Don’t know what the colortune device is but it reminds me of doing “plug chops” on my old H1 triple trying to balance the carbs and get the proper color of plug burn, then change it and do em again! Ah the good ole days

One other thing - the posted H72 cylinder head combustion chamber volumes for aq stock head are totally wrong. The Wiki says 29 to 31 cc's, I have a brand new NOS H72 head, never milled, installed, etc.. and it cc's at 41 for the chamber volume.

Wiki be wrong!!

Attached are the compression worksheets I created. This is the engine in previous posts with the Arias forged pistons, shaved crank, originally had a F10 flywheel & clutch , I'd already stole the Cannon single sidedraught manifold for the A15 in the car, H72 match ported head, etc...

I'm wondering if anyone has ran a similar setup w/a real worked up ratio ? I cc-ed the combustion chamber, piston volume, negative deck clearance volume, calc-ed the head gasket (Felpro Printoseal) managed to buy another NOS one - all metal gasket @ .041 compressed thickness. I've clearanced the pistons and head with clay so I know what all those numbers are now.

Have to talk to Delta Cam as its a fine line between grinds for above 10.5:1 and below.

Interested in how this will run. Obviously it'll need as high an octane as I can get but I think pump gas will be fine. Lookin for real world experience , thoughts anyone?

thanks,
evan

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Wow, it’s amazing how perceptions can differ.
In my Unhumble opinion Vegas were poor running , unreliable , rattling, poor quality tin cans of the era. Ranked up there with the likes of the other great America POS cars such as the Pinto, Chevette, Monza & Citation. Plymouth at least imported a Mitsubishi to badge as an Arrow or a Colt.
I don’t know about the Cosworth motors as I never saw one in the shop but trust me the above list were always in there plagued with repairs....the Citations less so as they were 80’s era tech.

I just remember working on Vega’s and test driving them thinking how poorly they drove and handled. One gals car was in all the time for clutch cable adjustments, brake issues, constant out of tune and body integrity issues inside and out-oh yeah, panels on those rotted out very prematurely too.

The big 3 were good at mid and full size cars, not the new econobox types like a 1200. Seemed like every import mfg-er had Detroit beat except perhaps Yugo.

Look back at GM’s 68 firebird with a Sprint 6 OHC motor- reliable, good tech, 4 barrel carb, belt drive cam I believe. That was pretty decent setup for the era and it was older they then the Vega era.The Vega and others were a rush to market solution to compete against everything imported.

Sorry if I’m raining on anyone’s parade , purely my unhumble, bias opinion based on my experience of working in a shop back in the day.

the head is off so I did all the CC volume on both the head and piston volume I just haven't gotten to the final calc's to figure out the ratio.

I set the piston at .300 down in the hole then filled so I need to compensate for that to work backward to the ratio, no time for math today!

I dont think the pistons have been milled either.

No seals on exhaust = smoke out of tail pipe....right ?? going in the chamber, burning in next cycle or in the pipe I'd assume, seems like good insurance - right or wrong?

Another question - stem seals on exhaust valves, good insurance or unnecessary ??

thoughts....

As stated in title - I need to figure out the volume of the cyl head chamber so I can determine compression, never done this before so not sure how. I figure someone here has done this numerous times and knows some tricks!

running Arias forged pistons, not sure how that affects the calculation as its certainly not flat which I assume changes how one computes the actual space between piston and head at TDC....

head gasket compressed at .041 - felpro Printoseal - steel sandwiched gasket, have original compressed one and new one for rebuild.

Thanks for the help!

Hi Ernie,

hey, thanks for the offer of the motor mounts, doug in Portland came up with a pair along w/stock pan & pickup. I was wondering who you use around here for machine work anymore --any suggestions.

course Im assuming you didn't pin you're own crank, maybe I'm wrong??

Thx - Evan

thought this was interesting in the motor, Pulled the head and found what I think are Arias forged pistons.

Compression came up to 190 PSI on all 4 cyl's , this might be a fun motor once back together.

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I wondered about the connection to the cam as well, I looked up while hand cranking the engine & I see the pump gear meshing & turning with the cam.

Only thing I can think of is cranking motor over with starter only the RPM's aren't fast enough to pull up oil into the pump let alone build oil pressure, engine has to run to make pressure. I cant imagine starter RPM's are at 800ish, probably more like 200 or less which seems like it wouldn't pull oil up at that rate.

Just speculation, I dont know. Thought maybe one of the hotshot engine builders of down under would know - I'll ask Rob at Action Machine if thats a reasonable guess.

It really seemed like the silicone plug I pulled out of the pickup tube end was the obvious stoppage, it was woven into screen basically capping the pickup - 4th pic, 1st post - looks like hair ball but rubbery