| Author | Message | ||
     barry Unregistered guest Posted From: 58.6.3.216 |
Does anyone know if the head studs in a Silver Shadow Block had heli-coil inserts or were they just taped into the alloy? We've unfortunately pulled one out and it doesn't seem to have a heli-coil like other bolt holes in the block. This would mean that we could heli-coil the hole to put the stud back in. Has anyone had any experience of this problem in this area? Engine number is 35189 (Message approved by david_gore) | ||
| Jon Rothwell Frequent User Username: jon_rothwell Post Number: 27 Registered: 4-2004 |
Just in case anyone was wondering, according to the manual the head studs are not helicoiled. We are making up some tools to allow us to tap to the bottom of the hole and insert a helicoil, so providing we can screw the insert deep enough in the block this should work fine. | ||
| Stephe Boddice Experienced User Username: stephe_boddice Post Number: 19 Registered: 2-2005 |
Don't bother re-inventing the wheel. Contact www.uni-thread.com Ususal disclaimers. Even posted to Australia I am sure that you will find the prices comfortable. Stephe Boddice www.boddice.co.uk | ||
| Jon Rothwell Frequent User Username: jon_rothwell Post Number: 29 Registered: 4-2004 |
Didn't get any response from various manufacturers we contacted so we made up our own tools to insert the helicoil deep in the block. Due to the damage within the block we couldn't get a helicoil to hold so we took the car to our local specialist. They used an oversized tap to put a new thread at the bottom of the stud hole, then made up a new oversized stud to suit. They also pressure tested the hole to make sure it didn't leak into the water jacket or crankcase. Problem solved and now the head is back on which only leaves us the brake pumps to re-kit before putting it all back together. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 880 Registered: 4-2003 |
Well done John. The head stud is so important that I kept out of this thread until now. One small point on Unithreads is that they are made from high speed steel. Helicoils are made from stainless steel. On the V8s, almost every engine thread for a setscrew is helicoiled, so I would be very wary about replacing a Helicoil by a Unithread. Apart from the strength, the two brands may have different outside thread requirements. Studs of course usually thread straight into the alloy using a deep thread for strength, so a HSS thread may do for a repair, but I would still go for a genuine Helicoil to keep to the standard type. Incidentally, in most cities there are mobile thread repairers who specialise in such jobs for vehicles and industry. They can save you loads of time and money instead of taking the vehicle or block along to a shop. I used this service in Sydney once and was staggered at the perfect result. Astonishing is the range of special tools and methods employed, and the staggering range of threads, nuts, bolts and specials that can all be crammed into a side-opening van. Although many of us are quite adept at cuttng threads, for these vitalally important repair I always go to a professional. In Jon's case, he took the one and only decision sensible. If you mess up a head stud repair you are in very serious trouble indeed. The professionals also guarantee their work. I have seen jobs done which you would not imagine possible. RT. | ||
| Jon Rothwell Frequent User Username: jon_rothwell Post Number: 30 Registered: 4-2004 |
After almost 5 months the car is now back on the road and running better than ever. We did a lot of other jobs while the heads were off, and only had Saturday mornings to do anything which slowed us down. We had both the heads rebuilt and tested (as the original problem was a dropped valve guide), replaced the brake pump seals, did some minor electrical work, replaced a helicoil on one of the accumulator mounting holes, soldered up the heat riser tube to the choke, replaced the high pressure hose to the power steering, fitted new carby filters, spark plugs, HT leads, fanbelts, heater hoses, etc etc. We also did some painting and detailing of all the bits, cleaned out the 30 years worth of crud that had accumulated inside the sills and rustproofed the area. At times it felt like we would never get it finished and the car seemed to be fighting us every step of the way, but we got there in the end. |
