I see your original plan included head work. I would keep your $600 but that's just me... hopefully you get replies from people who have installed SE110 heads on a 103.

Google it, i know it's been discussed before

 

This has potential for all kinds of worms.
I would go all 103, or all 110.
May be that dude is wanting to use you as the guinea pig.
Can't blame you for inquiring, but you may as well factor in the possible costs of what might later come up, especially if cost is important to you at this stage. If funds were more disposable, you could play with this as a pet project in all kinds of fun, creative ways.
BTW - the 103 is generally very reliable. How many miles/issues have you had with your 103? Mine has been wonderful...

 

Nothing wrong with a 103 build at all but If I had to replace the pistons then I'd do the S&S 110 drop in kit and you could use those heads but it still depends on the combo, what cam's is he talking about, the 1st one's you mentioned not so much.

 

OP,

i say, stick with the original plan. im running the 408-6 in my 120R. the cam pulls like a freight train, but, i got the compression, heads and set up for it to perform

in a 103, i say you would be better off with a different cam and sticking to working on your original heads.

i also agree if you want to use 110 heads, go completely 110. i would also suggest if you go 110, put some compression in the 110 above factory. At least 10.5 to 1.

overall the 408-6 is a great cam, it just needs more than a 103 was built to give IMHO.

 

110 heads can work great on a 103 but not by just bolting stock ones on. They need some porting and piston/cam/throttle body matching by someone who knows what they are doing with those heads. If ya really believe ya are working with that guy, give it a try. My guess at + $600 ya are not...

 

I had 408-6 cams in my 103 fatbob. They do pull hard, but are huge cams and were quite noisey.

 

110 heads in the hands of a good porter can be made to run. Worked over and set atop a 124” motor you can get fantastic power.

BUT for a 103” motor they have too large of a combustion chamber and will lower the compression too far. By sticking them on your bike without domed pistons or cutting the heads down you’d be taking a step backwards.

 

Big valve 103's are a great option. All components must be matched just like any other engine build regardless of size.

I find it funny that people are stuck on the displacement of a motor with the mention of these heads. If HD hadn't named them "SE 110" heads would people still be saying they won't work on 103" motors? I doubt it.

The 110 heads are very good out of the box and can be made to work even better. Yes they have large valves and large chambers with a unique shape. Nothing the proper piston can't over come. Suburban Speed and SE both make a piston for that head in a 103" bore size.

Now match a cam to that along with a throttle body and exhaust and you will have a monster of a 103" on your hands. Ward Performance does a great job porting those heads for 103".

Is it a better option than your original plan? No idea, that's up to you.
Zach

 

Here's a couple of examples. Both of these builds are SE 10.5 +.010 pistons, Ward Performance ported CVO110 heads, Tman 590 cams, SE58mm TB's with 4.9 injectors a good 2-1 exhaust and solid tune.

Both go over 1.2 hp/cube. That's getting it done.







Zach

 

My '08 FLTR had a 103 kit installed w/255se cams. Began tearing up the starter and related parts because of ccp of the 255s. Had MVA heads installed. At the time they were the only heads with CRs. After all was said and done my dyno chart was almost identical to the stock heads. My advice would be to find some stock heads (used) with acr's, do a little cleanup and save some $$$. Stock heads on a stage 2 motor will breath just fine. The 110 heads are not required and in the end gains are negligible.