stewie
NAXJA Forum User
When i picked up these hood vents i didnt know of very many people running them. i like the way these look on an xj. but the part i liked the most about them is that they have drip pans with them as well. my jeep does not like to get the engine wet- runs like crap until the TPS dries out. i had put this project off for about 8 months so far. originally i had found a set of Le Baron hood vents, but that wouldnt work for me with the engine getting wet and i wasnt too keen on their looks. ideally i would have loved to find a set of ZJ hood vents but those have pruven to be a very difficult part to get my hands on. Good thing i waited though as i later found a couple sets of vents off of a Chevy Lumina Z34. later i also found a huge hood vent off a dodge laser with a massive drip pan, but i like the z34 vents better.
here are the vents that i picked up
the first thing that i did was to create a template. i knew it needed to be somewhat rigid, but still easy to cut to shape. at first i had tried to use corrugated cardboard but that was too thick for the way these vents mount up (via "nubs" on one side, pictured later) and could not give me an accurate fit up. so instead i used an old cereal box. heck, it was a good excuse for me to gorge myself on some cereal- i needed the box, never mind the box was nearly full.
i dont have any pics of making the template as i had made it several months ago while i procrastinated on starting the actual install. to make it i basically traced the outline of the vent (which was upside down) onto the cardboard. that gave me my first reference line to go off of. DONT USE THIS FIRST OUTLINE TO CUT!! it is only a reference line. to find where the line to cut on is you have to do a lot of measuring. measure how far in you want the metal to go under the lip of the vent. it varies on each side. the side that where the metal get sandwiched between the nubs and the lip may be difficult to get an accurate measurement for. in that case, slide the edge of the cardboard template in that groove and mark the cardboard at the outer edge of the lip on the vent. remove the vent and measure the distance from the mark and the edge of the cardboard. that measurement is how far in the cut line has to go inside of the outline on the template. the other sides are easier to measure as a tape measure can get in there. i put the short sides in enough that the cut is just outside the slightly angled part. the remaining long side was measured so the cut is just outside of the three female threaded stud posts. measure not once, nor twice but a whole heck of a lot of times. once you are satisfied with your measurements transfer them to the template. double check the lines placed on the template are correct. cut the template out on the cut line. a very sharp knife or box cutter works great. i marked on my template which side has the nubs on them. the fit was not quite correct with the sides opposite of how it was laid out. this means that the template would have to be flipped over (like turning the page in a book) when laying out the other side on the hood.
my template is actually a copy of the first one i had made out of corrugated cardboard, so mine does not have the outline on it, just the cut line, annotation for the nubs and forward reference arrow.
here are the nubs that i was taking about.
after cutting your template, check to make sure it fits ok. this is where the thinner paperboard comes into play instead of the corrugated cardboard. the cereal box template can slide in between the nubs and lip as the vent will when installed on the hood. adjust the size of the hole on the template as needed. when finished it should look something like this:
now that tedious part is done we can move on to mocking up where you want the vents to go. for all the steps up to final installation, i am using a second set of vents that i have so that i will not mar the paint on the other ones. plus they were still drying from their final coat. the pair of vents i used on the working steps are white while the ones actually installed were painted with engine enamel (to help with heat resistance) gloss black. i dont know yet how the paint will hold up to the arizona sun. if it doesnt do to well then i will just respray the vents in hammered black.
lets move on to mocking the vents up- i am sure you probably did that when you got them too as i did. placement of the z34 vents is a little more critical than that of the lebaron vents to avoid hitting the hood supports. do not cut the supports as this could weaken the hood. to mock these up i just slid the lip of the vent in between the hood and the hood supports. this held them in place for determining the general area to put them in.
here is a general mock up on the underside of the hood.
and closer up of the mock up
and this is of just the vents without the drip pans. sorry that the edge of the vent is hard to see with the white on white
ok, so now we know about where we want them. time to take some measurement of the hood. before doing this though, as you can see in the above pic, i have removed obstructions to make my job a lot easier without having to fight the hood latch cable and the hood light. i ended up wanting my cut line to be 1" out from the upper fold in the crease that runs the length of the hood. any much wider than that and i would end up cutting away parts of the hood supports. also to avoid the supports i put the vents cut line 4 3/4" forward from the back of the hood. in hindsight the 1" from the upper bend or crease was great but i could have moved the vents to be 4.5" or even 4 1/4" from the back of the hood and been ok. i ended up chewing away a small amount of the forward hood support, but not enough to weaken it much.
