Lotus Elan

HELP. Engine mount spacers Weber vs. Strombergs

PostPost by: gearbox » Sun Jun 09, 2013 12:24 am

In the final throws of finishing up my 26R mods on my frame, and wanted to get an acurrate location for the exhaust cut out on the frame to clear a set of TTR headers (1.5" primaries and 1.75" down tubes). So I offered up the bare block with a new set of Motor Mounts. The car orginally was a Stromeberg engine and I am installing a weber motor in it's place. The new mounts are for the Weber. But the 4 spacers that was off of the Strombergs were 1.125" long and was way too wide to mount in the chassis. I took them off and bolted the mount without the spacers and they appear to be off between .5" to .75" too short. So the question is, are the spacers different between a Stromberg and Weber set up? If so, what is the proper length for the Weber motor? I looked up the part in the manual and it only shows one part number. So before I go milling down the spacers, what is suppose to be in there? Thanks Allan
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PostPost by: gearbox » Sun Jun 09, 2013 2:13 am

I spoke with two other Elan owners and they both believe the spacers should be 1.125" for both the Weber and Strombergs. I put the spacers back on the block again to see if I could force the issue. I am still off by an substaintial amount. With the exhaust side bolted to the frame, the carb side mount does not even clear the chassis mounting point. So do I have the incorrect mounts?

On the Exhaust side I have a dimension from the back of the motor mount plate to the center line of the frame mounting holes of 2.75"
IMG_0502.JPG and


On the Carb side (the same dimension I took from the other side) reads about 3".
IMG_0503.JPG and


As you can see, I am off quite a bit on the carb side, about 0.60", and no matter how much you try to muscle it, it will not line up with the frame mount. Any suggestions? Thanks Allan
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PostPost by: gearbox » Sun Jun 09, 2013 4:58 am

After struggling with this for another 3 hours, I jury rigged some spacers at 0.60" so the mounts could fit the chassis. Now the engine is skewed about .50" to the exhaust side, about the same amount that I shortened the spacers. Can anyone verify that the special Weber mount (carb side) is correct for the Elan or did I get a +2 Weber mount? The distance between the mounting surface to the block and the center line of the chassis bolts is 3", I think it should be 2.5". This would make everything fit with the 1.125" spacers. Any help? Thanks Allan
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PostPost by: rgh0 » Sun Jun 09, 2013 6:20 am

Are you fitting a 1600 tall block - the bosses on the casting are wider on that block and require modified spacers.

The spacers used on Stromberg and Weber 1500 block engines were the same. Just the lift on the RH mount for a Weber is higher to enable them to clear the foot well top underneath.

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PostPost by: oldelanman » Sun Jun 09, 2013 7:45 am

Hi Allan,
Just measured a number of mounts I have and they are all around 2.7" from block face to hole centre - as Rohan says the Weber carb side mount is the same width just a different height. My 681 block is 8.25" wide across the mount bosses and the spacers are 1.125"
So when assembled I get .....2.7+8.25+1.125+2.7 = 14.775" The hole spacing between the chassis brackets is 14.75" so the mounts are very slightly compressed when fitted.

Engine mounts 008.jpg and
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PostPost by: peterexpart » Sun Jun 09, 2013 10:58 am

Allan
My 1969 S4 Stromberg Engine is out of the Car at the moment and measures Exhaust Side 3.75" from Block Face to Centre of Bolt Hole and on Carb Side 2.75" from Face to Centre, hope that helps
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PostPost by: gearbox » Sun Jun 09, 2013 11:33 am

I completely disassembled the mounts from the car so I could get some accurate measurements. This is what I had found out. Both new mounts are the same height, the dimension from the mounting surface to the center of the holes are 2.75".

IMG_0507.JPG and


Then I compared the orginal mount with the new ones and found that the old mount was about 0.125" shorter at the same measurement.

IMG_0506.JPG and


With the engine out, again, I measured the distance between the chassis holes and got 14.5625" or 0.1875" too narrow. Easy fix with the Porta Power. So this accounts for a total of 0.3135" out of spec with the two mounts. The frame tweaking I can get back to spec, but I am begining to believe that the new mounts are also correct for an Elan, but just made incorrectly, unless the .125" difference is for a +2. So, after I tweak the frame back into position, The only option would be to slot the engine mount holes .125" on each side, add the .125" for compression, I will have about 0.4375" which may be just enough. If someone can post on the +2 mounts I think we may have a final solution. Really hate to slot the engine mount holes, but I don't think I have much of a choice. Hopefully this will help others, especially if these new mounts are all coming in this way. Thanks Allan
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PostPost by: rgh0 » Mon Jun 10, 2013 12:04 am

Hi Allan

The Plus 2 mounts are identical. The Plus 2 uses 2 of the lower lift mounts as it does not have the same problem with the Webers hitting the foot well and thus does not require the high lift mount on the carb side.

The old mounts distort over time so it does not surprise me they are a little different from the new ones.

Have you confirmed you do not have a 1600 tall block with the wider engine mount bosses? The block you have looks new from the photos

regards
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PostPost by: gearbox » Mon Jun 10, 2013 2:33 pm

Hi Rohan; Thanks for the clarification on the mounts, good to know. Seems that some of my issues was caused by the frame. Despite spending a few days flattening all the panels and getting every edge true, straight, and making the usual crack repairs, the dimension I had was 14.5" between the frame mounting holes, should be 14.75". The block is a standard Lotus Ford block that came from my 1969 SE, just freshly back from the machinist, and it does measure 8.3". But I do think the new mounts were a bit wide also. After a bit of gentle persuassion with a porta power, I restored the 14.75" dimension. I was very surprised how easily these frames can be twisted about and the main reason I fabricated and welded in the 26R mods to triangulate the flat sheet metal panels. Fortunately, I decided to test fit the engine to determine the header clearance cut in the frame before welding the front panels in. But I have to say, the mods does stiffen the frame considerably and at only 8 pounds of metal, it's worth evey ounce. Thanks to all for the help, Allan
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PostPost by: mark030358 » Sat Jun 22, 2013 9:38 pm

I had exactly the sae issue with the re-manufactured motor monts on my cars. I put the original sets back on anf filled the void at the top with Sikaflex.

New ones are pants.

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PostPost by: EdHolly » Wed Jun 26, 2013 9:53 pm

My car is a series 1 but has a 701M block in it.

First thing I did when I bought it was replace the engine mounts which were both completely failed as someone had used the original spacers on the wider 701 versus 681 block. Sure must have taken some force to get them in, just machined off the difference on the wider side spacers (from memory it was the exhaust side) and they fitted fine.
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