket this ups my compression to 11.5:1. So I can grind them by a lot without falling below 10.5:1 compression. Should make for a nice combustion chamber once I'm finished with them.
All within a range of 64.8 to 65.2 ccm. How nice!
With the flat tops and a .027 MLS gasket this ups my compression to 11.5:1. So I can grind them by a lot without falling below 10.5:1 compression. Should make for a nice combustion chamber once I'm finished with them.
#24
09-09-2017, 08:58 PM
Enjoying the details of the engine rebuild. Please keep it coming. It would be great if you would give some tips and suggestions on how to do a less intense rebuild, but get some good results at a cheaper price. That would be appreciated after you have completed this project and reflect on the steps.
#25
09-13-2017, 04:11 AM
Thanks for the comment.
For the thoughts:
IMHO could be built for less than 3'000$ with the following limitations. Max rpm 4'500 (OEM redline) Max hp about 200.
Comp cams mild camshaft for some
200$
Timing chain set (aftermarket)
100$
Set of 8 flat top's from JE or SP depending on the actual CD of the pistons even the high ones from the 350
200 - 400$
Heads
maybe from a 96' from the junkyard
100$
Valves
120$
Machine work assuming the block is in good condition and crank is re-usable
Checking, cleaning, bore and hone, new bearings, decking, heads decking
1200$
Plus some 100 - 200 hours of your time building it. Head work etc.
What the outcome would be? I can't even assume. Guesstimating I would opt for some 15 - 25 hp more. Eventually when doing a proper mapping to the ignition and injection 20 - 30 hp more. Is it worth it?
You decide
For the thoughts:
IMHO could be built for less than 3'000$ with the following limitations. Max rpm 4'500 (OEM redline) Max hp about 200.
Comp cams mild camshaft for some
200$
Timing chain set (aftermarket)
100$
Set of 8 flat top's from JE or SP depending on the actual CD of the pistons even the high ones from the 350
200 - 400$
Heads
maybe from a 96' from the junkyard
100$
Valves
120$
Machine work assuming the block is in good condition and crank is re-usable
Checking, cleaning, bore and hone, new bearings, decking, heads decking
1200$
Plus some 100 - 200 hours of your time building it. Head work etc.
What the outcome would be? I can't even assume. Guesstimating I would opt for some 15 - 25 hp more. Eventually when doing a proper mapping to the ignition and injection 20 - 30 hp more. Is it worth it?
You decide
Last edited by error_401; 09-16-2017 at 07:56 AM.
#26
09-16-2017, 08:06 AM
The crankshaft
The crank I had in the engine was just barely within limits. It was scratched and gouged by particles in the bearings. To fit new bearings it would need grinding one under to use the first oversize bearings.
Shipping cranks around the world is expensive, the shipping costs more than the cast iron crank. But I lucked out with a marine shop nearby. The guy had a crank sitting for 20 years in his stock in decent condition. A couple of nicks but nothing serious so I have a crank to build upon. Should that crap... oh crank ever fail on me and I'll still be a Blazer aficionado I'll buy an expensive Arrow Precision billet one good for 700 hp and modify the block for 4 bolt mains and do a dry sump all out racing bottom. (Hopefully not within the next 10 years)
Crank inspected and measured. Within 1/10'000 of what it should be.
Again ground all sharp edges on the counterweights and the throws using a pair of old bearings to protect the surfaces against inadvertent slips with the file or Dremel grinder. Then worked the oil holes. The oil holes have a sharp edge on nearly all OEM cranks. The idea is to slightly chamfer them to get a thicker edge and then to polish it. The holes are huge so one tries to keep them as small as possible. This is required as we will have the crank nitrided for a harder bearing surface.
Pics show:
- the rod throws on the "split-pin" of the crankshaft. This is the offset of the V6 crank to make it even-fire. See the sharp edges...
- The throws with the left one polished and the right one showing the traces of the stone to egalize the small dents. (actually to make sure there are no protrusions/burrs.)
