Welcome to Club SAITO !
RE: Welcome to Club SAITO !
ORIGINAL: Hobbsy
Saito instructions say .004'', Enya instructions say .002'', I take what the instructions say to be the, ''supposed''. Bill Robison is not Mr. Saito. The Saito engineers should know what the engine needs for longevity.
Saito instructions say .004'', Enya instructions say .002'', I take what the instructions say to be the, ''supposed''. Bill Robison is not Mr. Saito. The Saito engineers should know what the engine needs for longevity.
Richard/Club Saito #635
My Feedback: (102)
Join Date: Dec 2001
Location: Colonial Beach, VA
Posts: 20,370
Likes: 0
Received 25 Likes
on
25 Posts
RE: Welcome to Club SAITO !
Hey Richard, the thing is we don't know the thermo dynamics of the engine, for example, we don't know if the pushrods get much heat from the cam area on the Saito. They are out in the breeze on most applications even in a cowl. The valve stems are not long enough to expand and contract much in differing temperatures. Compared to the cylinder temperature variances in fkight the pushrods are probably pretty stable once at their operating temperature. The cylinder length probably changes quite a bit because its aluminum but the pushrods are shorter, so, I choose to let Mr. Saito make the rules.
RE: Welcome to Club SAITO !
ORIGINAL: Hobbsy
Hey Richard, the thing is we don't know the thermo dynamics of the engine, for example, we don't know if the pushrods get much heat from the cam area on the Saito. They are out in the breeze on most applications even in a cowl. The valve stems are not long enough to expand and contract much in differing temperatures. Compared to the cylinder temperature variances in fkight the pushrods are probably pretty stable once at their operating temperature. The cylinder length probably changes quite a bit because its aluminum but the pushrods are shorter, so, I choose to let Mr. Saito make the rules.
Hey Richard, the thing is we don't know the thermo dynamics of the engine, for example, we don't know if the pushrods get much heat from the cam area on the Saito. They are out in the breeze on most applications even in a cowl. The valve stems are not long enough to expand and contract much in differing temperatures. Compared to the cylinder temperature variances in fkight the pushrods are probably pretty stable once at their operating temperature. The cylinder length probably changes quite a bit because its aluminum but the pushrods are shorter, so, I choose to let Mr. Saito make the rules.
Another thought: how about someone making the valve covers quickly removable on a Saito (1.25) engine, run it at WOT for long enough to stabilize the temps, then measure the valve lash compared to the original cold setting? I would, but I don't have a 1.25 (yet) and I don't have another Saito set up to run on the bench right now.
Richard/Club Saito #635
My Feedback: (102)
Join Date: Dec 2001
Location: Colonial Beach, VA
Posts: 20,370
Likes: 0
Received 25 Likes
on
25 Posts
RE: Welcome to Club SAITO !
If Saito cams have acceleration and deceleration ramps then running them too close defeats this. Bill could not quite determine whether they did or didn't. For those who might not know, these ramps gently lift the valve at first off its seat and then gently set it back down so it doesn't bag shut. By the same token setting them too loose also defeats this feature.
Senior Member
Join Date: Jul 2003
Location: Near Princeton,
WV
Posts: 157
Likes: 0
Received 0 Likes
on
0 Posts
RE: Welcome to Club SAITO !
I'd bet Saito says they need more gap than they really do for one reason, you can NOT trust the end user to do things properly and they don't want engines returned because people set improperly.
I'm also confident that the gap increases with heat. The aluminum cylinder expands more per degree than steel, and the aluminum definitely runs hotter than the steel push rods.
I just looked it up and Saito says .002" to .004" in the book I have for the 100. IMHO this means that Saito engineers believe that .001" to .005" won't hurt it, if they did any research on people using a feeler gauge.
Cory
I'm also confident that the gap increases with heat. The aluminum cylinder expands more per degree than steel, and the aluminum definitely runs hotter than the steel push rods.
I just looked it up and Saito says .002" to .004" in the book I have for the 100. IMHO this means that Saito engineers believe that .001" to .005" won't hurt it, if they did any research on people using a feeler gauge.
Cory
RE: Welcome to Club SAITO !
it is hard to say but I think the gap tends to close up with heat. The valve stem gets slightly longer when hot. The pushrods tend to grow in length as well. Not a lot because the engine is small. But the gap would close up slightly when the engine is hot. Granted the cylinder grows a little bit longer too. but I don't think it is enough to offeset the gap closing up a little bit.