with those measurements in mind tape the underside of the hood. this will help keep from chipping as much paint away while cutting and provide for a cleaner cut.
and again with those same measurement in mind tape the top of the hood for the same reasons. it also gives you a better surface to trace the cut line onto.
i found it easier to work with the hood if i propped the front of it up with a couple pieces of 4x4s. it kept the hood from latching closed so that i wouldnt have to go an pop the hood each time i needed it up and also raised the hood up so that there would be less chance of cutting anything in the engine.
now take those measurements and put them on the hood. i measured 1" out from the top most crease in the center part of the hood but do not trace the line yet. now i measured and marked the 4.75" forward from the back of the hood. remember though that i found the 4.75" to be a bit too much. if anyone tries this based off my write up, please confirm with me what measurement worked for you. i made multiple marks to help aid in accuracy. draw that line. this is going to be how far back the rear corner of the vent will be.
aligning the template with both the line drawn on the rear portion and the marks on the center of the hood place your template. i tried to get mine as close as i could. if your off here, it would most likely be visible on the finished project. once satisfied with the placement of the template tape the template down like seen below. after all we dont want the template to shift positions on you while tracing it.
after both sides are traced you should have something like this:
before starting to cut metal, i wanted to protect my engine both from the debris as protect hoses, lines, wires etc from the saw blade. so i put a moving blanket down over the engine and under the hood.
ok, ready to cut some sheet metal? i am!
but before we start we must select our tool. i had at my disposal a batt powered sawzall, scroll saw, and a 4.5" angle grinder. originally i was going to use the sawzall but the batteries were all dead. so i chose the scroll saw with a bi-metal blade. choosing a blade with a finer tooth count can help prevent distorting the hood as it will not be taking as large of a bite with each stroke. a blade that is too coarse will bite a larger amount and often will cause the saw to kick or distort the metal. if you use an angle grinder be sure to cover anywhere on the xj where you dont want burn marks from the sparks. this includes the rest of the hood, windshield (especially), and roof. the sparks will pit paint and glass. dont say i didnt warn you....
to get your blade to cut it must first pierce the metal. for this i used my drill with a 3/4" hole saw. as i said above i had planned on using my sawzall. so i made two holes overlapping so the opening would be large enough for the sawzall blade. after finding that all 3 of my batteries were dead, i switched gears and grabbed the skill saw. i am glad i did. it allowed me to do a cleaner job on the corners. but i would have liked a slightly straiter cut with a wider blade, but all worked out well
here are the vents that i picked up
the first thing that i did was to create a template. i knew it needed to be somewhat rigid, but still easy to cut to shape. at first i had tried to use corrugated cardboard but that was too thick for the way these vents mount up (via "nubs" on one side, pictured later) and could not give me an accurate fit up. so instead i used an old cereal box. heck, it was a good excuse for me to gorge myself on some cereal- i needed the box, never mind the box was nearly full.
i dont have any pics of making the template as i had made it several months ago while i procrastinated on starting the actual install. to make it i basically traced the outline of the vent (which was upside down) onto the cardboard. that gave me my first reference line to go off of. DONT USE THIS FIRST OUTLINE TO CUT!! it is only a reference line. to find where the line to cut on is you have to do a lot of measuring. measure how far in you want the metal to go under the lip of the vent. it varies on each side. the side that where the metal get sandwiched between the nubs and the lip may be difficult to get an accurate measurement for. in that case, slide the edge of the cardboard template in that groove and mark the cardboard at the outer edge of the lip on the vent. remove the vent and measure the distance from the mark and the edge of the cardboard. that measurement is how far in the cut line has to go inside of the outline on the template. the other sides are easier to measure as a tape measure can get in there. i put the short sides in enough that the cut is just outside the slightly angled part. the remaining long side was measured so the cut is just outside of the three female threaded stud posts. measure not once, nor twice but a whole heck of a lot of times. once you are satisfied with your measurements transfer them to the template. double check the lines placed on the template are correct. cut the template out on the cut line. a very sharp knife or box cutter works great. i marked on my template which side has the nubs on them. the fit was not quite correct with the sides opposite of how it was laid out. this means that the template would have to be flipped over (like turning the page in a book) when laying out the other side on the hood.
my template is actually a copy of the first one i had made out of corrugated cardboard, so mine does not have the outline on it, just the cut line, annotation for the nubs and forward reference arrow.
