Y-Blockhead
Well-known member
I agree, just make sure you are calling out the correct person. In this case I believe you were not.
High Compression Head Review
- Thread starter Model A Ron
- Start date
I agree, just make sure you are calling out the correct person. In this case I believe you were not.
Jim Brierley
Well-known member
My head hurts!!!
Dave in MN
Well-known member
On the average, from my dyno running of engines, the 6:1 will produce about 2 hp more than the 5.5:1 head. Not lots of difference but close to 5% more hp.
Good Day!
Good Day!
Well, Ron has stated a universal truth as proven out by most comments that follow.
Ron, you did alright, you found a combination that makes you happy driving your car. Your turn around to make a recommendation on the 5.5 head for an otherwise stock engine makes sense since there are many who are wondering the very same things that you were.
Stingray70
Senior Member
johnneilson
Well-known member
That's because your compression is too high!
or he might be running a little retarded.....timing!
John
Model A Ron
Well-known member
Thanks GeneBob
I do think the 6 to 1 head makes more sense if you plan on making additional modifications and I do think it's a good head but then again that's just my opinion. As for me the 5.5 head works and once I have my Mitchell in my modifications will be finished. My vision was to have a Model A that could do 55/60mph all day long if needed. I do think 45/50mph is a better speed however I do plan on taking long trips in my car and I will have the need to travel a little faster on occasion.
I actually expected a certain member to play the part of "Mean Girl" so I intentionally said:
"In my opinion and remember everyone has one....I could not tell a difference between the two"
I just never expected it to come out in the way it did but I am a big boy and I can take it. I actually find it rather entertaining having someone question my mechanical ability because I recently acquired my Model A. I may have not made a business out of restoring cars but I can find my way around my shop.
I have actually been criticized on hear for asking questions and was told to drive my car and I would magically get experience
I guess to some people drawing from hundreds of years of experience for opinions is a bad thing.....better to just re-invent the wheel lol 
. Just for the record this is not my first car but as I become more acquainted with it I can tell you it's the most simple car I have ever owned. lol Regards,
Ron
Last edited:
Ranchero50
Senior Member
Ron, one thing that hasn't been noted is that most efficiency improvements are leveraged by percentage, not outright HP. That's why the head works oh so much better with a B cam and manifold setup. Kind of neat that a 4hp improvement in +10% on a 40hp engine.
Also to figure out your best timing play with the adjustment on a long slope with the same throttle setting. It'll let you know when the timing is correct. It's also interesting that after the model A, that lever went away so it truly didn't pass the test of time.
Model A Ron
Well-known member
Ron, one thing that hasn't been noted is that most efficiency improvements are leveraged by percentage, not outright HP. That's why the head works oh so much better with a B cam and manifold setup. Kind of neat that a 4hp improvement in +10% on a 40hp engine.
Also to figure out your best timing play with the adjustment on a long slope with the same throttle setting. It'll let you know when the timing is correct. It's also interesting that after the model A, that lever went away so it truly didn't pass the test of time.
I appreciate the advice. I feel that I may need to give the 5.5 a little more advance than I have been doing so you tip is very useful to me.
As for the Model B cam and set-up I am not sure if I want to go there. I will see how she drives with the Mitchell in a few weeks but all I was after was a constant 55 to 60mph when needed without racing the engine. To be honest 45 to 50mph is just fine most of the time until the speed limit jumps up to 55. I do not like to be the guy holding up traffic and getting passed all the time.
Thanks again
Ron
Last edited:
If I had not needed to rebuild my engine, I doubt I would have made as many changes as I have. If the engine had been rebuilt when I bought it, as I was told it had been, I would probably be running a 5.5 or 6:1 with the Weber and the cast iron "header". I think that would be the best bang for the buck; plus the ignition maybe. Even then, I am not sure the Weber and exhaust manifold would be worth it on a stock engine.
If you want to see a good comparison, check out Piriano's website. They have dyno runs on a lot of combinations so you can see which changes make a real difference.
If you want to see a good comparison, check out Piriano's website. They have dyno runs on a lot of combinations so you can see which changes make a real difference.
Jack Shaft
BANNED
soak it in cider...
