Printable Version of Topic

Posted by: morehills Feb 29 2024, 06:30 AM

I'm doing a fairly large project on the interior of my 1971 914-6 GT clone this winter. I'm converting to 911 steering and ignition, adding a GT roll bar and harness mounts and a few other bits and bobs.

While it's open, should I cut an access panel? Is there any impact on the structural integrity of the firewall? How difficult is it to lean over the engine and adjust timing without the access panel? While it would be more convenient, I wonder if it's really needed to properly time the car every few years. It's a '71 2.2 liter "E" cam engine.

Thanks for any advice. John






Attached image(s)

Posted by: Cairo94507 Feb 29 2024, 06:43 AM

If you have a factory 914-6, I would not cut the firewall; did not cut mine either. I have modded my 6 but the body is still essentially stock with the exception of my louvered front trunk floor to vent the oil cooler. I think the biggest hassle is if you need to change your fan belt or alternator. It can be done in the car, but it's a task best left to young, thin mechanics with long arms. The best plan for these cars is to just drop the motor for maintenance. Valve adjustment, address any leaks, new fan belt, etc. Timing them is a slight pain, but manageable with the engine in the car.

I think structurally, if you cut an opening in the firewall, make a nice metal panel that seals tightly when installed - maybe riv-nuts. I do not believe it is going to weaken the firewall.

Posted by: gereed75 Feb 29 2024, 06:59 AM

There are lots of threads and lots of opinions on this

http://www.914world.com/bbs2/index.php?showtopic=81727

Race car - absolutely. Street car ??? Remember, you have to cut fabricate fasten. For use you gotta remove seats and backpad.

For me a “no”. For others a “why not”. Timing is not a big deal. For as much as these cars typically get driven, belts last a long time. Engine likely coming out for valve adjustment and other maintenance. Service the belt then.

Posted by: Superhawk996 Feb 29 2024, 07:06 AM

But only one right answer

Posted by: brant Feb 29 2024, 07:24 AM

Drop the motor for valve adjustment

Geez. I do the valves 6-8 times every summer and never drop the motor for it

Posted by: Superhawk996 Feb 29 2024, 08:29 AM

I haven’t read that thread in a while.

Here’s the thing that isn’t even discussed in that thread. An air cooled engine is way louder than a water pumper.

OEMs go to great lengths to seal even the tiniest holes in a modern firewall? Why?

NVH (Noise Vibration Harshness)

It is amazing how much sound can be transmitted through even the smallest holes, unsealed weld seams, and past rubber grommets, and foam. All modern cars have multi layer NVH solutions to help quiet things down. But it all starts with minimizing protrusions through the sheetmetal.

Posted by: Steve Feb 29 2024, 09:06 AM

I've had my 914-6 conversion since 1986 and only recently cut the firewall to replace the alternator with my 3.2. Otherwise getting to the belt, distributor and valves has never been a problem.

Posted by: Steve Feb 29 2024, 09:08 AM

I bought the PMS fiberglass cover, versus finding someone to cut up their firewall for a cover plate. https://patrickmotorsports.com/collections/patrick-ms-parts/products/bod914bhcpms?_pos=3&_sid=ca3958367&_ss=r

Posted by: morehills Feb 29 2024, 09:25 AM

Thanks for all the great replies and sorry to re-litigate this issue. So much good information here but it's sometimes hard to find.

Posted by: gereed75 Feb 29 2024, 09:51 AM

Do my valves routinely in car also. I guess I was thinking about next time. Engine coming out for a bunch of other work.

Not sure there is a best answer for street cars. No in an original six, owner preferences on a conversion.

I think if I were doing it I would maybe try to make a clean cut and then fab and weld in a bolt ring/flange and use the cutout to reseal the hole.

Posted by: SirAndy Feb 29 2024, 10:28 AM

The clue is in the name ...
Firewall

Cutting a big hole in a wall that is supposed to protect you from an engine fire (to give you a few extra seconds to get out of there) is really only a good idea if you are prepared to deal with it in an emergency.

Posted by: rgalla9146 Feb 29 2024, 10:47 AM

IF you choose to put the access hole in, there is no better cover than a piece
cut out of a junked car .
It will fit perfectly and look like it grew there.
Timing and valve adjustment can be made much easier by marking your flywheel
as done on original 914 6s Use the marks on your crank pulley to position the flywheel
for marking.
No need to be young, thin or acrobatic.
Changing / adjusting your fanbelt is a challenge. Get the right tools.
If using an aftermarket front mount be sure there is clearance to remove /install
the V belt
Practice replacing and adjusting before leaving on long journeys.

Posted by: 930cabman Feb 29 2024, 10:57 AM

I cut mine for the /6 conversion. It's a simple patch to put things back together

Posted by: Superhawk996 Feb 29 2024, 11:17 AM

Ya all must be changing fan belts like underwear to need that much easy access.

I’m wondering how many of you are driving modern cars where you can’t even see the serpentine belt?

Posted by: mlindner Feb 29 2024, 11:40 AM

I put one in my GT Tribute, helps a lot with service. I built the car for myself, not to worried about resale. Best, Mark

Posted by: brant Feb 29 2024, 12:10 PM

Ours



Attached image(s)

Posted by: Beach914 Feb 29 2024, 12:25 PM

I'm planning to do it on my GT conversion but will not even think of doing that on my -6 for obvious reasons.

