Need help on initial jetting after rebuild Johnson V4 1980 140hp

**FMP** · 04-22-2018, 08:26 AM

BTW did you fit the rings in the bores and check end gaps at different bore heights? #s?

**spybot** · 04-22-2018, 11:05 AM

Yeah checked each hole in 3 different places. They were all with in spec, but still checked each set to the bore it was going in to. I was expecting some of them may have needed filed down but no all ok.

**FMP** · 04-22-2018, 01:32 PM

How wide?

**spybot** · 04-23-2018, 04:41 AM

If i mind right it was 0.020 mm

**FMP** · 04-23-2018, 05:59 AM

" or mm? .00078" won't work lol
You probably used SAE feeler gauge not metric. If it's metric and 0.2mm it's too big a gap. Consider up sizing rings .010" KD3510 if available and re fitting with filing after some simple dimension math to check how they should fit in your finished bore. Example a .010 ring will be so much longer resulting in a reduced end gap of x ".

**spybot** · 04-23-2018, 01:18 PM

I went with the wiseco spec

**FMP** · 04-23-2018, 04:37 PM

Okay but you're the guy who measured.

**Chaz** · 04-23-2018, 07:05 PM

As 71v eluded to , stock carbs are generally pretty rich from the factory . Nothing you did was earth shattering , just a basic clean up of the passage ways .
The main thing that has not been stated is that for the most part carburetor's are self compensating . Meaning , if you move more air thru them , they will meter more fuel .
Unless your tune-up is out in left field , or did something to kill the signal , the only time you need to jet differently , is for changes in atmospheric conditions or the specific gravity of the fuel changes .

So FuMP .... the guy has a 38 year old engine that got wounded .

Standard bore .

He hones it long enough , to get it good enough to go back together .

And you put doubt in his mind that maybe he measured wrong and should have file fit a set of std rings ? Pppffftttttt

Tell the truth ... you been pulse-huffin grape mmm crappie in your wig-wam all winter ...

**FMP** · 04-23-2018, 08:36 PM

No , didn't say he should file fit standard rings, read it again. He has raised compression with cut hiC heads though. Good to hear from you.

**71V153** · 04-23-2018, 09:15 PM

Originally Posted by Chaz

As 71v eluded to , stock carbs are generally pretty rich from the factory . Nothing you did was earth shattering , just a basic clean up of the passage ways .
The main thing that has not been stated is that for the most part carburetor's are self compensating . Meaning , if you move more air thru them , they will meter more fuel .
Unless your tune-up is out in left field , or did something to kill the signal , the only time you need to jet differently , is for changes in atmospheric conditions or the specific gravity of the fuel changes .

So FuMP .... the guy has a 38 year old engine that got wounded .

Standard bore .

He hones it long enough , to get it good enough to go back together .

And you put doubt in his mind that maybe he measured wrong and should have file fit a set of std rings ? Pppffftttttt

Tell the truth ... you been pulse-huffin grape mmm crappie in your wig-wam all winter ...

Harrumpf! ...

**FMP** · 04-23-2018, 09:35 PM

Originally Posted by 71V153

Harrumpf! ...

gesundheit

**Chaz** · 04-23-2018, 10:16 PM

Originally Posted by FMP

No , didn't say he should file fit standard rings, read it again. He has raised compression with cut hiC heads though. Good to hear from you.

I didn't check behind your math , but now that I did look , as usual , your written text and math contradict each other . And yes , your incorrect ....... twice .

Welp ... three times actually if you want to now count the heads statement .

He never said he changed to a "Hi-Compression set of heads" .

Part of his repair was :

High Comp Heads Lapped

As in .. making sure what he already had ...... was flat .

FuMPsan ... wax on , wax off ! You may call me Mr. Miyagi

Spybot , If you plan on doing any more of these in the future . Buy yourself a dial bore gauge off of e-bay . You can then quickly check the bore , top / bottom along the thrust face and then the same @ 90* to see if the hole is straight , tapered or if there is any egg shape to it . Then when you want to check ring gap , you can put an old ring in the second groove of a piston and use it as a squaring tool . Just set the new ring in the bore , slide the piston down till the old ring stops it , measure , move to the next hole ...

**spybot** · 04-24-2018, 06:00 AM

Originally Posted by FMP

" or mm? .00078" won't work lol If it's metric and 0.2mm it's too big a gap.

Are you saying the shop manual have given the wrong dimensions?

Manual says Ring Gap max 0.43mm - 0.18mm min.

If anything its closer to the min than max or at least thats what the factory manual dictates.

**FMP** · 04-24-2018, 07:00 AM

Heck no , that range is right. The high end is probably better with your pistons. Going to blame it on my eyes and this keypad, .02mm being too tight. That you would need to file.
If you did have too big a gap .010 upping the rings and filing could work.

**Chaz** · 04-24-2018, 07:19 AM

Here's the easy way and it's darn near applicable to everything from lawn mowers to cylinders that you and I could walk around in .

Five thousandths gap for every inch of bore .

Five - ten - fifteen , an a half = " seventeen "

.005 x 3.5 = .0175

Then if you want to convert it to Chinese you'll find that it will fall just under a half a mm . So yes your .4x mm answer would be correct .