Got the 272/282 solid lifter Lunatidyne in today with extremly disappointing results! graemlins/angry.gif

I will be putting the 276/286 hydraulic right back in, only straight up and not advanced. I'll also ditch the CC lifters for some of Cranes!

What a waste of time/effort/money!!! My motor didn't like the 272/282 at all!!! It sparked knocked so bad it was scary!!! And my seat of the pants dyno tells me I lost about 100HP and even more torque!!!

Anybody want a 272/282 with about 1 1/2 hr. on it let me know!

If I still have spark knock issues with the 276/286 straight up, then I'll just have to go to open chamber heads!!!

Detonation usually causes a loss in power...

Hope you didn't damage your engine.

James,

I must admit I haven't been following you cam change closely. Other than the smaller profile what was different about the new cam? Can you post your whole combo? What were you hoping to accomplish with the cam change? I'm certainly no expert but I'll try and lend some advice if I can. Sorry to hear things didn't go as expected :(

James,
1 1/2 hrs of running is not enough time to even start dialing things in for the new cam. Did you make any changes to ignition timing and carburetion ?? Just swapping a camshaft without tuning the rest of the engine systems to work with it will not automatically increase performance. The fact that you were getting detonation means that the camshaft is "probably" making more cylider pressure. This could require less timing to make more power. Same goes with the carburetion, probably will need some recalibration. I don't know all the details on your combination, but just looking at the cam spes, I would not have expected that much of a difference. Are you sure you have the new cam installed properly ??
Just some thoughts,

I am sure I didn't run it hard enough or long enough to hurt the engine.

Thanks Ken! The problem I was trying to cure was detonation but I made the situation much worse! I thought the solid cam would be fine but again I missed the combo! The 276/286 has proven to be much better power/torque wise. I had it advanced 4 deg and would get some spark knock but nothing like with the 272/282!!! I have learned this lesson well!!! The 276/286 is going back in only not advanced, and any further detonation problems will be remedied with a change to open chamber heads, no more experimenting with cams for me! It's my own error for trying to push the envelope with a static compression ratio of 10.5. I am not going to try to solve the problem by changing the DCR with a cam. The 276/286 was giving me good fuel economy, good off idle power/torque, and very good throttle response. I'll be sticking with it and going with whatever heads I can find that it likes! graemlins/clonk.gif

Bill, normally I would agree that 1 1/2 hrs. is not long enough to dial anything in, but, I made several timing changes and even though I could reduce the detontion with less timing the loss in power was too signifacant, for me, it's now a no brainer, I screwed up and the old cam is going back in!

Oh, I am confident the cam is installed correctly and I run an A/F ratio meter which idicated that the carb was well within suitible parameters.

:(

James,I don't understand..I'm running the UD 280/288 with 10.5 to 1 (with closed chambered heads) with no detonation problems what so ever..wish I was nearby to help you out..

James, emailed ya . i may be intrested in your cam

Please remember it's the intake valve closing timing event that set's the compression ration!!

That's why installing the cam retarded from say, 106 to 110 or from as advertised to straight up install thing lowers the CR...

I would have thought you would have went bigger, not smaller b/c to me you would automatically have made it worse..

Notice as mr 4 speed is running the 280 intake duration cam successfully!!

Jmho and sorry it didn't work better for you...

pdq67

Jim,maybe your distrbutor's weight are over centering and causing the timing to advance when its under load and causing your detonation problem..something you won't see with a timing light..my vote is try another distributor (like an HEI) its easier then a cam and head swap,and cheaper too.You run a Mallory distrbutor now,correct? I had this happen once to me before,and had me stumped..
Your motor with that compression,cam and those valves should be an absolute terror..don't give up yet.You got a low 12 second/high 11 second combo there if you get it to hook!

the solid cam will act smaller than the hydraulic...b4 you switch back..try tightning the lash some...and richen up the carb..retard the timing a touch

big,

You said it right there!! "Act smaller", thus more DCR.!!!

pdq67

James,

I'm sorry about the problems you're having, they aren't typical for that cam. It may be the ignition, I'm no expert on that.
However, to drop your DCR, set your valve lash .012"/.016" COLD, then .014"-.016" HOT on intake, .018"-.020" HOT on exhaust. This will increase the cam duration by about 4°-6°, mostly on the intake's CLOSING side, lowering your DCR.
The 272/282F ALWAYS has a lot more power than the 276/286H, so something's not right.....

UDHarold

I love my 272/282 in my 408... So much that I'm thinking of running it in my 462...

James, Forgive me if any of my advice is old hat to you. First be sure you've set the lash right. I've experienced detonation before when the valve lash on one intake valve had increased about .008 or so. Like to drove me nuts figuring out what was wrong. I thought I'd gotten a tank of bad gas. That also agrees with what Harold said about tightening lash to reduce detonation. Obviously solid cams are much less forgiving on rocker adjustment. Set lash on the intake valves when the exhaust valve for that cyl just starts to open. Set the exhaust valves when the intake valve for that cyl is fully open and is just starting to close. That ensures the lobes are close to centered on the base circle. It's easy to get valves and cyls mixed up when setting lash too, so be very careful there. Also my experience with BB iron heads is that the lash is about .002 tighter hot than cold (it tightens up as it gets hotter- set them .002 looser cold). If you remove the cam to sell or reuse, you should keep the lifters marked so they go back on the exact same lobe upon reinstallation. I put each one in an individual zip loc bag and mark it with masking tape and pen (i.e. #3 exh).

