What OEM Heads Does a Stock 2012 103" Twin Cam Use?

[dolt]

I will dig out the Sach's data; just have to find it.

Don't know if you are planning something but a set of OEM heads ported and machined for a particular configuration will always get better results than a set of off the shelf heads from the MoCo, S&S, etc. and usually cost less.

 

[Rod Stewart]

Just kind of considering a few options at the moment.
If I wind up retrofitting the '07 103" into the '04 FLHTC I might get some headwork done beforehand. It would be way easier to do before putting the engine into the frame, and was something I was going to do next anyway on the 103". At the same time I will likely change over to a 50mm TB. The current SE255 cams are likely all I am going to need in that department. I don't want to get too crazy and jeopardize drivability.
I have a spare set of low mileage 17192/93-06 heads (that I got a few years ago) lying around, so I would send them away beforehand for porting. Then when they are back I can do the head swap the same day while I still remember how all the pieces fit together! LOL
Or if I wind up selling the 103" then I could still slip the same heads above into the 95" that is currently in the '04 and improve its breathing al little. I also have a complete spare 56 mm 103" cable TB lying around that may work OK on that engine as well, but that gets into the wiring compatibility issues we discussed in another thread. Research continues!
Rod

 

[dolt]

thaSach's flow test data first, then a couple of comments on your previous post.

Lift .300" .400" .500" .560"
2006 178.8 207 211.3 211.3
2005 169.5 196.7 192.8 192.8
2002 156.6 189.4 197.7 196.4

The SE Pro 50mm T/B is probably the best one HD has made so far; good performer and should work well in a 103" configuration with a set of cleaned up or "street" ported heads with the 255 cams. Street port defined as BigBoyz, basically a "blue print" job; OEM springs and valves are retained, mild work on the intake runner, bowl blending and clean up of the exhaust runner. I would not do any serious porting with the 255 cams; they cannot take advantage of better breathing. Obviously, there are aftermarket cam choices the would perform better, i.e., make more HP without sacrificing reliability. The 255 cams are torque cams but light on HP, you could expect maybe 110TQ/85-90HP with that configuration and, if that meets your goals, great.

I would suggest the same for the 95" assuming you would run the 255 cam in that motor as well. However, a 56mm T/B for a 95" configuration is overkill IMHO unless the configuration included different cams, seriously ported heads with larger valves that will flow 260+, higher compression and cams with .600" plus lift. You won't gain much at all from a mild 95" motor, mileage could take a hit and TQ could take a hit unless you swing for the fence with the 95" configuration. Another option would be boring the '04 T/B from 43mm to 48mm. The '04 T/B is a two piece unit (T/B and intake) and the throttle plate is 43mm but "necks" down to 41mm just behind the throttle plate. Dan Vance can bore the throttle plate to 48mm and the bore behind the plate to 44mm which will allow the use of the OEM o-ring to seal the T/B to the intake or he can bore to 48mm all the way but lose the o-ring seal which can be sealed with Yamabond, etc. $300 for that but the SE Pro 50mm runs about $340 from discount dealer and worth the $40 upcharge even though the fittings must be changed via the Zipper's kit. Just depends on how comfortable one is with changing the connector fittings.

Most importantly, matching the intake port on the head to the intake manifold ID should be addressed; something most DIYers over look. JMHO.

 

[Rod Stewart]

dolt thanks a bunch for all the info and comments. Greatly appreciated.
Duh, my mistake where I said I had a spare 56mm TB to go on the '04 95". What I meant was a spare 46mm TB. I figured this might be a nice little upgrade from the stock 44mm TB on the 95" (which started life as a stock 88" of course), and go well with the mildly ported '06 heads, whilst still maintaining the current SCR because the '06 heads are the same nominal 85cc chambers.
Sorry for the mixup.
The SE Pro 50mm TB sounds like a great upgrade for the 103" after some head porting. And if I understand you correctly would make a nice moderate driveable street package. I have read where others are seeing in the range of 110/90 tq/hp with similar configurations, and that would be fine for me I think. (At least for the first couple of weeks! )
Rod

 

[dolt]

That spare 46mm T/B you have on hand is probably the best T/B the MoCo has made to date and works very well at 46mm. However, it can be bored to 50mm (Dan Vance) for about $300 plus the cost of the Zipper's connector kit. I believe the conversion will also require the '06 up fuel line between the tank and the TB. IIRC, the 05's have a longer metal tube from the TB than the 06 up. A check of Ronnie's part finder to compare the early to late fuel line will confirm. I have seen used SE Pro 50mm T/Bs go for $200 on Ebay and other forums; some guys just have to have the bigger T/Bs but truly, bigger is not always better.

 

[Rod Stewart]

dolt thanks again for the distillation of information you have provided. It certainly helps me out, and I imagine others who may be considering similar setups.
If I wind up retrofitting the 103 into the '04 I am now certain that I will go for the Bigboyz port job (likely the street port) on the spare '06 head set, along with ACR drilling. And also I would send my spare 46mm TB off to Dan Vance and get it bored up to 50mm with his transitioning treatments as well. From what I can see these mods would be money well spent before bolting her in.
Rod

 

[dolt]

dolt thanks again for the distillation of information you have provided. It certainly helps me out, and I imagine others who may be considering similar setups.
If I wind up retrofitting the 103 into the '04 I am now certain that I will go for the Bigboyz port job (likely the street port) on the spare '06 head set, along with ACR drilling. And also I would send my spare 46mm TB off to Dan Vance and get it bored up to 50mm with his transitioning treatments as well. From what I can see these mods would be money well spent before bolting her in.
Rod

I hope you are considering replacing the 255 cams as well.

Bean's "street" port retains OEM valve size and springs. Springs are OK and most will go to .610" before coil bind. Bean will install 1.9" intakes at customer request for a few more $$. If increasing T/B size, you should consider larger intake valves. JMHO.

Good luck with whatever path you choose.

 

[Rod Stewart]

I hope you are considering replacing the 255 cams as well.
Bean's "street" port retains OEM valve size and springs. Springs are OK and most will go to .610" before coil bind. Bean will install 1.9" intakes at customer request for a few more $$. If increasing T/B size, you should consider larger intake valves. JMHO.
Good luck with whatever path you choose.

I'll probably leave the 255 cams as is initially. It's easy enough to swap out cams later in-frame, especially with quick fit pushrods.
So that can be done most anytime after I get a chance to see how everything is running initially.
Thanks,
Rod