NITROUS OXIDE ( nos / n2o ) advice forum

Damn computers, here i go again!

Right, basically, car sluggish, overheating terribly, few people incTrevor suggested the cam was probably shot, so i decided to replace it and refresh the motor after athorough inspection!

Shes been built about 18 years, did it at my parents, with the help of my dad. Done i estimate conservatively 60,000 miles, used to use it every day to go to work up until recently. Been driven in anger a lot at York raceway, been to Belguim with classic ford, and has had 75 or 100 BHP of Trevors finest injected for about 6 years on the button, no progressive! all fitted and jetted by me.

Has been run wit zero oil pressure many times, due to sticking pressure relief valve, zero fuel pressure on 100bhp of gas due to me cocking up the fuel pumps, many 7000 rpm burnouts and line crosses, right up until my last visit at york!

so anyhow, i have just pulled a slug to check the oversize on the bigends, and thought id share howshe looks, im a gutted it isnt completely shot having lost allegedly 70bhp!! it used to make 220 at the wheels at my favourite rollers, which im told is impossible, all i know is i used the same guy, so if it went up or down i knew id made a difference!

All comments welcome, good or bad!

Heads off, very clean piston tops, zero DET, i just wiped the muck off one to see how much carbon was present, which was bugger all!


Bores have a very tiny bit of a wear lip, but its negligable, maybe a thou or 2!


crank area, all the nice ARP studs and bolts mmmmm!




cam chain, metal gears, stretched but ive seen worse!



cam lobes, not as toasted as i was hoping! even the last 4 are nt showing any signs of major wear!


lifters(rhoads) all pretty normal stuff, now concave mind you!



Crank, has a slight score wear some swarfe has picked out of the oil hole, but certainly wont need a grind if they are all this good!



Piston, sides wiped to inspect blow by, but topp as removed!





And the big ends, some wear but hey its not a new engine!! cap side


And top, certainly more wear, but better than expected to be fair, no scoring thank god apart from that mentioned earlier,


Must be an easier way to get to the starter motor!



So, all in no major wear, i have yet to inspect the valves ad guides, has it had a healthy oil habit, that certainly wasnt from the bores! so im expecting to have to change at least the guides, think i will use real steels phosphor bronze numbers to try and rteleive some of the side loading wear associated with cropped guides. My mate and i have summized that all the little bits of wear are sapping the power, mixed with the timing issues of the stretched chain etc, and im hoping for a new lease of life after the rebuild

one last point, what hydraulic lifters are people using, i have read that sd1 lifters rev to 6500rpm without float, is this true, as im not over keen on the rhoads as they amplify the camminessgiving very little below 3500rpm, but i need to hold the revs a bit to make full advantage of the cam (usually shift at 5500 - 6000 and i only have a 4 speed box so need this to cross the line as i run out of gears!)

I hoped you were joking about the 'lack' of cam wear when you first mentioned it but from the final comments it seems you weren't, so let me assure you, YOUR CAM IS SHOT - BIG TIME!!!!!

Even from these vaguish pics that's OBVIOUS to me and that will without doubt, be the ONLY reason for the loss of power.

The cam pre-load could NOT have been set correctly (if at all) when the engine was built, which is not surprising as even 99% of pro builders don't even know of the term, never mind how to do it. Without the pre-load set correctly you would NEVER see the full potential from the engine and the cam lobes and followers would start to wear even before you first fired the motor up and will have suffered accelerated wear ever since.

I also thought you might be joking about the lack of scratching on the journals, because that's also obviously bad from the pics but luckily its no big deal and can be overcome cheaply with a bit of string, metal polish & elbow grease.

Your oil problem is not the guides as such (because they're NEVER going to prevent oil passing), it'll be the crappy valve guide seals or lack of them that's the cause of that. The standard items are USELESS and your best bet is to make some retainers for them, because otherwise they just stay at the top of the valve stem (rather than the top of the valve guide) and do bugger all.

Based on my EXTENSIVE experience of these motors I would STRONGLY advise you AGAINST trying to replace the valve guides, as it will lead to VERY COSTLY TEARS. If you must replace the guides have an engineering shop with EXPERIENCE of ROVER heads do them, as the normal end result is WRECKED heads, because the guides tear out ally when they are removed and have to be bored oversize to accept replacements.

