1965/67 Hillman Imp pick-up (bonnet repair)

The photos of the water outlets are taken with the engine sitting on a frame I just finished - details in the G15 thread. I made it full drivetrain length so I can test the entire thing before dropping it in the car - Just need to make a lower frame for it on casters so it can be moved around easily.

So Saturday night was back to the engine-stand. I spent a bit time cleaning muck off the 533 head but didn't get as far as lapping-in the valves like I intended. I have the pasts and stick from doing this on my Mondeo a while back and the difference in performance after it was amazing.

Anyway the revised idea was to find a good position for the bottom of the frame to be parallel to the flat part of the sump and catch as many studs as possible and keep the starter-motor area free.

I found that I could catch two studs on the bottom left corner of the frame and satisfy the other conditions but the top left corner was obscuring the thermostat housing.

I haven't managed to liberate this from the 533 head yet but I could see it wouldn't fit.

I therefore cut that corner off and welded in a new sloping piece which caught two more studs

I did the last cuts all by hand as I thought I'd make an of the angles doing it on a chop-saw but this time I used a grinder with thin blade and it was much quicker and still pretty accurate

When I offered up the starter it struck me that the next obstacle might be the flywheel contacting the frame

The stud protrude about 1 1/2" from the face of the bellhousing and the frame is 1" thick so that doesn't leave much room for nuts or a gap between the frame and casting.

So that was it for the night but I took a stud out to check size/TPI to order bolts which would take their place. I made them 3/8 UNC (16 TPI) and will but like 3" or longer bolts but will offer up the crank and flywheel before I commit.

I also want some tubing to weld onto the frame and slide over the 'studs' so that they are not just waggling about in holes in the frame.

I've bought various sizes of tube in the past and weirdly they seem to fit metric & Imperial applications very well. Like the OD listed is some random 12.7mm and when you take off the thickness of the walls it becomes exactly 3/8" ID



frame parallel with sump



but now encroaches on thermostat position



corner cut off frame



new sloping piece welded to corner



frame still clears starter

Watched the videos. Very interesting but wish he'd included the bit about getting the thermostat housing off with his BBQ

I'm still playing with mine and noticed (like the head-bolt tappings) that they are open on the head casting. I'm pretty sure it'll be corrosion on the studs that's stopping the housing from coming off so it might be possible to remove the studs or at least one of them to get some movement going. This worked for me on the carb-bowls. The stud could be wound down or up to get it going.

Also watched the Aston martin block-cleaning vides that came after the Imp ones. That was of interest due to the problems I had with my V12. Was pleased to see he used Devcon for pitting on the block. I had seen videos on YouTube with ppl using JB Weld for problems like that but wasn't sure if they were fantasists or not.

I know you can get heads welded or skimmed to d/w pitting but as Andy said in the vids this can then distort the component or upset all the other related clearances so filler is an attractive option imo

So, not as planned, I'm doing more work on my 'original' 533 head.

One of the reasons for this is that I think I'm going to have big problems finding the original hoses for the Sport head. I'm pretty sure I'll still have whatever ones were on the car when I got it, to use with the 533 head, but whatever the case there doesn't seem to be any supply of original types for either standard or Sport .

So the remit for the 533 head is basically: clean it thoroughly, lap the valves in, re-assemble it with new gaskets throughout. Don't think I'll bother getting it skimmed either.

I started lapping-in the valves on Friday night. They really were in VGC but the seats looked a little marked. I just used the fine paste for a couple of minutes and got good continuous rings on both.


One of the things I needed to do if I was using the Sport head was rob the 'stat-housing from the 533 so I did plan for this but even if I'm using the 533 head it would make sense to check/renew the 'stat so would need to get it off anyway.

Yesterday I dragged the hotplate out after spending hours trying to free the housing with conventional methods. There is quite a bit of room between the studs and the housing and after lots of penetrating-fluid and a bit prising and the help of a heat gun I could clearly wiggle the housing at one of the studs.

