Number 1 cylinder, top dead center

[2wrench]

Paul, I think my cam is a GT6 or something like that.
It is a very conservative bump up. All settings,
as I understand it, should remain to standard specs;
but about 12 or 12+? horsepower increase.

I just didn't want to get too crazy.

Just gotta get it in properly.

Got photos of the cam pushed in and pulled out both,
so might as well post them here.

Pushed in:

Pulled out showing the notch for the retainer:

 

[2wrench]

So I messed with it and tried something slightly
different.

I put a split washer behind the retainer plate.
Torquing down to about 16 pounds, maximum, and I
can turn the cam with my fingers, but it hits a spot
where I feel a slight resistence; but, I can push it
past that spot anyway.

In terms of end play, well, frankly, there isn't any.
I mean none. I think the tolerances are so tight, that
any amount of distortion of the retainer from torquing
binds the cam; but if I take it to about 12 pounds
torque, it seems to turn just fine....again, no, no
end play. She's just right there.

 

[dklawson]

Is the retainer new and if so, does it appear to be a stamped part where there might be a raised surface around the hole for the cam... something that perhaps could be stoned or filed flat?

 

[DrEntropy]

I'd be for lapping it a bit with "wet-or-dry" #600 and some oil, on a truly flat surface. Steel plate or as previously mentioned, glass... It has to locate the cam specifically, or the lifters may wear "funny". For it to bind the cam, it sounds like Doug has a good suggestion: it may be "burred" at the edge which locates the cam.

 

[TR3driver]

Also, if torquing the bolt is binding the cam but the cam isn't coming up against something else, then the retainer plate must not be flat to begin with (hence is distorting when tightened).

 

[Guest]

Can it be flipped upside down?

Also, that is an awful lot of cam lube on there, don't think you need that much.

 

[2wrench]

Is the retainer new and if so, does it appear to be a stamped part where there might be a raised surface around the hole for the cam... something that perhaps could be stoned or filed flat?

You make a good point. No. The retainer is not new. So...new cam
shaft, old retainer.

I'm getting to the place where I believe the cam's machining and
tolerances are so close, that any amount of tourqing distorts the
the retainer just enough to bind the cam up.

Leads me to choices: Find a vendor that sells a retainer that is a bit
thinner (doubt it will exist, but you never know).

Sand the existing retainer to a smaller/thinner size to accommodate needs.
or

take the retainer and crank to the machine shop and have whatever
part seems best machined down. Seems I'd go to changing the retainer
cause it's just gotta be the cheaper part if we mess it up.

It has occurred to me that it could be possible that the machined slot
in the cam is not true, or actually, the cam itself is defective,
although I do doubt this.

I retain,
Forever baffled,

 

[2wrench]

Can it be flipped upside down?

Also, that is an awful lot of cam lube on there, don't think you need that much. [/quot


Bill: I did try a different orientation on the retainer. I don't
think you can actually put it on wrong. It didn't look like it would
have worked for me. Trying to install on another side resulted in the
bolt holes did not line up. Flipping it upside down and installing
I think could work, but did not have any type of improvement toward
the better.

Oh, yeah, and the lube.....really didn't know. I thought the
jucier....the better....so I lubed it up. Figure too much is porbably
okay.....but too little would suck.

You do make me feel better, cause I've been fussing with it so much,
thought I might have removed too much lube.

 

[DrEntropy]

Do NOT machine the cam groove, Dennis. Lap the retainer.

...just a short FYI....

 

[Brosky]

2W,

BPNW sells the new retainer plate and they are in stock.
https://www.bpnorthwest.com/.sc/ms/dd/TR250-6--Main Engine Components/9837/Camshaft Lock Plate

Just for the heck of it, take a break and call Greg or Leighton on Monday and ask them to mic theirs and compare it to the thickness of yours.

 

[2wrench]

I'm very tempted at sanding down on the darned retainer.
All these close tolerances got me thinking twice,
though. Might be best left to a machine shop.

Got this nagging thought that there could be more
of a probem with the cam. It's like I doubt it...
but, just don't want to ignore the possibility.

