1500cc hot street motor build

[Jepp78bertone]

Here is the template I made to open up the combustion chamber shape. Template is a direct trace of the stock 1500 combustion shape

 

[Jepp78bertone]

I dropped the head off at the machine shop this morning to start with installing the new seats. Once I get that back I will do all the bowl work and porting before sending it back to have the bronze valve guides installed and the valve job done.

 

[fiatfactory]

just a couple of thoughts....

M12 ARP head studs will require that you machine the head bolt washer pads at the spark plug side of the engine, the ARP's are too short for this application by a few threads, so the best engineering solution is to machine the pads. Do this at the diameter of the ARP washers, not the standard Fiat washers or you will break into water on the two ends.

the ends need 11mm removed and the middle three need 6mm removed.

Sinking the exhaust valve down really does have benefits, but I'm talking 1mm to 2mm lower than the inlet, sounds like your thinking a lot smaller number than that and that has zero benefit.

If you have a reground cam (poor choice IMO you should have gone for the billet) then the reduced base circle ill let you move the exhaust valve up. Obviously you loose spring tension and need to refit an extra washer or two under the spring to make up installed height and keep tension.
Plus (like most peopel) you've gone for the biggest lift / longest duration cam avaiable (another not so informed choice IMO) as you simply havent considered the DYNAMIC compression you will acheive with this combination... cam choice should be based on this.

Just go with standard replacement Fiat springs, the iskys are a compromise. and there are much better choices if you look but just not offered by the usual suspects (the usual vendors)

Are you pulling the pistons to at least replace rings? 100k km is reasonable mileage and replacing the rings should give it a new lease of life.

as far as finished combustion chamber shape goes, look at well finished Chevrolet small block heads, thats the combustion chamber shape yu want to aim for.




SteveC

 

[GregS]

Change of Plans and Finally executing some progress.

It has been 2 years since I've made any progress on the x19 engine build and its about TIME to get it back on the road.
However I've made some changes to the engine build plan and I'd like to share this process as I put it all together.

The old plan was to use the original US spec 1500cc cylinder head milled down to remove the circular recess to bump up compression. The machine shop ended up removing 0.085" stating that they needed too to ensure the head surface was perfectly flat, even though I had requested they only milled enough off to remove the circular recess. I measured the combustion chambers with my burette and they only measured between 25.2-26cc resulting in my CR being far higher than I had anticipated and it was simply a poor choice on my end to have the head milled without specifically clarifying that the max amount removed should be no more than 0.065"-0.070".

So I've abandoned that head and am starting fresh with a brand new NOS Yugo 1100cc head that I will modify in similar fashion to the way Rob Plenter did his on his 1603cc engine build. See his thread for his awesome build including what he sourced for a lightweight valvetrain. Which I wish I could afford doing myself. https://xwebforums.com/forum/index.php?threads/1603cc-engine-build.25589/

CYLINDER HEAD build plans are as follows
- starting with a NOS yugo 1100 10 bolt head w/ 36/31mm IN/EX valves
- M10 stud holes will be drilled out to M12 to fit ARP head studs
- Combustion chambers opened up from 80mm to 86mm to suit 1500cc bore size. Initially just copying the stock 1500 combustion chamber shape until later to fine tune the cc and maximize swirl into the cylinder - Essentially trying to replicate a 1500 EURO head
- All seats are being replaced to suit 39.5mm Intake and 33.4mm exhaust valves
- Ports are being opened up to 28.5/29mm and Bowl work blended into larger seats as per stevec's ultimate SOHC guide
- Bronze valve guides to be installed and trimmed back to be flush with port roof
- 3 angle valve job and 30degree back cut on all valves
- sinking the exhaust valves slightly lower than the intake valves as per stevec's recommendation (plus i'll be using my old 33.4mm exhaust valves from my old head and they have been ground a touch before so this will move them up a tad to match the brand new AE Intake valve length )
- cam housing surface of head shaved 1mm (0.040") to accommodate reground cam's smaller base circle

CAMSHAFT
- PIPER cams FIAX19BP300 regrind camshaft
- advertised 290 degree duration BUT I emailed Piper cams and they stated duration @ .050" = 258 degrees
- advertised Valve lift = 11.18mm BUT measured Cam lobe lift (32.9mm overall lobe height - 22.8mm base circle) = 10.1mm lift (I've emailed Piper cams to ask why this would be and if it seems right)
- Valve timing - 39-71/71-39
- Stock cam tappet buckets with 3.5mm shims (+/- 0.05mm)
- Using Alfa 8mm Lash caps to achieve Valve clearances of Intake .010" and exhaust .012"
- Still deciding on what valve springs to use - either ISKY race springs or a set of new Alquati springs. Depending what I end up confirming about the cams max lift will determine the route I take for springs.
- Adjustable Cam pulley - what I believe is a Millers Mule brand

