- This topic has 20 replies, 12 voices, and was last updated 9 years, 7 months ago by
.
-
Posts
-
On the same subject as my earlier spare post, on the CMC Fiberfab spare tire mount, the instructions say to put the spare tire on the mount and then carefully scribe the two top slots of the rim onto the fiberglass to cut for air to flow out from the engine compartment. Is there really any reason to do this? Do any other kits say/recommend to do this?
Thanks
Allen Caron
VW based 53MGTD - "MoneyPenny"
"If one thing matters, everything matters" - from the book The ShackThe reason is air flow in the engine compartment.
Not sure how othermanufacturers handled this.
But the Classic Roadsters Duchess engine cover is open behind the wheel. The steel spare tire carrier bolts to the z-bars from under the engine cover and comes through about a 12″ hole in the enging cover. So there is a good size air flow opening behind the wheel.
Paul Mossberg
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica RoadsterIf you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)
My Fiberfab kit has the 12 inch hole in the engine cover that has what I calll a fiberglass “Hat” that fits throught the hole from the inside and rivets to the engine cover. That hat has a thick 6 inch metal strip with two lugs protruding through to mount the tire to. I’ll take a picture when I get to it again or you can check the CMC downloadable manual, page 39.
Allen Caron
VW based 53MGTD - "MoneyPenny"
"If one thing matters, everything matters" - from the book The ShackAllen, My VW based car has an opening that is about the same size as the wheel [about 15”] . The tire fits tightly against the engine cover and air can circulate thru all the oval holes in the wheel.It would appear that water would also enter thru the holes ,but it has set out in the rain all day and never failed to start. In the original VW, the engine tin is sealed to the body with rubber gaskets . This is to keep the hot air from the heads from being sucked into the cooling fan intake . The air for cooling came thru vents either in the hood or the panel between the hood and rear window. I have never seen a kit car that has the engine tightly sealed to the body . It appears that most can get air from under the car and it must work OK. Many builders remove the VW thermostst and the ring that blocks off the intake opening in the shroud which allows the fan to suck in all the air it can handle .My car also uses the aftermarket tin that many say is not as efficient as the VW tin, but I have never had a problem with overheating.
Bridget has a loosely fitting cover under the wheel and tire. There’s a slot on one side but nowhere near a foot diameter hole. Seems to do fine that way. I don’t guess a single PICT 34 feeding single port heads is gonna need a lot of CFM.
My Duchess has no special cover under the hole in the engine cover.
Returning from a national kit car show in Indianapolis, I drove the Duchess through the worst rain I have EVER driven in, regardless of the vehicle. I had no water problems with the engine.
Paul Mossberg
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica RoadsterIf you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)
My engine runs much cooler with the hot air side of the engine separated from the cool air side.
Phil
Correct Phil.
The engine compartment on a Beetle (or any of the air cooloed VW’s for that matter) is sealed so the top end and bottom end are insulated from each other.
Exhaust and heads are below the engine compartment floor.
To the extent we can replicate that environment in our TDs, our VW engines will be much happier.
PMOSSBERG40570.4208217593
Paul Mossberg
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica RoadsterIf you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)
Thanks everyone for all the input. My biggest concern I guess is structural intyegrety after making all those slots. On my CMC kit, the spare tire support holds the spare tire with two lugs through the rear face of the support. That weakens the support enough and now I have to add several slotted holes on the rear face. Just worried that the fibeerglass may crack with all the bouncing and vibration from normal driving and finally give out. I guess I’ll press on and trust the CMC folks.
Allen Caron
VW based 53MGTD - "MoneyPenny"
"If one thing matters, everything matters" - from the book The ShackAllen,
my CMC/Fiberfab has the same setup you describe. The original builder did not cut the slots in the spare tire mount, nor did I. I am not having a heat problem without the slots cut even on a hot 100 degree southern day. My engine oil temp maxes at about 205. It seems there is enough airflow, that upper compartment heat build up is not a problem. If it was me I would try without the slots.
Mike
I had muffler heat problems melting the fiberglass panel that sits right above it so I lined that panel with an aluminum sheet and ran the sheet all the way up to the V/W sheet metal. I agree with the idea that the fan should not be sucking in all that hot air.
My al sheet solved the melting problem, anyway!
Old message thread, I know, but I used “search” and found this because I don’t have any venting at the spare wheel/engine cover. Although I discovered by accident, while washing the car, that gaps exist between the vertical back side when the cover is closed. There’s a slight curvature to the main body of the car so the gaps vary from almost closed to about 3/8 inch open at the middle. And even though rubber seals are there, as well as everywhere else along the edges where the cover closes, it obviously doesn’t close that gap. I can actually see the engine, or fan shroud, from outside when it’s closed.
