Process for swapping rockers gear over
Discussion
Have been told that to put my new 1.5 rocker on I have to drain the water system?, then undo the back set of nuts take off rockers (on my tr's on a separate centre set of holes in the centre of the head not holding the head own so a piece of piss), fit the new ones, tighten the back set to around 40 fl/lbs, back the front of a tad from the 55 to around 40ish and then follow the proper sequence to tighten all progressively to 55f/lbs.
The set the tappets.
Do I really have to drain the engine - WHY?
The set the tappets.
Do I really have to drain the engine - WHY?
Because the rear set of studs are also the main head studs.
In fact, by loosening them you are running the risk of a subsequent head gasket failure after re-torquing and you drain the water in case a leak into the oilways of combustion area occurs during the work.
Personally I will only change a rocker shaft by taking the head right off and changing the head gasket and manifold gasket at the same time. A 'bind' to be sure, but better safe than sorry.
Tip: If you do this, it's best to use 5/16"UNFx1.25" hex head bolts to fit the manifolds to the head as this makes subsequent removal very easy.
In fact, by loosening them you are running the risk of a subsequent head gasket failure after re-torquing and you drain the water in case a leak into the oilways of combustion area occurs during the work.
Personally I will only change a rocker shaft by taking the head right off and changing the head gasket and manifold gasket at the same time. A 'bind' to be sure, but better safe than sorry.
Tip: If you do this, it's best to use 5/16"UNFx1.25" hex head bolts to fit the manifolds to the head as this makes subsequent removal very easy.
It only had the head off very recently for a fresh set of valves and a new gasket at Vmax.
Vmax had the rollers and load of other bits of week all turned up bar roller rockers and needed car so said stuff it put it all back together (new LCB, gasket head check, redo a valve seat an 8 new valves) he did this then tells me when I come to pick it up that the roller rocker set was now in stock and could have tomorrow - Ooh F*&king great! Cancelled the order on rollers pissed off.
Then get then some time later (less tan 1500 mile on engine since all the above) and noow ready to put on.
Ahrrrr.
But the twin 2x Hs6's are taking for ever to get all the brackets and lugs sorted that it is now looking like it might make more sense to take the bloody head off and do ALL at once - MAKE MY BLOOD BOIL.
Vmax had the rollers and load of other bits of week all turned up bar roller rockers and needed car so said stuff it put it all back together (new LCB, gasket head check, redo a valve seat an 8 new valves) he did this then tells me when I come to pick it up that the roller rocker set was now in stock and could have tomorrow - Ooh F*&king great! Cancelled the order on rollers pissed off.
Then get then some time later (less tan 1500 mile on engine since all the above) and noow ready to put on.
Ahrrrr.
But the twin 2x Hs6's are taking for ever to get all the brackets and lugs sorted that it is now looking like it might make more sense to take the bloody head off and do ALL at once - MAKE MY BLOOD BOIL.
To be quite honest, I don't know that 1.5:1 rockers make that much difference. I had some on my 1964 rally car and it gave about 115 bhp at the flywheel. Then I got nervous about the regulations and decided to fit a set of the original lightweight 'S' forged rockers that I managed to get hold of and it still gave 115 bhp, but at slightly lower revs. Valve guide wear is less with 1.3:1 so I've stuck with them ever since. IMO they are really best suited for racing where the really high revs, biggest valves and ultra-high overlap cam really suit their use.
Now I guess lots of others will disagree with me, but I can only speak as I've found over the years.
In your case I would take the head off, set up the new carbs onto the head on the bench and match everything up properly, then fit new head and manifold gaskets, bolting the manifolds on rather than using those horrible studs. If you are using a hot cam presumably you will open out the head inlets tracts and the manifold, in which case you'll need to dowel-locate the inlet manifold to the head. I normally do this using 2 gear-linkage roll pins cut to length. I bore the holes in the manifold to be a tight fit and the corresponding holes into the head to be a slack fit, then I fit the dowels using 'Loctite' into the manifold. The dowels need to project about 1/4" from the manifold face. By setting it all up on the bench you'll get the best set-up possible. Use an old manifold gasket for the initial trial fit, then drill the new manifold gasket in exactly the same places for the dowels before final installation.
I hope all this helps,
Peter
Now I guess lots of others will disagree with me, but I can only speak as I've found over the years.
