Valve clatter could it be timing?

jeffnoel · Sep 14, 2007

OK some of you know I recently fired up my engine and broke in a new cam. Engine sounds great in the garage under no load but when driving it I'm getting some noise from the valvetrain (I think) when accelerating.

Here is what I did to the engine:

1978 302 shortblock with 41K miles
Edelbrock Performer Plus Cam Duration at 0.050" Intake: 204° Exhaust: 214° Lift at Valve: Intake: 0.476" Exhaust: 0.502"
1990 E7TE heads (rebuilt) with stock valves and springs
Crane 1.7 ratio pedestal mount roller rockers
Cloyes double roller timing chain
Edelbrock 302 Performer intake
Holley 600cfm Vac Sec carb
Factory Duraspark distributor
MSD 6A with MSD coil
Professional Products 28 oz Damper
Hooker super comp headers with 2.25 " pipes
C4 with shift kit and stock convertor
8" rear with factory 3.00 gears

My stock compression was 8.4 with 69cc heads so with the swap to the 64cc E7s my CR is around 9.0 so 87 octane should be OK right?

My initial timing is set at 12 degrees with vacuum advance disconnected and plugged. I put a vacuum gauge on it and I'm pulling about 19" of vacuum at idle with little needle fluctuation. And when revved the needle moves steady not jerky (see attached video). Total timing seems to peak at 29 degrees at 3K rpm.

I just went through and checked/adjusted the lifter preload. Some of them did need to be shimmed and I have them all torqueing at about 1/2 turn past zero lash. It does rattle less today than it did before, I found 2 of the rocker saddles were cracked.

Can anyone point me in a direction? I'm still running the stock springs but since I'm not really pushing it I would think they should be OK for know.

D.Hearne · Sep 14, 2007

You may have to run 89 midgrade with your compression and cam. I have basically the same combo in a roller 5.0 but with an F4TE factory cam. It pings with that much timing on 87. If you have a full tank of 87, run it down halfway and fill back up with premuim, a 50/50 mix yields 90 octane fuel. 89 is a blend of 35% 93 octane premium and 65% 87 octane regular. The stock roller springs are perfect wirth that cam. Also pull the plugs and read em, to see if you're running lean, that will too cause pinging.

jeffnoel · Sep 14, 2007

OK, I really didn't think with that low of a CR that I would need run run a higher grade of gas but I'll give it a try since I only have a 3-4 gallons of 87 in the tank.

I was planning on pulling a few plugs tomorrow while the engine was cool and given them a look see..

rbohm · Sep 15, 2007

jeff, too much timing combined with a lean mixture, and a high load at low rpms will cause detonation. pull the timing back 2 degrees and see if that cures the problem. something else you need to look at is teh dynamic compression. if you have a cam with wider lobe centers than stock, that can also cause detonation.

jeffnoel · Sep 15, 2007

rbohm said:
jeff, too much timing combined with a lean mixture, and a high load at low rpms will cause detonation. pull the timing back 2 degrees and see if that cures the problem. something else you need to look at is teh dynamic compression. if you have a cam with wider lobe centers than stock, that can also cause detonation.

I tried backing the timing to 10 and it still pinged/knocked and was harder to start. As for the lean mix I adjusted the air/fuel with a vac gauge and think I've got that OK, larger jets maybe in the primary not sure whats in there now. Dynamic compression what is it and if it's the cause of my detonation what can I do about it?

jeffnoel · Sep 15, 2007

I pulled the plugs and took these pics. The plugs were new when I broke-in the cam and currently only have about 2-3 hours on them most spent running in the garage maybe 5-10 miles on the road.

Here are links to the fullsize pics if needed.
http://www.supermotors.net/getfile/563648/original/100_1928.jpg
http://www.supermotors.net/getfile/563649/original/100_1930.jpg

D.Hearne · Sep 15, 2007

4 of em are leaner than the others, but you really have not run it long enough to be accurate. Fill the tank with premium and see what happens. If you can't back off the timing anymore, then that's your only choice other than richening it more, and that's not going to guarantee it'll solve it.

CraigMBA · Sep 15, 2007

If you retard the timing it should crank/start easier. Have you verified your total adavance with a timing light or are you guessing?

I like to use 1/4 of a turn of preload.

Reading plugs on unleaded gas with an MSD is hard (so much energy it burns the garbage off), but you can do it. You need to do a plug check under power, and kill the engine cold. When I lived in Corcoran I could drive a half mile and be in the country, so I'd drive out and let the engine warm up, go through the gears, kill it and coast, and pull a plug. I'd usually just do one hole to see if I was close.

I'm with DH on putting better gas in it and trying again.

CraigMBA · Sep 15, 2007

jeffnoel said:
I found 2 of the rocker saddles were cracked.

You got a picture of this?

rbohm · Sep 15, 2007

if you back the timing off, and it is harder to start, then you might try advancing the timing and see what happens. it could be that your timing is too far retarded, and that to will cause detonation.

jeffnoel · Sep 15, 2007

Could it be I'm running the wrong plugs? The AP666s that I'm running are what's called for the in 78 heads I used to have on the engine. Since I'm now running E7s from a 90GT that car calls for AP25s, I haven't gone to the store to look at the difference but could that be my problem?

And for my timing I tried 14 and it wasn't as bad as 10 but not as good as 12, and yes I am using a light. I tried using a regular flashlight but couldn't blink my eyes in time with #1.

Here's a pic of the broken saddles for CraigMBA.

CraigMBA · Sep 15, 2007

I run Motorcraft plugs so I can't be of any help to you on the plug selection.

Those saddles should of never broke. I'd call the cam company you used and send them the pictures of those saddles.

jeffnoel · Sep 16, 2007

These saddles(pedestals) crack/break all the time, they are the weakest link in the pedestal mount rocker setup.

D.Hearne · Sep 16, 2007

jeffnoel said:
And for my timing I tried 14 and it wasn't as bad as 10 but not as good as 12, and yes I am using a light. I tried using a regular flashlight but couldn't blink my eyes in time with #1.

Good one !! I don't know the plug diffference either but both heads should use the same style plug, one may be hotter than the other with the different number. I don't think you've run it long enough though to tell a need for a change in heat range.

jeffnoel · Sep 16, 2007

CraigMBA said:
I run Motorcraft plugs so I can't be of any help to you on the plug selection.

Well converted to Motorcraft my old 78 heads called for ASF52Cs and the newer 90 GT E7s call for ASF42Cs.

D.Hearne · Sep 16, 2007

52's are one range hotter than 42's, I do know that much. The called for heat range though is more related to the vehicle application than the head that it's used in. A 1978 application would also have an 8 to 1 compression ratio where the 90's all were in the 9's in that regard. You could run a hotter plug with less compression.

danny clemens · Sep 16, 2007

Did you degree your cam?

jeffnoel · Sep 16, 2007

danny clemens said:
Did you degree your cam?

No

10secgoal · Sep 16, 2007

Did you check rocker arm geometry ? It will get worse as rpm's go up if it's wrong. Will sound like loose rockers....

jeffnoel · Sep 16, 2007

10secgoal said:
Did you check rocker arm geometry ?

How do I do it?

Valve clatter could it be timing?

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