1st differential install - what went wrong? Long and some dumb questions.

sleeperstang · 05-06-2003, 11:37 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 any replies!!!

WADS56 · 05-06-2003, 11:53 AM

I only read half of your post up to the part... "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."

You ALWAYS check PTV clearance when installing a cam! It takes about 30 extra minutes to do this and will save you allot of time and money in the long run. You have a bent valve if it wont close all the way, or something is stuck between the valve and seat.

sleeperstang · 05-06-2003, 12:16 PM

Ooops, I knew I would leave some detail out....

The Machine Shop did the installation of the camshaft as well, so that would be their responsibility as far as I'm concerned. I didn't take apart the heads nor pulled the camshaft out because it may have voided the warranty. Thanks for pointing that out....

Mike Souslin · 05-07-2003, 12:13 AM

FritzDaKat · 05-07-2003, 07:33 AM

Quote:

Originally posted by sleeperstang
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 any replies!!!

If he's that quick to say "no" try and be there when they pull the head, AND be there when they replace it in the event the valve punched thru the piston just in case they try slipping in a "cheaper" part.

05-06-2003, 11:37 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 any 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

05-06-2003, 11:53 AM	#2
WADS56 gear banger Join Date: Aug 2000 Location: CHICAGO Posts: 1,144	I only read half of your post up to the part... "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." You ALWAYS check PTV clearance when installing a cam! It takes about 30 extra minutes to do this and will save you allot of time and money in the long run. You have a bent valve if it wont close all the way, or something is stuck between the valve and seat. __________________ 79 Hatch: NA 347, Stage 2 Canfield Heads, Victor JR. Intake, Blueprinted Holley 750 HP, Solid Roller Cam, Shooting for 10's on motor 93 LX: Tremec, dual friction clutch, fms flywheel, Hedman shorties, O/R H-pipe Ricer hater's club member #49

05-06-2003, 12:16 PM	#3
sleeperstang Registered Member Join Date: Jun 2001 Location: Lynwood, CA, U.S.A. Posts: 82	Ooops, I knew I would leave some detail out.... The Machine Shop did the installation of the camshaft as well, so that would be their responsibility as far as I'm concerned. I didn't take apart the heads nor pulled the camshaft out because it may have voided the warranty. Thanks for pointing that out.... __________________ 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, 12:13 AM	#4
Mike Souslin Registered Member Join Date: Sep 1999 Location: Grove City Ohio Posts: 226	oops __________________ 91 Coupe with fresh rebuild. Running Stage 2 Avenger heads (51cc chambers), Stage 2 cam (.549, .566)1.72 Crane Gold Race rockers, Port matched GT-40 upper & lower, 75mm Bullet MAF, 65mm Accufab TB, MSD 6AL, Long Tubes through off road and 2 chamber flowbastards. Stock T-5, 3.73 gears, Center Line Convo-Pros with skinnies up front. My baby is now bottle fed!!! Best time on the motor was 12.92 at 109.57. UPDATE - Getting Ready to install: Tremec 3550, Blowproof Bellhousing, Strange Shocks/Struts, Moroso Springs, Upper/Lower control Arms, 31 spline axles and new differential. After this..... 347 heart transplant and Rollcage.