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Isky, Piper and other performance camshafts for the 2.5 V8

fredeuce
Posts: 51
Joined: Mon Feb 29, 2016 10:56 am
Location: South Australia

Re: Isky, Piper and other performance camshafts for the 2.5 V8

Post by fredeuce » Wed Jan 09, 2019 10:25 pm

The sheet attached is a grind that I will be utilizing on my new cam I am having made here in Australia. It should be completed by the end of the month.
Will then need to re-assemble engine and install new pushrods to suit.

Key specs are : Duration @ .050 : 237 deg
Valve lash .016"
Inlet Open 39 deg BTDC Close 63 ABDC
Exhaust Open 75 deg BBDC Close 27 deg ATDC

Max valve lift : 0.434"

Runs with a rotating mushroom type lifter being a modified Ford Y-block V8.

Image

tjt77
Posts: 496
Joined: Wed Mar 23, 2016 7:01 pm

Re: Isky, Piper and other performance camshafts for the 2.5 V8

Post by tjt77 » Thu Jan 10, 2019 8:45 pm

Given that the camshaft and lifters tend to wear quite rapidly on these engines .. Im wondering if there are known ways of extending longevity in these parts.? also..what are the shortcomings of the original cam profile ? the narrow intermediate main bearing also wear at an alarmingly rapid rate.. adding power at higher RPMs will accelerate an existing well known problem.

I do recall that some 30yrs back I fitted lightly modified majestic major engine into V8 saloon with manual /odrive box attached, allied to a jaguar 3.77 'powr-lok' diff, and it performed well above expectation..all that was done above a freshen up with rings and bearings, was light porting , .040" shaved off head faces, stronger inner valve springs only (heads were sent out to my 'go to' head guy at the time) and that the engine pulled cleanly to 6,500 rpms with no obvious stress and was immensely powerful...however some 40k miles of hooligan driving, and it began to smoke and guzzle oil and got rattly on both valve train and lower end.... so the car (not in the best of condition) was broken up for parts ..

I have several majestic major engines on hand today, aquired with the intent of repeating that same powertrain formula....but decided to go a different route because a Ford 302/351 V8 is more durable, lighter, takes up far less space, and can be modified to produce an easy 260BHP for a fraction of the cost of a basic rebuild on a turner V8 and there are no issues with adapting a 5 speed or 4 speed overdrive auto box as these engines came with a variety of gearbox options.. Im aware its not 'daimler' but it is a far more practical solution if you want power,reliability. longevity and have budget concerns. I got smarter after buying an already modified car and re-commisioning it (modifications were done in 1980s) .. and I have to say whoever converted the car, got it 'right'.. so Im improving this successful formula for a 21st century but 'period correct' daimler V8 2 1/2 litre saloon that will out perform a jaguar Mk2 by a huge margin..and should run for 100k+ miles with minimal 'issues' and have the added comfort of air conditioning and 'other' niceties to improve driving experience and spend minimal time in maintenance.

daimlersteve
Posts: 339
Joined: Wed Mar 09, 2016 11:20 am

Re: Isky, Piper and other performance camshafts for the 2.5 V8

Post by daimlersteve » Thu Jan 10, 2019 9:04 pm

The cams wear due to regrinding through or near through the case hardening. The solution is to rebuild the profile the regrind or use a billet that has been hardened . The cam/follower should have a hardness difference to reduce wear. If the base circle is reduced much to give more lift the system is compromised.
This topic has been covered a few times
Steve

tjt77
Posts: 496
Joined: Wed Mar 23, 2016 7:01 pm

Re: Isky, Piper and other performance camshafts for the 2.5 V8

Post by tjt77 » Thu Jan 24, 2019 8:41 pm

Steve.I always though that excess cam wear was a 'design' issue.. a lot of friction with this style of 'non rotating' or 'fixed' lifter.. I've yet to pull down a turner V8 that does not have scores on cam and lifters.. the fact that no other car engine manufacturer has used this design should say enough..( i imagine that Turner simply copied the design from his speed twin motorcycle engines)
my observation on stages of engine wear in 'our' cars is thus :- (1) intermediate main bearing shells ( commonly showing wear in auto box saloons after 50k miles.. a little longer in manual/overdrive cars) (2) con rod bearings (they seem to outlast the intermediate mains however) (3) cam and lifters.. wear visible after 60k miles on average.. the SP250 engines tend to last far longer.. less weight to pull and taller gearing the likely reason..

Things have evolved considerably since the late 1950s.. most engines supplied today are good for 200k miles before they show signs of wear.. the excrerable UK built 'flat head' fords produced till '59 rarely lasted above 45k miles.. contemporary Mk2 jaguars had unusually long engine life.. sometimes they suffered exhaust valve burning around 70-80k miles.. but rarely had bore or lower end wear below 120k miles.. expected engine life for a V8 2 1/2 litre saloon 'back in the day' averaged 70-80k miles before overhaul ..'normal' for the time period.. contemporary Rover V8 (a late '50s US design) rarely gave problems before 100k..(head gaskets the most common issue) 200k miles quite common..
For practical reasons Ive given up on the turner V8s.. far too costly and shortage of bearings that will hold up forced me to shift direction.. larger displacement with less stress is my new friend..

daimlersteve
Posts: 339
Joined: Wed Mar 09, 2016 11:20 am

Re: Isky, Piper and other performance camshafts for the 2.5 V8

Post by daimlersteve » Thu Jan 24, 2019 10:06 pm

I agree TJ. The only reason i've hung in there with the org. radiused followers is that my research will benefit others who aren't as open to modifying the org. So my own profiles are to that end.

regards Steve

Ozzsp250
Posts: 184
Joined: Tue Feb 16, 2016 12:35 am
Location: Arizona, USA

Re: Isky, Piper and other performance camshafts for the 2.5 V8

Post by Ozzsp250 » Wed Jan 30, 2019 4:54 am

I finally got to run my engine on the test stand again after removing the inlet manifold and re-installing it using Hylomar sealant and replacing all the throttle linkages, now no play in linkage. At idle engine only draws ~ 15" vacuum and no leaks were found [original reason for removing manifold] I'm thinking with the camshaft currently in the engine with its non-standard greater overlap is probably the reason. At 2000 rpm vacuum is in the 18 - 20" range. I believe the engine to run rougher than I expected [although others think its smooth] so I'm going to replace the current installed distributor with its electronic ignition with my spare which has original dual points and ignition leads purchased from BT and see if there is a difference.

