Bent Valve? Valve Didn't Seat? I Don't Know What's Going On.

fords2live

fords2live

Member
Apr 12, 2013
84
4
9
#1
Just put a 302 together. Re ring, new bearings, new cam, new pushrods and new valves. I got it out to break it in AFTER I broke in the cam ( held it at 3000 for 5 mins or so to start the lifters in their rotation on the cam) I got it out and started putting a load on it. I didn't give it time to warm up but didn't go over 4000 just through the neighborhood. Got it back to the house to do some tuning and then got it out on the main road. Took it to 5000 a couple times and let the rpm come back down with it in gear. Did that maybe 6, 7, or 8 times. Let it idle for a min or 2 then went to get back on it to keep seating the rings. Got out on the main road and Low RPM and Low Speed getting on it. Basically trying to kick it loose, and it made 4 or 5 cracks which kinda sounded like a back fire but more mechanical. It was in the valvetrain. It started idleing like :poo: and a valve isn't sealing. Its just one though. I get a puff of air come out of the carb at cam speed. WTF is going on. All I did when i got new valves is just throw them in there too. Didn't get them machined.
 
#2
Start by inspecting the valve train to make sure nothing came loose (don't want to risk further damage if so). Next re-adjust valves & timing & check for vacuum/wires that came loose to rule out the easy stuff. If problem persists, do a cylinder leak down test to check for mechanical issues with valve seal.

I never sleep right the week after an engine build...good luck!
 
#3
wonder if either a valve spring retainer popped out or your springs were too weak and floated a valve. I normally take a small dead hammer and give each spring a couple of raps to make sure they are properly seated while the heads are on the bench.
 
#4
fords2live said:
Just put a 302 together. Re ring, new bearings, new cam, new pushrods and new valves. I got it out to break it in AFTER I broke in the cam ( held it at 3000 for 5 mins or so to start the lifters in their rotation on the cam)
Click to expand...

If this is a roller cam, then this was not necessary or beneficial.

All I did when i got new valves is just throw them in there too. Didn't get them machined.
Click to expand...

That was a mistake in itself. They should have at least been lapped to check the margins.

I would do a compression test to get a better idea of what's going on.
 
#5
Mikestang.. Nothin was wrong with the springs. Trust me, they hold to 7000. I pulled valve covers off before I posted this to check everything out. The reason I posted was so I could Ideas before I pulled the top end apart.

65ShelbyClone.. It's a flat tappet cam.. Yes you break those in.. And when I say "And all i did was throw the valves in there" Most would assume the mistake was noted by tone of text..

But for an update. Had a little bit of detonation and blew a head gasket. That was the only problem.. Lapped the valves.. Valve runout was damn good. Probably over 100 thousands of an inch probably like .15"
 
#6
So detonation caused blown head gasket & that caused misfire - and now all is well? That's a relief. I was worried you had hung a valve & bent it on a piston but didn't want to say it.
 
#7
Where did the head gasket fail? Were you able to find out what caused the gasket to fail that combo really shouldn't have any detonation issues

Sent from my XT907 using Tapatalk 2
 
#8
fords2live said:
65ShelbyClone.. It's a flat tappet cam.. Yes you break those in.. And when I say "And all i did was throw the valves in there" Most would assume the mistake was noted by tone of text..
Click to expand...

Tone of text? You left that out along with almost all details of what you're dealing with. I know what a flat tappet cam is and I know that they have to be broken in; that's why I said if.

Valve runout was damn good. Probably over 100 thousands of an inch probably like .15"
Click to expand...

You have 0.150" of runout? Are the valves pretzel-shaped or something?
 
#9
Stangclone. I ment the valve to seat margin. Thought it was called runout. Guess not. I don't know everything about cars, but I do know the "common sense" things about them. It just pisses me off when people assume I don't know what im doing. I know how to break in an engine. I'm just having problems doing it.

