Rover V8 adjustable rockers (Volvo?)
Discussion
copied from Griffith forum at Seasider's suggestion:
I read here http://www.pistonheads.com/xforums/topic.asp?h=0&a... and I have been told elsewhere by an engine builder with some experience of Rover V8, that adjustable rockers from Volvo can be used in the Rover V8. Can anyone provide more details on this please? Which model Volvo do they come from? Is the complete Volvo rocker gear used, or are just the rockers put on the Rover rocker shaft or what? Are the Volvo pushrods used, or something else?
Cheers, Pum.
Cheers Matt - you mean the old 240 saloon car box thing?
OK, this is where my knowledge is rudimentary, and I'd appreciate input from the knowledgeable people that inhabit these forums. My engine is suffering low compression on some cylinders. It was a recon short engine not too many miles ago, retaining my old but good heads. Rhoads hydraulic lifters were fitted at that time with adjustable pushrods. All was working fine. The reason for the adjustable pushrods was so that pre-load could be set for each valve independantly, instead of the one-size-fits-all approach of rocker shims.
Two reputable places have examined the engine for the source of the current low compression without completely striping it down, and reckon the block, cylinders and bores are fine and not causing compression loss. They both reckon the loss is through the valves.
The first de-coked the heads and replaced the former adjustable pushrods (a couple of which were split) with standard pushrods, and setup the rockers with shims. Whilst the heads were off they check the bores and pronounced them fine. The compression problem remains, but may have moved about the cylinders a bit.
The second reckons that without adjustable pushrods or adjustable rockers the pre-load cannot be properly set on all the valves. They say this is due to the inevitable uneven wear of the varous parts involved. So when new, all the valve stem lengths etc would have been fine with the crude adjustment available from shimming the rocker posts, but now the engine has had some wear, shimming cannot get all the clearances and setting close enough.
I don't fancy adjustable pushrods again as I really didn't like the way they split after a few years. So I'm looking at adjustable rockers as the alternative to be able to get the valve gear adjustments right on every cylinder and hopefully then cure the compression problems.
As far as adjustable rockers go, it's either Yella Terra, which are out of my price range, or something more mundane, like the Volvo rockers which I orginally enquired about.
Thought and wisdom gratefully received.
I read here http://www.pistonheads.com/xforums/topic.asp?h=0&a... and I have been told elsewhere by an engine builder with some experience of Rover V8, that adjustable rockers from Volvo can be used in the Rover V8. Can anyone provide more details on this please? Which model Volvo do they come from? Is the complete Volvo rocker gear used, or are just the rockers put on the Rover rocker shaft or what? Are the Volvo pushrods used, or something else?
Cheers, Pum.
350Matt said:
Not certain but I think they're Volvo 240 items which run on a rover shaft. They were used back in the touring car days of the SD1. Why do you need them? Are you running a solid lifter cam?
Matt
and I replied:Matt
Cheers Matt - you mean the old 240 saloon car box thing?
OK, this is where my knowledge is rudimentary, and I'd appreciate input from the knowledgeable people that inhabit these forums. My engine is suffering low compression on some cylinders. It was a recon short engine not too many miles ago, retaining my old but good heads. Rhoads hydraulic lifters were fitted at that time with adjustable pushrods. All was working fine. The reason for the adjustable pushrods was so that pre-load could be set for each valve independantly, instead of the one-size-fits-all approach of rocker shims.
Two reputable places have examined the engine for the source of the current low compression without completely striping it down, and reckon the block, cylinders and bores are fine and not causing compression loss. They both reckon the loss is through the valves.
The first de-coked the heads and replaced the former adjustable pushrods (a couple of which were split) with standard pushrods, and setup the rockers with shims. Whilst the heads were off they check the bores and pronounced them fine. The compression problem remains, but may have moved about the cylinders a bit.
