geodoc
Cruisin' Guzzisti
- Joined
- Oct 27, 2008
- Messages
- 205
I learned something on my Tonti-engined Loop that I thought worth passing along.
The guides were worn in the donor Convert engine and rather than replacing the guides, I decided to go with K-Line swedged inserts. The shop that installs them reported good service and no complaints in various car & bike engines. Before installing them, their machinist called me up and pointed out that in the process of opening up the guide bores, the oil "scraper" sections on the top of the guide would be removed. I told him to go ahead and see how they did in service. As it turns out, without the scraper sections at the top of the guide, both intake and exhaust had considerable oil traveling down into the ports past the valve stem and guide. Apparently, the scraper sections do a pretty good job of keeping excess oil from entering the guide - valve stem clearance.
I've taken the heads off and we'll now install guide seals, both intake and exhaust Which should solve the problem. It will be a little ore complicated since I'm using a Megacycle X10 cam with about .45" lift at the valve and only about .015" clearance between the top of the guide and the bottom of the upper valve spring keeper. Lucky the machine shop has a fixture that will allow them to remove about 1/8" or so seal lip clearance off the top of the guide in place along with making a groove for the seal.
I also noticed when taking the heads off that the Smith Bros. RH intake push rod had a worn spot (not just rubbed). Where it was located is about mid-way down the tube tunnel in the Gilardoni 950 cylinder. It appears that the casting in there is a little smaller than in the other tunnels, so I'll be opening it up with a die grinder just slightly and getting a replacement push rod.
Learning by doing ...............................
PS: had it on the dyno a week ago to tweak jetting. Ended up with:
MJ: 135
PJ: 60
Slide: 50/3
NJ: 265AB
Needle: K5 lowest notch
1000SP Gilardoni cylinder kits
36mm dellortos
Megacycle 620X10
Stock Loop "cigars" w/ large outlet
Stock Loop airbox / filter
Loop single-point distributor w/ heavier (slower) advance springs and transistor ign. booster
Didn't get a print-out, but ended up with 54 HP @ 6500 RPM after which it started to drop off a little. Torque curve was Guzzi-typical flat. The dyno was a brake-type, not a Dynojet & apparently shows about 10-15% lower HP #'s than the Dynojet.
The guides were worn in the donor Convert engine and rather than replacing the guides, I decided to go with K-Line swedged inserts. The shop that installs them reported good service and no complaints in various car & bike engines. Before installing them, their machinist called me up and pointed out that in the process of opening up the guide bores, the oil "scraper" sections on the top of the guide would be removed. I told him to go ahead and see how they did in service. As it turns out, without the scraper sections at the top of the guide, both intake and exhaust had considerable oil traveling down into the ports past the valve stem and guide. Apparently, the scraper sections do a pretty good job of keeping excess oil from entering the guide - valve stem clearance.
I've taken the heads off and we'll now install guide seals, both intake and exhaust Which should solve the problem. It will be a little ore complicated since I'm using a Megacycle X10 cam with about .45" lift at the valve and only about .015" clearance between the top of the guide and the bottom of the upper valve spring keeper. Lucky the machine shop has a fixture that will allow them to remove about 1/8" or so seal lip clearance off the top of the guide in place along with making a groove for the seal.
I also noticed when taking the heads off that the Smith Bros. RH intake push rod had a worn spot (not just rubbed). Where it was located is about mid-way down the tube tunnel in the Gilardoni 950 cylinder. It appears that the casting in there is a little smaller than in the other tunnels, so I'll be opening it up with a die grinder just slightly and getting a replacement push rod.
Learning by doing ...............................
PS: had it on the dyno a week ago to tweak jetting. Ended up with:
MJ: 135
PJ: 60
Slide: 50/3
NJ: 265AB
Needle: K5 lowest notch
1000SP Gilardoni cylinder kits
36mm dellortos
Megacycle 620X10
Stock Loop "cigars" w/ large outlet
Stock Loop airbox / filter
Loop single-point distributor w/ heavier (slower) advance springs and transistor ign. booster
Didn't get a print-out, but ended up with 54 HP @ 6500 RPM after which it started to drop off a little. Torque curve was Guzzi-typical flat. The dyno was a brake-type, not a Dynojet & apparently shows about 10-15% lower HP #'s than the Dynojet.