BOTTOM END
- Stock 1500cc block bored out to fit 86.8mm pistons
- Stock 63.9mm crank and con rods / new bearings installed throughout bottom end when built in 2015
- FIAT OEM 1300 Small flycut pistons (only markings on the crown are a small stamp that says "fiat113" and the marking 6/10) CH unknown. 0.6mm pop-up "pimple"
-piston is currently sitting 0.5mm below deck at TDC, I am considering disassembling the bottom end and having the block decked to have pistons at zero deck , but still need to finalize head gasket choice/and crunch the numbers to achieve Squish/Quench of 1mm.
- Will also need to determine how to go about enlarging INTAKE fly cuts on pistons to accommodate new 39.5mm intake valves (ive heard this can be done with the pistons remaining the block, but I have yet to find any information on it, can anybody walk me through this?)

CARBURATION
-2x weber DCNF40's
-Port matched intake manifold
-32mm chokes
-ITG duel DCNF foam air filter

IGNITION
- YUGO Bosch Electronic Ignition
- Bosch Distributor
- Doug's (rx1900) premium ignition wire set

I will attach photos of progress as I go

Jepp, I have almost exactly the same engine spec in my track x1/9. I have that piper cam but billet one, I find it has good torque for both on the road and track, and it still likes to rev to over 7,500rpm. I run 40 DCOEs with 34mm chokes, same valves, 4 - 2 - 1 headers, 10.7 : 1 C/R, getting about 135 hp at 7,000rpm.

 

[Jepp78bertone]

Jepp, I have almost exactly the same engine spec in my track x1/9. I have that piper cam but billet one, I find it has good torque for both on the road and track, and it still likes to rev to over 7,500rpm. I run 40 DCOEs with 34mm chokes, same valves, 4 - 2 - 1 headers, 10.7 : 1 C/R, getting about 135 hp at 7,000rpm.

Hi Greg,
believe me, I have read your build thread on t124 many times over!!
I'm sure I will have some questions for you as my build continues.

 

[Jefco]

US spec 1500cc cylinder head milled down to remove the circular recess to bump up compression. The machine shop ended up removing 0.085" stating that they needed too to ensure the head surface was perfectly flat, even though I had requested they only milled enough off to remove the circular recess. I measured the combustion chambers with my burette and they only measured between 25.2-26cc resulting in my CR being far higher than I had anticipated and it was simply a poor choice on my end to have the head milled without specifically clarifying that the max amount removed should be no more than 0.065"-0.070".

The misunderstanding you had with the machine shop was likely because the top of the decompression recess is domed; I got one of Matt's performance heads for my '86 (10mm bolts) that came with a spec sheet showing a .065 shave, and the recesses weren't totally gone, there's a little left in the center.

 

[Jepp78bertone]

The misunderstanding you had with the machine shop was likely because the top of the decompression recess is domed; I got one of Matt's performance heads for my '86 (10mm bolts) that came with a spec sheet showing a .065 shave, and the recesses weren't totally gone, there's a little left in the center.View attachment 46290

you're absolutely right Jeff, It was my mistake for not clarifying the amount. Oh well, lesson learned.

 

[Jepp78bertone]

just a couple of thoughts....

M12 ARP head studs will require that you machine the head bolt washer pads at the spark plug side of the engine, the ARP's are too short for this application by a few threads, so the best engineering solution is to machine the pads. Do this at the diameter of the ARP washers, not the standard Fiat washers or you will break into water on the two ends.

the ends need 11mm removed and the middle three need 6mm removed.

Thanks for all these tips SteveC, I have shared them with my machinist and he will do just that.

If you have a reground cam (poor choice IMO you should have gone for the billet) then the reduced base circle ill let you move the exhaust valve up. Obviously you loose spring tension and need to refit an extra washer or two under the spring to make up installed height and keep tension.
Plus (like most peopel) you've gone for the biggest lift / longest duration cam avaiable (another not so informed choice IMO) as you simply havent considered the DYNAMIC compression you will acheive with this combination... cam choice should be based on this.