here are the nubs that i was taking about.
after cutting your template, check to make sure it fits ok. this is where the thinner paperboard comes into play instead of the corrugated cardboard. the cereal box template can slide in between the nubs and lip as the vent will when installed on the hood. adjust the size of the hole on the template as needed. when finished it should look something like this:
now that tedious part is done we can move on to mocking up where you want the vents to go. for all the steps up to final installation, i am using a second set of vents that i have so that i will not mar the paint on the other ones. plus they were still drying from their final coat. the pair of vents i used on the working steps are white while the ones actually installed were painted with engine enamel (to help with heat resistance) gloss black. i dont know yet how the paint will hold up to the arizona sun. if it doesnt do to well then i will just respray the vents in hammered black.
lets move on to mocking the vents up- i am sure you probably did that when you got them too as i did. placement of the z34 vents is a little more critical than that of the lebaron vents to avoid hitting the hood supports. do not cut the supports as this could weaken the hood. to mock these up i just slid the lip of the vent in between the hood and the hood supports. this held them in place for determining the general area to put them in.
here is a general mock up on the underside of the hood.
and closer up of the mock up
and this is of just the vents without the drip pans. sorry that the edge of the vent is hard to see with the white on white
ok, so now we know about where we want them. time to take some measurement of the hood. before doing this though, as you can see in the above pic, i have removed obstructions to make my job a lot easier without having to fight the hood latch cable and the hood light. i ended up wanting my cut line to be 1" out from the upper fold in the crease that runs the length of the hood. any much wider than that and i would end up cutting away parts of the hood supports. also to avoid the supports i put the vents cut line 4 3/4" forward from the back of the hood. in hindsight the 1" from the upper bend or crease was great but i could have moved the vents to be 4.5" or even 4 1/4" from the back of the hood and been ok. i ended up chewing away a small amount of the forward hood support, but not enough to weaken it much.
with those measurements in mind tape the underside of the hood. this will help keep from chipping as much paint away while cutting and provide for a cleaner cut.
and again with those same measurement in mind tape the top of the hood for the same reasons. it also gives you a better surface to trace the cut line onto.
i found it easier to work with the hood if i propped the front of it up with a couple pieces of 4x4s. it kept the hood from latching closed so that i wouldnt have to go an pop the hood each time i needed it up and also raised the hood up so that there would be less chance of cutting anything in the engine.
now take those measurements and put them on the hood. i measured 1" out from the top most crease in the center part of the hood but do not trace the line yet. now i measured and marked the 4.75" forward from the back of the hood. remember though that i found the 4.75" to be a bit too much. if anyone tries this based off my write up, please confirm with me what measurement worked for you. i made multiple marks to help aid in accuracy. draw that line. this is going to be how far back the rear corner of the vent will be.
aligning the template with both the line drawn on the rear portion and the marks on the center of the hood place your template. i tried to get mine as close as i could. if your off here, it would most likely be visible on the finished project. once satisfied with the placement of the template tape the template down like seen below. after all we dont want the template to shift positions on you while tracing it.
after both sides are traced you should have something like this:
before starting to cut metal, i wanted to protect my engine both from the debris as protect hoses, lines, wires etc from the saw blade. so i put a moving blanket down over the engine and under the hood.
ok, ready to cut some sheet metal? i am!
but before we start we must select our tool. i had at my disposal a batt powered sawzall, scroll saw, and a 4.5" angle grinder. originally i was going to use the sawzall but the batteries were all dead. so i chose the scroll saw with a bi-metal blade. choosing a blade with a finer tooth count can help prevent distorting the hood as it will not be taking as large of a bite with each stroke. a blade that is too coarse will bite a larger amount and often will cause the saw to kick or distort the metal. if you use an angle grinder be sure to cover anywhere on the xj where you dont want burn marks from the sparks. this includes the rest of the hood, windshield (especially), and roof. the sparks will pit paint and glass. dont say i didnt warn you....
to get your blade to cut it must first pierce the metal. for this i used my drill with a 3/4" hole saw. as i said above i had planned on using my sawzall. so i made two holes overlapping so the opening would be large enough for the sawzall blade. after finding that all 3 of my batteries were dead, i switched gears and grabbed the skill saw. i am glad i did. it allowed me to do a cleaner job on the corners. but i would have liked a slightly straiter cut with a wider blade, but all worked out well