My advice to get the best from your motor (starting at the bottom) is as follows;

1) De-burr the crank journal oil ports as they join the journal surface - this will remove the likely causes of the scratches in the shells/journals and improve oil flow.
2) 'String' the crank journals using a coarse grade of string and metal polish - this will remove the high points created by the scratches and prevent the new shells from getting scratched.
3) If Real Steel still do them, I'd fit a set of their service exchange con rods - if not I'd get yours big ends re-sized and trued up.
4) De-burr all oil ways
5) Fit new oil pump gears and pump base
6) Fit new shells
7) Fit new cam
8) Fit new lifters Rhoad's are as good (if not better) than any other when fitted correctly and should enhance rather than exaggerate the matter you mentioned
9) Replace the cam chain and sprockets - although it makes little difference as it'll be just as badly stretched soon after being fitted
10) Make/fit valve guide seal retainers
11) Glaze bust the bores and fit new rings
12) SET THE CAM PRE-LOAD

Follow that advice and you'll see more power (and torque) than ever before (even using the same spec components) and it'll last 10 times longer.

Thanks Trevor, thats pretty much what i had in mind, the cam is now out and as you say, shot to shit, its a lot easier for my painted on eyes to see now its on the bench!

i did set the preload on the rhoads, (cant remember, think its 40thou, id have to check) using the method they describe using a pieceof wire the correct thickness to fit under the snap ring etc

the valve guides had no seals fitted, as you say there was no point, i fitted the ones supplied and they were a joke, so ran without to stop them being broken up and blocking the oil pick up pipe! The guides real steel sell (the posphor bronze ones) take the modern clip on style seals that are supposed to help substantially, but the guides are truly oval, so they have to be changed, i was going to bore the guides out at work on the pillar drill or milling machine and collapse them in with the haed heated up, but i will price up having them done at the machine shop, as it probably wont cost a lot and id rather not damage the head castings

the journals look worse than they are on the pics, and its only the first that has any marks, the rest are fine, so no biggy, they are round too which is a bonus!

The block is an early RV8 by the looks of the ribs in the valley??

I agree with all of Trevs comments.
What are the head numbers.. ERC ????
I guess they will be early heads that had rubber washers as oil seals and small valves?

My guess on the oil consumption will be due to worn rockers and rocker shafts allowing excess oil flow into the rocker galleries so the level builds up to a point where the level of oil reaches the valve guides.
I would also hazard a guess that your cam bearings are shot!. This will also lose oil pressure and show odd wear marks on the cam lobes and lifters. It will also starve the dissy drive of oil as well.

You dont need to change the valve guides. Just find a head shop that will machine the tops of your existing guides so you can fit the knock on oil seals as per Range Rover. Real Steel will do this for you for not much money. While you are having this machine work done, you might as well get then to trim the tops off the guides so you can fit a better cam as well. You might also ask them to open out the spring pans so you can fit decent double valve springs to the correct height. See RS DW050 springs etc... Its only about £40 to get the guide machined for better seals.
See price list here
http://www.realsteel.co.uk/engineering.pdf

I cant see any honing marks left in the bores. But as the block seems to have already been bored +20, as Trev says, Glaze bust the bores and fit new rings. If you want to run Nitrous on the motor you may need to increase the fitted ring gaps a tad. We can discuss this later on as you do need to index each piston ring to each bore to make sure all your ring gaps are equal on each bore?

You can buy a glaze buster on ebay pretty cheap. They are easy to use once you have had a bit of practice. If you are not far from Milton Keynes I have some spare blocks you could practice on with my glaze buster

The wear on the timing chain is not the worst Ive seen. My first RV8 had 3/4" of slap on the chain. I could tune it to idle ok and run shit on gas. Or to idle like crap but have the right timing for use on gas. Fit a Cloyes true roller timing chain set from Real Steel. I've been ragging my set on the strip for 5 years now. And at the last pull down this year I only measured 3mm of deflection. £80 well spent I reckon.

Questions!!!
1. What cam is in the engine??
2. What oil pressure do you see at hot idle and at 2000rpm hot??
3. What oil do you use?
4. Are you rinning carb or EFi?
5. What size is the engine?
6. What is the full engine number??
The part of the number I can see tells me it may be a "Morgan +8 9.75:1 CR EFI" Block??
If this is the case then your wheel horse power figure is bloody fanstastic??

If you decide to change the guides then get a pro to it mate... It does not cost that much to be honest.. I've tried to do this myself and got into a world of pain despite following all the guidelines I found on tinterweb... A pair of second hand pre sd1 heads are worth about £20. And worth about 50p as scrap metal after you have knacked them after spending out loads on all the parts dude!!

