OHV conversion durability/longevity

G

G_Don

Member
I posted this over on the HAMB, but was hoping I could get some better insight especially from some of you guys who have toured with an OHV conversion.

I have a 30 phaeton with a B block. It's stock at the moment and have been researching some banger speed equipment. I plan on driving it to work pretty frequently as my commute is 10 miles and all back country roads. I'm wondering how well an OHV conversion will hold up after a lot of miles.

I've done a bunch of searches trying to find something about durability/longevity of an OHV but haven't found anything specifically related. Are OHVs impractical or more troublesome in a daily driver? Would a HC head be a more practical/durable option (cost aside)?

Anyone with a link to a thread I may have missed, or some personal opinions/experiences with OHVs and dependability/longevity of it would be greatly appreciated!

Thanks for your time,
Gordy
 
It all depends on a lot of things. How good is the bottom end. Are you going to put it to the limit all the time. The bigger problem might be getting it dialed in, what carb and manifold. I have made my own overhead and also used a 455 olds head and a 1928 chev head.

You might like a nice 6-1 flat head if you do not want to mess with it to get it running right.
 
To add to what George said, what brand head are you planning to use? A repro or an original? Many original heads were very poor castings.
 
I have B engine with babbit and an original CRAGAR. Also
have an A with inserts and a BF super head. The B produced 59 HP at the rear wheels and the A did 60HP. The car in my avatar has the OHV, T-5 transmission and F-100 steering. Both engines have headers, electronic ignitions and Weber 32/36 carbs. Neither car was cheap to build. Both cars are great performance wise, however the ‘29 with the stretch cab is a more comfortable touring car. Both engines were built years ago and I would be hard pressed to say one was better than the other.
 
Hey Gordy,
Some , like Riley/Cragar were built for and run on truck engines, so durability and dependability were important for those applications. They were advertised this way, in addition to their use on race engines and some on daily drivers. Truckers and especially racers put them thru harsh use. They used what proved to show (with proper maintenance) endurance. If you get a good original (without repairs/cracks), or go with newer repop versions you will enjoy the power gain. But , be ready to get a good sized $loan$ and expect to do whatever maintenance and tuning is necessary.
As said, a good flathead (7:1 or so) is much cheaper, but not so cool and/or as much work. A lot in making this decision should be based on what type of short block you have ?
 
Beyond the engine reliability, consider the body style's ability to survive and to keep its doors closed at speed. Even if comfort be dammed, safety shouldn't be.
 
Where are all the OHV heads that were produced over the years?? Never seem to see any for sale or installed??
Paul in CT
 
If I may add a couple comments here, you are probably much better off not using an old original casting. The casting process is much better now than before and aging an old casting doesn't help. That said, any casting should be pressure sealed with resin as a precaution and while the casting is new. No guarantees, but better to stack the deck in your favor.

If the intended purpose of this is to make a touring motor, OHV, you do not need a 4 port design. The older Cragar/Schoefeld/Millers were siamese port designs (2 port) and more than adequate. You will also not need a lot of compression, this in my opinion is where folks get into bottom end trouble.

Lastly, there is a dedicated monthly Banger thread on the HAMB here is the new one for Dec. https://www.jalopyjournal.com/forum...eet-little-saint-nick-banger-powered.1087920/

J
 
Gordy, As John says (above) too many old conversions are a lot of trouble just because of their age and the fact that many were made during depression years, with a minimum amount of iron, and sometimes poor material. The ones now on the market are very good, as is their reliability. I would go with the Miller because of its simplicity, it has modern valves, rocker arms, etc. One big advantage of an OHV head is they expel heat out the head instead of thru the block, making it easier on blocks. They are expensive, but IMO worth it. For what you are doing, you would get good performance out of a 6 or 7:1 flathead, with much less cost. If you look at the HAMB site posted above, the last photo is of crazydaddio leaving the line at the Antique Nationals, my green speedster is on the left.
 