I cut and saved a section from Frankencarcass back when I was parting it out.

Posted by: dr914@autoatlanta.com Feb 29 2024, 12:28 PM

NO WAY!!!!!!

Posted by: burton73 Feb 29 2024, 03:07 PM

@http://www.914world.com/bbs2/index.php?showuser=27202

I have what you want. I was going to put in my V8 car body but went a different route.
I have 2, the bigger one may be better. Super clean part. I will list it in parts for sale.

Best Bob B Burton

Boxed in a 24x24x5 box. 10 lb for the big one as it cam from Garold a few years ago

Posted by: 930cabman Feb 29 2024, 04:21 PM

Looks very clean to me, I can't see how this can compromise the firewall?

Posted by: Mitox Feb 29 2024, 04:56 PM

I cut mine, and found a firewall section to make the cover from. Haven’t finished it yet, but it will have a bead-rolled recess around the cover edges locate a seal.

Posted by: burton73 Feb 29 2024, 07:13 PM

Without having UL test the fire rating, it really will not comprise the fire wall if bolted down. Small seal to quite noise intrusion.

This is not like double 5/8 drywall in construction or solid fire doors with one-hour rating.

Bob B

Posted by: worn Feb 29 2024, 08:58 PM

The hole sure was handy when the alternator failed. I got the firewall from a parting out event. Cut a cover that fits perfectly and then welded a couple dozen bolts to the sheet metal to make the seal secure. Yes, it is a firewall, but the gas tank is located right at your feet with a clear open passage to the passenger compartment. I use a lot of fasteners but using a screw gun makes it easy to take apart,

Posted by: Dion Mar 1 2024, 06:22 AM

My version. Had a section from a donor car. Added weather stripping to inside of cover for noise/odor control. Works well, especially when I changed out the cast iron distributor for a 123.


Attached thumbnail(s)

Posted by: ClayPerrine Mar 1 2024, 08:39 AM

I will forever remember the fire behind me on the freeway. There is no way in hell I am cutting a hole in something called a "FIREWALL"

On our six, I drop the motor yearly for valve adjustments. Yea, you can do it in the car, but it is much easier when it is out. And that gives you the chance to change the fan belt, check the CV joint bolts, and inspect the shift linkage bushings.

You have to drain the oil to adjust the valves, and you have to separate one oil line to drain it. So what is the big deal with just disconnecting the rest of the stuff and dropping the motor?

Posted by: mepstein Mar 1 2024, 08:53 AM

Yes it’s called a firewall. Yes a plate that’s screwed into the back will secure the firewall. It’s been done on many race and street cars for years.
Definitely worth changing up to stainless fuel lines from tangerine racing.

Posted by: Superhawk996 Mar 1 2024, 09:03 AM

come on Clay, you know the lengths 914 owners will go to to avoid dropping the engine.

Continues to be a source of amusement to me how many buy a mid-engine vehicle then try avoid the engine drop that mid-engine cars practically necessitate.

Posted by: ClayPerrine Mar 1 2024, 05:34 PM

It seems to be a no-brainer to me. But I can have the engine and transmission out of a 914 in 30 minutes. I would spend more time trying to adjust the valves on the six with the engine IN the car.

Posted by: mb911 Mar 3 2024, 07:03 AM

I have always been tempted but have stayed away from cutting the hole. Its to risky for me when my kids ride in the already small car with plenty of associated risks

Posted by: mlindner Mar 3 2024, 04:22 PM

I don't get it. If you have a engine fire isn't the rear window going to go first. I think the fire wall is just for flying parts, kidding. Mark

Posted by: 930cabman Mar 3 2024, 05:12 PM

Several years ago I was in the market for a 355, mid engine V8 5 valve engine. Virtually all of maintainance was completed with the engine out. A part of having a mid engine machine.

I couldn't justify $80.k, a couple years later I fell into the 914 abyss

Posted by: davehg Mar 3 2024, 06:17 PM

I’m with Team Firewall Access bay!!!!

Posted by: mlindner Mar 3 2024, 06:21 PM

Wow, nice Dave.

Posted by: ClayPerrine Mar 3 2024, 08:32 PM

No.

Been there, done that. The window was still intact for a long time after the fire started.

Posted by: windforfun Mar 3 2024, 09:08 PM

Doesn't the firewall consist of two layers with a 1/2" gap in between? A hole might be a good place for a sub-woofer. I saw a 911 years ago with this set-up. I have no idea how he isolated the engine noise.

Posted by: fixer34 Mar 3 2024, 09:21 PM

"You have to drain the oil to adjust the valves, and you have to separate one oil line to drain it. "

Not that I disagree that dropping the whole -6 motor/trans makes some things a lot easier to do, but the times I have done valve adjustments with the engine in, I have never had to drain the oil. Am I missing something?

Posted by: sixaddict Mar 3 2024, 09:27 PM

Track car…..all the stuff about what can be done by pulling the engine doesn’t make sense to me. Break a belt at the track …..and a well done access plate means you are back in business without much hassle.



Attached thumbnail(s)