Another update.. All went well. It ran like a bat outta hell when I got everything together. I didn't have a timing pointer set up and ended up be 20* more advanced then I thought I was. Which I assumed caused detonation, Idk. It got alot further this time then last. 7 miles. Ended up doing the same thing though. It did good pulling in 4th on the highway, No problem kicking them loose in first and second at full throttle. But after about 7 miles I stuck it in 3rd pulled to 5500 and it made a friction noise then sounded like a blown head gasket again.. felt like it too. Just no backfire. It broke right in between 6 and 7 cylinder last time. Havnet taken it apart yet to see what happen.. Ideas?

Dual pattern cam/Old 302 firing order.
-int. @ valve .520" & 304 dur.
-Exh. @ valve .544" & 314 dur.
-Stuck it back in straight up
-Dual Plane intake
- 600 Vacuum sec. Carb
-E7TE Heads
-MSD E-Curve distributor
-25* initial & 50* total by 2500rpm
-Which that was what I had it at before
-Comp Cam Beehive springs
-118 ft/lbs seat pressure & 375 ft/lbs open pressure
-
 
#11
OH MAN, There's SOOOO much pull to it. Way more than the straight grind I had (.498" lift & 282* dur.) And it only had pull to 5800 maybe 6000. This cam; It's violent.. Even at a roll start.
 
#14
What's the duration at .050 on that cam? Personally the cam is too large for that combo the head just doesn't flow at the high lift, no matter how ported an anemic E7 head is.

What's the installed height and coil bind of the springs? I wonder if your binding... did you measure and install new pushrods? Are you still using the stock rockers? What's the fuel pressure set to?

Get a timing pointer and set it properly to tdc when you pull the heads again with out this you are taking a huge risk...let alone running the hell out of it before you know everything is OK.

I'm an engine builder and if the rings are seated properly there is no harm running it hard BUT I am a huge advocate of making sure everything is OK before I would do it.

I'd set max advance to 32°


Sent from my XT907 using Tapatalk 2
 
#16
Maryland.. That's the cam. P to V was over 100 thousandths on both sides. There is no clearance issues. And Yea I have a degree wheel. Yes I used it; On the stand and 2 days ago. It matches up with the cam card. Also used it to set up a new timing pointer
I checked coil bind on the stand
I clayed it 4* retarded; Straight up; and 4* advanced on the stand
Yes there is new pushrods in it with 20 thousandths of an inch lifter preload with valves closed; I had to get new ones going from roller to flat
And Maybe you havent heard of 50 total but that's what my engine likes so I run it. And where did you read that the cam I have is to big? My car doesn't think so.. 9.64:1 comp. and 3.55 gears; Like I said it's pretty violent when I get on it. Even more than the specs on a cam that people say is just right. I come here for suggestions; but nothing more. So will you guys work with me and understand that I know MY ENGINE and give me suggestions rather than talk down on what i'm doing with it.
 
#17
I wasn't talking down to you, I gave an educated response based on many years experience and dyno testing. So to get to 9.6 I assume the heads have been milled a lot or you have dome pistons? Can you give me a little more detail? I've NEVER had a car run 50° timing I will admit I am very, very skeptical about that.

I've made a lot of power with much less and have NMRA factory stock and Pure Street experience using E7.

Personally with a small cube, small bore and stroke motor you need the rpm to make power and more compression would help. You really need more rear end gear...

What's the intentions with the combo?

Sent from my XT907 using Tapatalk 2
 
#18
fords2live said:
So will you guys work with me and understand that I know MY ENGINE and give me suggestions rather than talk down on what i'm doing with it.
Click to expand...


Most of these questions are in fact, suggestions. Both of us are asking questions and confirming what you've done. I don't care about the cam you used, I wanted to confirm the cam specs and ignition and cam timing. Did you have the heads surfaced?
 
#19
Heads have been milled 20 thousanths last fall. I've never given them the opportunity the warp though. No high temps. I found out though that after '92 mustang started going down hill with quality engine parts. They put Torque to Yeild bolts in the heads which have been reused over 5 times now.. I did have to replace a couple though and did notice they went about a full turn further than the factory bolts.. Could be the problem.
 
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