You'd think the movement would be enough to break the bond on the other stud but it didn't.

As mentioned before I also thought that I could perhaps remove the free stud by locking 2 nuts on it and therefore get much more swivel on the stuck one. The nuts weren't gripping it as they were too near the end so I tried grips on it and this naturally didn't work.

So I put the head on the hotplate and quickly covered it with a very slack Kingspan box to keep the heat in then went and did something else.

The box was soon smoking so I assumed everything was roasting but it was actually just a load of oil that was trapped where the oil-drain would be. Perhaps a question for another day but would there have been any downsides to running a car with a head that has the oil-drain provision but having the port blanked?

Anyway as things were hot I took the chance to quickly remove the steel hose-spouts before it cooled and one came out with just a little pressure. The other seemed reluctant so I didn't force it as they don't really need to come out. I just wanted to see if they would.

After that I worked on loosening the housing but long story short it wasn't budging.

After a few more hours of wiggling and penetrating fluid I decided to drill the stud. This normally goes pear-shaped very quickly when the component is wobbling about on the floor held with one hand and you are guessing your drill is straight in the other.


Well the hole started pretty much bang-on centre and stayed that way as I widened it out till only a thin shell was left. I drilled down about to what I thought was high enough above the head casting to leave me something to grab onto once the housing was off but also be insignificant enough to not stop the housing breaking free.

Once there was no more I could drill without cutting into the housing I tried punches etc to upset the thin shell and flooded it with fluid and lots more wiggling and levering and it still would not let go. I could actually see minute movement of the housing round the remains of the stud. It was getting near midnight by this time and I was determined to get it off so I resorted to (linear) force. Never a good idea but there was a tiny bit of the housing on the stuck-stud side that I could strike with a hammer and screwdriver and sure enough it started to move along the stud a fraction. After that it was just a case of tapping it back down again then up then more fluid then wiggle then tap. You get the idea.

So it's off and the studs should come out ok as I've scraped away the corrosion where they meet the head and left them soaking in ACF50 and will put the head back on the hotplate till it's good and hot.

Only bit I'm not happy about is I caught the top of the housing with the drill and it's enlarged the hole but it's fine at the bottom. Just caught the top of it



valve-seats prior to lapping



seats after light lapping-in



valves after lapping



makeshift oven



head on hotplate



steel spout came out of head fine after hotplate



drilling stuck stud



even with most of stud out, pool of penetrating fluid and wiggling housing would not yield




finally off



still some work to do




snug-fitting (8.5mm) drill bit shows some damage to housing at top of one stud-bore

So I now have my fitted-in-the-8os 533 head bare and ready to assemble.

I don't have gasket set yet so bit premature as (may) need stem-seals for the inlet valves but more on that later.

I just wanted to get the valves etc re-fitted as they have been sitting in the right order on the barn floor for a while now and it's guaranteed that won't last.

Yesterday I finished lapping-in the valves and degreased everything one last time including the filthy cam-carrier.

The valves handily have their part-numbers stamped at the top of stems.

I was very easy to put the valves back in compared to my Mondeo. The tool has plenty clearance and perhaps the springs are softer but you can do each one in minutes so it won't be that big a deal if I need to do the inlets again to fit stem-seals and possibly the paper thing that sits under the cup.

After getting the valves in I put the cam-carrier back on, without shims, just to keep the tappets/buckets in the original positions. Is all this business about putting things back in original position actually worthwhile? I'm not sure I believe it but I always do it as everyone says you should. Abusive comments welcome lol

So wit the tappets back in I noticed the heights were noticeably different

There are all sorts of factors that could cause this but assuming that:

• the valves are same lengths
• the valve heads and seats haven't been excessively lapped or ground
• the spring-caps are all in same condition
• the valves collets etc are seated correctly

It means that the buckets are different thicknesses. This could be handy when shimming if you don't have the perfect selection of shims. I only have 8 that were on this head. Or it could be a bad thing if it's not permissible to swap the buckets around into different locations.