The engine has the extra spray bar for oil in the tappet chest and once engine is at normal temperature I determined an oil pressure loss of ~4 psi is experience when the spray bar is active - to test I put hand valve in-line from the outlet of the spin on oil filter to the spray bar inlet. The engine oil pressure is a little over 40 psi hot engine above 1400 rpm which is of concern. Currently running a straight 30 weight 'break in oil'.

daimlersteve
Posts: 339
Joined: Wed Mar 09, 2016 11:20 am

Re: Isky, Piper and other performance camshafts for the 2.5 V8

Post by daimlersteve » Wed Jan 30, 2019 5:42 am

Here's a thought ,
-- I'd be reluctant to load up the cam drive gear anymore than needed , so the idea of an external pump ( belt driven )just to feed the cam might not be a bad Idea. Not nearly as complex as a dry sump setup and could still be feed from the sump . The pump capacity would be calculated to be just enough to do the job so as to limit areating the oil as could happen when over feeding and bypassing to relieve supply.
By blocking the feed from the rear cam journal to the rockers and feeding them via the new external layout two birds with one stone could be dispatched . Just needs a special 5/16 drilled /cross drilled and filled bolt to accomplish this.
Have done the seperate feed to the rockers before as a take-off from a remote filter installation.no problem but to feed a spray bar is another kettle of fish indeed. The std. rocker feed is intermitent via the drilled through- hole in the rear cam Journal.
Often the std. feed and the feed bores in the rocker arms are not what they could be .

Regards Steve

Ozzsp250
Posts: 184
Joined: Tue Feb 16, 2016 12:35 am
Location: Arizona, USA

Re: Isky, Piper and other performance camshafts for the 2.5 V8

Post by Ozzsp250 » Fri Mar 01, 2019 2:07 am

Have had the opportunity to work on the 'new' engine a bit and she is running a lot better after setting the float levels for the 2" ex-majestic major carbs to correct level. It was over fueling and not reaching more than 4000 rpm prior to change and would miss with hesitation with large throttle openings. I'm also testing with 2 different distributors, one with electronic module set up and the other with the standard dual points -- so far not much difference although starts are instantaneous with electronic module unit.

I need to establish the correct valve clearance settings as the Isy camshaft document stated .016" for both inlet and exhaust. I want to make sure the engine is set up correctly prior to putting it in the car.

The neighbors so far have not complained about running the engine on my test stand in the driveway, it is loud even with 2 mufflers on each bank in series.

fredeuce
Posts: 51
Joined: Mon Feb 29, 2016 10:56 am
Location: South Australia

Re: Isky, Piper and other performance camshafts for the 2.5 V8

Post by fredeuce » Sat Mar 02, 2019 12:03 am

Ozzsp250,

Good to hear your testing is going well.

As to your distributor choices my take on that is that the module fitted distributor will clearly give an advantage in relation to the maintenance and tuning area as it eliminates the need for periodic cleaning/replacement of points, adjustment and so on.

The real advantage would be the ability to use a higher performance coil. I have a Pertronix II module in the distributor and an MSD Blaster Coil. These coils are low resistance and burn points quite quickly even with a ballast resistor however permit plug gaps of .050-.060" . That certainly seems a lot but I run mine at .055 and it runs fine with that. The coil works well with the module I have fitted. The improvement with start up is obvious. Only caution here is that with a road car there will be the need to consider appropriate plug leads and noise suppression.

Re-reading the post you made regarding the Isky cam specs you have. Clearly there are errors as mentioned already. Have you thought to put a degree wheel on the front pull and set up a dial gauge on one of the cylinders and obtain some hard data on what you have? That would be interesting to see.

Cheers, Fred

fredeuce
Posts: 51
Joined: Mon Feb 29, 2016 10:56 am
Location: South Australia

Re: Isky, Piper and other performance camshafts for the 2.5 V8

Post by fredeuce » Wed May 01, 2019 1:02 am

I have posted this picture elsewhere on this forum however given the topic of this thread I will repeat it here.

Something of a step forward today for me with the payment for my new iron billet camshaft from Ivan Tighe Cams in Brisbane. Should take delivery of it next week. See pic attached and the spec sheet. To make sense of it look at the lift figures at 0.014" or 0.016". That represents the valve lash and the effective duration. The usually quoted duration at 0.050" is also there. Comes in at around 238 degrees. The original is an asthmatic 176 degrees. Valve lift will top out around .0430".

Now starting work on the modification to the tappet chest to make room for the mushroom tappets.

I am having some reservations about the Y-block Ford lifters. Having removed the Daimler lifter a weight comparison reveals the Daimler item at 34 gms and the Ford item at 61 gms. That to me is a substantial weight increase.

My thinking now is to machine the Ford item to accept the Daimler ball and reduce weight ( and use the original pushrods) or an alternative mushroom tappet that is hollow. I am more inclined to the latter as chilled iron the material the lifters are made from is machined by grinding due to its hardness. Making some inquiries about each of these options .

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