"one last point, what hydraulic lifters are people using, i have read that sd1 lifters rev to 6500rpm without float, is this true, as im not over keen on the rhoads as they amplify the camminessgiving very little below 3500rpm, but i need to hold the revs a bit to make full advantage of the cam (usually shift at 5500 - 6000 and i only have a 4 speed box so need this to cross the line as i run out of gears!)"


Thats why I use Rhoades lifters?? They give better performance at low rpm for good road manners at low throttle. But then pump up just over 3500 rpm to bring on the full lift of the cam at higher rpm's?? Thats what they are for. But if you are only using a standard cam they will make the engine lazy at low rpm because you are losing lift??

If you have a better cam you will see when the lifters pump up on the dyno sheet. But for this you need the valve guides trimming down.

If you decide to stick with a standard cam you can retard the cam timing a few degree's to move peak torque further up the rev range so you can make better use of what you have as you seem to like shifting gears at quite high rpm? For this you will need either a Coyes timing gear set or fork out on a Vernier gear set.
If you have had the car on the rollers can you post up a printout of your best dyno sheet that shows Torque and BHP please..
I make peak torque on my 4.6 with nitrous at 3900-4000 rpm. My old 3500 was not far off this either on gas. Are you sure that you are shifting gears at the correct rpm to make best use of your power??

Lets have some more data on this project and what your final goal is for the car on the 1/4 mile??
Once we know what your actual engine setup is we can give more advice

sorry !
I seem to have rambled on a bit there Lets have some more info Mr Capri

Regards
Perry

The cam is a real steel viper typhoon, its .480" lift, 218 duration. The guides were cropped by myself 100thou when i built the engine all those years ago. It has the DW050 springs that are the same strength and length as SD1 single coils, but with one less coil to allow for full lift.

It and the rhoads were all new when i built the engine originally, and the cam bearings were also replaced when the block was rebored and the crank reground. All the bearings were/are vandervell.

The rockers were, are and always have been shot to shit, a chap called Adrian who dealt in rover v8's years ago told me this led to low oil pressure, so my dad peened me some oil restrictors that we tapped into the head below the rocker pedestals to restrict oil flow, it added around 10psi.
To be fair, i initially shimmed the relief spring too, but it simply added a lot of heat to the oil, and as the engine is a high volume rather than high pressure system, i riverted to a standard spring and tadpole valve that gives around 60psi at high revs cool and about 45 hot (makes 25psi at idle)

it really wasnt suffering from low oil pressure particularly, and the bottom end wasnt knockoing, i think ive pulled it down just in time crank wise, although having looked at real steels listing, i can get another 10thou undersize in both mains and big ends, so i may just do that and next time get a fresh crank.

I have a spare pair of heads, but i spent quite a few hours porting these, and to be fair they had initially far smoother and larger ports than the other set (both are SD1, single spring heads, these are circa 1983) i am told some were cast in leeds rather than birmingham and were better, but it was only what a chap told me once!

As for oil, i only ever use valvoline racing 20w50, it is the only oil i trust to, a not stick the relief valve, b maintain pressure, and c not get very hot under heavy use, any thing else pours from every gasket and orifice after a healthy quarter!

The block is stock as a rock SD1 originally, as i said, '83 vintage, thin webs, single valve springs, very well seasoned i fitted the cast high comp pistons from the P6B high comp to give 9.75:1 with the SD1 heads (new i hasten to add from real steel)

It runs a weber 32/36 DGAV carb, i opened the plenum beneath so each cylinder sees both sides of the carb, and theres a single crossfire in a half inch WIZNOS plate under a phenolic spacer for the nitrous that Ant tapped up for me.

the front of the block is drilled to allow for better dizzy drive lubrication and to aid drain back to te sump (two 1/4" holes)

Stock rods, ARP main studs and big end bolts, new oil pump gears, oil pump face sanded flat on a pane of glass with fine wet and dry then gringing paste Brand new front timing cover/oil pump etc,


dont know rthe casting numbers off the top of my head, but can check tomorrow if you still need them!

All sounds fine but doesn't explain the cam wear. They do wear rapidly whatever you do but yours seems to be quicker than I'd expect.

To be fair it may have done more than 60,000 miles, it was a conservative estimate, and it is a reasonably aggressive profile, its about 1 step away from going to solid followers, so i always expected it to wear a lot more quickly.

