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Search found 113 matches

by Nut124
Sat Sep 19, 2020 10:04 am
Forum: Engine Tech
Topic: Reducing cam bore ID in an aluminum cam pulley?
Replies: 12
Views: 282

Re: Reducing cam bore ID in an aluminum cam pulley?

I got some aluminum foil tape ready to put on the cam. There's these guys for allowing bearings to be mounted in oversized, loose-tolerance housings. Take a look at their "AN" series. I don't know how you get just one, maybe ask for a sample or find a distributor? http://www.usatolerancerings.com/i...
by Nut124
Thu Sep 17, 2020 7:08 pm
Forum: Engine Tech
Topic: Reducing cam bore ID in an aluminum cam pulley?
Replies: 12
Views: 282

Re: Reducing cam bore ID in an aluminum cam pulley?

The US vendor is sending me a new pulley. It is likely be just like the one I already have. I got some aluminum foil tape ready to put on the cam. This is a 2-piece adjustable pulley. I find that there is about 0.015 radial play between the inner and the outer piece as well. This would affect concen...
by Nut124
Thu Sep 17, 2020 9:01 am
Forum: Engine Tech
Topic: Reducing cam bore ID in an aluminum cam pulley?
Replies: 12
Views: 282

Re: Reducing cam bore ID in an aluminum cam pulley?

The next Captain Obvious move to check both cams and sprockets ("pulley"). If the sprockets are consistent in ID then... Perhaps closer examination of the camshaft is called for, particularly the journals. ~~~~~~~~~~~~~~~ Twenty thousandths of an inch is close to .5mm (FIAT is metric). A novice mac...
by Nut124
Thu Sep 17, 2020 8:56 am
Forum: Engine Tech
Topic: Reducing cam bore ID in an aluminum cam pulley?
Replies: 12
Views: 282

Re: Reducing cam bore ID in an aluminum cam pulley?

Thanks for the suggestions. Yes, bore and sleeve would be the correct solution but would likely cost me $150 or so.

I think I will try the shim wrap on the cam. It is needed there to keep the pulley centered while I torque the cam bolt. Once tight I do not think it would move.
by Nut124
Wed Sep 16, 2020 10:25 pm
Forum: Engine Tech
Topic: Reducing cam bore ID in an aluminum cam pulley?
Replies: 12
Views: 282

Reducing cam bore ID in an aluminum cam pulley?

I had to remove a DOCH Fiat ex cam pulley because it was not running "true". The pulley OD, and the timing belt, was wobbling by about 20-30 thou causing a pulsating belt whining noise. The problem seems to be that the cam boss bore in the aluminum pulley is about 20 thou larger than the cam boss, p...
by Nut124
Wed Sep 16, 2020 12:14 pm
Forum: Engine Tech
Topic: Cast rings for nos
Replies: 2
Views: 227

Re: Cast rings for nos

Get a steel top ring. I got mine from Total Seal. $$$ but worth it to me.
by Nut124
Wed Sep 16, 2020 11:35 am
Forum: Engine Tech
Topic: Piston rings
Replies: 5
Views: 309

Re: Piston rings

Is it possible to use 4.094 bore rings on a 4.087 bore with just a file fit I would say yes. The difference in circumference is only about 20 thou. I did something similar in my recent build, had to file about 20 thou and have excellent cranking compression and no blow by. The ring I used, from Tot...
by Nut124
Mon Sep 14, 2020 2:07 pm
Forum: Engine Tech
Topic: Cam intake lobe vs exhaust lobe
Replies: 11
Views: 1484

Re: Cam intake lobe vs exhaust lobe

Exhaust valves usually run larger valve clearances, like 20 thou vs 16 on the intakes. In order to keep valve seating velocity the same IN vs EX, the grinds would have to differ ever so slightly at the low lift area where the valve is closing/opening. If the same exact gring were used at EX as in IN...
by Nut124
Sat Sep 12, 2020 10:23 pm
Forum: Engine Tech
Topic: Cam lobe decel ramp - valve life?
Replies: 32
Views: 1327

Re: Cam lobe decel ramp - valve life?

FYI only, in case anyone is interested, I swapped out the "bad" cam and installed my old Alquati 40-80 intake cam. I adjusted the clearances and checked timing. C/L is 105ATDC. Target is 107-108. Will adjust tomorrow. BTW, this cam, as installed now, producdes 190psig cranking compression. the "bad"...
by Nut124
Fri Sep 11, 2020 7:28 pm
Forum: Engine Tech
Topic: Cam lobe decel ramp - valve life?
Replies: 32
Views: 1327

Re: Cam lobe decel ramp - valve life?

I appreciate the help, thanks. Particularly Mike - Thank you. I removed the "bad" cam and installed the old faithful "Alquati" 40-80 cam I had ran for 20 years. I would like a bit more cam, but suppliers are out. The old cam will run "quiet" and may produce OK power when timed correctly. I ran it fo...
by Nut124
Fri Sep 11, 2020 7:18 pm
Forum: Engine Tech
Topic: Cam lobe decel ramp - valve life?
Replies: 32
Views: 1327

Re: Cam lobe decel ramp - valve life?

williamsmotowerx wrote: Fri Sep 11, 2020 12:05 am What does the opening side look like? Speculating cam could have been ground backwards?
It's the same.
by Nut124
Thu Sep 10, 2020 11:27 am
Forum: Engine Tech
Topic: Cam lobe decel ramp - valve life?
Replies: 32
Views: 1327

Re: Cam lobe decel ramp - valve life?

Mike, just to confirm: The 0.0008/deg maximum is based on crank degrees, not cam degrees, right? No, it's cam degrees. sorry I didn't clarify that. .0008" per cam degree Mike, thanks for the clarification. With cam degrees, this cam looks even worse, seating velocities in the 3-4 thou/cam deg vs 0....
by Nut124
Thu Sep 10, 2020 9:26 am
Forum: Engine Tech
Topic: Cam lobe decel ramp - valve life?
Replies: 32
Views: 1327

Re: Cam lobe decel ramp - valve life?

What kind of max velocity limits are being recommended for valve seating? You want the velocity at the lash point to be under .0008" per degree. If it's over .001", I would worry. Mike, good info. just what I needed. Thanks! Will take me a day or two to get numbers... Busy making vaccine. Mike, jus...
by Nut124
Wed Sep 09, 2020 8:24 pm
Forum: Engine Tech
Topic: Cam lobe decel ramp - valve life?
Replies: 32
Views: 1327

Re: Cam lobe decel ramp - valve life?

What kind of max velocity limits are being recommended for valve seating? You want the velocity at the lash point to be under .0008" per degree. If it's over .001", I would worry. Mike, here is the data. It kind of confirms what I'm hearing. In this test, I have the #1 valve lash adjusted to 0.005 ...
by Nut124
Wed Sep 09, 2020 11:26 am
Forum: Engine Tech
Topic: Cam lobe decel ramp - valve life?
Replies: 32
Views: 1327

Re: Cam lobe decel ramp - valve life?

What kind of max velocity limits are being recommended for valve seating? You want the velocity at the lash point to be under .0008" per degree. If it's over .001", I would worry. Mike, good info. just what I needed. Thanks! Will take me a day or two to get numbers... Busy making vaccine.