Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

Sign in to follow this  
mwells

Single cylinder briggs engine horse power changes

Recommended Posts

mwells
Ok I've been doing some research on the old cast iorn single cylinder engines, and was wondering what they all change on the engines to get more hp. From my understanding and please correct me if I'm wrong, the 10hp-16hp have the same carbs. Are they changing compression of the engines with the raised fin heads? For example my 12hp has a flat head, my 13hp has the raised fin head. As for the 14hp-16hp the bore is again bigger to add more hp. I don't have a 14 hp, but both my 15+16 hp engines have the raised fin heads too, so what is the difference in the 15+16hp engines to gain 1hp more? Are all the cams/valves the same on the 12-16hp engines? Or is that where there getting the extra hp? Thanks in advance for your imput!!

Share this post


Link to post
Share on other sites
D-17_Dave
Some had no change, it was just a marketing ploy. Some were rpm changes from 3300 to 3600rpm's. The raised fin engines were basicly the same. I have heard of some variation in the jet size of the carb, but since there were so many changes in internals of the carbs anyway it's hard to track.

Share this post


Link to post
Share on other sites
Talntedmrgreen
When ordering carb kits for some of the various models, there are different P/N's, and subsequently, different sized ports in the main jet. There were also different intake manifolds, and I'm guessing minor changes to the fuel/air mixing and intake resulted in changes to combustion/claimed hp. This has always been my thought, anyway.

Share this post


Link to post
Share on other sites
powerking_one
Also, the 325xxxx and 326xxxx series of engines had a more "breathable" and less restrictive air cleaner system (using the pre-filter jacket and dry element along with the longer intake manifold. Briggs may have done some additional tweaks with the cam lobe profiles along with what others have said about the head design/changes. Tom(PK)

Share this post


Link to post
Share on other sites
MikeES
I started tractor pulling with a 12hp 30ci bored out to a 16hp piston 32ci. I did find differences in carb bores. The 15/16hp 32ci engines had a larger bore carb than the 12hp. That was 14 years ago, but I think the difference was about 1/16" The later 32ci engines 14, 15, and 16 hp were identical except for a little tab on the throttle stop to prevent the throttle plate to open all the way on the 14 and 15 hp.

Share this post


Link to post
Share on other sites
timflury
quote:
Originally posted by mwells
Does anyone know if the valves and camshafts are the same on the 12+13hp or the 14-16hp engines?
The best way to accurately find out is to downlaod the respective manuals and compare part numbers. I'm willing to bet that there are different specs not on the inatallation of the cams, but on the mechanical valve timing itself between the different size engines.

Share this post


Link to post
Share on other sites
timflury
I am referring to the actual cam lobe sizes that deal with lift and duration, Bob. Static timing should be the same through the entire engine family. So there must simply be a larger bore and different synchro balancing between the 30 and 32 ci engines, right??

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Who's Online (See full list)

    • TomSchmit
  • Today's Birthdays

    1. acey
      acey
      (68 years old)
    2. Gary
      Gary
      (68 years old)
  • Recent Status Updates

    • SonOfCreepfeed

      SonOfCreepfeed

      Thinkin' about this old girl.

      · 1 reply
    • Dean McFadden

      Dean McFadden

      Good morning peeps! I’m always searching for helpful information with my AC collection. Hope to find out new information and pass on my own experience in restoration. Here are some pics of my babies. I’m still looking for front rims for the 410 so yesterday I put the 310 wheels on took it for a drive. Working pretty good but still needs some carb work. Gotta get the 310 running next. Have a great day!😁
       

      · 1 reply
  • Adverts

×