Vintage Mustang Forums banner

41 - 60 of 105 Posts

·
Registered
Joined
·
221 Posts
A few years ago, Comp had a large batch of blanks with bad gears on them. I know small block Fords were affected, don't know if there were others. **
Ughhhhhhh....... I have a Comp cam that I bought 3 years ago and haven't run yet. Is there any way to tell if it's one of the bad ones?
 

·
Registered
Joined
·
20,177 Posts
It seems like every time I read about someone having distributor gear problems they have a Comp Cam. I’m using a $29 MSD Melonized gear for my Ford factory steel cam. No issues after 2 years.
 

·
Registered
Joined
·
801 Posts
Just for the record, I did have a serious problem with a HV oil pump. It twisted the rod between the dizzy and pump, giving only intermittent oil pressure. The previous owner also disconnected the oil pressure warning lamp, so I didn't know that there was anything going on until my motor started running hot.

When I stopped to find out why, there was a lot of blow-by coming out my breathers, so I checked my oil. It looked fine at first glance! Level was good on the stick. But when I looked at the rag I'd used to wipe it, it looked like silver paint.

I towed it home, tore down the engine, and despite the fact that it started easy, ran smooth, and seemed fine (except for the blow-by), my main bearings were riding on top of each other.

So my advice? If you're going to use an 'improved' pump, make sure the engine's been built with that in mind, and use a hardened ARP pump shaft. Also, idiot lights suck. Especially when they don't work.
 

·
Registered
Joined
·
3,375 Posts
Discussion Starter #46
Just a casual observation, but that seems like a lot of wear on the cam thrust plate for relatively low hours.......
You can see that from that photo? It's the smooth surface where the brass ring behind the cam gear rides, it's not a worn surface.

Sent from my SM-G955U using Tapatalk
 

·
Registered
Joined
·
3,375 Posts
Discussion Starter #47
It seems like every time I read about someone having distributor gear problems they have a Comp Cam. I’m using a $29 MSD Melonized gear for my Ford factory steel cam. No issues after 2 years.
New Como Cam, new Comp Cam gear. It's all new with a warranty this time.

Sent from my SM-G955U using Tapatalk
 

·
Registered
Joined
·
3,375 Posts
Discussion Starter #48
Just for the record, I did have a serious problem with a HV oil pump. It twisted the rod between the dizzy and pump, giving only intermittent oil pressure. The previous owner also disconnected the oil pressure warning lamp, so I didn't know that there was anything going on until my motor started running hot.



When I stopped to find out why, there was a lot of blow-by coming out my breathers, so I checked my oil. It looked fine at first glance! Level was good on the stick. But when I looked at the rag I'd used to wipe it, it looked like silver paint.



I towed it home, tore down the engine, and despite the fact that it started easy, ran smooth, and seemed fine (except for the blow-by), my main bearings were riding on top of each other.



So my advice? If you're going to use an 'improved' pump, make sure the engine's been built with that in mind, and use a hardened ARP pump shaft. Also, idiot lights suck. Especially when they don't work.
I know how to, and have built this and several other motors. To eleavate the non existant issue of a HV pump, I will be drilling a 1/32 hole in the lifter galley plug. This will give all that extra oil a place to go and the engine will not suffer from too much or too little oil.

Sent from my SM-G955U using Tapatalk
 

·
Registered
Joined
·
3,375 Posts
Discussion Starter #49
So it seems the photos do not do a good job of representing the items. Thrust plate was on tight and has normal wear. The lifters were pulled and only a couple show light Mark's of rotation on the bottom surface, the majority look brand new. The cam was pulled and all the bearings show none to slight indications of the cam being installed. The lobes are all normal looking, appear to have no markings or scratching indicating a wearing issue. The gear teeth on the cam does show excessive wear on the one side of each tooth. Casual inspection shows no Nick's or chips in the teeth. The cam bearings are smooth and correctly clocked for the oiling. All oil passages are clean and clear as they should be. All 4 gears of the gear drive look as if they are brand new.