I set the valve-clearances on my old Mondeo a while back and it was a real pain but the car did run like a dream afterwards. There are no shims used on the Mondeo (1.8 Duratec) but the buckets have the varying sizes etched on them. I found that these didn't seem to be totally accurate and a 0 to something micrometer would have been handy to check them.

Would be interesting to check the Imp ones but that means another delay getting a suitable micrometer. I have a couple of bigger ones but don't think I have a small enough one to do buckets

Another strange finding is that there are oil-drillings in the tappet-bores - but only in 3 of 8.

And lastly I found the bearing-shell (lower) for the centre cam-journal seems to have melted but there's no apparent damage elsewhere. Maybe the camshaft is bent but then you'd expect damage to both halves.




very oily cam-carrier from 533 head





carrier degreased




exhaust valve 7100854



inlet valve 7100465


exhaust valve before cleaning


exhaust valve before lapping-in




inlet valve before cleaning/lapping-in




ports after cleaning



seat for ex valve (L); seat for inlet (top) and stem seal



ex valve seat over valve-guide and 'paper' seal over inlet valve-guide


followed by inlet valve seat c/w seal inside


installing valves



valves all in



melted shell on centre journal




drillings in tappet bores



only 3 bores have the drillings (yellow dots)


buckets installed, without shims, seems to be sitting at different heights


Now to the thing that I will spend the next 3 days or so trying to work out...

Off the top of my head is what I know right now but am sure this will be subject to several changes after studying parts-list, books etc and getting opinions from other Imp enthusiasts

1. the 533 head, known as L4, was standard but had Sport cam, Sport cam-carrier and an oil-drain
2. the 533 head may have had Sport inlet valves fitted but I'm not sure about this
3. if Sport inlet valves are used there are no seals and the bottom cup differs and an extra thing on top is needed
4. if Sport inlet valves are used they take double springs
5. my 533 head doesn't have a Sport cam in it and the oil-drain was not employed
6. if I utilised the oil-drain would I have to use Sport inlet valves with no seals?
7. if the heads on Sport valves are larger how could a 533 head have standard inlet valves in it?

There appears to be logic in only drilling some of the tappet holes... Racers AFAIK will drill all 8.
The oil hole in the cam end might be ground about 1/4" into a 'bathtub' sort of relief = allows slightly more oil into the bucket/followers. Grinding a groove all the way around play hell with oil pressure, I think..

Keep At It 👍

OVIMOR

So it's been about a month since I worked on the frame but, unexpectedly, made a little progress late tonight.

I've been busy getting my Mondeo ready for MOT most of week but was using the MIG for a couple of things and had a couple of hours to spend before midnight home-time so turned to the frame.

I basically needed something to support the tube coming from the timing-chain casing. An apex perhaps

So there was a piece of the old frame that I've been cutting up which had a ready-made right angle so I drilled a strong 12mm hole in it and slid that over the tube. This gave me a triangle thing with one long leg and one short. I cut the spare bit off the T-shape frame remains and welded this to the short leg. After that I cut both of the legs at 45 degree angle about 45cm length.

I could then turn it right way up and see how it sat. The legs are a bit short but I'm adding 'feet' to the transmission end anyway so can do this on the legs also. The legs are probably far enough apart as it and making them longer would have increased this. If I'd made the apex-angle sharper it would also have brought the legs closer together but we'll see how it develops.



bits of the old frame. T-shape bit was starting point for tonight's work




T-piece turned into a triangle with no base




engine roughly how it will sit



feet need to be added at both ends

I very much doubt thats the original belt, that's what I know as a link belt, you can adjust the length by adding or removing links, normally used as a temporary (or emergency) belt.
From what I remember Imps used standard v belts.

It certainly looks ancient
I used those type belts when I worked for the NCB ( late 60's to late 80's) and I've seen them offshore. You can still buy them, mostly used in industry, its a very old design originally made from leather IIRC.