New Rockers/ CAM Installed

JOCS · Post by **JOCS** » Tue Mar 01, 2011 10:26 pm

Last week I installed new cam MED HT (timed to 110 deg) and 1.5 Rockers. Now have the car up and running again with the timing chain adjust correctly and valve clearances set etc. Prevously megajolt was working fine with the SPI2 map.

I am using the SPI2 map again and now I am getting two problems.

1st is when the engine is under heavy load (uphill) It missfires really badly and lacks any power. (My question is this caused by to much advance or to little as haveing looked at the RE13 development map which is on similar spec mini to my one it seems to maintain a high advance under high load is this correct ?
David Vizard book says to retard when fitting higher ratio rockers and an agressive CAM so I am really confused as this goes against what I have read on the forum and i am now reluctant to actually try the RE13 map.
Have booked a tuning session at Geralddale motorsport near hastings as I need to get the fueling sorted out anyhow as I am pritty sure this is part of the problem far to rich in bottom end and to lean at mid to top end.

2nd is that on deceleration the revs dip dangerously low and have stall it a couple of times. However reading othe topics I have a rough Idea why this is so can probably sort it out by adding another column for 500rpm.

Any answer would be appreciated as would like to understand the problem rather then just takeing to someone else to sortout.

Something I should also mention I did have a run on problem caused by spark plugs getting red hot have used a cooler plug now and this sorted the problem. However did not improve the lack of power when going uphill.

JOCS · Post by **JOCS** » Wed Mar 02, 2011 9:17 pm

Ok so this evening I have tryed a few things. I tryed retarding all values in the spi2 map by 5 deg. Very little or no difference made to uphill power. Then tryed takeing raw map and just bumping up a few of the advance figures round the high load area to make it flatter. This made a little difference to the uphill power. Decided to finally try the RE13 map this made no difference. Thierfore have come to conclusion that the problem not advance related. I suspect it is probably more to do with something else. Have attached a picture of the datalog for this evening two uphill sections with spi2 +5deg (Starts around pink vertical line) and RE13 (Starts around half way extends to right) maps can be seen each uphill run can be seen ending with REVS droping red line to zero. Delibrately stoped engine to mark the spot.
Full engine spec.
1310 A series 10.5:1 with lightened flywheel
Hiff 44 (unkown needle however i suspect its standard which may well be part of the issue)
Ported head 36inlet 30exhaust
MED HT CAM
1.5 Roller rockers
K & N Filter
Megajolt (running with EDIS and ford coil pack and Leads, NGKBP7RES plugs)
Facet Fuel pump and bowl filter
RC40 / Custom Mainfold
Does it look fueling related ?

toenee · Post by **toenee** » Wed Mar 02, 2011 9:40 pm

We really need to know what needles in the carb, with that sort of spec i'd be trying the BDL maybe the BDD. Have a look what's in there and report back.

JOCS · Post by **JOCS** » Thu Mar 03, 2011 7:30 am

Thanks Toenee was going to do this but limited time at momment. Never tuned a Carb engine before only fuel injection. When I have the needle out is thier an easy way to tell what it is ? Ie will it be marked on the needle where it clamps in with the three letter code ?
Also I believe after read an David Vizards book that the spring may also be wrong. Again not sure what spring is in the Carb I expect stock which may be yellow when I should have a red one in.

toenee · Post by **toenee** » Thu Mar 03, 2011 9:39 am

Yep once the needles out, they are marked on the part thats actually clamped into the dashpot piston.
Remove the dashpot cap/plunger and then the 4 screws holding the dashpot on. Lift the piston off the carb carefully so you don't bend the needle, now tip it up and pour the damping oil out and undo and remove the screw on the side which holds the needle in place. The needle and holder should just pull out revealing the three letter code, be careful not to lose the small spring which is attached to the needle.

JOCS · Post by **JOCS** » Thu Mar 03, 2011 11:04 am

Cheers Toenee will take a look tommorrow when I get home. Do they paint the spring end on the HIFF44 to signify if its yellow or red ?

toenee · Post by **toenee** » Thu Mar 03, 2011 7:31 pm

Yes the springs are I.D'd by a coloured patch, which will be long gone. The paint indicated the weight of the spring and the main mini springs were: Red = 4.5, Blue = 2.5oz. The HIF 44's usually have the Red spring fitted as standard.

JOCS · Post by **JOCS** » Fri Mar 04, 2011 8:39 am

The Needle is BER (Was this standard out of factory for minis ?) but I think someone has been at it with a file. The spring I am pritty sure is standard red. No paint left could test it at work but will leave it till next monday as they said they have a selection of parts for SU carbs. I have a copy of winSU now so I am going to see what that recommends.

toenee · Post by **toenee** » Fri Mar 04, 2011 10:08 am

That'll be the problem, have you not got a BDL you can try ? Quite a common needle, if you don't have one someone in your local mini club may. So see if you could borrow it for testing purposes.

JOCS · Post by **JOCS** » Wed Mar 09, 2011 8:13 pm

Ok update. I took the car down to Geraldale on monday. Car was almost running on air as expected. Gerald changed the existing needle and adjusted it to make the fueling safe with current ignition map (SPI2). This has sorted the fueling issue so that I can adjust the advance map without worrying that the fueling is poor. Gerald also gave me some advice on the ignition map. I have now updated the map so that on the flat the advance is correct. Gradually getting closer. As for Rolling road I have found one in crawley who are willing to make the map. However the map I have created so far is very different from where I started off with the SPI2 map. I put the map up for refernce after I get it completed.

JOCS · Post by **JOCS** » Mon Mar 21, 2011 6:12 pm

Took car to Austec in crawley today the map is now sorted but needs to have other problems sorted before I put it up. It appears the valve clearances arewrong or the cam timing may be incorrect. Will have to strip down and check again.......

toenee · Post by **toenee** » Mon Mar 21, 2011 10:31 pm

MED HT cams about 280 degrees duration iirc, valve clearances would need to be 15thou with this cam.
Cam timing did you just line the dots up ? If so you need to measure what angle it's giving max lift at and get a offset key. Available at minispares.