The second reckons that without adjustable pushrods or adjustable rockers the pre-load cannot be properly set on all the valves. They say this is due to the inevitable uneven wear of the varous parts involved. So when new, all the valve stem lengths etc would have been fine with the crude adjustment available from shimming the rocker posts, but now the engine has had some wear, shimming cannot get all the clearances and setting close enough.
I don't fancy adjustable pushrods again as I really didn't like the way they split after a few years. So I'm looking at adjustable rockers as the alternative to be able to get the valve gear adjustments right on every cylinder and hopefully then cure the compression problems.
As far as adjustable rockers go, it's either Yella Terra, which are out of my price range, or something more mundane, like the Volvo rockers which I orginally enquired about.
Thought and wisdom gratefully received.
I'm going from memory here but iirc they came from the older style volvo and you do need the shafts as I think the diameter is different. The rockers are iron and you can space them with bras sleeves on the shafts.
As for the loss in performance I doubt it's down to wear that couldn't be rectified by normal means. I'd replace the worn componant/s not compensate by trying 16 new rockers and all the gubbins to suit. If it's a dodgy cam or valve just replace those parts.
Boosted.
As for the loss in performance I doubt it's down to wear that couldn't be rectified by normal means. I'd replace the worn componant/s not compensate by trying 16 new rockers and all the gubbins to suit. If it's a dodgy cam or valve just replace those parts.
Boosted.
Cheers Boosted, I'd agree with replacing the worn components, if I can identify them. The first place that decoked the heads said that the valves, seats and cam were fine. They replaced the split adjustable rods and said all would be OK, but they didn't re-test the compression after the fix, which seemd odd to me. I got it checked when my usual mechanic was available again, and he found compression still down on a few cylinders.
I don't want to get new heads, valves, rockers and rods, which is why I'm inquiring here to try to help identify the correct course of action.
I don't want to get new heads, valves, rockers and rods, which is why I'm inquiring here to try to help identify the correct course of action.
I haven't got the figures in front of me, but from memory 2 or 3 cylinders were down by alot more than 10 PSI, though that depends on what you regard as OK. I think the bad ones were down to 120 something PSI, when they should be as high as 160-180 - I can't remember the good values I've been quoted.
Might be talking bollox here but, when trying to solve a problem with getting preload correct on all valves on a Griff' 500, it was down to the fact that some valves had receeded into the head [tops of valves were differing heights] so made it impossible to get correct preload overall.
okay for what its worth pre-load/length of pushrod/rockers etc have no relation to compresion providing you have at least some pre-load, it is the distance from the cam lobe to the rocker arm and as the lifter can take a lot of slack up as i say the pre load becomes irrevalant..., just be very carefull with those rhoades lifters you are using, i take it they are the anti-pump ones? if say most of them have leaked down and some havent which is very common your cr's will be all over the place!! not being funny but does the engine sound ok? pull ok etc..., the first thing you should really be doing is giving the engine a leak down test, listen for where escaped air is coming from, plenum/exhaust or oil filler, there is absolutely no need to go to adjustable valvetrain to sort this problem. good luck
) - cheers! 
I thought I'd post the outcome of this. My preferred mechanic was moving workshops, so the work was somewhat delayed.
Initial compression test showed values ranging from 150 to 115. Heads were removed, valves re-machined in, and adjustable rockers fitted. This improved compressions to the range 175 to 130.
Rings were then checked and gap found to be too high. After a new set of rings compression improved to 190 to 175, which sounds pretty good.
I'm now waiting good enough weather to run it in and then enjoy in the spring.
Thanx to all that contributed suggestions on this; they were very much appreciated.
Initial compression test showed values ranging from 150 to 115. Heads were removed, valves re-machined in, and adjustable rockers fitted. This improved compressions to the range 175 to 130.
Rings were then checked and gap found to be too high. After a new set of rings compression improved to 190 to 175, which sounds pretty good.
I'm now waiting good enough weather to run it in and then enjoy in the spring.
Thanx to all that contributed suggestions on this; they were very much appreciated.
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