My engine cover has a piano hinge across the top. On left and right sides, top inside of cover, there is a thick hard rubber block about an inch square so there’s no way for the cover to close completely anyway. At least not at the hinge itself. Not sure why those are there, especially since it looks like they would add stress to the hinge being right next to it.I was planning on cutting at least a couple holes where the spare wheel is mounted to help ventilate the engine. And yet, if the oil temperature gauge is reading right, I have only seen it reach 190 on a sunny 75 degree day after going 15 miles at 65 MPH. As I understand it, as much as 230 is not unusual.I think all the “tins” are fitted correctly. No airtight enclosure surrounding the fan shroud, so front to back air flow isn’t prevented, as was mentioned in this message thread.What had me wondering about all this is engine pinging under load or hard acceleration. I began with a timing advance of 32 degrees (once I figured out how to set it for the 009 distributor), then tried 30 degrees, and finally 28. Just haven’t had the chance to test drive yet for this final setting.I ride a air-cooled motorcycle so that aspect isn’t new to me, in fact the oil temps are probably very similar from what I can tell. The pinging problem is what I haven’t dealt with from the motorcycle, so I can only hope I find the solution to that.Since you are running a single (?) Weber and a 009 distributor, someone has been tweaking your engine trying to get more performance out of it. Do you really know what the displacement is? Which cam?
Your oil temps seem to be relatively normal. You might want to verify these temps with another guage. I wouldn’t go cutting holes in the fiberglass engine cover just yet. If it ain’t broke………
Pinging: Under hard acceleration if you still (at 28 degrees) get pinging, you might want to check your plugs. A colder plug may cure. Do you know if the prior owner increased the compression ratio? If he did, you may have to try premium gas. Try it anyway, it won’t hurt the engine and may decrease pinging, but premium is an unnecessary expense for most of us. Carbon buildup in the cylinder can cause pre-ignition also. If your pinging is only noticeable at certain throttle positions, you may have a carb adjustment problem. This whole pinging issue is really a big and complicated subject. I am not trying to solve all the problems in a short paragraph but with aluminum heads, it needs to be tended to.
Okay, yeah, I won’t go cutting vent holes just yet if the temperature pans out to be good.PO said he hadn’t done anything to the engine when he gave me a book he had, it’s about performance upgrades for the VW engines. So I can only guess it just has the dual port intakes and (single) Weber, no way I would know of more than that. He only suggested I might want to give the book a read if I wanted to make changes.
Won’t be driving the car until later, crossing fingers the reduced 28 degrees timing advance helps.I replaced the spark plugs with what a foreign car parts place sold me, and didn’t realize until doing that how they were different from the originals. They’re Bosch SuperPlus and have semi-pointed ground electrodes with non-flat undersides, either purposefully or caused by the angled cut of the tip. So the outer edges are actually closer to the center electrode than the middle.Worried me that the gap wasn’t even across the gap so I tried to average it out. Filing it flat would have been the better idea.Old spark plugs looked a little sooty to me, but good normal color without excessive carbon buildup. That was my first thought before I had the timing adjusted and heard the pinging, that maybe carbon had formed on the heads or piston tops.Silly of me not to look with my boroscope inspection camera when I put the new plugs in! Was an afterthought.I replaced the air filter because it didn’t wash out as well as I wanted, and might have been making an overly rich fuel condition. Won’t know anything until I check the spark plugs… sooner than later because of the strange electrodes.LRH2015-05-05 16:39:17
Not too sure about those super plugs. I run NK BP5HS and am a big NGK fan. If retarding the timing a bit doesn’t fix the pinging, I think I’d change to regulation old plugs.
I have not heard of an overly rich mixture causing pinging.
Yep, I prefer regular spark plugs. Thought these were them. I use NGK in my motorcycle.
You read me wrong there (a lot to read!). Was just saying I think the old dirty air filter probably richened it up a bit. If anything I’ll need to be sure new air filter didn’t cause it to go too lean now, hence another possibility for the pinging.Aaah! Re rich and pinging: yes, you are correct, it is possible that a clean filter did lean up your mixture. I read your post wrong.
Royal2015-05-05 20:03:50I bought a spare tire cover and covered the spare tire .I started having overheating problem immediately. Since I liked the cover I asked around and decided to cut a 3 X 10 rectangle on the top of the engine cover and bought a grate to cover it . It looks nice and run about 180 to 220 degrees .
MP Lafer has 3 slotted panels on top of engine cover.
Personally, I’d try sealing the engine compartment before I’d start cutting additional vent holes in the fiberglass. Unfortunately, most TDr kits seem to make no effort to do so…
The engine compartment on stock VWs was totally sealed around the engine to force the cooling fan and the carb to suck in air from above the engine rather than up from below, over the hot engine and more specifically the exhaust system. Most TDr kits that I’ve seen have angular corners on the rear splashpan, rather than being curved to fit the original VW engines “tin.” That gap means the engine is sucking in hot air from the muffler area rather than from over the transmission…
You can close that gap with aluminum or something similar, then add the sealing rubber from a VW bus to close and seal the gap. Note that that rubber seal had double wide flaps. The lower flap should get pressed down (with a dull screwdriver or putty knife) so that it goes below the corresponding lip on the engine tin, while the top flap lies and rests on top of it. At low RPM the top flap seals the gap, while at higher RPM the partial vacuum created by the cooling fan sucks the lower flap up to close the gap. Ideally on a TDr, all air being sucked into the engine compartment by the fan or the carb would be coming in over the transmission and not from below, up over the engine…
In stock VWs, the air originally came in from the vents below the rear window, above the engine lid (except from convertibles which had no vents there and had vented engine compartment lids/hoods). When they went to dual port engines with a bigger engine cooling fan and dog- house oil coolers, VW added vents to the engine compartment lid to provide the 20% added airflow required for that bigger fan…
Early FF TDr on 69 VW pan
Slowly coming back from the ashes...
- You must be logged in to reply to this topic.