Jack Shaft
BANNED
The camshaft ties it all together.. I'm no expert on cam profile but I can tell you Ford redesign of the cam for the 'new and improved' 4 cylinder of 1932 was a noticeable departure from the model a design. Basically the useable torque band peaks at about 2400 rpm for the A,2900 or so for the B. As others said, performance is a sum of all parts, one compliments the other. Beware, its a powerful intoxicant.
BRENT in 10-uh-C
Well-known member
IMO, the best bang for your buck is a Stipe IB330 camshaft change. A stock A-6050-* Cylinder Head has enough power to make the engine pull a vehicle in excess of 60 mph. A stock camshaft allows this engine to make good torque which is needed to make a vehicle accelerate. Yes, the higher compression does allow for an increase in performance however a properly designed camshaft like the IB330 can do this too with a narrower Lobe Separation Angle as it makes the engine think it has more compression than it really does. Adding to that, adding more valve lift over a stock (-or reground) camshaft increases the ability to add more fuel into each cylinder, -and increasing the duration of the valve being open allows for more fuel & air to enter the cylinder which increases volumetric efficiency. Increased VE out-trumps increased compression in most Model-A engines.
While I agree that a camshaft change along with an increase in compression and increased air-flow all compliments each other, however because most Model-A camshafts are worn, my experiences have been that a cam change wakes up performance more than a higher compression head does if you can only change one thing.
Brent,
I was referring to a good stock engine as a starting point, which I think was Ron's starting point. Changing the camshaft is a lot of work compared to the "bolt on" parts that I listed. The "bolt on" parts I listed will improve flow and compression about as much as you will get before going into the engine. That's why I did the whole deal when the engine needed to be rebuilt anyway. If you are starting with a tired engine, no amount of "bolt on" will make up for a poor starting point.
I was referring to a good stock engine as a starting point, which I think was Ron's starting point. Changing the camshaft is a lot of work compared to the "bolt on" parts that I listed. The "bolt on" parts I listed will improve flow and compression about as much as you will get before going into the engine. That's why I did the whole deal when the engine needed to be rebuilt anyway. If you are starting with a tired engine, no amount of "bolt on" will make up for a poor starting point.
Model A Ron
Well-known member
My Starting point was a good stock engine. At this point all I have added was the 5.5 Head.......certainly open to options but for now the car meets my needs.
Ron
Jim Brierley
Well-known member
the quickest and easiest way to more power is compression and a bigger carb, a cam change alone doesn't help much. I ran my tudor at the Auburn hill climb years ago with a stock B engine. A few months later I ran it again with a 6:1 Winfield head and my time was a full second quicker. That same day I removed the A carb and manifold and installed a Stromberg 81, the time was almost a second quicker. At a later date I changed from the 81 to a 97 and gained about 3/10s of a second. It does no good the make alterations if a bigger carb isn't installed, the carb limits the air flow.
Changing the cam lobe center-line changes the torque curve RPM. A 110* center line will put the power curve a little higher than stock. Stock A is 113, stock B is 112. For normal driving s/tock is better.
Changing the cam lobe center-line changes the torque curve RPM. A 110* center line will put the power curve a little higher than stock. Stock A is 113, stock B is 112. For normal driving s/tock is better.
alexiskai
Well-known member
Cam replacement is one of those upgrades where the bang-for-the-buck isn't consistent – it costs more bucks for some people because they need to acquire equipment and possibly replace other parts (e.g., tappets), plus it's a larger investment of time. Heads and carbs are popular as much for their low barrier to entry as anything else.
Jack Shaft
BANNED
I come to this from a different angle..no engine should be modified till you are actually sure of what you're starting with.. Pull engine. adjust bearings, clean and inspect oil pump. rings if necessary, pull valves, check seats and guides, measure springs.lap...at that point pull the cam, upgrade it and use a metal timing gear.. Basically do a complete inspection and clean up repairing what's needed, then hop it up..it gives you peace of mind to have some fun with it..
Model A Ron
Well-known member
Jim
They are both good but I think you are going to like your new 5.5 head.....the hill climbing ability is impressive over stock. For me it was a conservative decision because I do not have insert bearings and what Paul Shinn and his Model A Dad said made sense. This was the right decision for me and I am not looking back.......
High Compression head is checked off the list for me
Ron