High compression question.

Bassman/NZ

Bassman/NZ

Well-known member
Does high compression (155lbs) require a step hotter plug, or should a standard plug do the job? How about the distributor advance plate setting? More advance or less advance? This is a stock C59A with milled heads.
 
Start with the standard ones and check how they act then.
Depending on if you run it hard and get issues with selfignition you might need colder ones.
You can swap in colder plugs untill you get issues with fouling or hotter until you get selfignition.
Somewhere in betweeen is where you want to be !
 
Generally good advice posted above. 155 lbs. is not really "high" cranking compression. One of my Flathead cars has 170 lbs. and uses stock(H-10 equivalent) spark plugs without a problem. I am aware of others with even higher cranking compression using stock heat range plugs. Iron heads and NASCAR-type driving might call for a colder plug.

Yes, higher compression ratios usually need slightly less spark advance than lower ratios. This is especially true at high speeds.
 
My 40 coupe has 160# cranking compression, I built that engine 40yr's ago, got over 100G on it. I had a lot of pinging problem, running crab dist, I kept welding up the advance slot weights to about 17-18* total, played with vacuum retard, screwed down about half way. Run the cheap gas, no ping, will scream to 5000 like nothing. Walt
 
My thinking is that the engine will never need more than factory advance max degrees.
It may need to come in sooner or later but never above max.
The basic configuration of the engine never changes , ie: same valve type, and engine design.
Do anything ya want but its still a flathead...

Heres an extreme flathead from Ken Makuch

https://www.facebook.com/ken.makuch.3/videos/vb.100007419553975/1429365660654072/?type=2&theater

180 mph with no blower!!! Twin 4 barrells 780 cfm each......
 
The curly pipes must quiet it down a lot.
For making that much hp, it sure isn't very noisy.
Even as it is, those guys are going to have ringing ears without ear muffs.
 
Tim Ayers said:
Agreed. Man, that was bad a**!

Walt,

I noticed you said your motor has 100K miles on it? Man, that's awesome that it is still so healthy. Is the same motor that you run the 4X2 intake on?
Click to expand...

Tim, it's the same engine with the 4 97's, I've had everything on top from 2 carbs-3carbs- 4bbl, McCa Super charger, I did break a second ring land on one piston at about 50G, I couldn't get one 1/8 piston so I bought a new set, the new set was .002 bigger so I just hone .002 and had a new engine again, It has the same main bearings for 40 years, I did put a new set of rod bearing in with the pistons. I've done a lot of long trips, T5 trans and 9in. rear with 3:50 gears, 60mph 2000rpm, that's probably saved the engine on long trips. Walt
 
what are you guys doing to get such high compression numbers? please be specific, if you would.
thanx,
tom
 
276ci, 3-5/16x4, not relieved, 40thou piston clearance, this is in my 40. I have 2 of these engines, I have a 3rd, in my dragster, 286ci, less comp ratio, big reliefe , 2.600 intake valves, Potvin 425 cam, this engine is a screamer. I have one 276 on my test stand for sale, I,ll post it on the sell section. Walt
 
BUBBAS IGNITION said:
My thinking is that the engine will never need more than factory advance max degrees.
It may need to come in sooner or later but never above max.
The basic configuration of the engine never changes , ie: same valve type, and engine design.
Do anything ya want but its still a flathead...

Heres an extreme flathead from Ken Makuch

https://www.facebook.com/ken.makuch.3/videos/vb.100007419553975/1429365660654072/?type=2&theater

180 mph with no blower!!! Twin 4 barrells 780 cfm each......
Click to expand...


How much horse power is that thing making? Sounds quite fit.
Martin.
 
scooder said:
How much horse power is that thing making? Sounds quite fit.
Martin.
Click to expand...

I thinks its 300 horse power , first time i have ever heard about 300 HP with out a blower. Theres a couple threads on the hamb board about Ken and this engine . They have done a ton of camshaft work etc...
 
Although some may disagree, I don't believe 200 HP is obtainable with out extensive block modification. Going back ti the 50's when guys like Bob Francisco and Ray Brock built an dynoed an engine in Hot Rod nag they couldn't get over 200 hp with out Nitro. In a week or two a 294 with Eaton blower will be on the dyno in CT. looking forward to the results.
As for max advance in a flathead: this is a trick question. Max advance depends on the combustion chamber configuration at WOT and Cruise load. I and others have found that between 18 and 20 is max at WOT and even a slight retard at hi revs. In cruise is another problem, Here the AF and cylinder turbulence and spark plug location will determine the amount of advance is needed.
Yes this can be averaged out for a so-so advance curve that works OK, because the factory tuning methods of the 40' through 80's did it that way. Today we hav engine management systems that can improve on them and have a cleaner running to boot. We just have to have an open mind, and it's not just "good enough" We can make it better, we just have to thimk???
 
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