This winter I plan to pull my heads and get some port/polish done, 1.9 intake valve, etc. While its off will boring the throttle body a few mm be any benefit? Just a 103 with Andrews 57 cams, 2-1 pro pipe, air cleaner and tune it with tts. Going 107 is out of budget and figure headwork best route to add with cams.

 

Where are you getting a bigger butterfly?

 

I planned on taking them to axtell to get done unless hillside or someone can justify me shipping them vs dropping them off somewhere. I assume that would be part of them boring it is reassembly. I could tear it down but rather let machinist do it. I know a local Indy who could do the heads but know they need done particular to my camshaft

 

2x post

 

Not enough of a HP gain unless you're going to go BIG STROKER motor and I mean BIG. You may be able to pick up a total of 1-3 HP and maybe 5 TQ overall. A 50 mm TB will handle anything you can throw at it on a 103. Not very cost effective for what it's going to run you.

 

You want a fast flow rate through the throttle body. If the heads don't flow the rate the larger opening enables, it will not provide a power benefit and be detrimental.

 

it really depends on what work your doing with the heads.even on a 103",if its going to be a fairly aggressive build,its a very good idea to do the t. body also.one thing overlooked is the runners & port opening.just boring the t. body leaves a lot on the table.stock HD t. bodies can have the runners opened to 1.700.

 

Heads just 1.9 intake valve, port/polish intake and exhaust ports, upgrade valve seals. The stock springs shouldn't need replaced for the 57 cam for the year head and beehive spring I already have. Run .030 head gasket to bump comp to around 9.8 and want to keep CCP around 200+. The $700 or so a 107 will cost in parts I don't feel I will need as I expect 100/115 once heads are done with stock bore. If the 103 had issues in regards to stock internals I would go 107 but have not heard anything bad outside of cam bearings and lifters which have been changed already.

 

Many tuning centers have seen great increases with 58mm S/E t/bodys on 103" engines.
Scott

 

I don't know that I would do a throttle body right off the bat. I would do my heads and my dyno then decide. When Mike did my tune he didn't mention any need for more flow. The 57's work best with a mild head so I don't know that you would use the extra flow.