One should consider that if using a "B" block for the heavier lower end, the use of an overhead conversion that has both the intake and exhaust valves in the head eliminates the concern for the cracking issues in the upper portion of the "B" block. If you have a "B" block with cracks in the valve area, you can salvage it with the use of this type of head with proper gasket installation.
One such head I have installed on two customer's "B" blocks is the Miller High Speed Head. The installation and set-up was pretty simple and the torque range was very good. This head would make a very strong touring engine.
I have no affiliation with the manufacturer...just experience with installation and running it on my dyno. My next overhead for myself will likely be one of these units.

I have attached a link for those that are interested.

http://www.millerhi-speedheads.com/index.html

Good Day!

www.durableperformance.net
 
I have a Miller head on a B engine. It seems as dependable as a flathead. It is an original Miller and I ran it most of the length of Highway 1 in Cali for a break in. Later we took it to Bonneville just for nostalgia. The weak link in my OHV is I am using a Miller Carburetor with a rotating venturi. I have had very little luck in finding much info on this carb. I have thought of changing it to dual Stromberg 81s or some winfields, but the Miller wins for its rarity. This setup is in a 1930 Coupe.
 
Thanks for all the information. It seems as though the miller OHV would be the one to look into if I decide on an OHV.

Is it a pretty simple bolt on procedure, or is there a lot of tuning involved?

One other question. How much HP gain is the OHV compared to a 7:1 flathead? I'd hate to spend a sizable amount on an OHV, when I could get similar power out of a flathead setup, or am I just delusional thinking it'll even be close? lol

Thanks again!
Gordy
 
G_Don said:
Thanks for all the information. It seems as though the miller OHV would be the one to look into if I decide on an OHV.

Is it a pretty simple bolt on procedure, or is there a lot of tuning involved?

One other question. How much HP gain is the OHV compared to a 7:1 flathead? I'd hate to spend a sizable amount on an OHV, when I could get similar power out of a flathead setup, or am I just delusional thinking it'll even be close? lol

Thanks again!
Gordy
Click to expand...

The installation was a simple bolt-on. The tuning was also simple.

The head on a full pressure "B" produced 115 hp with two 97 Strombergs. It produced about 90 hp at 2800 rpm with the dual carbs and other equipment I had on it. Personally, I would de-tune it and and target 80 hp at 2800 rpm. At this output, the head, crank and other drivetrain components should be very reliable.

Good Day!
 
Everything else being equal, an OHV will produce more HP than a flathead. How much, in actual practice it depends on a lot of other things in the set up. My flathead dynos at 114 HP at 3600 on a 6.8 CR. Better than a lot of OHVs, less than a lot of OHVs. A lot depends on the cam, carbs, bore, ports, valves, etc etc.
Whether to spend the money on an OHV depends on what you want to use it for and how much perfromance you want. For ordinary cruising or some racing save the money and get a good flathead setup. For all out performance get an OHV.
As a very general proposition, in the FAST hillclimbs, the fastest flathead is about .5-1 second slower than the slowest OHVs. (There are exceptions.)
Personally I like flatheads, but there is a "cool" factor in the OHVs, which has nothing to do with money or performance.
 
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I have an "A" block with much work & a 7-1 lion 3 head . it seems to be a good all around motor . I have thought about an OHV , but really happy with my flat head . not having a dyno , I guess my hp is 75-80 . 125# per cylinder .
 
Dennis Piranio in TX has many "dyno sheets" published here http://www.modelaparts.net/dynosheets.htm/dynosheets.html

As the old saying goes, "your mileage may vary" this is very good information.

I do not subscribe to "Horse Power" bragging figures, they are calculations.
Instead look at the delta between tests and configurations. The equipment used is very accurate and calibrated frequently. So far the best data I have found.

John
 
john , mine is just a guess as I have no access to a dyno . looked at the page you referred to , but nothing real close to mine . thank you for the page
 
When the Miller first came on the market in 1928, they advertised double the HP by installing the new head and a slightly larger carb. HP can go up from there easily, depending on other equipment used. The odd thing about the Miller/Cragar is they need lots of spark advance to perform really well.
 
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