Ian new to this site ,any assistance would be great..
Building a speedway car for my son

Am allowed to use ea.eb,ed motors.which is the better block if any..
Which is preferred head,,,i have a head with swirl piece around the inlet valve,is that an advantage..
also have a motor with a head with casting number 3.9 4 ..
Any huge advantage in boring a 3.9 to a 4lt...many thanks

only suggestion i can gice is to use a ef/el cranks they have more weights to balance them.

Not allowed el crank.they inspect prior to sealing engine.that goes for head and sump also,,no restriction on camshaft..even the ecu gets sent away and sealed

Are you restricted to using EA-ED Motors only? Can you use things like EF/EL heads?

Got a link to the rule book?

Thanks for the line to rules.
Being you state you can use EA-EB-ED engines, i'm assuming you are running an ED falcon.
As far as the short motor goes, try and find the latest ED engine you can get.
You are allowed a 60thou bore, so do that. Have the crank indexed and make sure it's right on the stroke limit, and go down to the smallest bearing undersize you can get.
The AU gasket won't work with that much over bore, So use a normal ACL gasket.
Measure the compressed gasket, (use a bit of lead shot or similar and put it on the block in an open part of the gasket so that when you torque the head down it crushes the shot. The thickness of the shot after this is you gaskets compressed thickness
Deck the block to get the pistons out of the top of the bore to give 30thou piston to head clearence.


Do you have a flow bench near you, find out if they have velocity pitot probes.
Get a sample of each head, EA through to AU and have them flow tested and velocity tested.
junk the lowest flowing heads and pick the highest velocity from the 3 highest flowing heads, Even if it means picking velocity over flow.
You can go 60 though on the head, but don't. Go enough to make it flat and then deck the block to get the compression up. See above, then only face the head if the compression is still not high enough.
The rules don't say you can port the head?
They also don't specify what you can do with the valve seats.
There is power to be had with the right valve seat angles.
If you are not force to use a 45 degree seat cut, get a head and some valves and put a 30 degree seat on one valve and seat and 50 or 55 degree on a second one. Flow test them.
The 30 degree seat should out flow both the 45 and 50 seat at low lifts but loose a little peak flow.
The 50 or 55 seat should loose a little low lift flow but gain high lift flow. If you get enough change in flow, do a complete head and dyno it.


Thats easy, resurface it untill it's 20.5mm


Call Phil at Surecam. Make sure he knows the rules, and that the stock EB rev limit is used.



Do what you can internally to reduce windage and control the oil


Get the latest EB ECU that you can, since you don't have to contect the coolent temp sensor, contect it wiring to a POT and use it do make adjustments to fueling. (crude yes, but it's all you have) HIDE IT VERY WELL


Get both part numbers and chose the one with the best spray pattern.
Then buy as many as you need to in order to test them all for actual flow rate and only use sets of six the flow THE SAME.




Where do they measure 'standard exhaust size. the pipe from the engine to the cat is bigger then the rest of the system.


The rules all seem pretty tight, but there is still a lot you can do to try and get the edge over the others

wow, seems like you have done this before tickford_6.

my advice.... ^^^follow the hell out of what he said ^^^.

I have never seen those rules before.
But when the rules are that tight it's all the small things that will make the difference.