j4 kent pt50... in a jp4?

[tillygti6]

As above really, anyone running these cams in a jp4?
Is there likely to be any valve clearance issues with the increased lift of these.?
Ive had a bit of a search but cant really see anything of use. Id also guess its getting to the point a remap will be adviseable.?
Current spec is jp4 with j4 cams pullies springs lifters etc. Would be nice to eek a few more ponies out of what is already a nice little motor.

All sensible info appreciated.

[Simon]

I have PT50's in a j4 engine.
Remap was not required.

Hope that is of some help.

[tillygti6]

Thank mate. I had read a couple of your previous posts. It made a good gain considering no remap.
Once the cams arrive il have to do some measuring, as i obviously dont want to damage the valves....
I think the j4 management may be hard pushed to run unmapped with the bigger valve head of the jp4 though.
Anyone else run the same setup?

[jones91]

I might be wrong, but I think running pt50 cams in a jp4 will cause the valves to hit the pistons, the standard j4 cams in a jp4 engine cause the valves to get pretty close to the pistons, so I think anything bigger and you will have problems tbh

Best bet I think would be to get some fast road cams made to fit the jp4 as the pt50 cams are j4 cams, not sure of the codes for the cams on a jp4 but there should be an equivalent for the pt50's made for a jp4

[tillygti6]

These cams where too cheap to turn down. Hadnt even planned on buying them tbh. But it would be nice if they can go in my s1.
I think your right that there is a difference in the profiles between same spec cams for j4 and jp4.

If it came to it i could always measure up a j4 headgasket to free up a bit of space. Itl lower compression but still be in the same ballpark as the j4.
It would be nice if they will go.
I remember years back when we first did the j4 cams in the jp4 everyone said they wouldnt fit. But years later everyones doing it.....

[tillygti6]

The highest lift cam listed by kent for the jp4 is about .8mm lower than the pt50 so it looks on paper like a no go unless theres enough meat in the piston crown for a skim.

[Sophia_Bush]

enough material in jp4 pistons to get proper valve cut outs done no problem

[jones91]

You could sell on the pt50's and spend the money on a set of jp4 cams, also bear in mind that the highest lift cam Kent spec might also be for a high compression engine, which would require forged pistons anyway, so you might need to find more than .8mm if that makes sense

The j4 hg is I think 0.9mm bigger than the jp4 hg, so as a rough guess you would either need a j4 & jp4 gasket, or 2 j4 gaskets to run the pt50's

You could also get the pistons cutout, but you might as well go forged if you do that due to costs

[Sophia_Bush]

iirc its about 150 or so to get done last time i looked into it

[tillygti6]

Sounds a plan, but now its gone from a quick swap over to full rebuild lol

I think its worth pursuing definately in the quest for affordable power.

[tillygti6]

Looking at the spec of the jp4 kent cams they arnt that inspiring tbh.
I dont really want to go forged, because they will be the dearest part of the car.

[jones91]

If you want to use the pt50 and don't want to mess with the bottom end then just use a j4 hg or whatever you need to stop the valves and pistons clashing

Would still make 145-150ish with breathing mods I'd say

[axsaxoman]

do a dry build with s/h gasket and clay on pistons --4 /bolts fit belt=tension --turn over by hand --remove head and see how thick the clay is --that will tell what needs to be done
also measure valve lift at lifter -then push valve down with cams out and make sure spring is not coil bound when fulled lifted-

[axsaxoman]

do a dry build with s/h gasket and clay on pistons --4 /bolts fit belt+tension --turn over by hand --remove head and see how thick the clay is --that will tell what needs to be done
also measure valve lift at lifterwith cams still fitted -then push valve down with cams out and make sure spring is not coil bound when fulled lifted-

[tillygti6]

Thanks for the info mate. Had the same issues years back on one of my a series motors. Ended up pocketing the block for the big valves.
Ive kept a selection of used hgaskets which will be helpfull. What is the safe minimun clearance between valve and piston?