One thing that did surprise me is the wear appears visually to be pretty even front to back, i remember taking the original cam out that had covered around 120,000 miles, and the lobes at the back of the engine were visibly more damaged, in fact they were only just present at all!

If i could just ask Trevor, how do you, or better what tools would you use to chamfer the oil holes in the crank? Im terrified of scratching the journals especially ifi have it groud again, i would probably wrap them with tape first anyhow, but do you do it manually with a needle file, or with a small die grinder tip??

Thanks

When I was building engines on a regular basis I had a set of special drills ground for me that located in the original oil way and created a radius when rotated. Unfortunately they didn't work on all the drillings because of some of the angles they are drilled at and for those I used a de-burring tool or needle files as appropriate.

Thats not important now we have more info.

Lets go back to the overheating issue. When does this happen??
How fast does she cool down at idle with the fans running after a 1/4 mile blast?

I agree about the dyno figures. But at least if you always use the same dyno you get an indication of better or worse after each mod eh?

You need to look at your dyno plots to see where your peak torque (on gas) is though. This is what you need to base your rebuild and gearing on.
Mine ran out of puff at the 1/8th mile marker. My peak torque is around 3900rpm.
I fitted bigger rear tyres which helped. And now I'm experimenting with altered cam timing to move my peak torque further up the rev range. It looking good so far

Well, seeing as im avoiding going out to the batic conditions in my garage i will reply now!

Got back from the machine shop, and he checked my mains and bigends, I said id rather not go to the next (last) undersize due to strength issues, but would follow his recommendations. He agreed that a quick polish should bring the journals back up, and that they were well within tolerance when he micrometered(!?) them. Plus they were definately still round! So im going to let him polish them for me as the operation makes me a tad nervous, and a little knowledge is a dangerous thing!

He recommended leaving my valveguides in and sleeving them, not only to stop the heads getting damaged but also to remove the need to recut the valve seats, plus he said they can do it as often as necessary without major hassle in the future and ream them to my existing valves if they are ok. Which is nice!

Perry, im changing the cam and lifters, they shouldnt be flat underneath, they should be slightly convex, i think its false economy to try and salvage either, i really have to change the cam, and if i nause it with a set of shoddy rebuilt followers id be gutted, so i may as well drop a new set in.

I was planning on a new rocker set up anyhow once shes all nailed back together, although i tghink i willleave my oil restrictors in all the same!

as for overheating, its whenevr shes stationary, i have a big thermostatic electric fan that pulls the temp down nicely, or did until the cam completely shit itself, it was also getting very hot on the strip this year, but again the cams shot, so that will have aggrevated it. I used it at the start of winter to go to work (school) in, and even though it was around freezing she got mega hot, although the backfires were less prevalent!

Im sure it will be ok once its all back together, only issue is fitting the more modern valve seals to the guides, so i may buy a guide and seal and have the machine shop mod the tops of mine to make them fit, it should only mean milling the top to the same shape and diameter im guessing

John Eales does this mod for only a few quid mate. But I'm pretty sure that opel Manta seals will drop onto the stock guides. They are the same type as the blue Rover seals. I'll ask my Manta mate now as I'm sure he gave me a part number a while back

Perry

Capri!!
I just re read your first post about the nitrous..
Are you using a button on the steering wheel for nitrous in each gear or a throttle micro switch or maybe a clutch microswitch??

Regards
Perry

Both a WOT switch and a button on the wheel

I have never been able to afford a progressive controller, so i had to launch in first, hook second and when i got some grip, hit the button!

I could never use the extra torque in 1st as it just broke the grip.

However, my mate has got a fred and having had a look at it, i think i would be able to make good use of it, so i hoping Trevor will get something similar in, then i can step up the gas to around 200bhp, and go for broke (ho ho)

after ive fitted an lsd etc etc etc!

That sounds good news about the seals, either way, i was thinking i could make a tool to shape the guides if needs be, depends what the shop wants to rush me i suppose really!

What rear tyres do you use??

If you have good tyres you can get away without LSD for a while. I cant afford a decent lsd so I use a spare axle with the diff welded up so it cant slip
If you have good sticky rear tyres you may be able to launch with gas in 1st gear to gain valuable 10ths ??

What times do you get with the Capri.
Can you show us a timing slip so we can see how your runs progress on gas from start to finish ??

