Discussion
hi there, just a quick one.......
when putting a 1300 head onto a 1000 block, use 1300 or 1000 push rods?
i have the old presses steel rockers and have tiged them up on the top edge.
oh yea, one other thing. these rockers do not sit square onto the valve stems, good or bad?
cheers Rob
when putting a 1300 head onto a 1000 block, use 1300 or 1000 push rods?
i have the old presses steel rockers and have tiged them up on the top edge.
oh yea, one other thing. these rockers do not sit square onto the valve stems, good or bad?
cheers Rob
Yep Rob you can use the old push rods. I did for a time of a year or so until I replaced them. I wouldd try and get a set of the sintered rockers though, they are better. If you are building a 998 screamer then you want rockers that will stand up to a good amount of abuse. Prolonged uses over 5500rpm won't be good for the pressed steel rockers.
When you mean square, do you mean, doesn't sit in the middle of the rocker pad?
What spec is your engine?? I've never come across another person who has gone the whole hog and tuned a 998, I'd be interested to see how it compares.
When you mean square, do you mean, doesn't sit in the middle of the rocker pad?
What spec is your engine?? I've never come across another person who has gone the whole hog and tuned a 998, I'd be interested to see how it compares.
The centre line (c/l) of the rockers often doesn't line up with the c/l of the valve stems, so don't worry. You can sometimes shim the rocker shaft to improve this, but it's not that critical. With push rods you just do a check to make sure that the geometry is correct and the angle the rocker makes with the valve is looking about right in both free and compressed positions. Half way between closed and full open the rocker should be horizontal. You can use the 1300 push rods and put packers under the rocker shaft pillars to achieve the correct geometry if you need to do this. If quite a bit has been skimmed off the head this can tend to bring the geometry back to be more correct if high lift rockers/high lift cam is used. A trial build will show you (use an old gasket for this).
However, the old 'A-Series' is very tolerant of minor geometrical inaccuracies, but increased valve guide wear can result from the rocker not pushing at the optimum angles, if you see what I mean.
I hope this helps,
Peter
However, the old 'A-Series' is very tolerant of minor geometrical inaccuracies, but increased valve guide wear can result from the rocker not pushing at the optimum angles, if you see what I mean.
I hope this helps,
Peter
hi there, sat and mused over the engine today, for the rods i did need the 1300 ones. the tappet adjusters were on the extream when used with the 1000 push rods. i have the sintered rockers too, i was told that they were, for lack of a beter word, 'rubbish'. i was told to use the pressed steel ones with the top welded together to stop them splitting...... any opinions?
the spec for wildfire,
Ex swiftune A+ race block, rebored +0.010 pocketed for 1300. fully ported and polished 1300 mg metro head, stainless valves etc piper 270 cam duplex etc.... have steel flywheel and backplate, med nitrided and balanced crang, and the donkey, standard rods. (funds wouldnt allow for any different!)
drop us an email if you would like pics, should be running in a week or two..... fingers crossed!
the spec for wildfire,
Ex swiftune A+ race block, rebored +0.010 pocketed for 1300. fully ported and polished 1300 mg metro head, stainless valves etc piper 270 cam duplex etc.... have steel flywheel and backplate, med nitrided and balanced crang, and the donkey, standard rods. (funds wouldnt allow for any different!)
drop us an email if you would like pics, should be running in a week or two..... fingers crossed!
That sounds really nice.
The best rocker shaft would be the original Cooper 'S' one with the forged rockers. I guess they're a bit on the rare side now. I use a set on my 'S' rally car as I'm not allowed 1.5 roller rockers under the regs for Historics. I've often thought about machining some MG Metro type rockers (as used on all late 'A-series', but I've not got around to it yet. The MG Metro ones are a bit heavy, but very strong and unless you want to use well over 7000, which you may with your 998, they should be OK.
The best rocker shaft would be the original Cooper 'S' one with the forged rockers. I guess they're a bit on the rare side now. I use a set on my 'S' rally car as I'm not allowed 1.5 roller rockers under the regs for Historics. I've often thought about machining some MG Metro type rockers (as used on all late 'A-series', but I've not got around to it yet. The MG Metro ones are a bit heavy, but very strong and unless you want to use well over 7000, which you may with your 998, they should be OK.
thanks for the info cooperman. its nice to have someone aprove my 1000 route for once!
i shall have a look at the rocker situation sometime next week, may see how it goes when i actually put the head onto the block properly. get a few more opinions too, more info can never hurt can it!!
like you said. i do plan to have the red line above 7k so this may be an issue......
i shall have a look at the rocker situation sometime next week, may see how it goes when i actually put the head onto the block properly. get a few more opinions too, more info can never hurt can it!!
like you said. i do plan to have the red line above 7k so this may be an issue......
I thought the sintered ones were a bit hit and miss whether they failed or not. I'm running a set on my 270 cammed 1380 and wondering when it's going to shit itself. I heard the welded up ones were really good. With regards to the pushrods, which are the longest sort? I need some longer ones for my supercharged engine.
Sounds really cool Rob, I run pretty much the same thing:
1040, lightened and balanced, Piper 285 Cam OAP custom Dizzy, Fully ported and flowed 1300 head with 36 x 31 valves. etc, etc. I planned to go to ally 1.3 rockers, but it looks like I may sell the car. My car redlines at around 7000 in 4th. Great fun to drive and you always get a smile when you pass the 1300s on the track.
Sadly I haven't run the car for around 3 years.
1040, lightened and balanced, Piper 285 Cam OAP custom Dizzy, Fully ported and flowed 1300 head with 36 x 31 valves. etc, etc. I planned to go to ally 1.3 rockers, but it looks like I may sell the car. My car redlines at around 7000 in 4th. Great fun to drive and you always get a smile when you pass the 1300s on the track.
Sadly I haven't run the car for around 3 years.
Don't touch sintered rockers - they are a material cost down late in the Mini/Metro A+ engines life. They are heavy and hence don't like high rpm. What you've done with welding the presssed steel ones along the top (to give beam strength) is spot on. I use the same on my Mini se7en. 8500rpm all day long with no issues. Rocker ratios on the pressed steel ones are far more consistent (and from measuring V sintered give a bit more lift!).
David Vizzard recommends the modified pressed steel rockers IIRC, and knowing the typical failure modes of pressed steel vs sintered (i.e. bend and snap respectively) I would go for the pressed steel ones everyday. Unless you can get hold of some 'S' forged items, (which are apparently often a bit down on lift from what I recall, not read the bible in a while).
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