I recently installed a camshaft in a 427 and i have had timing issues with it from day one. Granted, i discovered that one valve had been eaten by a roller tip rocker, reason unknown still, but it was ok until very recently.

Details

-427/390Hp car with TI ignition. Before you say that 390hp cars did not come with TI ignition, all Air injection reactor California cars did. I had the distributor completely reworked by TI Specialities. Rebuild included an NOS vacuum canister and distributor shaft. Apparently the reproductions are not correct.

-Specs for cam i installed in the engine.
Duration @ .050 (Int/Exh): 221/230
Gross Valve Lift (Int/Exh): .515/.515
LSA/ICL: 112/106
Valve Lash (Int/Exh): Hyd/Hyd
RPM Range: 1200-5800

The engine was calculated to have a 10.2:1 compression ratio with the standard deck, speed pro domed pistons, and stock cast cylinder heads. I have all of the calculations and measurements the engine shop took somewhere in the file, but i havent located it yet. Its a rather thick file.

My thoughts were that i would pep up the 427 engine by adding a camshaft with slightly more duration and lift. However, i know that the cam selection programs might not exactly calculate in all factors and therefore, i might have picked a cam that doesnt necessarily agree with my 390hp TI ignition system.
So, while i have the engine partially broken down to fix the valves, i am wondering if i shouldnt just go ahead and install an original spec cam. Im worried that i am going to get it all back together and still have some timing issues.
Before i make a decision i would like to get the thoughts of others that might be well educated in cams, timing, and vacuum canisters.
Thanks

What do you mean by timing issues?

Wouldn't it be easier to simply install a regular old distributor and see if the problem goes away before changing cams?

Doug

what timing issues are you having??...with 10-1 compression, you should be from 34-38 degrees total
as far as the cam, why not call lunati and go with a solid flat tappet with approx. the same duration you have with more lift and ask them for a recommendation as far as lsa....probably 114

I wouldn't worry about the distributor being incompatible with the warmer cam - or the cam being incompatible with the TI Distributor. I have an original 390 HP TI unit with a modified advance curve powering my aluminum open chamber head 427 with a big cam, 12.5 pistons, L-88intake, 800 Holley and it does just fine. To make things more odd - I'm powering it off of an ancient Accell CD unit I painted black, using a custom wiring harness I created in my garage and custom wrapped into the wiring harness.

At most you might need to mess around a little with the advance curve but the TI distributor itself is dead simple. It should do the job.

I'll call myself "well educated" by having messed up just about every valvetrain component that could possibly BE messed up on a big block, so let's see if any of this helps.

I seem to remember you had some up top oil problems. Make sure you get the correct size and placment oil groove, and the correct 3-hole grooved rear cam bearing bearing for reassembly. Your eaten valve tip could have been from lack of oil. I've been running those same roller tip rockers for 12 years and they haven't caused any problems with my valves. You do have to check the rocker arm geometry, which may also have been your valve tip problem. The roller tip should make contact exactly in the middle of the valve stem when the valve is at 1/2 of full lift. You may have to get custom length pushrods if the geometry is way off - usally caused by milled heads, milled block and other things that change the length from the cam centerline to the valve tips. Make sure you you have enough spring travel. If you can't get a paper clip wire between the coils at full lift, you need to get different springs or reset the uncompressed spring height.

You can certainly pep up your 390 HP motor with a good cam change. Factory oval port heads will support 450 HP very easily. I used to run a factory street solid lifter cam (#3863163- 242 deg @.050 lift/.520 total lift on intake and exhaust) with oval port heads in another car. It was a fantstic combination. I would recommend it any day. That cam even idles reasonably well, and the lobes are not very aggressive by modern standards. Cam failure is very unlikely if you take any care during break in.

When I bought this motor, I asked the builder to put in a hydraulic cam close to the specs of the factory street mechanical cam. He dutifully picked a Comp Magnum 292H (245 deg @ .050) thinking these were "about" the same specs. Wrong! .050 lift specs are about 10 degrees more on an equivalent solid lifter cam. That and Comp Cams seems to grind a lot of 110 degree LSA cams. They idle like crap and have poor low speed throttle response. Stay away! I can also tell you not to bother with hydraulic cams. The valves in a BB are just too big. The hydraulic cams I ran would float so bad at 5500 RPM it was like shutting the key off. Others have recommeded "beehive" springs as a solution. I can't say whether they work or not, but my current solid lifter cam screams through 6500 without a whimper.

If you have the $$, put big valves in your oval port heads (2.19 intake/1.88 exhaust) and get some bowl cleanup porting and a 3-angle valve job. Worth every penny. I'm squeezing 454 HP out of my antique POS with only 10.2 compression.

Hope this helps. I could spend an hour on here telling about all the things that broke because my machinst didn't follow instructions and just assumed that off the shelf parts were made correctly. As President Reagan used to say "trust but verify."

Clearly, there was something bad going on with the valvetrain and i would actually be quite foolish not to think that was what was causing the slight miss. However, i just thought i would check since the TI system is still a bit of a mystery to me and seems to be fairly temperamental. I had rocker stud problems initially, then a distributor problem, and then the wiped valve. However, whatever caused the wiped valve, whether it is/was the springs on the heads, a misadjustment by me, wrong length pushrods, lack of oil, a bad hydraulic lifter(if that can even happen and only damage a valve and not the cam), or some combination of the above, that is what caused the miss.

Thanks for the responses! I guess i am just being slightly paranoid at this point. I just hate to get all back together again just to be forced to pull it apart once more. 3rd time is the charm, right???

Someone told me once that the TI ignition system has trouble with the reproduction plug wires. I think he said that it had to do with the core material. Is the core material different in the repro wires vs what was used back then? Does anybody know if it would make a difference?

Gerry

My understanding of the K66 TI system is that it either works or it doesn't. I don't think they are prone to intermitant problems. If the distributor is in good shape (bushings, advance etc), your problem is likely elsewhere. If you learn something different, let us know. I had an engine similiar to yours many years ago and a Comp Cam "street roller" (called something else now) with 280/288 duration really made a difference.

Mike

"a bad hydraulic lifter(if that can even happen and only damage a valve and not the cam)"

Yes, it can happen. I did a rebuild in early 1999 because that Comp Cams 292 Magnum actually had a lifter shatter. I had to pull the cam, lifters and pan and clean out chunks of metal. I then went to a Comp Cams 274H hydraulic. Metal residue caused a few rod bearings to get wiped out. Had the crank cleaned up, put in new bearings and off I went. Drove about 25 miles and started to hear this awful squeaking sound that changed with engine speed. Pullled off a valve cover and found one, dry, roasted rocker arm and valve stem. What happened? I reused the same lifters from when the bearings got wiped. Some metal dust got in one lifter and plugged it. The cam lobes, fortunately, are lubricated by splash and leakage out of the lifter bores so no harm done. Replaced the lifters and all was well (other than that crap of the engine dying at 5,500 RPM).

There are no compatibility issues between your cam and your ignition system; the ignition system could care less what cam you're running. It just delivers spark based on the initial timing and the centrifugal and vacuum advance systems, whether the cam lobes are square or round.

I think 99% of TI problems was with the old style electronics in the modules. Apparently the new style electric guts have solved most of that. The distributors themselves are really simple and reliable. Good luck.