I run crap rear tyres, 2nd handers offa vitara fat boy! 265x50x15

a guy at york said i was wasting my time with them, but i knew that really, they were just slotted on to check the fit of the rear wheels and arches

i have been using a sniff of gas in 1st this year, just before the 2nd gear shift as it was hooking up ok with the slapper bars, but i think i only got away with it cos the engines so tired. I think if it was on song id have no chance!

I run 13.6 best at around 107 this year, used to be 13.6@112, but on a different tyre set up and carrying more weight, im fairly sure she would run high 13's offgas once the engine is rebuilt, and hopefully high 12's with the same direct hit rig up

with a progressive and a bigger sniff, id like to better my GTR that ran 12.4 out of the box, but im fairly sure with the slipper, engine rebuild alone and the 75 i should do that

with all the other stuff sorted, some better tyres etc, id like to see high 11's

i will try and dig out some slips, its a bit academic really with the engine being so down on power, it will have effected the whole dynamics

If you run naff tyres then at least treat them to a tin of Grip Tyre softener. This is not cheap at around 25 notes a tin but it will make your shit tyres a lot more sticky
And it will treat many tyres.

You can get this stuff From Geoff at Hauser Racing by post.

http://www.hauserracing.com/pages/Parts.aspx

My MGB GT wieghs in around 1300kgs and I ran 12.4's on my 3500 RV8 with a 150 shot all day long when it was a manual tranny. When I swapped the 4 speed manual for a 3 speed auto with quick shift I knocked another 0.4 off my times ?? I was quite happy with a flat 12.

This was when I fitted a stock 4.6 lump and I'm now working my way back up to big shots of gas. My PB for last year was 10.6 but I ran out of puff due to lack of gearing so I got bigger tyres and I'm looking for a 9 in 2011

id be happy with that, the mg is a big heavy car too

ive found some old slips, these were run when the engine was fit(ter), 75bhp of gas, semi stripped, and 205x60x13 remould rally tyres (dont ask!)

2.444 60ft
9.233 1/8th @ 81.76
13.8 quarter @: 107.37

2.342 60ft
9.050 @ 83.68 1/8th
13.643 @ 107.58 quarter

2.493 60ft
9.194 @ 82.08 1/8th
13.886 @ 104 quarter


these were with stock leaf springs/shocks, battery in the boot, nitrous towards end of 2nd gear and me slipping the clutch off the line, car has/had grp wings, bonnet, bootlid and front valance and as said, 205 tyres on 8" wide 13" dia rims

Few vids of its last outing on here, show how it reacts, 13.6's were against my mate in the little MK

http://www.youtube.com/user/nosjockey#p/u

slowest run was 13.7 all day

cant find the slips, but i have them somewhere!

You are losing your time in the 60 foot !!

If you get those 60 foots down to 2 seconds you should see a much better ET.

I played the traction card in 2009 and got my 60 foots down to 1.5 and 1.6 seconds. This was with big sticky slicks. So my eT's dropped right down into the 10's.

This was a PB run in my MG at York a few years back before I ran slicks.

http://www.youtube.com/watch?v=DFNOxHyMElo

And with sticky slicks against my mate Sean in his 5.7 Mustang with nitrous ...
http://www.youtube.com/watch?v=cRtUSeiFUKI

X2 - VERY IMPORTANT - the higher and longer you hold the revs up the better - unfortunately that can be a BIG problem if you don't set the timing and fuel to be cock on BEFORE cranking, which itself can be a problem with new builds.

hey perry the 2nd vid is fantastic the mustangs taking some air while your gone love it..

Great video versus the Mustang. I've seen your MGB at the Pod a few times. I'll have to say hello next time.

I should be ok with the initial break in this time, as the basic spec of the engine wont have changed much as im putting the same spec cam back in, so the jetting should be ok as a starting point, i have an oil pump primer i made years ago, and i know my initial dizzy settings, so if i watch the temp i should be able to give her so revs right off the key.

The vids are great perry! The bain of my life is grip, not helped by yorks surface as you will be aware! However, i am making some ladder bar brackets at the mo too, and will be slotting in some bars once the engine is buttoned up (and i can afford the tube and rod ends!) so im hoping that will help things too - just wish i could get some street legal tyres to help grip, as i have to drive to and from the strip and like to run it fully street legal, although slicks are getting tempting!

Anyhow, cranks ready to pick up (they were quiet!) so i can order the shells, rings and core plugs this aft and when my man flu has cleared get the bores deglazed, oil ways cleaned and the block washed off.