Fiat-Abarth 124 16v under dev

GC porting, development, valve and seat work, combustion chambers, cams, head construction, etc
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Guy Croft
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Fiat-Abarth 124 16v under dev

Post by Guy Croft » Mon Oct 27, 2008 1:04 pm

A very rare early Gp4 16v Fiat Abarth head under dev at GCRE, started as a raw-unfinished head straight from the factory, owned by the well-known Mick Wood for his 124 CSA.

More later,

GC
Attachments
M Wood 124 16V 08.171 test 1,  in port as-is at dia 22mm flows 97.1cfm @ 10in.jpg
testing head as 'raw factory casting' & rather tiny ports. Port 4 (right) is the dev port where I proved out the effect of porting to c 25mm dia to get an idea of flow potential.
M Wood 124 16V 08.171 test 1, in port as-is at dia 22mm flows 97.1cfm @ 10in.jpg (115.81 KiB) Viewed 16013 times
MW 124 16v cc's dressed and seat bores prelim machining prior to full inlet porting.jpg
head after cc relief and prelim boring ops centred on guide bores after precision reaming. Note the tiny M10 spark plug threads..
MW 124 16v cc's dressed and seat bores prelim machining prior to full inlet porting.jpg (113.71 KiB) Viewed 16012 times
MW 124 16v porting 012, checking splitter thk with calliper.jpg
when you're working on a raw casting you have to check very diligently that the port features and dimensions match the development port
MW 124 16v porting 012, checking splitter thk with calliper.jpg (111.96 KiB) Viewed 16005 times
MW 124 16v porting 017,  port from cc end, showing throat 'roughed out' by hand prior to machining to final dia when seats go in.jpg
next op is ex ports then design and installation of GC race guides to the 34/28mm 7mm stem valves
MW 124 16v porting 017, port from cc end, showing throat 'roughed out' by hand prior to machining to final dia when seats go in.jpg (116.93 KiB) Viewed 15994 times
gc 075.jpg
GC adaptor to original inj manifold to carry twin 45 DCOE
gc 075.jpg (111.91 KiB) Viewed 15027 times
gc 074.jpg
carb angle is designed to be 5 deg downdraft, right on the Weber design limit.
gc 074.jpg (116.19 KiB) Viewed 15022 times
gc 071.jpg
View thru adaptor into inboard section of old Abarth inj manifold
gc 071.jpg (111.16 KiB) Viewed 15014 times

Guy Croft
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Re: Fiat-Abarth 124 16v under dev

Post by Guy Croft » Wed Nov 19, 2008 2:00 pm

shot of the engine bay on the 124 CSA with the (pre 131) 16v head
Attachments
124 CSA 16v underhood.jpg
124 CSA 16v underhood.jpg (95.01 KiB) Viewed 15330 times
gc 023.jpg
ex ports marked out to same dia as intended valve throat
gc 023.jpg (111.41 KiB) Viewed 14999 times
GC 009.jpg
The throats, well I could have had them bored out when the prelim bores for seats were done I guess but here I am doing them the hard way. The seat setup is drawn on cad first to tell me the throat diameter I need, I fettle a bit undersize and will finish after seat installation
GC 009.jpg (117.46 KiB) Viewed 14989 times
gc 026.jpg
Near finished ex port - you can see how much metal has had to come out - ready for prelim test. The E/I turned out at 65% - low partly because there is no seat fitted (which disupts the flow) and because the throat is not at final spec. The ex valves are 28mm with 34mm inlet, I may need 29mm ex, so will fit oversize seats - just in case.
gc 026.jpg (117.62 KiB) Viewed 14980 times

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Re: Fiat-Abarth 124 16v under dev

Post by Guy Croft » Thu Dec 11, 2008 9:38 am

Fully finished ex ports at 120 grade with final coarse Scotchbrite finish - finished excepting that there will of course be some corrective work to do around throat after inserts go in. Next job guides and seats. Ex ports are nominally 24mm dia thru, same as valve throat diameter.


Gc
Attachments
MW 16v 124 ex ports finished.jpg
MW 16v 124 ex ports finished.jpg (112.68 KiB) Viewed 14753 times
MW 16v 124 ex ports finished (5).jpg
MW 16v 124 ex ports finished (5).jpg (116.86 KiB) Viewed 14727 times
MW 16v 124 ex ports finished (3).jpg
MW 16v 124 ex ports finished (3).jpg (107.44 KiB) Viewed 14724 times
MW 16v 124 ex ports finished (4).jpg
MW 16v 124 ex ports finished (4).jpg (116.06 KiB) Viewed 14721 times

Guy Croft
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Re: Fiat-Abarth 124 16v under dev

Post by Guy Croft » Tue Dec 15, 2009 8:36 am

Not had a chance to update this thread for months but here goes at last...


