Plum 95 engine project

[mcssmostwanted]

tell him to quit crying!

[my95z28]

Pry bar ftw!

[DETROITMUSCLE]

the worst part about this is you guys could have easily replaced the motor mounts with poly ones while it was out and there would be no problems whatsoever.

[Derek]

He actually threatened to take his headers off and go back to stock yesterday... The y-pipe is rattling against the floorboards and he said he'd rather go back to stock than listen to them rattle. Gonna have to shove a thick piece of rubber or something inbetween the floorboard and the y-pipe so we don't hear it.

HORRIBLE IDEA. I tried that, not only will the rubber melt eventually, but it makes the issue 10X worse. The whole car shakes. I took the rubber piece out immediately after the test drive. On my friend Brian's LT1 bird I had him pull down as I tightened the band clamps and we got a nice amount of extra room out of it. That would be hard for you guys on your backs though... As for my car I had to replace the engine mounts with poly to get rid of all the rattles because my setup fits so tight. You should have just did the poly mounts while you were in there, I'm sure his rubber ones aren't any good these days anyway. for 50 bucks its either go out to eat and drinks one night or have a car with no rattles forever..

[meissen]

I hear ya guys - I wanted to do all that stuff but he just wanted to get the car back together.

[JoeliusZ28]

thats not necessarily the case either. Pacesetters on LT1s are very very well known for having that issue. I smacked my floorboard up with a hammer an inch or so and forgot about it. When i do install new motormounts ill make sure to measure if there was any difference, but the way the driver-side header sits i doubt new motor mounts would fix the problem for long.

[MP81]

What about dynomat or something?

[meissen]

That's exactly what I told him to do - smack it with a hammer.

[DETROITMUSCLE]

thats not necessarily the case either. Pacesetters on LT1s are very very well known for having that issue. I smacked my floorboard up with a hammer an inch or so and forgot about it. When i do install new motormounts ill make sure to measure if there was any difference, but the way the driver-side header sits i doubt new motor mounts would fix the problem for long.

well that sucks, I know on my car I never had a problem but most guys that do don't gain clearance with the poly mounts they just make the exhaust more solid and the engine hardly moves at all so unless they are already hitting when installed they won't vibrate.

As for you Larry, I'm sure Brian has heard from you to "take it slow and do it right the first time around" a time or two, now its biting you in the ass lol.

[JoeliusZ28]

well that sucks, I know on my car I never had a problem but most guys that do don't gain clearance with the poly mounts they just make the exhaust more solid and the engine hardly moves at all so unless they are already hitting when installed they won't vibrate.

As for you Larry, I'm sure Brian has heard from you to "take it slow and do it right the first time around" a time or two, now its biting you in the ass lol.

yea and thats just the reason i want new motor mounts too. Now that i have 3" piping after the collector it will still hit the floorboard if i let the clutch out aggressively. When i had 2.5" piping it would rarely happen.

But yea, as it was when i installed it the header collector was dumping directly into the cross brace of the floor board in that spot. Really wasnt even close to where it should be.

[c0ncEpT]

I would do like Derek said. You need someone to pull down on the ypipe with a pry bar as the other tightens the ypipe. I'm sure that's not going to fix your problem but it should help it quote a bit.

They only real fix is poly or solid motor mounts. Everything else is just a bandaid.

[98blackbeauty]

The headers fit very well in the engine bay and around the K frame. the issue is the collectors are only 1/4" from the floor boards. the passenger side is better but is hitting the heat shield. I don't think looking at the geometry of the motor mounts new poly mounts would help, infact they could make it worse by slightly raising the engine.
The added performance of the headers are not worth the rattling and clunking noise. I have decided to play with them for a week and if I can't resolve the noise then off they come. lucky I save the old exhaust manifolds and y pipe. If New motor mounts would resolve the issue I would put them in.

[DETROITMUSCLE]

I would do a littile bit of research on the mounts Larry, I know on LS1 cars poly mounts cure any and all header problems, they aren't any bigger than the stock ones just stiffer. I haven't even noticed a difference in interior noise either so its a win win for me.

[9T8W66]

I agree with Jeff,
The poly mounts will usually cure any issues with Y pipe clearence.
Let me put it to you this way, I had a trans mount issue at one time. Seems the worn out Drivers side motor mount was allowing the engine to twist enough to tear my trans mount in half it also broke the I pipe of my Catback right where it clamps to the Y pipe. Upon removal of the motor mount and seperation of the clam shells the rubber just fell out on the floor (when it's supposed to be bonded to the clam shells).
Installed a poly motor mount and trans mount and problem solved. Not that this is the really similar to your issue but just wanted to let you understand the torque force we're talking abot here.

[JoeliusZ28]

The headers fit very well in the engine bay and around the K frame. the issue is the collectors are only 1/4" from the floor boards. the passenger side is better but is hitting the heat shield. I don't think looking at the geometry of the motor mounts new poly mounts would help, infact they could make it worse by slightly raising the engine.
The added performance of the headers are not worth the rattling and clunking noise. I have decided to play with them for a week and if I can't resolve the noise then off they come. lucky I save the old exhaust manifolds and y pipe. If New motor mounts would resolve the issue I would put them in.

First things first, you dont need that heat shield. Its not like youve got one on the driver side.

Again the clearance issue is well known but its not hard to fix. I would recommend dropping your y-pipe then put something like a baseball bat inside the collector and bend it down, while heating the header with a torch. Also smack the floor board up a tad.

You can fix these issues in a lot less time than you would spend putting stock manifolds back on, not even replacing motor mounts. Replacing mounts is only going to increase the stability of the engine, its not going to gain you the clearance you needed to have in the first place.

I have 3" pipes on mine and mine only barely touch when im coming off the line hard and my clutch is chattering. Original 94k mile motor mounts. Mounts should be the last thing you try doing.