[axsaxoman]

all depends on rpm limit = valve =spring quality you can go as close as 1.5mm --but i would suggest you make it 2.5mm min-- --remember if you alter cam timing then the clearance at critical point will change --so time up cams correctly for the test

[tillygti6]

Good plan. Any ideas of the clearance in a stock engine?
I dont have a set of jp4 stock cams to work out the increased lift of the pt50.but im sure i can make it work

[Ross]

Dude, you're talking about an engine strip/rebuild for a set of cams. Why? Just sell those (at a profit if they're so cheap) then buy the correct JP4 cams.

Run without checking clearances and you risk a problem (suppose the head's been skimmed in the past?). Check clearance and find out it's too tight, so shave pistons, and lose compression/power... False economy tbh.

Just sell those, buy JP4 cams. Laugh to the bank with the savings :)

[tillygti6]

It wont make sense to most. But when people say it cant be done, i say why?
The piper jp4 cams are barely any different to j4.

[tillygti6]

Also the cars a toy. My hobby. My relaxation and peace and quiet in the workshop. So any excuse to tinker really.

[axsaxoman]

you could fit them turn engine to tdc where inlet and ex vlaves on same cylinder are opening and closing --then at approx 5-7 degrees before tdc the ex will be closest and 5-7 after tdc the inlet wll be close -get a good screwdriver and press down on those valves and see how much more they will go --thats your clearance (excepting that the springs could be getting coil bound
you don,t know if the head has been skimmed on your engine ,so I cannot say what clearance YOU will have
testing is the only safe way

[tillygti6]

Dont worry i wont try holding you responsible if it goes horribly wrong.....
I know the engine in discussion hasnt been touched by a machine shop but id always do a dry build

[Ross]

I'm not poo-poohing it because it can't be done - its just a shitload of hassle and will cost you more than buying the "correct" cams in the first place lol :p

[Kwik-Nick]

As above really, anyone running these cams in a jp4?
Is there likely to be any valve clearance issues with the increased lift of these.?
Ive had a bit of a search but cant really see anything of use. Id also guess its getting to the point a remap will be adviseable.?
Current spec is jp4 with j4 cams pullies springs lifters etc. Would be nice to eek a few more ponies out of what is already a nice little motor.

All sensible info appreciated.

I'm using these cams in JP4 engine, they fit without any modification and ran even without remap. The car made 138.5bhp (110 stock)

[tillygti6]

nick, thats intresting to hear, have you any photos of the build?

going by the specs i can find online, they are likely to be pretty close to the pistons. and certainly out of the safe zone that kent leave themselves.

[Kwik-Nick]

http://c2club.co.uk/showthread.php?8625-1.6-Cams-Your-Options
If you look here, the PH3 cams(for jp4) has the same lift and duration as kent PT50(for j4 engine).

[tillygti6]

CatCams 1323703 Sport (straight swap) £428.85.
Inlet valve lift : 9.5 mm,
Exhaust valve lift : 9.0 mm

j4 pt50...
Cam Lift(mm) 9.34mm Inlet/Exhaust
Valve Lift(mm) 9.34mm Inlet/Exhaust

so going by the figures from cat and kent. (on paper) it would look like they may not be a problem.
it would also appear that they run safely with the stock jp4s springs. so the j4s will cope.
again this is totally theoretical at the moment. the engines coming apart anyway so a bit of time doing a dry build wont hurt.

or have i totally missed something?
please let me know if theres a flaw in the plan??

[axsaxoman]

jp4s is different than a jp4 engine
jp4s is c2 vts with the ally manifold

[tillygti6]

intrestingly these cat high lift cams have a much larger valve lift than most, and all they spec is uprated valve springs and retainers. no mention of forgies etc
Inlet valve lift : 11.00mm,
Exhaust valve lift : 8.90mm
CatCams 1322708 (not plug and play) £480

Requires the following mods... £240
CatCams retainers: 99311
CatCams springs: PAC-S90015

[axsaxoman]

its not up to the cam maker to check your piston /valve clearance --they assume you know what you are doing

[tillygti6]

assumption is the mother of all feckups, and as you rightly said a dry build is the only way to be sure.
but unless ive missed anything glaringly obvious, (very likely) on paper it should work. ive read kwiknicks thread on the c2 forum and his motor is running the pt50

actually its a very different car hes built and worth a read.....