This block was used back in the 80's and 90's with no issue so i will rule out the block. As I have used 2 distributors and 4 gears I am going to rule out a distributor problem. As i have replaced the oil pump i am going to rule that out as well. I checked the oil pump shaft and found no binding. Once all the lifters were removed the cam rotated easily and also was removed easily from the block.

The last item is the cam itsself. The new CompCam and lifter set has arrived and will be I stalled. Lifters will be primed first, conventional oil with break in additive will be used for the cam break in. I will interrupt the 30 min break in at to be decided intervals so that I may pull the distributor to inspect the gear.


Sent from my SM-G955U using Tapatalk
 

·
Registered
Joined
·
2,444 Posts
I haven't read the whole thread, but you are correct to replace the camshaft.

I went through the same thing on a high hp 351W decades ago.
Whether it was bad steel on the camshaft
Whether the camshaft gear teeth were dented from a bad install at the mechanic
Whether the cam was walking around.

It didn't matter, whatever dizzy went in, the gear was destroyed or whatever.

When the engine was taken apart, there were multiple issues, but the camshaft was changed at the same time.
No more busted gears
 

·
Registered
Joined
·
674 Posts
Not sure I would pull the distributor at all during the cam break in as the new gears also require a similar 30 minute break in cycle . . . . . If you don't set it back in exactly where it might disturb the break in. I believe that you already know to use a break in lube (such as what you put on your cam lobes) on the gears too.

One thing I don't remember seeing previously in this thread was anything about the installation height of the distributor gear on the distributor shaft (sorry if I missed it.) If the gear is installed too high or too low on the distributor shaft it will cause gear issues. Has the gear height been measured compared to end of the distributor housing and does the shaft have some up and down freeplay when installed in the block? I run billet cams and this is definitely an issue I have dealt with when installing hardened steel cam gears.

Basically there must be some distributor shaft up and down play when it is installed but the travel must be physically limited by the block on the lower side of travel and by the distributor housing on the upper side of travel.

The distributor height can be something you can visually check once you have the cam installed with the timing cover off. (The top timing gear must also be in place to set cam for and aft clearance.) Bolt the distributor down and move its shaft up and down while looking through the block casting openings. The gear itself should bottom out on the inner casting of the block. It should also be able to be lifted off the same casting by pulling the distributor shaft upward fully (were talking about maybe .020" total shaft movement from being bottomed out to be fully lifted off the block.) Out of the block the distributor shaft should offer more travel than it when in the block (about .030".)

One other thing I do on my billet cam/steel gear combos is to debur the sharp edges of the edge of the gears and then burnish them on a wire wheel. Burnishing may not be required on cast steel cams and gears but a little light deburring isn't going to hurt the process as long as items are cleaned afterwards.
 

·
Registered
Joined
·
5,521 Posts
Not sure I would pull the distributor at all during the cam break in as the new gears also require a similar 30 minute break in cycle . . . . . If you don't set it back in exactly where it might disturb the break in. I believe that you already know to use a break in lube (such as what you put on your cam lobes) on the gears too.

One thing I don't remember seeing previously in this thread was anything about the installation height of the distributor gear on the distributor shaft (sorry if I missed it.) If the gear is installed too high or too low on the distributor shaft it will cause gear issues. Has the gear height been measured compared to end of the distributor housing and does the shaft have some up and down freeplay when installed in the block? I run billet cams and this is definitely an issue I have dealt with when installing hardened steel cam gears.

Basically there must be some distributor shaft up and down play when it is installed but the travel must be physically limited by the block on the lower side of travel and by the distributor housing on the upper side of travel.

The distributor height can be something you can visually check once you have the cam installed with the timing cover off. (The top timing gear must also be in place to set cam for and aft clearance.) Bolt the distributor down and move its shaft up and down while looking through the block casting openings. The gear itself should bottom out on the inner casting of the block. It should also be able to be lifted off the same casting by pulling the distributor shaft upward fully (were talking about maybe .020" total shaft movement from being bottomed out to be fully lifted off the block.) Out of the block the distributor shaft should offer more travel than it when in the block (about .030".)

