crcain

Love ya Ted! We will try this tonight.

nitz

iTrader: (3)

update: more tribulations
measured the intake cam again with the new method of reading at 0.005" of lift with crank turning in clockwise direction. we recorded 37.5 degrees BTDC. then went over peak lift. then spun the crank counter clockwise and read at 0.005" of lift again on the left side of the base circle. we recorded 149 degrees BTDC and calculated LC = 87.5 degrees ATDC. this still not anywhere near 109 degrees published. such a large difference only seems correctable by moving a cam gear tooth over on the timing belt then fine tuning with adjustable gears.

we then decided to try the exhaust came and caculated LC = 112.5 degrees BTDC (i don't remember the exact ATDC numbers we recorded). this is much more inline with the 111degrees published for the exhaust.

i'm at a loss with regards to the intake cam. is it just full of it and i should ditch revolvers for something else.? any advice is most welcomed.

thanks again

Ted B

iTrader: (6)

IF you took those measurements as per my instructions, and the intake opening point is 37.5 deg BTDC, and the exhaust closing point is 31 deg ABDC, that works out to an advertised duration of 248.5 deg, and a lobe centerline of ~87 deg ATDC.

Obviously, that doesn't sound good, so what you may want to do is find any other intake cam of known brand and specs, and check it. Your findings will be most interesting.

crcain

We should be putting the head and shortblock together of our friends Buschur motor anyday now. He is running HKS 272's so we will check those and see how are measurement techniques stack up.

I'm very confident in our technique. When checking peak lift directly with the dial guage, and also the .005" method, both methods landed us at 87 degrees ATDC.

With the exhaust cam peak lift method gave us 115 I believe and lobe centerline method 112.5 BTDC.

I'm 99.9% sure peak lift is occuring on that intake cam about 87 degrees.

The cam gear and crank pulley marks are lined up perfectly.

Ted how would a motor behave with an intake cam advanced 23 crank degrees?

crcain

And what's the most you've seen or heard of a cam off from it's published figures?

I really believe these Revolvers are lacking some quality control.

Ted B

iTrader: (6)

Poorly - not to mention the real risk of valves and pistons making contact.

Let's see what you get with the HKS cams before we draw conclusions.

94AWDcoupe

iTrader: (125)

webcamshafts.com has a nice tutorial on how to degree cams. It sounds like you are doing it right and the intake cam is way off. That would explain why some have had very bad results using these cams. Would also explain why some have even heard what sounds like valve contact inside the intake manifold. I would not scrap the cams. Just buy some gears and make you own marks on them when you get them setup correct. one tooth is 7.5 degress. so get it close by moving the gear tooth first. then do the rest with the cam gear adjustment. If you are taking the time to use degree wheel you should have adjustable gears to get the cams where the designer intended them to run.

Ted B

iTrader: (6)

I am suspecting the same possibility, but it is prudent to check the HKS intake cam as well, which should either prove or eliminate the accuracy of the cam gear indexing itself as an aggravating factor. If the HKS intake cam checks out, there is one problem. If it doesn't, there is at least one problem, maybe two.

crcain

Ted, et al.. thanks for your help.

Tonight we swapped the Revolver intake cam with an HKS 272. Once installed, we took measurements again and found that the lobe centerline was at 102.5 degrees.

We then put the Revolver back in, and just to double check quickly looked for peak lift and indeed it was still ocurring in the high 80's ATDC.

This experiment helped us reach the conclusion that are method is sound, and indeed there is a significant issue with the Revolver intake cam.

Right now we are contemplating tossing the Revolvers for some Jun's... or simply moving the Revolver over a tooth on the cam gear (~15 degrees crank) and also another 3.5 degrees on the cam gear (7 crank)... which given the 87 degree centerline.. should give us 87 + 15 + 7 = 109 ATDC (published spec for the cam).

It's a bit of a tough call at the moment.

Ted B

iTrader: (6)

Three questions:

(1) Is the entire valvetrain gear installed and tensioned as if the engine were running?

(2) Have you checked any exhaust cams?

(3) Have you repeated any testing with a factory cam gear?

94AWDcoupe

iTrader: (125)

Use the revolvers. Its not that big of a deal to move gear one tooth. And you would be doing the community a favor by proving a bad set of revolver cams can be fixed by indexing them.

nitz

iTrader: (3)

i'll try and answer these

Not exactly sure what u mean by this, but all valvetrain components are installed and the timing belt tensioned. We used the mitsubishi tensioner tool to introduce enough slack to slip the intake cam gear off and swap cams in and out, while making sure to keep tension on the lower part of the timing belt. let me know if you mean something else. Tensioner tool was then removed and engine turned a few times to take up slack. This is all on an engine stand.

Yep! we did the revolver exhaust cam and got LC=112.5 as mentioned earlier in this thread (post #47). Spec is 111.

All of our work so far has been done only with the factory gears, not adjustable gears. We wanted to keep the variables to a minimum.


One last thing to note is that the dowel pin on the revolver intake cam did not play nicely with the cam gear. It did not slip entirely into the gear. The gear sat a little precariously and you could rock it back and forth, almost as if the pin was not positioned correctly. We had to use the cam bolt to tighten the gear onto the cam to seat the pin further in. From what we can tell everything appeared true after that, so I don't think it's an issue. The HKS cam had no issues, and the pin fit right it. Just another area where revolver seems to be lacking quality control.

Thanks

Ted B

iTrader: (6)

Well, all of this certainly points to the Revolver intake cam as a large source of cam timing error. A variance this great will have a profound effect on the power characteristics of the engine, and threatens to bring contact between the intake valve and pistons (something that has apparently already occurred with several members). Bottom line is if one things he hears valve clatter with Revolver cams, it could be serious.

It's interesting to see the HKS cam was also 7.5 degrees off.

If you do go the JUN route, you may as well check those too.

It looks like I better do some checking myself with my new setup.

nitz

iTrader: (3)

I was also concerned about the fact that we were so far off with the HKS cam, which are known to be quite accurate, but just don't see how we could do the degreeing process any better.

So you do not think it's worth it to adjust the revolvers by a tooth, as that still may introduce piston/valve contact?

Ted B

iTrader: (6)

Retarding the Revolver intake cam by one tooth should be enough to eliminate the possibility of piston to valve contact. The cam will never give expected performance however without an adjustable gear.