Just go with standard replacement Fiat springs, the iskys are a compromise. and there are much better choices if you look but just not offered by the usual suspects (the usual vendors)

The PiperBP300 reground cam I have turns out to be more of a mystery than I had thought. My measurements of cam lift ended up indicating that this reground cam has an actual lift of 10.1mm, not the advertised 11.18mm. I've emailed Piper and they confirmed that on some cams sent in for re-profiling they cant get the full profile cut but that the measurements that I provided are what they would use. I have to figure out now if I'm going to stick with this cam, and figure out all of its measurements, or find something different.

Are you pulling the pistons to at least replace rings? 100k km is reasonable mileage and replacing the rings should give it a new lease of life.

I have pulled the bottom end apart, and I will be replacing the rings and most likely the rod and main bearings. See new post for bottom end condition.

as far as finished combustion chamber shape goes, look at well finished Chevrolet small block heads, thats the combustion chamber shape yu want to aim for.
View attachment 46224



SteveC

 

[Jepp78bertone]

Took the bottom end apart to remove the pistons to have the fly-cuts enlarged. This is what the bearings look like after just shy of 100,000km's looks like since the engine was built in 2015.

What should be the indication for them to need to be replaced?



Main bearings on block side. First pic being belt side, last being flywheel side

Crank Shaft

Thrust washer

Rod Bearings (they all had similar amounts of wear)

 

[Dr.Jeff]

Since you are going through everything with a performance build, maybe consider having the crank journals polished and install all new bearings...just for peace of mind.

 

[fiatfactory]

a few more thoughts,

1) I use a 22mm radius for the inlet flycut enlargement, just make sure the cut has a reasonable raduis to the inside if the cut, not a sharp / squared edge, (but your machinist should know that) and make sure you "break the edge" and smooth / round off the top sides of the cut as well, you don't want sharp / pointy edges anywhere.

2) If you are gong to retain a 300degree duration camshaft, then you really need to give thought to also skimming the block, to get the piston crown level with the deck surface, at the moment I think you said it's about 0.5mm down from zero when the piston is at TDC. You really need to get the static compression up, as otherwise your DYNAMIC compression will be too low.

With these engines I try to aim for the 9.5 - 9.75 : 1 range for simple dymanic compression ratio... and to get those sorts of numbers with a lobe that closes the intake valve at 80 ABDC you generally need to head above 11:1 static compression ratio ... but it actually requires you do do some math, you cant wing it and guess this.

below 9.5: simple dynamic ratio (with 95 octane premium fuel) performance wont be up to par, above 9.75:1 and the engine will have a tendancy to pre ignition/ detonation issues , so it's quite a tight window to aim for, hence the need for direct measurement.

the other way to get the simple dynamic ratio up is to reduce the inlet lobe duration, so the inlet valve closes earlier and the piston is further down the bore on it's compression stoke when this happens.

If the fuel you're using is below this sort of octane level, then the dynamic target drops down. (or if you had an engne with a cast iron head for example, the dynamic CR target window isnt a one size fits all)

This is why I spend a few hours doing math before I choose components for an engine build, evrry time.

3) Looking at the big end bearings I would be double checking the con rod big end journal I.D. for size, perhaps they are a little out of round?

4) I would also try and choose a better quality big end bearing. See how the machining cuts to the bearing go "across" the grain ... at 90 to rotation ... thats the simpler method of manufacture... but the machining pattern will tend to release the trapped oil wedge, letting it flow away from where it's required. Better quality big end beaing shells will have the material machined to size by planing the material "with the grain" and the machining grooves will be along the bearing and not across it... Old Italian made Clevite and Vandervell are like this ..the grooves running this way will tend to hold the oil wedge in place a bit better.

SteveC

 

[Dan Sarandrea (Phila)]

Inconsistent wear patterns on the mains could indicate out-of spec line bore or possibly ever so slightly bent crank. Were you planning to have the machine shop balance the rotating assembly? If so, have them check the crank for straightness, and send the block along as well, it might turn out that they will want to check the line bore. It's hard to be sure from pix, but the crank journals look like they need to be ground to the next undersize.

 

[Jepp78bertone]

Hi Steve,

a few more thoughts,

1) I use a 22mm radius for the inlet flycut enlargement, just make sure the cut has a reasonable raduis to the inside if the cut, not a sharp / squared edge, (but your machinist should know that) and make sure you "break the edge" and smooth / round off the top sides of the cut as well, you don't want sharp / pointy edges anywhere.

My pistons are now with my machinist who will be enlarging the inlet flycuts. He did contact me to ask me if I knew the exact radius size of the stock flycuts so he could find the center line and know exactly where to position the new cut?

