dartfreak75
Restore it, Dont part it!
I installed it straight up dot to dot the cam had 4 degrees advace cut into it. Dot to dot
Too much timing?
- Thread starter dartfreak75
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That's pretty good. I'd say just right for a street engine. Can you refresh my memory on the cam specs again? I'm sorry for all the questions, I cannot remember.
But now, hold on hoss. Did you put the degree wheel on it and SEE that 4 degrees? If not, you could be 10 degrees retarded.
dartfreak75
Restore it, Dont part it!
Yes I degreed it and it was what the cam card said it should be. I can't remember now I think it was 3 degrees btdc
I thought I remembered you degreed it.
dartfreak75
Restore it, Dont part it!
Y e a that's how i found that wonky timing chain and @Dartsun was nice enough to send me a new one.
We got some super good folks on this site.
mopowers
Well-Known Member
What are the cam specs?
dartfreak75
Restore it, Dont part it!
Ok, there you go. That 112 is helpin you out on the cylinder pressure. If you work with that timing, you can probably go 20 initial, 34-36 total all in by 2500 and it'll likely never spark knock. I think you're in a good place. Just get the timing curve worked out and I bet it'll run on 87.
dartfreak75
Restore it, Dont part it!
Its set at 20 intital right now and the bottom end feels good. Nice and strong idles good and is really responsive.
I wouldn't drive it a pile like that until you get the FBO limiter plate and get the total limited to somewhere tween 34-36. And get it all in by 2500 and it'll scoot.
What rpm does the idle drop to in gear
dartfreak75
Restore it, Dont part it!
Yea im gonna buy one and start on that.
dartfreak75
Restore it, Dont part it!
Around 650-750
Don't be a cheap *** either. Get the full kit with the sprAngs too. lol
dartfreak75
Restore it, Dont part it!
Lol ok sounds good.
which is it 650 or 750 ? where is the timing at in gear ?
I'm going to start mine with one light and one medium spring. Might be a good place for you to. I think two light springs may have it advancing some at idle. Don't want that.
dartfreak75
Restore it, Dont part it!
The timing didn't change at any rpm below 1000 600-1000 it doesn't change over 1100 the mechanical advance starts to open up and kick in I played with the idle speed went all the way down to it almost dying all the way up to 990 and the timing never changed
mopowers
Well-Known Member
Can you explain how you did the cranking compression test?
Not that it matters - because it is what it is - but I'd expect more than 150 psi with that cam and a true 10:1 SCR. For reference, my 9.6:1 SCR (measured) 340 has an intake closing after yours and cranks 170 psi.
Don't be afraid of giving it more initial advance. If it wants it, it wants it. As long as it doesn't buck the starter, you're fine. I run 26 initial and the 340 loves it.
That 112 is eatin a lot of cranking pressure up. Probably a good thing.
dartfreak75
Restore it, Dont part it!
I disconnected the coil and cranked the engine over a few cranks. 150 psi is pretty close from what I've read. I may be under 10:1 some that was original figures and after I checked my valve to piston clearance I never worried about it anymore. Let me run the numbers again and see what I get. I know I was .012 under the deck with 5 cc flattops 65cc heads and a .050 head gasket i think my original numbers was with a .028 head gaskets and I opted for the thicker ones.
mopowers
Well-Known Member
Was the throttle open? Engine warmed up? How many cylinders did you test? Since the engine is fresh, it may be a good idea to test all of them and stash the results in a note pad as a baseline for use down the road. That's good info to have.
Either way, sounds like a good running little motor.
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I crank it over until it stops pushing the gauge up. It'll only push it up so far.
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