cutting off the front

**Krazymaan** · 03-08-2017, 05:26 PM

I often hear about cutting .050 off the front. I know what means. I am assuming thats on the reed side or the bearings wouldn't work.
Lets say I bought a front half or an complete motor. How would I know if someone cut .050 off of it. Is there a measuring point from A to B. Like the front half will now be .050 under 3" or how ever deep one is.
Why do they say don't go further. It doesn't look like the crank could ever hit the reed cage. Or could it.
Would there be no benefit to cut .050 off the front and then you go and put a 1" spacer block in there.
Fill me in before I go and cut .080 off of mine. Just kidding. No, but explain this milling purpose to me.
Thanks

**FORBESAUTO** · 03-08-2017, 06:01 PM

It moves the reeds in closer and raises crankcase compression. The 1 inch spacer goes between reeds and intake to straighten intake tract out. 0.50 is the norm for most applications. Depends on lots of factors. General rule is when you cut rod slots and remove metal from crankcase for whatever reason, you remove some area from crankcase and lower cc pressure from stock. However much is removed needs to be put back somewhere else. The 0.50 seems to work across the board though even if not much removed. Hope I didn't butcher that up too bad.

**90 5.0** · 03-08-2017, 06:12 PM

.050 is what I normally hear, I've heard of some doing .065 but you have to be real careful of interference after that.

**FORBESAUTO** · 03-08-2017, 06:19 PM

You can look at distance between bleeder ports and mounting surface to tell. You can take a lot off of a 4-petal without interference problems. Can't take much more off a 7-petal until screws that hold reeds on block hit case(unless you cut reliefs for each screw lol). But more than 0.50 under normal situations is unpractical.

**FMP** · 03-08-2017, 06:22 PM

Forbes, do you only tune on the Mercs?

**FORBESAUTO** · 03-08-2017, 06:23 PM

Can't afford to do any more lol. Trying to get my brother in law to let me play with his 70 Evinrude for drag racing.

**FORBESAUTO** · 03-08-2017, 06:27 PM

I'm running a 4-petal with .070 removed and extensive milling for rod slots, that should stir some people up lol. But works great with loads of torque on bottom end and will turn 8000 plus easily.

**FORBESAUTO** · 03-08-2017, 07:05 PM

Let me rephrase my comment im post 6 to can't afford to screw up any more lol

**wrechin2** · 03-08-2017, 07:13 PM

Originally Posted by 90 5.0

.050 is what I normally hear, I've heard of some doing .065 but you have to be real careful of interference after that.

Not a problem with interference. The deciding factor on a 5 petal is the amount of area left around the bleeders. I have cut .110 off (early castings) before with no issue. 7
petal I find .040~.045 is good as the reeds will hit the front (NOT THE RODS) and will have to have a little material removed on the mounting bosses but is not a big deal.

**wrechin2** · 03-08-2017, 07:15 PM

Opps....like Forbesauto said.

**phillnjack** · 03-08-2017, 07:17 PM

if you lived near me forbesauto you could have a go at my 70 ha ha would love to see what you could do to this .

if no internal work has been done to a motor does the taking 50 thou off give any benefit or only when other mods are done.

I have never heard of this before so am curious to what it does or does not

**Krazymaan** · 03-08-2017, 07:30 PM

Now i am curious if my rod slots have been altered. Damn it.

**FORBESAUTO** · 03-08-2017, 07:56 PM

I feel like if motor is bone stock the manufacturer usually does a great job with tuning of exhaust and cc pressures and such so you may not gain as much. (Unless it's something they have defined to lower hp on a particular engine, or emmisiom related garbage). When you make changes it usually requires changes elsewhere to really get the full potential of changes made. I really havnt tried shaving front on bone stock engine to know for sure of results. It will help velocity which is always a good thing.

**Krazymaan** · 03-08-2017, 09:08 PM

I think mine has been cut. at least .090 I think other fun stuff was done to it too.

**FORBESAUTO** · 03-08-2017, 09:10 PM

Originally Posted by phillnjack

if you lived near me forbesauto you could have a go at my 70 ha ha would love to see what you could do to this .

if no internal work has been done to a motor does the taking 50 thou off give any benefit or only when other mods are done.

I have never heard of this before so am curious to what it does or does not

We could definantly give a try, we may could even turn your 70 into a 25 before we get it figured out lol!