2) If you are gong to retain a 300degree duration camshaft, then you really need to give thought to also skimming the block, to get the piston crown level with the deck surface, at the moment I think you said it's about 0.5mm down from zero when the piston is at TDC. You really need to get the static compression up, as otherwise your DYNAMIC compression will be too low.

I went ahead and had the block skimmed to get the piston crown level with the deck surface.

3) Looking at the big end bearings I would be double checking the con rod big end journal I.D. for size, perhaps they are a little out of round?

I had the engine builder measure and check the crank and rods and they checked out perfectly. He says I can use STD sized bearings. He polished the crank.

4) I would also try and choose a better quality big end bearing. See how the machining cuts to the bearing go "across" the grain ... at 90 to rotation ... thats the simpler method of manufacture... but the machining pattern will tend to release the trapped oil wedge, letting it flow away from where it's required. Better quality big end bearing shells will have the material machined to size by planing the material "with the grain" and the machining grooves will be along the bearing and not across it... Old Italian made Clevite and Vandervell are like this ..the grooves running this way will tend to hold the oil wedge in place a bit better.

Just received my new bearings from MWB. Matt had Clevite Rod bearings in stock, and Factory OE main bearings.


Once I can figure out the flycut's I'll get the bottom end back together.

 

[fiatfactory]

I don't know the exact size of the flycuts in the psitons you've chosen, but they are usually around R19.5, I recut them to R22.

SteveC

 

[Jepp78bertone]

Getting somewhere!

Its been nearly a year since I've last updated this thread on my engine build. Things have slowly been heading in the right direction. After waiting 8 months for the machine shop to finally get to work on my cylinder head (can't really blame him as Covid sadly forced so many of the other local machine shops to close their doors, he's acquired much of their customers and is swimming neck deep in orders that were placed a year ago) I finally have something to show for it.

Heres a summary of what I've recently accomplished.

CYLINDER HEAD
Starting with a NOS Yugo 1100 10 bolt head w/ 36/31mm IN/EX valves
- M10 stud holes will be drilled out to M12 to fit ARP head studs
- Combustion chambers opened up from 80mm to 86mm to suit 1500cc bore size. Initially just copying the stock 1500 combustion chamber shape until later to fine tune the cc and determine desired CR - Essentially trying to replicate a 1500 EURO head
- All seats are being replaced to suit 39.5mm Intake and 33.4mm exhaust valves
- Ports are being opened up to 28.5/29mm and Bowl work blended into larger seats as per stevec's ultimate SOHC guide
- Bronze valve guides to be installed and trimmed back to be flush with port roof
- 3 angle valve job and 30degree back cut on all valves
- sinking the exhaust valves slightly lower than the intake valves as per stevec's recommendation (plus i'll be using my old 33.4mm exhaust valves from my old head and they have been ground a touch before so this will move them up a tad to match the brand new AE Intake valve length )
- cam housing surface of head shaved 1mm (0.040") to accommodate reground cam's smaller base circle
- mill cylinder head surface to ensure true flatness and good mating surface to gasket

 

[Jepp78bertone]

BOTTOM END
- Stock 1500cc block bored out to fit 86.8mm pistons
- Stock 63.9mm crank and con rods with new Clevite bearings installed and clearances checked
-Crank polished and balanced
-Crankshaft oil galley plugs removed and cleaned out. tapped and plugged with 1/8" NPT plugs
-ARP stud kit 203-5403 installed for main caps (installed as per SteveC's stud installation guide)
- FIAT OEM 1300 small fly cut 34.7CH 0.6mm pop up pimple pistons with INTAKE valve pockets opened up to accommodate new 39.5mm intake valves
-Pistons and rods all balanced
-Block decked 0.5mm to establish pistons sitting at ZERO deck at TDC
-Cylinder bores measured and checked out within spec
-Block painted with High Heat Engine block enamel
-Cylinder walls freshly honed
-new piston rings file fit and gapped to spec
-true TDC established and marked on front crank cover
-Oil pump condition checked and measured within spec

 

[Jepp78bertone]

EXHAUST
-ANSA 4-2-1 header sandblasted and sent to be CERAKOTED
-header collects into a 2.25" pipe into DYNOMAX Ultraflo muffler
-Once engine is installed I can finalize the fabrication of the remainder of the exhaust system and how it exits out the back (i'm probably going to stick with the left side of the car like the ANSA Muffler I once had on it, as thats how the Ansa downpipe is configured.)

 

[FiatFunk]

You're doing nice work How'd you get everything so clean? I am doing a rebuild right now and you've got me thinking I should out more effort into making the head and cam boxes shine.

