Rebuilt Engine Problems

sleeperstang · 05-06-2003, 11:27 AM

So this Sunday....

I finally got my engine ('68 spec 302 w/Xtreme Comp Cams XE256H) all set and ran it for a half hour. Ran somewhat smooth, but with some slight surging (mostly evident through exhaust). I figured it was part of the break-in, so then I come home yesterday (Monday) and go to turn on the engine. It's running the same for about 15-20 mins when all of a sudden I hear 3 metal pings, and it's clear it's from metal contact. I take off the driver side valve cover and tell my brother to crank the engine.

One of the #5 cylinder head valves is stuck about 1/4 of the way through (haven't determined if it's an exhaust or intake valve yet, and I'm at work). I bought this engine as a long block from a machine shop. Before any work on the engine was performed (installation of parts) I called the shop and asked if all bolts and springs on the heads had been set to spec and they assured it had.

When spec'ing out my engine I made sure by calling Comp Cams if this cam would have any problems with clearance of any sort as far as valve to piston, and they said there wouldn't be any, so that part of the equation is clear is not the problem.

I call the machine shop guy this morning to let him know what happened with the engine. He states that what probably happened is that due to the higher lift on the cam, it probably requires stiffer springs (engine had been built to stock specs including spring stiffness). He says that they probably just have to install stiffer springs and fix the valve and the engine should run fine.

My concern now is the following: Obviously if the valve is stuck, and I tried pulling it closed but it didn't budge, it's bent, so this would suggest that it's collided with the piston. I would say that the engine was running at 2000 rpm, so would this collision cause any damage to the piston?

I asked the machine shop guy the same question and he stated no, but I want to be sure that he is right so that I don't feel like I might be getting cheated with a bad piston when I go to drop off my car to get fixed.

Thanks in advance for your replies!!!

8T4SVOChick · 05-07-2003, 08:35 AM

I'm going to move this to the Classic Mustangs section. You might get more replies that way. I'm not sure it was actually intended to be in the Female Power Forum. There were a couple of funky things on the board this morning. Good Luck with your question.

zach0 · 05-07-2003, 09:46 AM

Anytime you have a valve hit a piston there is great concern to whether it damaged the piston or not. It could damage it at any RPM. My concern is why did the valve stop and hit the piston. There are alot of factors that may have caused this so it would be hard to point to just one thing right now. You may want to get ahold of some of the car clubs in your area and ask them for some good machine shops or stop a car show and ask. If you are in the Hampton Roads are in VA I could help you but not many people seem to on the boards from around here. Good Luck.

sleeperstang · 05-07-2003, 10:17 AM

As far as I can tell, it seems that the machine shop put in stock springs with possibly low stiffness. The camshaft has an approximate exhaust lift of .484" so I imagine that coil binding is the culprit.

P.S. 8T4SVOChick - I had originally put this message in both the classic mustang forum as well as the Windsor power forum, and no other. Weird stuff....

Jeff65 · 05-07-2003, 04:08 PM

Piston/valve collision does not seem like cause for surging. More like significant vaccuum leak.

thunderbolt · 05-08-2003, 10:09 AM

I think your heads need to come off and the pistons need to be inspected. If you had a piston valve collision, you could have cracked a piston. Also, I would call comp cams and see what valve springs they recomend for your application. Then I would clay test the valves for clearance before putting it back together. A really big mess, sorry to hear about it. Hopefully, no significant damage and you can get it back together soon.

sleeperstang · 05-08-2003, 10:19 AM

I called Comp Cams yesterday actually. I have a copy of their catalog, and when I took the camshaft to the machine shop I gave them the specs of the cam, so they knew what it would require.

I'm going back there on Saturday and they will have to replace the springs as it seems that the spring bound up. I don't think the camshaft is damaged since the valve still would open it just wouldn't close all the way.

I too hope that the piston isn't cracked, the machine guy thinks that nothing happened, so I'll have to wait and see. Thanks for the replies guys, really appreciated.