Senior Member
Join Date: Jul 2003
Location: Near Princeton,
WV
Posts: 157
Likes: 0
Received 0 Likes
on
0 Posts
RE: Welcome to Club SAITO !
ORIGINAL: earlwb
it is hard to say but I think the gap tends to close up with heat. The valve stem gets slightly longer when hot. The pushrods tend to grow in length as well. Not a lot because the engine is small. But the gap would close up slightly when the engine is hot. Granted the cylinder grows a little bit longer too. but I don't think it is enough to offeset the gap closing up a little bit.
it is hard to say but I think the gap tends to close up with heat. The valve stem gets slightly longer when hot. The pushrods tend to grow in length as well. Not a lot because the engine is small. But the gap would close up slightly when the engine is hot. Granted the cylinder grows a little bit longer too. but I don't think it is enough to offeset the gap closing up a little bit.
Aluminum 12.3 (10-6 in/in oF)
Steel 7.3 (10-6 in/in oF)
The aluminum is outrunning the steel quickly.
Cory
RE: Welcome to Club SAITO !
I'm considering purchasing a used Saito for a Sig Rascal 40. I just had a Magnum 52 RFS on it, but was not enough power to call it a sports plane. What would be a good Saito candidate? Realize that the Rascal 40 has a wood cowl integral to the fuselage, so I can't go too big.
Thanks.
Thanks.
Senior Member
Join Date: Jul 2003
Location: Near Princeton,
WV
Posts: 157
Likes: 0
Received 0 Likes
on
0 Posts
RE: Welcome to Club SAITO !
ORIGINAL: w8ye
All the Saito singles 62 through 125 have the same cam and rocker arms so the valve lift would be the same.
All the Saito singles 62 through 125 have the same cam and rocker arms so the valve lift would be the same.
A quote from Bill's article.
When set at 0.0005" cold, the running, hot clearance is close to the 0.002" specified. The clearance always opens as the engine warms up.
RE: Welcome to Club SAITO !
I read what bill said and thought he may have said it back to front meaning .0005 was hot and vicky verky so to speak.Anybody here get stuck on the low speed needle because your engine idles and transitions so well then wind the heck out of the main to get a half decent top end?
Senior Member
Join Date: Jul 2003
Location: Near Princeton,
WV
Posts: 157
Likes: 0
Received 0 Likes
on
0 Posts
RE: Welcome to Club SAITO !
ORIGINAL: w8ye
Try Bill's valve lash settings? The engine will not idle for toot and the high speed will be weak.
.002'' cold is about it.
Try Bill's valve lash settings? The engine will not idle for toot and the high speed will be weak.
.002'' cold is about it.
Cory
My Feedback: (102)
Join Date: Dec 2001
Location: Colonial Beach, VA
Posts: 20,370
Likes: 0
Received 25 Likes
on
25 Posts
RE: Welcome to Club SAITO !
It is exactly .004" and Enya's is exactly .002, I miked them both.
OF, if you attach the prop to the HS needle and wind the heck out of it, it might have more power than the crankshaft.[8D]
OF, if you attach the prop to the HS needle and wind the heck out of it, it might have more power than the crankshaft.[8D]
My Feedback: (102)
Join Date: Dec 2001
Location: Colonial Beach, VA
Posts: 20,370
Likes: 0
Received 25 Likes
on
25 Posts
RE: Welcome to Club SAITO !
The reason Jim alluded to the ragged idle and weak top is that running the lash too close causes the valves to open sooner and close later. This would be fine if the load were reduced and the engines ability to breath were enhanced and it could turn higher rpms. This engine is a 1.20 ABITAR, the recommended prop is a 14x6 in lieu of the normal 1.20 sized 15x8. On 10% Wildcat it turned an APC 14x6 at 12,180 rpm. With four valves and bucket cam followers it was set up to rev and breath at those revs.
Senior Member
Join Date: Jul 2003
Location: Near Princeton,
WV
Posts: 157
Likes: 0
Received 0 Likes
on
0 Posts
RE: Welcome to Club SAITO !
I just miked mine since .005" was stuck in my head, but calipers was all I used before. Mine is .004" on one end, and .0055" on the other.
Cory
Cory
My Feedback: (102)
Join Date: Dec 2001
Location: Colonial Beach, VA
Posts: 20,370
Likes: 0
Received 25 Likes
on
25 Posts
RE: Welcome to Club SAITO !
Cory, check the thick end and and see if the edges are ragged from the stamping process. I bought NAPA stainless guages removed the .002 and .004, in fact I cut them in two also.