I will talk on Monday to bpnortwest as well as the
machine shop. I'll keep you posted.

 

[Brosky]

Smart move.

Call first, reduce thickness after measuring, not before.

I'm curious to see how the measurements are going to match mine. No, I don't have my retainer here, or I would have given you my stock measurements. I do have a new one due in from TRF on Tuesday. I forgot to order it from BPNW when I ordered the cam. I'll have the new one, and my old one to compare to yours by then.

 

[RomanH]

2wrench,
You have to fit the retainer plate for your application. Lap the thickness down until you reach the range of end float specified in Bentley's. I believe the manual even states that it is necessary to do this procedure.
Is this the cam you bought? This is a performance camshaft for a TR250, TR6 and GT6. Spec's Duration 270, Intake lift .410, exhaust .400. Good idle, stock valve springs ok, 12-15 HP gain over stock.
If it is you are going to love it! Put this one in my 6 last year. the power just builds from around 2K RPM and keeps pulling past 5600 with no let up. Very nice! :thumbsup:

 

[TR6oldtimer]

2wrench, I don't think the float spec. has been mention, so here it is. Using a feeler gauge, you should have .004-.008" end float on that cam.

 

[TR3driver]

Just a thought ... is it possible the groove on the new cam isn't quite as deep as the old cam, and the retainer is bottoming in the groove instead of binding against the sides ? Seems like some careful measurements, plus maybe some tests with machinist's blue would be in order. Also maybe check the front plate where the retainer sits against it; perhaps it is not flat.

 

[70herald]

Just to repeat what I said earlier, I had the same problem with the cam retainer that I bought. My guess is that some of them are a bit to tight.

 

[2wrench]

2wrench,
You have to fit the retainer plate for your application. Lap the thickness down until you reach the range of end float specified in Bentley's. I believe the manual even states that it is necessary to do this procedure.
Is this the cam you bought? This is a performance camshaft for a TR250, TR6 and GT6. Spec's Duration 270, Intake lift .410, exhaust .400. Good idle, stock valve springs ok, 12-15 HP gain over stock.
If it is you are going to love it! Put this one in my 6 last year. the power just builds from around 2K RPM and keeps pulling past 5600 with no let up. Very nice! :thumbsup:

Y-e-s, Roman! You just gave me the chills. That's what I'm talking about.
Just what I had hoped for. Not tooo much, but just enough to dig it!
I'm excited. I've not compared exactly, but I'm sure you've described the
cam I bought....I recall now the 12-15 horse power, etc.... the GT6. Cool!

Further, I am encouraged to run my retainer plate to the machine shop
for a shower and a shave.

Thanks to all,

 

[2wrench]

Just to repeat what I said earlier, I had the same problem with the cam retainer that I bought. My guess is that some of them are a bit to tight.

Oh, and just so you know, I appreciate you have likely been right on the issue
the whole time. I just didn't know that machining the retainer was actually
common practice. If it's in the Bently, I missed it.

You know, you just want to think you can buy a part, after-market or not,
and have it fit as it should without rebuilding parts.

Oh, well, I'm not hung up. I'm actually relieved at the thought that what
it looked like I should do, is probably what I should do.

Thanks again to all of you for your good input,
Sincerely,

 

[Brosky]

2W,

Mine (new) should be in tomorrow. Machine shop says they don't care how it feels to them or anyone, that's why they have feeler gauges with numbers on. He'll lap it in to allow for a snug fit to the tolerance allowed, but no resistance.

It is not a resistance item to be worn in, any more than a main or rod bearing, so continue your due diligence and lap it for the proper clearance. Or better yet, let the shop do it. That's how they make a living and know the proper way to insure that it's done evenly.

 

[Brosky]

My new cam retainer came in today and I measured the old one before leaving this morning. I didn't have time to take pictures of the new one, but it measures 0.184" exactly at three points around the part.

As you can see, the old one is a 0.0015" smaller at the start and in the worn areas is down to 0.1775" at the lowest point, which is on the lower side of the plate. Go figure???

Anyhow, for those inquiring minds, here is what we've been talking about.