GC
Attachments
MW_01 post-seat port correction (8).jpg
MW_01 post-seat port correction (8).jpg (115.86 KiB) Viewed 10269 times
MW_01 post-seat port correction (10).jpg
MW_01 post-seat port correction (10).jpg (120.03 KiB) Viewed 10269 times
MW_01 post-seat port correction (11).jpg
MW_01 post-seat port correction (11).jpg (111.79 KiB) Viewed 10269 times
MW_01 post-seat port correction (3).jpg
MW_01 post-seat port correction (3).jpg (116.87 KiB) Viewed 10269 times
MW_01 post-seat port correction (6).jpg
MW_01 post-seat port correction (6).jpg (116.32 KiB) Viewed 10269 times
MW_01 (9).jpg
MW_01 (9).jpg (109.69 KiB) Viewed 10269 times
GC04 Sept 09 015.jpg
GC04 Sept 09 015.jpg (118.89 KiB) Viewed 10268 times
MW 08.171 valvetrain 006.jpg
measuring valve stem diameters, not the 'truest' valves in the world I have to say..
MW 08.171 valvetrain 006.jpg (113.89 KiB) Viewed 10268 times
MW 08.171 valvetrain 007.jpg
recording tip heights and collet positions. When you are working from scratch on heads like this it is SO easy to make them 'unshimmable', every detail of the valvetrain had to be slavishly drawn up BY ME before any seat machining work was undertaken. You can 'take it off' - but you can't 'put it back on' is the guiding principle..
MW 08.171 valvetrain 007.jpg (109.04 KiB) Viewed 10268 times
leak testing valves head _01.jpg
leak testing valves head _01.jpg (114.23 KiB) Viewed 10268 times
head _02 RTB.jpg
this second 124 16v head (_02) has been left 'as-is' from Abarth, all I have done is major deburr, seat regrind and reface. it outflows _01 that I have prepped (above) on ex by a marginal and insignifcant amount but is nowhere near as good on the inlet side. This head has a 36cc chamber compared with mine at 30cc, all to do with valve setup height really.
head _02 RTB.jpg (113.41 KiB) Viewed 10268 times
_02 chamber closeup after seat overhaul.jpg
_02 chamber closeup after seat overhaul.jpg (118.92 KiB) Viewed 10267 times
cc'ing _01.jpg
cc'ing _01.jpg (110.66 KiB) Viewed 10267 times
GC 025.jpg
the most diligent regime is needed here as the cam end float is set by gaskets in the end housings. Not fun. Numerous locating diameters on front and rear housings can 'clash' with each other and it's vital to ensure the cams turn freely. Get the end float minutely wrong and the cam lobes hit the housings too..
GC 025.jpg (111.85 KiB) Viewed 10267 times
bolting cam thrust plate in housing.jpg
bolting cam thrust plate in housing.jpg (112.41 KiB) Viewed 10267 times
checking cam end float (over and over).jpg
checking cam end float (over and over).jpg (112.72 KiB) Viewed 10267 times
checking proper distributor meshing..jpg
Any damage to the gears and they won't turn at all which is very alarming till you find the cause
checking proper distributor meshing..jpg (111.53 KiB) Viewed 10267 times
MW_01 trial shimming.jpg
Terrific amount of 'sub assembly'work has led to this point and the hard bit is only just starting. Both heads need to be 'trial' shimmed to make sure they can be shimmed 'at all', esp the scratch-prepped _01 with GC seats. The work's all the more difficult because there are about 6 thicknesses of cambox gasket available, both heads use solid buckets and top hat shims and the gaskets settle every time you unbolt the camboxes. Quite simply, you have to build over and over tillthey stop and the clearances stabilise. Of course you have to adjust the shims each time. The biggest risk is the M8 threads 'giving up the ghost' after repeated strip/assembly.
MW_01 trial shimming.jpg (82.54 KiB) Viewed 10267 times
bolt lubrication.jpg
The bolts are stainless A2/70 or Zn plated 8.8 grade steel and they must have oil under the heads or they will gall on the washers. The threads MUST have copper anti-seize grease or they are going to rip the threads out of the head in an instant.
bolt lubrication.jpg (114.38 KiB) Viewed 10267 times
MW_01 fitting valves & springs without seals for trial shim.jpg
The sub assembly technicians at Abarth must have dreaded doing these; trial shimming without stem seals to avoid damage to them as valves are fitted and removed for tip height correction
MW_01 fitting valves & springs without seals for trial shim.jpg (113.84 KiB) Viewed 10267 times
GCCC 018.jpg
final (did I say that??) shimming on _02. In reality I had this apart 3 times over 3 days as the gaskets settled constantly. I really doubt if one of these EVER left Abarth with clearances (20 thou ex, 16 thou inlet) closer than 2 thou
GCCC 018.jpg (115.51 KiB) Viewed 10267 times
GC 001.jpg
These heads have very long tip valves and unlike most the springs never penetrate the buckets. I chose proven, modern 16v springs (Piper Honda VTEC for _02 and Piper Vauxhall XE for 01, both interference packs) and ran them thru my Lotus simulation software to assure their performance with the 16v 124 valvetrain and get an idea of float speed. _01 had my own design spring bases and I _02 - whose spring bases I could not remove (they were held fast by the Abarth bronze guides) so primarily I had to use a spring pack that was compatible with them. Mercifully the installed heights worked out OK but I must confess these heads taxed my patience on a daily basis.
GC 001.jpg (118.61 KiB) Viewed 10267 times
_02.jpg
ex-Abarth head ready to fit
_02.jpg (110.82 KiB) Viewed 10266 times
all 3 blocks RTB.jpg
3 x 1800 124 blocks fully ready for cranks and build. The one in the middle is a genuine Abarth one. A machining error at the factory led to it being 'scrapped' or at least - never used; a threaded hole was force right thru the main oil cross-feed gallery - hence the GC alloy plug in the middle of the block. That modest repair has turned 'junk' into something of incredible rarity value.
all 3 blocks RTB.jpg (113.74 KiB) Viewed 10266 times
TOP setups - GC and Abarth castings machined at GCRE.jpg
nice little selection of oil take-off plates: L-R heavily repaired/welded Abarth one, new Abarth one machined up at GCRE, Gc TOP. Fittings are anodised alloy. The TOP will carry a low pressure switch only and oil temp/pressure will go on the hose line/remote filter, allowing engines to be changed without messing about swapping instrument senders. Always a risk of debris from threads getting into the engine if you do that.
TOP setups - GC and Abarth castings machined at GCRE.jpg (108.83 KiB) Viewed 10266 times
GCC 009.jpg
oil pump clearances for both 124 16v units AND the GC 'Works Replica' 8V for Mick Wood were assessed before overhaul (and parts chosen from a big box of donor pumps) and then again after polymer coating
GCC 009.jpg (112.95 KiB) Viewed 10265 times
GCC 019.jpg
overhauled, coated, numbered, certified - 3 x oil pumps for 3 beautiful engines
GCC 019.jpg (115.35 KiB) Viewed 10265 times