In your case I would take the head off, set up the new carbs onto the head on the bench and match everything up properly, then fit new head and manifold gaskets, bolting the manifolds on rather than using those horrible studs. If you are using a hot cam presumably you will open out the head inlets tracts and the manifold, in which case you'll need to dowel-locate the inlet manifold to the head. I normally do this using 2 gear-linkage roll pins cut to length. I bore the holes in the manifold to be a tight fit and the corresponding holes into the head to be a slack fit, then I fit the dowels using 'Loctite' into the manifold. The dowels need to project about 1/4" from the manifold face. By setting it all up on the bench you'll get the best set-up possible. Use an old manifold gasket for the initial trial fit, then drill the new manifold gasket in exactly the same places for the dowels before final installation.
I hope all this helps,
Peter
John - It'll be a pain in the arse (que swearing - skinned knuckles - droppped tools and the almost obligatory Mini forearm rash) but changing the head gasket is the only safe way of doing especially as you are going to be putting the car to some serious (?) usage afterwards..... are you not?
To add to the High Lift rocker debate - Short duration cams and High Lift rockers give great torque for road usage, even with modest valve sizes.
To add to the High Lift rocker debate - Short duration cams and High Lift rockers give great torque for road usage, even with modest valve sizes.
fwdracer said:
John - It'll be a pain in the arse (que swearing - skinned knuckles - droppped tools and the almost obligatory Mini forearm rash) but changing the head gasket is the only safe way of doing especially as you are going to be putting the car to some serious (?) usage afterwards..... are you not?
To add to the High Lift rocker debate - Short duration cams and High Lift rockers give great torque for road usage, even with modest valve sizes.
Gareth, I guess that's why I didn't really see much of an advantage with my 286 cam and 37mm inlets. High-lift rockers are certainly easier to deal with than a cam change for a road car with a mild cam. Thanks for that.
Peter
Right - yep that wasa pain - but not for the obvious reasons. Removed rockers after warming and dumping water and allow to cool over nite, back off front studs slightly (1/8th turn). Then put the 1.5's on and set clearences. Horribly tappetty - removed and found the minisport tappets at the back (shraouding the tappet ball) were getting a mild beating! Cleaned and dressed them and put on again (only ran engine for 15 secs so not warm. Same! (Called Stuart Vmax) - luckily driving close an dpoped round for a quick look. Seems that we may have had more than a little off the head at Coopers or later, ther for the clouting of the shrouded balls. Need 2 - 3mm rocker pedistal shims (got on sat morn after letting go cold and this time dumping all oil and water (bit of water in oil). Shimmed and set clearences this time with fresh oil, filetr, water and pulling the studs gradually to 55ft/lb - Perfect.
Hmmm does not seem any perkier (a tad quieter I'd say - rollers helping instead of bashing as std!?) but until on the rollers AND the 1.75 SU's go on (christ ishas taken for ever to get all the bit made, moddified and rebuilt - should get last very short ram pipes with mess built in - bugger filters from burlen!) Maniflow manifold, with acceleration arm bracket and servo breather moddied for 20 by Vmax should be next weekend task and then get off to the rollers for setting up.
I could have not bothered with the rocker and got the std 1.25 SU's rebushed - but hay that would be boring and too easy.
Will have to get an under bonnet heat and sound matt from a large car ata scrapper and cut down!
>> Edited by jellison on Monday 17th April 18:27
Hmmm does not seem any perkier (a tad quieter I'd say - rollers helping instead of bashing as std!?) but until on the rollers AND the 1.75 SU's go on (christ ishas taken for ever to get all the bit made, moddified and rebuilt - should get last very short ram pipes with mess built in - bugger filters from burlen!) Maniflow manifold, with acceleration arm bracket and servo breather moddied for 20 by Vmax should be next weekend task and then get off to the rollers for setting up.
I could have not bothered with the rocker and got the std 1.25 SU's rebushed - but hay that would be boring and too easy.
Will have to get an under bonnet heat and sound matt from a large car ata scrapper and cut down!
>> Edited by jellison on Monday 17th April 18:27
Wildfire said:
I know you can't fit it to a high lift cam'd mini with a 1275 (like mine) but ona std 998? Just so you don't have to relace the cam.
I was thinking 12G295 ported and flowed head + std cam + 1.5s??
I would think that could be a very smooth and pleasant unit.
All the documentation says you shouldn't, but I once built a 998 Cooper historic rally car and fitted a 286 cam, a 'worked-on' 295 head, flat-top pistons, lcb and Maniflow exhaust with modified 1.25" carbs. It gave 75 bhp at c.6000 rpm and was reasonably easy to drive. Then changed the engine for a 970 'S' unit with s/c c/r box, a 4.1 diff, Omega pistons, a 286 cam and twin 1.5 SU's which gave 85 bhp at 6400. Not such a nice car to drive, but a bit quicker. Never liked the 970 though - nasty, cammy little lump.
Gassing Station | Classic Minis | Top of Page | What's New | My Stuff