310 cam help
Turbo Mini Forums

A mates just fitted a swiftune 310 into his 1380 and is having some running troubles atm.

Hes set the clearence at 15thou and im thinking 16 would be better. Its not revving properly.

1.5 rollers with and med stage 5 head and a weber 48.

Any thought would be great. Cheers eden

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

thats well too tight iirc, my 649 is set at 17thou, and if i fit rockers should be 19thou, try opening them out a bit, it'll sound like a bag of spanners at idle, but it should rev alot better

310 should be set at 16 thou with 1.5 rockers.
If he has changed from a lesser cam then it will probably be running a bit lean, a trip to the rollers is needed.
What did he time it in at?

Edited by paul wiginton on 15th Apr, 2013.

I seriously doubt it!

Was a simler cam just slightly untrusted (morspeed) and I belive it was spec so 110?

Il get him to go 16 thou and go from there

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

If its timed at 110 degrees tell him its wrong. Fit a new chain and time it to 104 degrees, It will quickly (within a couple of hundred miles) stretch to 106 degrees which is what it should be

I seriously doubt it!

Il find out for sure. What would the affects be with it off timed like that?

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

Its hard to say really, they wont be dramatic but together with the carb not being 100% set up right plus the ignition wont be quite right due to cam timing being out it just wont run properly.
You must bare in mind though that the 310 wont do much under 4-5,000 rpm anyway and remember that there is no point in having a good camshaft if not fitted correctly.
Let us know how he gets on.

Just one other thing Id say is the 48dcoe is a little big - 45 would be better. What size chokes does he have fitted in it?

Edited by paul wiginton on 16th Apr, 2013.

I seriously doubt it!

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

The thing with the A series engine is the funky 5 port cylinder head. What hppens there with cylinder performance is the two cylinders perform better than the other two. What happens when you advance or retard the cam timing is you make the poor cylinders better and the better cylinders poorer. The net result is you'll find the ssweet spot for cam timing on the A series at least, is a reasonably wide band befor power loss is noticed. This cannot be said for the scatter cams which are optimised so all cylinders perform well. That makes cam timing more sensative since if it is off, all cylinders will start to under perform.

How much advance or retard from the quoted figure before it affects performance i dont know, but i do know that the quoted figure is only a optimal starting point. How does the cam manufacturer know what your custom engine needs to give best results? The reality is that dyno testing is the only way to really find those extra few hp just by optimising the cam timing (or pay someone with that knwledge already )

Not to worry its timed at 106 with his ran in chain.

Going round to have a look over it with him. Going to do a comp test and a few checks then take it to 16 thou and go from there.

Wil keep you posted

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

Rite gave it a gd going over. Its lumpy when u pick the revvs up and bairly drives atm.

So far weve taken the clearence from 13! To 16 thou.

And changed the fuel pump as it wasent holding pressure unless it was idling.

Comp test was fine. Then we noticed that if we take 1 or 4 ht lead off it makes no difference to the running, but weve got spark fine.

Any ideas?

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

firing order correct?

Don't just accept the normal response people give to that question, physically check it. Set engine to TDC with both valves on cylinder 1 closed, remove dizy cap and see which plug the rotor points to, that should be #1, then set plugs in the firing order of 1342 blah blah.......

Just make sure that the rotor is pointing to plug #1.

Using the general rule of thumb that most reply with gets messed up when the dizzy drive has been installed in a different position.

Sorry shoulda said megajolt and all seems okay

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

I wonder if the megajolt is set for a normal cam but the scatter cam(if it is a scatter) makes the 1 and 4 valve timing slightly different.
I also wonder how accurate he got the timing, did he get a true TDC by taking a reading off the protractor 10 thou before and 10 thou after? Then a true full valve lift by also taking the reading 10 thou before and after?

Edited by paul wiginton on 16th Apr, 2013.

I seriously doubt it!

Thats good to hear paul, I was suspecting the map.

Have you got an example map for me to go from at all? And il have to check the timing with a strobe

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

it might be the map, cam timing with scatter cams maybe different but i am unaware of the ignition timing being any different, wasnt on mine anyway

Ok here's a thought

What compression ratio does this current engine set up have? If its less than 12:1, your wasting your time

Hate it when that happens

Edited by Sprocket on 17th Apr, 2013.

That could be an issue, I dont know the exact ratio but it only made 11 bar on the comp test ?

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

Well weve tried everything we can think of now and my last thought is the cam timing.

The bloke who did it is a vauxhall guy and im wondering if he timed it off #4 not realising that minis are the other way.

My question is would it then run (poorly) or fail to run compleatly?

Eden

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

How can you build a 310 engine and not knowing the CR? Sprocket is correct. Anything less than 11,5:1, get a milder cam. Loose loose situation.