21 stud hot rod motor?

E

E.PREUSS

Junior Member
Hey guys , I tried to do a search but couldn't get it to work... I have had a couple later hotrod flat motors one was a 53 merc bored 3 5/16 with mild port and 400 jr. And the other is a 3 3/8x 4 1/8 ported with a 3/8 potvin ...
A couple others just stock

Anyway more of a curiousity but how many have hot rodded them and whats your combo... How does it compare to a late flathead?
 
21 stud, the 37 21 stud is my chose, That's a nice little engine, you can bore it 1/8 to 3-3/16, put in a small cam, and Hi compression heads, and a couple carbs. Your not going to beat a pumped up 8BA like those other engine you had but in a light car there a good little street engine. They got a lighter crank and rev good. Walt
 
Sounds good Walt ... I was thinking a 4" merc crank , some port work and maybe a 400jr cam or equivalent ? I actually found a post on the hamb saying the LB blocks won't take too much bore... I wonder why the castings are so thick on the later motor and not early?
 
There were a lot of 21 stud hot rod motors back in the early days. A lot of speed equipment made for them as well.
 
Yes , I'm sure there was, I was just curious what one could expect from a "small flat motor" , I'm not well versed in all things flat but , but have experianced those two bigger flat motors a semi stock 8ba a wore out 59a and a 4-71 blown 59a ( favorite one!)

All in light roadsters, everything should be semi equal except 3 studs and bore deficiency I guess I'm kinda asking for a seat of the pants comparison or if anyone has done a big 21 stud
 
I will be building a 21 stud LB for my coupe, but when finished, I certainly won't push it, will be for cruising. Will probably use a stock 53 merc cam grind. I have a plenty hot 59L in my avatar roadster for "seat of the pants" thrills.
 
The pre 37 blocks don't readily exempt big bores Luke the 37.
Pre 37 (LB and earlier) will sometimes strike water at 0.060-0.080" over. As Walt said, a 37 will normally happily go 0.125", some will go bigger still.
A 4" crank needs some modifications to work, obviously you'll loose the light (stock) crank doing this.
Martin.
 
E.Preuss, Whereabouts are you? If you're in New Zealand, come down to my place and I'll show you first hand how a 21 stud can go. Bring some spare undies...you'll need 'em!
 
Many a little 21 stud engine was cast aside in favor of their bigger brothers, 59a and 8ba engines, but the truth of the matter is they can be built into nice little street engines as Walt, Brian, and others have said, that will run their hearts out for you. Anybody who has ridden in my Avatar '35 Sedan can tell you how well it runs. This engine is basically stock except for 0.030" over bore and milled heads for higher compression. I'm not going drag racing with it, but it sure gets this old man anywhere I care to go and as fast as I care to get there :).
 
My 33 Flathead runs just great! It has been bored & balanced has adjustable cam etc.
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I love mine in my 32 truck.
33/34 motor. 80 thou over with flat tops. isky 77b cam. Meyer heads and inlet. duel 97's. crab dizzy and speedway econo headers.
Runs well on the street, good for 17.4 sec quarters at the drags and 87mph at Pendine. Been driven to Belgium and back as well as being used for hill climbs and track days. I'm amazed it is still together! :)
Sure you could go quicker and faster with a fairly stock later motor but then so would a small block. ;)



On board video of one of my runs at Pendine.
https://www.youtube.com/watch?v=mTfjw8haWJE
 
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Gavin sweet pickup "Mate"
I too like them lil 21 studs. My stock 36 runs like a top , handles them Georgia Mountains with 4 adults aboard with ease during the cigar City Flatheads Moonshine Festival Cruise . I had to ask the tour leader to pick up the pace a little (239,s holding me up ) as she would pull strong in high gear but their too slow speed kept forcing me to second.
Cheers
KiWi-Tony
 
Thanks for all the imput guys ..

.. That's a NICE little 32 truck Gavin...I like it... Thinking about doing front suspension in similar fashion , with a dropped axle on mine... Could I get pics of the back where the frame rail and tierod are and a rough measurement if you have a chance?

Is anyone running a big cam or some dome pistons in their 21 stud?... Any major port work? Would it be possible to swing a 4 1/8 arm with that small of a bore?
 
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E.PREUSS said:
Thanks for all the imput guys ..

.. That's a NICE little 32 truck Gavin...I like it... Thinking about doing front suspension in similar fashion , with a dropped axle on mine... Could I get pics of the back where the frame rail and tierod are and a rough measurement if you have a chance?

Is anyone running a big cam or some dome pistons in their 21 stud?... Any major port work? Would it be possible to swing a 4 1/8 arm with that small of a bore?
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No problem I can get some pictures sorted. What measurement do you need?
 
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