Heater placement, drawing template

Hello,

I marked up my firewall sheet metal using the template provided in the supplementary instructions. The template says to position it 2" from the bottom of the firewall sheet metal... however, the cut on the sheet metal sticks up about 1/4" from the bottom of the cross member where it attaches. Am I supposed to measure from the bottom of the cross member or the bottom of the sheet metal? It doesn't feel right to measure from the bottom of the sheet metal as it is not a good reference (not square to the cross member).

Attachment 222946Attachment 222945

I hope I'm being overly concerned and it doesn't matter, but I searched and couldn't find any previous material on this topic.

Thanks,
Jay

First, and most important, don't use the template unless you have placed it over the heater core to ensure the holes for the tubes are positioned correctly. Historically the template has to be redone for those holes. In terms of placement, if your template, when tested on the heater core, lines up with the bottom of the plastic housing, then place it on the firewall to allow a little clearance above the 2x2 tube. So, for your photo, let's say the template lines up with the bottom of the plastic housing, then put the template 2 1/4 up from the engine side of the 2x2 tube to give you 1/4" of clearance. Measure from the bottom of the 2x2 tube, not the sheet metal.

All of the above applies to the Roadster. Not sure which vehicle you are referring to. Consider adding those details in your profile and they will show up at the bottom of each post that you do.

Pat

That's good to know. I also saw that advice in the instruction sheet. I'm on the fence with getting a heater/defroster, but was considering cutting the firewall per the template and then just covering the openings with sheet metal. The instructions stated it was easier to cut prior to firewall installation. I was just thinking if I wanted the H/D later on or if I sold the car, it would be a plus for me or a buyer to have the firewall already pre-cut. But now it doesn't sound like that's the case.

How more difficult would it be to cut and install once the car has been completed?

In my opinion it would definitely be easier to make the cut prior to install, but cutting later with a jigsaw could work to. But later you may have things like the wiper motor, and fuel regulator in that area that would make the cutting more challenging.

Also, one mistake that I made was that I mounted the heater prior to engine install. Then I discovered that there wasn't adequate clearance between the valve cover and the inside heater tube for the elbow to be added. I had to pull the heater fan and will be making changes to the core tubes for a different type of connection, probably a bead. Will post details to my thread when I get to that point.

Pat

I can confirm that my template was off by at least 1/4"-1/2". Measure the hole placement prior to drilling/cutting. The hole will be easier to cut out prior to installation. I also made an aluminum bracket as I wasn't confident screwing into the plastic housing
https://www.ffcars.com/threads/first...5#post-6087895
Post #311

That template is garbage and quite frankly FFR has no excuse to not update it. It's been wrong for as long as I have been paying attention to it. It cost me my first firewall.

Quote:

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Originally Posted by PMD24

First, and most important, don't use the template unless you have placed it over the heater core to ensure the holes for the tubes are positioned correctly. Historically the template has to be redone for those holes. In terms of placement, if your template, when tested on the heater core, lines up with the bottom of the plastic housing, then place it on the firewall to allow a little clearance above the 2x2 tube. So, for your photo, let's say the template lines up with the bottom of the plastic housing, then put the template 2 1/4 up from the engine side of the 2x2 tube to give you 1/4" of clearance. Measure from the bottom of the 2x2 tube, not the sheet metal.

All of the above applies to the Roadster. Not sure which vehicle you are referring to. Consider adding those details in your profile and they will show up at the bottom of each post that you do.

Pat

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Thank you very much. Those were very good instructions. I basically screwed the template onto the heater/blower assembly and remarked where all the thru holes, square cut, and 1.25" holes should be. Then transferred to the sheet metal, made the cuts, and the dry fit looks great. Thanks for the help.

Attachment 223072Attachment 223071Attachment 223073Attachment 223070Attachment 223069

Jay