I still vote for the distributor,as he had detonation issues with the other cam....

James,
Slow down,....while you are frustrated is no time to be making changes. Get your head clear. I am at 11.2 CR and run the 288/296 hydraulic, 230 psi cranking compression without detonation on 93 octane pump gas. It took some tuning, but I got it there. When I first installed it, I was disappointed, ran like crap and felt like it had no power. I tweaked my carb, ignition, cooling system....and here I am a full second quicker, 10MPH faster in the 1/4 and it never pings or overheats. Like I said, I am at 11.2:1, I have horrible quench also. Everything about my combo goes against the DCR calculator. Pistons are .080" down the hole, I have huge domed pistons, closed chamber heads. What temp does the motor run at? Don't give up yet.

Thanks guys, but my minds made up, it's coming back out. It's possible that it could make more power at higher rpm than my present cam but it pinged so bad I was not going to turn it up at the risk of blowing a hole in a piston. My decision to go to a solid cam was an error on my part! I should have tried a 280/288 and forgot about trying a solid cam. The off idle power of the 276/286 is very good and I was trying to improve my drag times by going with something else but that is also a mistake, I'm a cruise in/car show guy and I need my wrist slapped for trying to go faster instead. Especially since I was getting some respectanle times as it was.

As for the lash, I have it at a tight 20/22 instead of the 22/24. The distributor has the most conservative springs Mallory has for it and I have it as good as I could get it with the old cam. This cam has no bottom end power and the vacuum at idle is low and not strong enough to power the brake booster, reason enough for me to pull it right there.

If any more dialing in will be done it's going to be with the originally installed 276/286 cam! If the comparatively minor detonation continues with it set straight up I will try a stock HEI distributor and make sure that's not the issue before I go off the deep end with another set of heads.

Thanks for your input guys!!!

BigJames4XL,

Before you pull the cam, if you haven't already, double-check where it is at. I know you said it was in correctly, but your statements of low vacuum and no power make me wonder.
Take off your valve covers and turn your engine to #1 at TDC. Either both valves will be closed or both valves will be open. If they are closed, give the engine another complete turn, so that both valves are open at TDC.
Using something like a Machinist's steel rule, measure from the top of the retainer to the spring seat. The intake retainer should be about .040" to .060" closer to the head than the exhaust retainer. If it is, the cam IS in the engine correctly. If the EXHAUST retainer is closer, you have put the cam in retarded, and that is giving you problems, no power, no vacuum. Check it out and let us know.....

UDHarold

Thanks Harold!

Will do!

James,

I've been following this thread, I understand how you feel wishing you had just left well enough alone. But I'm with everyone else, I can't help but think somethings just not set right. I forgot to mention that my CR is 10.5 to 1 and I'm not getting any detonation at all with my 272/282.

UDHarold, how do I get in touch with you? I need to talk to you (or email) about my 462 buildup and get a cam recommendation. email me if you have time at bpursley@esc14.net

Good luck James!

Please don't be so quick to take that cam out. You may not be able to run pump gas even after you go through the tuning steps but after all the effort of swapping cams at least give the cam a chance. I would start by putting in at least a mix of race gas and pump gas to eliminate too low octane from the equation as you experiment with ignition timing and carb tuning. As already mentioned, if the engine is pinging or if you have to pull the timing back a lot to keep it from pinging, you probably aren't seeing any where near what that cam is capable of doing. Then after you have the ignition and carb sorted out start lowering the octane more and more to see how close to pump gas you can run.

Sorry Bob, but the switch is on, I have coolant draining from the radiator as I type!

IT'S VERY POSSIBLE THAT ADVANCING THE CAM CAUSED SOME OF YOUR PROBLEMS ALSO, COULD HAVE RAISED YOUR STATIC COMP. RATIO. YOU CAN CHECK THIS OUT BY RUNNING A COMPRESSION CHECK ON A COUPLE OF CYL'S, CHANGING THE CAM DEGREE AND RUNNING IT AGAIN, IF YOU LOOSE SOME SHOULD HELP YOUR PROBLEM
ROB...

I think that mr 4 speed might be on to it. You seem to always have had a detonation issue with that engine from reading your previous posts. I run 10.3:1 comp and open chamber heads which are SUPPOSEDLY more detonation prone and my engine never shows a hint of detonation. I think you have a timing issue.

James, sorry to hear. Your experience goes against every other experience I've had/heard about a switch to solids. Speaking of hearing, are you sure its not the valves you're hearing?But 10.5:1 is tricky with these small cams, and with iron, well, too much.

My old Crane cam , which is set on a 114 lsa ( intake closes at 80-82 ) would have been fine, or the 272/282 on a 112-114 LSA.

No matter, its a done deal, hope it goes well. Getting good at cam swaps yet, are ya!? smile.gif

If you are swapping the cam, do a compression test first to see what that cam is producing compressionwise. Then if you install your old cam straight up you can check the compression again and let us know what the difference was. I think the solid cam was a good decision but tuning would be required.