Snyder 5.5 Changes Things

[Brobrian]

I put a Snyder H/C head on my '28 coupe last week. The car runs quite differently now. This motor has been purring like a kitten for 20 years, but has seemed a little under powered. Especially with the higher ratio rear end I put in a few years back. (Sorry, can't remember which one. Might have been a 3.52)

With the new head it has a touch more power. Also, it cranks over more slowly when starting. It sounds a little more rumbly and runs slightly rougher as well. Today I noticed that when driving at less than full rpm and under a load the engine knocks (not a ping) a little when the spark is fully advanced. The knock goes away when I move the advance to about the middle. However, on the highway the car now cruises along at 50 -55 quite easily with the spark fully advanced.
Nothing scientific here, and I've heard a few of these comments from others hear at the Barn, but I thought I'd share my observations.

[Tom Wesenberg]

Don't use too much advance, or the engine can be damaged. The higher compression head will use LESS advance than the stock 4.2 head.

I have the stock head on mine and rarely use full advance. Full up to start, then half way down for idle and slow speed, and about 3/4 down for 40-45 MPH.

I'd like to have a 3.27 rear end.

[Mike V. Florida]

You will have to learn once again what your needs to operate now that you have the new head. Higher compression changes a few things; idle, advance, and exhaust sound are a few.

[Brian T]

Did you just purchase the head from Snyders? as they have been on backorder for some time, and was there a problem with stud length that as been discussed recently.

[Brobrian]

Never had to mess with the advance before. Full up to start and chug along, and full advance to run. That's were it worked best.
Now, things are different. I'm having to consider where to put the advance. Just got back from the hardware store and confirmed that I like town driving at about half advance. I still like the full advance at 50 - 55. Hell, I've never gone 55 in the car before unless it was coasting down hill.

[Brobrian]

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Originally Posted by Brian T

Did you just purchase the head from Snyders? as they have been on backorder for some time, and was there a problem with stud length that as been discussed recently.

I've had the head for a couple of months. I was waiting for the old man to come out so we could put it on together. He had a blast, by the way. Spent the whole four days messing with the "A''s. Brought down a motor he'd overhauled himself, and which he says he pulled from his father's (my grandfather's) combine harvester.

[Aerocraft]

You will find that the starter will labor if the ignition is not fully retarded.

Of course the higher power is terrific but I drive mine just as I did with the stock head unless I need more "zip" to get into traffic quickly. I do enjoy the much improved gas mileage. Gar Williams

[TerryH]

I've had my 5.5 HC head for about 5 years now on my 1930 TS and I have always been very happy with. I don't remember too much about it sounding and running that different at first, but maybe I have forgotten. I have also found that about 1/2 advance works best most of the time, and if I am on the freeway in overdrive at 60, then I usually give it 3/4 to full , but listen carefully to it. A great addition, especially on the heavier sedans. You will enjoy it!

[pat in Santa Cruz]

Rich Fallucca recommends no more than 28 degrees advance at any time, preferably only at high speed, with less when slow or laboring under a load. Les Andrews recommends around 25 degrees max with HC heads. If your timing is set at zero fully retarded, half mast is 20 degrees, full is 40. Count about 4 degrees per click. If you can feel the power level off as you advance that's where you want to stop. Too much will flatten your bearings pronto.

[Marco Tahtaras]

The increased compression speeds the burn of the fuel mixture in the cylinder which in essence advances your timing.

I set my timing so with the lever fully retarded I am essentially firing at TDC. Most folks set their timing a bit more retarded than that although they often don't realize it. When everything is setup as the cars were when new, the distributor had 40 degrees advance. If you have the timing set as I do that means full advance is 40 degrees BTDC which is way too much with 5.5-6.0 compression. In my experience 30 degrees is about the limit unless you are approaching 3000 RPM or more then you have a little more wiggle room. The result is NOT an audible spark knock but instead a pounding of the engine that resonates up through the controls. You can feel it but I doubt a passenger could.

