5.5 Snyder head, what else is needed or recommended?

Smokedtires

Smokedtires

Senior Member
Hello all, I bought my 30 Roadster last June and put almost 600 miles on it before putting away for winter. I'm interested in more torque for hill climbs while keeping everything appearing stock.

My question is, should the Zenith's jets be increased in size to accommodate the higher compression? Any other considerations to go with the new head? Currently it is restored with everything in stock form.

Thanks, looking forward to hearing from the pros here.
 
I have the Snyders 5.5 head on an otherwise stock car. It made a huge difference while driving here in the NC mountains. I run the GAV richer than with the stock head. No need to change jet sizes.
 
The 5.5 or the 6.1 from Synders is a good choice. I have both and a 7.1 Winsor which is aluminum. I live in the Sierras and prefer the the cast iron 6.1. Good luck and have fun.

Dan
 
You'll have to learn to work the advance lever more. My 6:1 needs less full advance than the stock head. I limit the travel with this.
 
An old tried and true method of increasing HP is to bore out your intake manifold to 1.125 + and run a B carb on it. It will gain you about 3-4 HP. I know it doesn't sound like much, but with a 40 HP, it a little less than 10%. Another way is to install an Aries muffler.
Terry
 
I have both hi-compression heads, the 5.5 & 6.0:1. As has already been said above, you will need less spark advance with these heads, especially the 6:1 head. With the 5.5:1 head, I found that I could only use 10 of the 12 spark lever notches without knocking (87 Octane Gas), so I pull the spark lever down 2 notches when timing the engine. For the 6:1 head, I pull the spark lever down 5 notches when timing the ignition, so I can use the full range of the quadrant. Averaging 50 mph with my Victoria, the 6:1 head delivers 23 mpg.
 
In my opinion, the 6.0 head from Snyders has a better combustion chamber design than the 5.5 head from them. It is more like the high performance heads used on the Harley Davidson and Briggs and Stratton engines. There is more to head design than the compression ratio.
 
OK, my low mileage engine that was stored for 30 was recently rebuilt by a local rebuilder and the babbitt was in good shape. The engine performs well, yet I'm looking for a bit more performance when climbing grades. I am considering converting to a 5.5 or 6.1 HC head. I'd prefer not to change the studs as they were not changed when the engine was rebuilt. Will the original studs work w/the 5.5/6.1? Any experience?????
 
Should be OK, as long as the block and head are FLAT, they're still torqued to 55 ft-lbs w/either head.
 
Paragon said:
OK, my low mileage engine that was stored for 30 was recently rebuilt by a local rebuilder and the babbitt was in good shape. The engine performs well, yet I'm looking for a bit more performance when climbing grades. I am considering converting to a 5.5 or 6.1 HC head. I'd prefer not to change the studs as they were not changed when the engine was rebuilt. Will the original studs work w/the 5.5/6.1? Any experience?????
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I am using the same studs for my Snyders 5.5 with no issues. Just make sure the studs are in good shape.
 
Clean those upper threads and always use new nuts. Biggest risk is that corrosion on the stud threads leads to some studs having low clamping force because too much torque went into overcoming friction.
 
I have both the 5.5:1 and the 6.0:1 heads on my A's and both run with standard studs. Does anyone know how much the combustion (explosive) pressure increases with these heads?
 
Bob Bidonde said:
I have both the 5.5:1 and the 6.0:1 heads on my A's and both run with standard studs. Does anyone know how much the combustion (explosive) pressure increases with these heads?
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Bob, My .040 over engine with Snyder's 5.5 head had the following cylinder pressures.(engine warm.) 76, 76, 76, 75 psi.

When I had the engine rebuilt, I replaced the 5.5 with the 6.0 head. Cylinders were bored to .060 over. Cylinder pressures are now 105, 104, 105,106 psi.

Not exactly an apples to apples comparison as the bore increase also increases cylinder pressure to some extent.
 
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