[GRN69CHV]

I had checked the piston/head clearance and have .400" across the dome and .250" at the plug side of the dome (H693CP-030 and GMPP/EDE heads), no problem. Checked the static clearance of the valves at TDC. I have .180" clearance before the 2.25" valve just hits the inside of the eyebrow. By comparison, I checked the clearance with a set of 049's and a stock 2.07 valve and have .400", so I know the relief is plenty deep, just not wide enough.

I still have to harvest the rollers and balance of valvetrain from the 408 before I can check with clay, but using the cam spec data for lobe lift at an installed ICL, I am looking at interfence - or darn close. Short of disassembly, flycut,, rebalance, etc. I am thinking maybe I can use an offest dowel to move the head down about .030 or so. I haven't used these before - is this feasible???? I did check Moroso makes these in both .030 & .050 offset, .030 should be plenty. Other than maybe having to use the 1/8" thck intake gaskets, I can't see any other issues -am I missing something?

 

[GOSFAST]

I had checked the piston/head clearance and have .400" across the dome and .250" at the plug side of the dome (H693CP-030 and GMPP/EDE heads), no problem. Checked the static clearance of the valves at TDC. I have .180" clearance before the 2.25" valve just hits the inside of the eyebrow. By comparison, I checked the clearance with a set of 049's and a stock 2.07 valve and have .400", so I know the relief is plenty deep, just not wide enough.

I still have to harvest the rollers and balance of valvetrain from the 408 before I can check with clay, but using the cam spec data for lobe lift at an installed ICL, I am looking at interfence - or darn close. Short of disassembly, flycut,, rebalance, etc. I am thinking maybe I can use an offest dowel to move the head down about .030 or so. I haven't used these before - is this feasible???? I did check Moroso makes these in both .030 & .050 offset, .030 should be plenty. Other than maybe having to use the 1/8" thck intake gaskets, I can't see any other issues -am I missing something?

Hi Grn, DONT get involved with offset dowel pins, you'll end up opening the "proverbial" can of worms. IF you have to make a piston notch larger (O.D.) don't waste time or money on rebalancing, there's no reason to do it. You won't be removing any substantial amount of weight from an aluminum piston. Thanks, Gary in N.Y.
P.S. This is another classic example of info up here that's totally incorrect. Light grinding on rods or light machining on pistons, after the fact, has NO negative affect on the balance job. If you were to take 10 grams off each piston, we would make the same statement. Some units we build over sometimes go out the door balanced with 49% or 51% factor. It don't amount to a "hill-o-beans". I know I'll get "slammed" up here posting this statement, but in the real world this is dictated by the "Laws of Physics" you CANNOT balance a V-8 unit, period. If any doubt this call the company that makes the equipment. I'm using the term here, "balancing", in it's techinical form. The only units that are physically able to be balanced in the true sense of the word are ones that require NO bobweights.This includes most "opposed" units (e.g. V.W.'s, Porsches, Corvairs, etc.), 4 cyl., 6 cyl., etc. The balancing that we understand on the V-8's (where bobweights get factored in) is merely making them "comfortable". Don't everyone jump on this, CALL the mfr. Also DON'T READ THIS AS "IT'S NOT NECESSARY TO BALANCE ANYTHING".

 

[GRN69CHV]

I understand what you're saying. I have read elsewhere where the minute removal of material from the notch should not cause an issue. Just a shame, because I had the assembly balanced to (I think) within 1 gram. It looks like the interference is occuring at only one point (approx 1/8" long) at what I would consider the apex of the valve in relation to the eyebrow. I am thinking I may be able to just smooth this area and gain the clearance. Probably only need to gain about .020 at the one point to make things work correctly.

 

[TC]

for sale ad deleted by mod

 

[Wolfplace]

Hi Grn, DONT get involved with offset dowel pins, you'll end up opening the "proverbial" can of worms. IF you have to make a piston notch larger (O.D.) don't waste time or money on rebalancing, there's no reason to do it. You won't be removing any substantial amount of weight from an aluminum piston. Thanks, Gary in N.Y.
P.S. This is another classic example of info up here that's totally incorrect. Light grinding on rods or light machining on pistons, after the fact, has NO negative affect on the balance job. If you were to take 10 grams off each piston, we would make the same statement. Some units we build over sometimes go out the door balanced with 49% or 51% factor. It don't amount to a "hill-o-beans". I know I'll get "slammed" up here posting this statement, but in the real world this is dictated by the "Laws of Physics" you CANNOT balance a V-8 unit, period. If any doubt this call the company that makes the equipment. I'm using the term here, "balancing", in it's techinical form. The only units that are physically able to be balanced in the true sense of the word are ones that require NO bobweights.This includes most "opposed" units (e.g. V.W.'s, Porsches, Corvairs, etc.), 4 cyl., 6 cyl., etc. The balancing that we understand on the V-8's (where bobweights get factored in) is merely making them "comfortable". Don't everyone jump on this, CALL the mfr. Also DON'T READ THIS AS "IT'S NOT NECESSARY TO BALANCE ANYTHING".

=
No slam here,,,
I could not agree more with the whole post.
In fact I just said the same thing to Joe on the phone

PS
Ha,, & you thought you were gonna come back & find me bitchin huh

 

[Guest]

He, He!!

The motor might throw a damper or two if you hammer the heck outta it and it's made out of UNBALANCED junkyard parts like my old junk301 was....

It would "sing" to me about three times going to above 7,000 rpm as it passed through "harmonic ranges"...

pdq67

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[GRN69CHV]

Update, I did get some .030 offset dowels, just to try. DId a mock up last night, everything fits like a glove. Bolts go right in, intake sits perfect with standard gaskets. .050 offset may have caused problems, but the .030 is perfect. Have .030 side clearance to the eyebrow now. Valves were just scraping prior. But the good thing is the valves have .390 intake clearance and .470 exhaust clearance at top dead center. I could run a cam with as much as .300 lift at TDC and still not have contact. Considering most cams are in the .070 - .080 lift at TDC, I am good to go.