One other thing I do on my billet cam/steel gear combos is to debur the sharp edges of the edge of the gears and then burnish them on a wire wheel. Burnishing may not be required on cast steel cams and gears but a little light deburring isn't going to hurt the process as long as items are cleaned afterwards.
Exactly. I asked, but it was never answered answered. You can install all the distributors you want, but if you don't measure the gear placement on any of them, it doesn't matter.
 

·
Registered
Joined
·
674 Posts
Exactly. I asked, but it was never answered answered. You can install all the distributors you want, but if you don't measure the gear placement on any of them, it doesn't matter.

Yep. One should never think that the hole in the new gear is in the proper location . . . . . I have found substantial differences from the same aftermarket manufacturer for the same part #. :shrug:
 

·
Registered
Joined
·
3,375 Posts
Discussion Starter #54
Did I measure the gear on the distributor shaft, no. But I did use a distributor (Mallory Dual Point) that I used for years in the past with no issues in the past, that had an issue this time around. Yes, both distributors have vertical shaft movement when out of the block, and I'll do a mock up and see if I can get a measurement on the movement before I do a final assembly.
 

·
Registered
Joined
·
9,465 Posts
Good luck with the new cam! Sorry you're having so many issues with your build. I'm not a machining expert, but based on what you're reporting, it seems apparent the cam is the problem.

I am surprised you went with another Comp cam.
 

·
Registered
Joined
·
3,375 Posts
Discussion Starter #56
Not sure I would pull the distributor at all during the cam break in as the new gears also require a similar 30 minute break in cycle . . . . . If you don't set it back in exactly where it might disturb the break in. I believe that you already know to use a break in lube (such as what you put on your cam lobes) on the gears too.

...
I know its not the best situation, but with the issues of destroying a distributor gear in under 30 minutes, it might be prudent to check it before I get too far into the break in to make sure I'm not sending more metal into the oil pan, again.

Whenever I pull the distributor I always make a reference mark as to where the rotor and vacuum port is pointing so that I can reinstall it in the same position. No moving of the crank with the distributor out.

Yes, and in the photos you should see the break in lube I put on the distributor gear so it was not going in dry.
 

·
Registered
Joined
·
3,375 Posts
Discussion Starter #57
Exactly. I asked, but it was never answered answered. You can install all the distributors you want, but if you don't measure the gear placement on any of them, it doesn't matter.
3.999" on the gear depth from the thrust collar. Within the 3.996-4.005 limit.

I had a straight edge on the bottom of the gear to take the measurement, but did not have 3 hands to take the picture.


Sent from my SM-G955U using Tapatalk
 

·
Registered
Joined
·
3,375 Posts
Discussion Starter #58
What was your camshaft end play set at?
Just read the cam install instructions. Priming the lifters prior to installation is not required. Just bath them in oil prior to installing in bores.

Checking camshaft endplay: This is not required on Flat tappet or solid flat tappet cams. Flat tappet cams have a taper ground into their lobes which pushes the cam into the proper position. Checking cam end play is also unnecessary with engines equipped with cam retaining plates.

So, with a flat tappet cam with a retaining plate, they do not give specs for end play as well as say it is not needed.
 

·
Registered
Joined
·
674 Posts
Checking cam end play is also unnecessary with engines equipped with cam retaining plates.
I would like to see where you found this information as Comp lists a cam clearance spec of .004-.008" for their timing chains with no reference to type of cam WHEN using a retaining plate on a SBF.
 

·
Registered
Joined
·
3,375 Posts
Discussion Starter #60
I would like to see where you found this information as Comp lists a cam clearance spec of .004-.008" for their timing chains with no reference to type of cam WHEN using a retaining plate on a SBF.
Sure, its in the instruction sheet that came with the cam, and its on their web site: http://www.compcams.com/catalog/COMP2012/pdf/COMP_Catalog_2012_404-407.pdf

Step 9, 2nd paragraph. I am running a hydraulic flat tappet cam with retaining plate:


"If you are installing a hydraulic or solid flat tappet cam in your engine, this step is not necessary in the majority of engines. This is because the taper ground into the cam lobes of these types of cams pushes the cam into the proper position and holds it there while the engine is running. Checking end play is also unnecessary in engines equipped with cam retaining plates, whether the cam used is a flat tappet or a roller."
 
41 - 60 of 105 Posts
Top