Guy Croft
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Re: Fiat-Abarth 124 16v under dev

Post by Guy Croft » Mon Feb 15, 2010 6:31 pm

2 not one built, shimmed and timed up ready to fit.

GC
Attachments
IMG_0062.JPG
IMG_0062.JPG (133.89 KiB) Viewed 9101 times
IMG_0061.JPG
IMG_0061.JPG (142.84 KiB) Viewed 9101 times
IMG_0060.JPG
IMG_0060.JPG (133.09 KiB) Viewed 9101 times
IMG_0063.JPG
IMG_0063.JPG (128.4 KiB) Viewed 9101 times
IMG_0064.JPG
fun with cam timing on the GC prepped head
IMG_0064.JPG (124.5 KiB) Viewed 9101 times

Guy Croft
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Posts: 5004
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Re: Fiat-Abarth 124 16v under dev

Post by Guy Croft » Thu Jul 21, 2011 2:57 pm

Skipped a few photo steps on this 1st build but finally got the new GC design HTD pulleys in for this engine so here is a snapshot of one of them nearly ready for test.



G
Attachments
MW 16v_final belt setup.JPG
MW 16v_final belt setup.JPG (264.97 KiB) Viewed 4361 times
IMG_3249.JPG
IMG_3249.JPG (277.88 KiB) Viewed 4361 times
IMG_3250.JPG
IMG_3250.JPG (278.91 KiB) Viewed 4361 times

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