 

[Dan Sarandrea (Phila)]

You're doing nice work How'd you get everything so clean? I am doing a rebuild right now and you've got me thinking I should out more effort into making the head and cam boxes shine.

Trying to get and keep aluminum clean is a losing proposition. Grime gets into the pores and does not want to get out or stay out, and then there's the corrosion, that white powdery stuff.

Krylon Dull Aluminum #1403 is Da Bomb, da spray bomb, that is. Seals the pores, easy to clean, and even though it is technically not hi-heat paint, it doesn't have to be hi-heat on the head or cam box & cover.

 

[Jepp78bertone]

Crunching the numbers to get 10.5:1 Compression Ratio.

Following SteveC's guide.

A basic compression ratio calculation looks like this:

Volume at BDC is (swept volume + minus deck volume - dome )+ flycut volume + ring land clearance volume + gasket volume + chamber volume.

Volume at TDC is (volume in gasket - pop up - dome) + flycut volume + ring land clearance volume + chamber volume.

Volume of BDC over Volume at TDC is expressed as a ratio to one (xx:1)

Bore is 86.80
These Pistons are 86.30 above the top ring land and the top ring groove is 7mm down from the crown.
The Valve Flycut volume is approx 1.5cc
The Piston sits at ZERO deck
The dome is 0.6mm high, 39.5mm in diameter and a "spherical cap" in shape.
The Combustion Chamber volume is 31cc (non decompression recess head)
Your head gasket is going to be 1.2mm compressed and has an inside fire ring diameter of 87.15mm and will give a SQ clearance of 1.5mm

So let's do some math...

Swept Volume of the cylinder.
Pi x R squared x Stroke
3.14285 x (43.4 x 43.4) x 63.9
3.14285 x 1883.56 x 63.9
378.120cc

Volume of the piston 'zero deck'
3.14285 x (43.15 x 43.15) x 0
3.14285 x 1861.9225 x 0
0 ZERO deck

Volume of the 'spherical cap'.
[3.14285 x (0.6 x 0.6) x (3 x 19.75 - 0.6)] / 3
[3.14285 x 0.36 x 58.65] / 3
0.221cc

Volume of the head gasket.
3.14285 x (43.58 x 43.58) x 1.2
3.14285 x 1898.78 x 1.2
7.16cc

Volume of the ring land clearance.
[3.14285 x (43.4 x 43.4) x 7] - [3.14285 x (43.15 x 43.15) x 7]
[3.14285 x 1883.56 x 7] - [3.14285 x 1861.92 x 7]
41.42cc - 40.95cc
0.47cc

and then put these numbers into the equation,

Volume at BDC = (378.120 + 0 - 0.22) + 1.5 + 0.47 + 7.16 + 31
= 418.03

Volume at TDC = (7.16 + 0 - 0.22) + 1.5 + 0.47 + 31
= 39.91

V at BDC / V at TDC = 10.47 : 1

------------------------------------------------------------------------------------

Now this completely depends on a few things.
One of course being achieving 31cc in the combustion chambers.
Right now I'm at 29.5cc so I have a bit of material I still need to find to achieve 31cc. I'm going to ask my machinist if he can scoop some of the material out of the face of the valves, especially the intake valve. AND i'm going to have him sink the exhaust valve 1mm lower as per SteveC's recommendation "for improved flow around overlap"
This will subsequently gain some cc.

Here are some shots of my current combustion chambers. Remember this chunk of alloy started as a NOS YUGO 1100 head. Before I had any of the seat work/bowl/porting work done I had opened up the combustion chamber to the 86mm fire ring line.

This is a shot of that.


Here is the only chamber I've now opened up more to de-shroud more around the valves and shaped the chamber on the spark plug wall to create more swirl into the cylinder. I've measure its current volume @ 29.5cc.


Here you can see the valves installed. I think I'll be able to achieve 1.5cc by scooping material out of the intake valve face and sinking the exhaust valve down 1mm.


Here is a photo of the two side by side.


Here is a photo of SteveC's finished chambers that I used as a reference photo (I believe on a TIPO head with 37.5mm intake valves. Steve, please correct me if I'm wrong)

SteveC's Ultimate SOHC guide has been instrumental in my understanding of this whole process. Huge thanks and kuddos to him for all the information he has shared to this community. Also a huge thanks to all of you who have gone through these steps before (GregS, Rob Plenter, Jim Agnelli, Hussein, to name a few) and shared your experiences with me, whether that be in direct messages we've exchanged, or in the endless forum threads to read on xweb of all of your builds. I certainly wouldn't be taking on such a task without all of your help.