05-06-2003, 11:27 AM	#1
sleeperstang Registered Member Join Date: Jun 2001 Location: Lynwood, CA, U.S.A. Posts: 82	Rebuilt Engine Problems So this Sunday.... I finally got my engine ('68 spec 302 w/Xtreme Comp Cams XE256H) all set and ran it for a half hour. Ran somewhat smooth, but with some slight surging (mostly evident through exhaust). I figured it was part of the break-in, so then I come home yesterday (Monday) and go to turn on the engine. It's running the same for about 15-20 mins when all of a sudden I hear 3 metal pings, and it's clear it's from metal contact. I take off the driver side valve cover and tell my brother to crank the engine. One of the #5 cylinder head valves is stuck about 1/4 of the way through (haven't determined if it's an exhaust or intake valve yet, and I'm at work). I bought this engine as a long block from a machine shop. Before any work on the engine was performed (installation of parts) I called the shop and asked if all bolts and springs on the heads had been set to spec and they assured it had. When spec'ing out my engine I made sure by calling Comp Cams if this cam would have any problems with clearance of any sort as far as valve to piston, and they said there wouldn't be any, so that part of the equation is clear is not the problem. I call the machine shop guy this morning to let him know what happened with the engine. He states that what probably happened is that due to the higher lift on the cam, it probably requires stiffer springs (engine had been built to stock specs including spring stiffness). He says that they probably just have to install stiffer springs and fix the valve and the engine should run fine. My concern now is the following: Obviously if the valve is stuck, and I tried pulling it closed but it didn't budge, it's bent, so this would suggest that it's collided with the piston. I would say that the engine was running at 2000 rpm, so would this collision cause any damage to the piston? I asked the machine shop guy the same question and he stated no, but I want to be sure that he is right so that I don't feel like I might be getting cheated with a bad piston when I go to drop off my car to get fixed. Thanks in advance for your replies!!! __________________ 65 Mustang Coupe...Comp Cams 262 Xtreme Energy, T-5 conversion, Romac Balancer, 620 Front Springs-4.5 Mid-eye rear springs.......work in progress Last edited by 8T4SVOChick; 05-07-2003 at 07:53 AM..

05-07-2003, 08:35 AM	#2
8T4SVOChick Mustang Junkie Join Date: Jul 2001 Location: Denton, Texas Posts: 82	I'm going to move this to the Classic Mustangs section. You might get more replies that way. I'm not sure it was actually intended to be in the Female Power Forum. There were a couple of funky things on the board this morning. Good Luck with your question. __________________ ~Shannon~ Asst. Editor, GirlsCanToo Event/Race Coord., Texas Rep., TeamGC2 Mustang Forum Moderator @ FordSpeed.net DFW Forum Moderator @ LoneStarStangs Visit FordCustoms!

05-07-2003, 09:46 AM	#3
zach0 Registered Member Join Date: Apr 2001 Location: Hampton, Virginia Posts: 227	Anytime you have a valve hit a piston there is great concern to whether it damaged the piston or not. It could damage it at any RPM. My concern is why did the valve stop and hit the piston. There are alot of factors that may have caused this so it would be hard to point to just one thing right now. You may want to get ahold of some of the car clubs in your area and ask them for some good machine shops or stop a car show and ask. If you are in the Hampton Roads are in VA I could help you but not many people seem to on the boards from around here. Good Luck. __________________ 1980 RX7 with 289 Ford V-8 bored .030 over, Very radical cam, Torker 2 high rise intake, Holley 650 Carb, MSD Nascar 6ALN ignition, MSD coil and distributor, Headers with dual open side exhaust. Over 300 horse. 1966 Mustang still in progress

05-07-2003, 10:17 AM	#4
sleeperstang Registered Member Join Date: Jun 2001 Location: Lynwood, CA, U.S.A. Posts: 82	As far as I can tell, it seems that the machine shop put in stock springs with possibly low stiffness. The camshaft has an approximate exhaust lift of .484" so I imagine that coil binding is the culprit. P.S. 8T4SVOChick - I had originally put this message in both the classic mustang forum as well as the Windsor power forum, and no other. Weird stuff.... __________________ 65 Mustang Coupe...Comp Cams 262 Xtreme Energy, T-5 conversion, Romac Balancer, 620 Front Springs-4.5 Mid-eye rear springs.......work in progress

05-08-2003, 10:19 AM	#7
sleeperstang Registered Member Join Date: Jun 2001 Location: Lynwood, CA, U.S.A. Posts: 82	I called Comp Cams yesterday actually. I have a copy of their catalog, and when I took the camshaft to the machine shop I gave them the specs of the cam, so they knew what it would require. I'm going back there on Saturday and they will have to replace the springs as it seems that the spring bound up. I don't think the camshaft is damaged since the valve still would open it just wouldn't close all the way. I too hope that the piston isn't cracked, the machine guy thinks that nothing happened, so I'll have to wait and see. Thanks for the replies guys, really appreciated. __________________ 65 Mustang Coupe...Comp Cams 262 Xtreme Energy, T-5 conversion, Romac Balancer, 620 Front Springs-4.5 Mid-eye rear springs.......work in progress

05-07-2003, 04:08 PM	#5
Jeff65 Registered Member Join Date: Jul 2002 Location: Oklahoma City Posts: 208	Piston/valve collision does not seem like cause for surging. More like significant vaccuum leak.

05-08-2003, 10:09 AM	#6
thunderbolt Registered Member Join Date: Oct 1998 Location: Houston, TX, USA Posts: 380	I think your heads need to come off and the pistons need to be inspected. If you had a piston valve collision, you could have cracked a piston. Also, I would call comp cams and see what valve springs they recomend for your application. Then I would clay test the valves for clearance before putting it back together. A really big mess, sorry to hear about it. Hopefully, no significant damage and you can get it back together soon.

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