Originally the spark lever quadrant had ten notches for the lever. Each notch advances the timing 4 degrees. The seventh notch is just slightly above parallel and provides very close to 28 degrees advance on my cars so that gives you an idea. From your description is sounds like you are running slightly more retarded than I am. That is actually too far advanced to just leave the lever in that position unless you keep the RPM way up through the gears like I often do but this is not common among "A" drivers.

As far as your engine running a bit rough, it shouldn't. In fact they often tend to run smoother when you increase the compression. My first thought is the added compression brought to light a minor weakness in your ignition system. While I've done ok running 3X plugs gapped at .035", Ford specified .025" gap with their high compression "Police head". my suggestion is to clean your plugs and try gapping them at .025". It may not pay off but it's worth a try.

[Geo. H]

Uh, Mister Ford Garage, maybe you're the only one in step, but I think you need to check your facts. Everyone I know thinks higher compression speeds the burn.

[dumb person]

Really?

[Marco Tahtaras]

Originally Posted by Geo. H

Uh, Mister Ford Garage, maybe you're the only one in step, but I think you need to check your facts. Everyone I know thinks higher compression speeds the burn.

That was just a VERY late night snafu (been there, done that). References have been deleted.

Thanks

[Aerocraft]

For what its worth, when installed in an airplane such as a Pietenpol, the generally recommended mag timing is 28 degrees BTC. Most of the mags that are used have an automatic retard termed an "impulse" that delays the spark roughly 25 degrees for starting. The impulse stops functioning when the RPM reaches 300 - 400 rpm.

There are a few of us that for years have tried to educate our local club members that the spark lever is not an "up to start, down to run" tool. Of course the "up to start" is correct, but "down to run" is not. We have tried to teach that "3/4 down to run" is much better for the engine. Of course, "tune it for conditions" would even be better.

As an aside, here is a picture of the drive for the magneto as recommended by Bernie Pietenpol.

Gar Williams

[Tom Wesenberg]

Gar, Is that a tach drive on the front of the camshaft?

Is that a special thrust bearing on the front of the timing cover? What is used to take the forward pull of the prop? Thanks

[gilitos]

Brobrian, Given your satisfaction with the HC head, maybe you should change your tag line to read "Fifty horses is plenty"!

[40 Deluxe]

Believe it or not, Tom, prop thrust was taken by the stock setup!

[TinCup]

Before I changed out heads I usually ran the advance about 3/4 down when running 40-45. After the head change I found that 2/3 was all that was needed to find that sweet spot. Other than the hi-comp head I have a stock motor. Didn't know about the gap for the plugs being .025". Will change that and see what we get.

[Brobrian]

Wow, I love all this info.!
It's cool to try something out and find your experience validated by the engineering as much as it is to discover that starting with the design translates to the experience. So I found the"sweet spots" in various situations. I was still a little uncomfortable with what I found. Thought maybe I'd made a mistake, until the rest of you guys shared the same observations and explained the reasons. Now I think I'll enjoy the new head with the different characteristics with more peace of mind.
Thanks, now I'm off for another drive.

[Aerocraft]

Originally Posted by Tom Wesenberg

Gar, Is that a tach drive on the front of the camshaft?

Is that a special thrust bearing on the front of the timing cover? What is used to take the forward pull of the prop? Thanks

Tom: Yes, the tach is driven by a cable that plugs into a drive very similar to the Model A speedometer drive. A fitting is screwed into the end of the camshaft.

What appears to be a thrust bearing is actually a holder for a Garloc seal which keeps oil from leaking out of the crankshaft. This engine has insert bearings done by Rich Falluca. The thrust loads are carried by a bronze split thrust washer on each side of the rear crankshaft bearing.

Due to the need of a tach drive, the two front castings which cover the timing gear are replaced by a split flat .062" steel plate. The front of the pan is cut off and half of that plate is welded in place. Originally, the rope front (rear in the airplane) seal was the oil seal. Pietenpol changed that by the addition of the two plates and he also installed a slinger to act as a "oil seal". The slinger works poorly at best and the Garlock seal works very well. My engine had the slinger and I recently machined the holder and added the Garloc seal.

Gar Williams