- The same throws after polishing both. You can also see the edges are no longer razor sharp. This also alleviates brittle material to brake off after nitriding.
- The counter weight before working on it. The edges are razor sharp
- And the counter weight after working on it.
The balance of the crank will not be affected by this as the removal of material is about 5 grams on the whole crankshaft. Now it is ready to be brought for nitriding.
For the inclined reader: https://en.wikipedia.org/wiki/Nitriding
Cleaned, polished for surface inspection. With a fine stone removed eventual burrs from all the nicks and dents. Then polished the crank again on a lathe. Now it's ready to go for nitriding. Next week I'll go for a ride (50 miles) to have it done and to advance this project. At the same time I'll get some more knowledge about nitriding.
Shipping cranks around the world is expensive, the shipping costs more than the cast iron crank. But I lucked out with a marine shop nearby. The guy had a crank sitting for 20 years in his stock in decent condition. A couple of nicks but nothing serious so I have a crank to build upon. Should that crap... oh crank ever fail on me and I'll still be a Blazer aficionado I'll buy an expensive Arrow Precision billet one good for 700 hp and modify the block for 4 bolt mains and do a dry sump all out racing bottom. (Hopefully not within the next 10 years)
Crank inspected and measured. Within 1/10'000 of what it should be.
Again ground all sharp edges on the counterweights and the throws using a pair of old bearings to protect the surfaces against inadvertent slips with the file or Dremel grinder. Then worked the oil holes. The oil holes have a sharp edge on nearly all OEM cranks. The idea is to slightly chamfer them to get a thicker edge and then to polish it. The holes are huge so one tries to keep them as small as possible. This is required as we will have the crank nitrided for a harder bearing surface.
Pics show:
- the rod throws on the "split-pin" of the crankshaft. This is the offset of the V6 crank to make it even-fire. See the sharp edges...
- The throws with the left one polished and the right one showing the traces of the stone to egalize the small dents. (actually to make sure there are no protrusions/burrs.)
- The same throws after polishing both. You can also see the edges are no longer razor sharp. This also alleviates brittle material to brake off after nitriding.
- The counter weight before working on it. The edges are razor sharp
- And the counter weight after working on it.
The balance of the crank will not be affected by this as the removal of material is about 5 grams on the whole crankshaft. Now it is ready to be brought for nitriding.
For the inclined reader: https://en.wikipedia.org/wiki/Nitriding
Cleaned, polished for surface inspection. With a fine stone removed eventual burrs from all the nicks and dents. Then polished the crank again on a lathe. Now it's ready to go for nitriding. Next week I'll go for a ride (50 miles) to have it done and to advance this project. At the same time I'll get some more knowledge about nitriding.
Last edited by error_401; 09-16-2017 at 08:33 AM.
#28
09-28-2017, 02:37 AM
Oh, true, looks gross.
One of the pics actually (the one with the counterweight with the step and balancing hole) shows it during chamfering the edges. In order not to touch the throw surface I took a pair of old bearing shells and a piece of electrical wire to hold them in place.
Got a few very fine scratches, and a dent from the previous owner. polished away, with a fine stone made sure there are no protrusions.
Yesterday got the crank back from nitriding. Already straightened out now waiting for balancing.
One of the pics actually (the one with the counterweight with the step and balancing hole) shows it during chamfering the edges. In order not to touch the throw surface I took a pair of old bearing shells and a piece of electrical wire to hold them in place.
Got a few very fine scratches, and a dent from the previous owner. polished away, with a fine stone made sure there are no protrusions.
Yesterday got the crank back from nitriding. Already straightened out now waiting for balancing.
#29
10-15-2017, 12:31 PM
Crank is back from nitriding. Had to clean it and polish all the radii and the throws as well as the mains. Then we had it on the blocks for straightening.
The master weights are readied and I hope to get it balanced this coming week.
The master weights are readied and I hope to get it balanced this coming week.
Last edited by error_401; 10-15-2017 at 12:33 PM.
