Hope my pics loaded with this diatribe that again brings up the compression issue. What I’d like to ask is what’re the chances this blower engine will survive with hypereutectic pistons with comp ratio of .312 pistons, 312 crank, .010 deck, .020 shaved 471s and sandwich gaskets. In an earlier note I mentioned I’d lost 2 engines to detonation with same config except .02 shaved Gs, whereby I learned barnyard tuning was fatal to this setup. I then built 2 more engines in same config but tire dyno tuned them, they’ve performed perfectly for many years but they don’t like less than 92 oct. Mr. Mummert suggested max 6 lbs pressure. I have to consider I’m again being stupid and should transfer the complete blower config to another engine with forged pistons, (like I have that kind of money anymore). I’d just change the pistons except I size bores to pistons.



The second question is how to vacuum a blower engine crankcase without big bucks for a vacuum pump? In Seattle an engine running short hops daily that doesn’t vacuum the case well gains too much water in winter. The only thing I can think of is a suction line in an exhaust pipe. My pal Frank sez even a blower engine usually runs with intake vacuum so he doesn’t worry about it, however he has far more F models than he can drive every day so may not get the water problem. Anyone know where I can find the stock power steering assembly for that Twuck? Had one once but didn’t install it cause I wouldn’t waste power on the pump, shirt sleeves don’t fit anymore.











Dan in Seattle

I'm a not a tech guy but my local race engine builder is convinced that I should keep compression below 9 to 1 for street use with my McCullouch. I'm measuring boost through the carb bonnet so am not getting a true reading. I see 6-8lbs of boost. Not  being sure how much boost you are running or compression I think I would try to stay in that range. Boost raises compression ratios and with todays lousy fuel you can have detonation problems (don't ask me how I know). I'm sure Ted Eaton will weigh in here with some tech talk but I understand 8 to 1 ratios are not uncommon for blown engines.

Is the engine going into the truck or the 57? The 57s are actually set up for cowl induction. That weird round plate on the drivers side firewall was used in NASCAR to bring fresh air in from the cowl. Many of us thought that they were access for the wipers but turns out it was another Ford bright Idea. Chuck in NH

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

I've been driving the F100 for 7 years now with the engine built as noted earlier, w/4 bbl it's way more than enough for those brakes/steering, gets 15-18mpg w/4:11/T85OD. That blower engine is installed in that Ranch but I'm not going to complete the car until I get a bit more education on this setup. I intend to use the Ranch as my driver and give the twuck to #2 son. I originally had the old school blower on that Ranch engine but couldn't get past the 50Hp it took just to turn it or the worry that those old pumps are constant wear when these new pumps are good for life and have no brng drag.



My real problem is that I have no compression base line for what I'm doing to these engines and am afraid of losing another good engine. BTW, that Ranch came from 28 year carport storage in Reno and was originally a so cal car. It was a complete runner when I got it and showed little rust, when it came back from the blasters it was holier than god himself, even the roof edges along the drip rails which I haven't seen in local 57s, here we rot them from the top down. Gary the seller said the carport was a dirt floor so the Ranch rotted from the ground up, I'm still ok cause he charged me a fair price and sent along a good real 57 312 for my EBird and spare T85OD to boot.



Something every day, I did indeed think that access was for wipers.

Dan in Seattle

Engine vacuum systems that use exhaust flow to generate a negative pressure at the crankcase are typically ineffective when the headers are run with mufflers and a full exhaust system in place; there’s just too much back pressure for a vacuum signal to be produced at the headers.  A vacuum pump off of a diesel engine would be an easy option though and these are available in both belt driven and electric formats.  But under normal driving and until the blower goes into boost mode, you do still have manfold vacuum present which means you can run a PCV valve.

 

With a 3.800” bore, 3.44” stroke, 78.6cc chambers with 471 heads milled 0.020” assuming they were 82cc’s to begin with, the pistons 0.010” in the bore, and a 10.1cc head gasket, the static compression ratio is in the neighborhood of 8.06:1.  With this in mind and using a mild camshaft, 6psi boost and a conservative ignition timing curve will keep the engine alive on premium fuel.  If the fuel mixture is leaned, too much total ignition timing is employed, the fuel octane is low, or just a small combination of each of these occurs, the engine will see damage regardless of the parts being used.  A camshaft with a later intake closing event along with being ground on a narrower lobe centerline will give more latitude in the tuneup before experiencing engine damage.  But modifying the camshaft specs so that the engine is less sensitive to the use of lower octane fuel will normally sacrifice lowend driveability and performance so the tradeoffs must be considered.

Lorena, Texas (South of Waco)

Thought I stuck a reply here this morning but don't see it, hope I did a better job getting the const. crew in gear.



Ted, looks like you did quite a bit of work helping me here so thanx very much, I think this will work just fine as long as I mind my tuning, gas and manners. Not sure what you guys call a mild cam, all of mine are .465 with my 1.54 rockers, .228@.05 except the blower cam is 113C/L, they're radical enough for me.



I just tripped over Tim McMasters head chart and see his note about Ford comp ratio calc is just the head chamber. Suspect the note that 'most comp ratios are 9% higher' is a typo and meant lower.



Also thanx for the clue to the diesel vac pumps. Now to find some money so I can get that Ranch painted up and on the road. Really anxious to see what it does on the chassis dyno.




Dan in Seattle

I figured Ted would hop in here. That means your compression ratio is fine all things considered. I'm running the G heads and suspect its a bit much. Ted is reworking some blower heads for my new engine. Like I said I am certainly not a engine tech in fact far from it. I wish I could find a decent Y-Block tuner here in New Hampshire but no luck so far. There are quite a few Y's but not many performance minded owners. Chuck in NH

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Shoot, I'm a member of the local Bird club and there are lots of Yblock cars around here but same as you're seeing, most just build them near stock, some of these actually have bias ply tires on them! Felony waste sez I.

Dan in Seattle