4age rebuild

[static]

Good evening boys,
Its late and im tired so im not going to go into details but I recently purchased a 4age with twin solexs from the parts for sale thread on this site only to put the motor in and find out its basically stuffed. Theres pressure building up in no4s intake passage which is blowing out the coins that have been siliconed into the injector ports (its got carbs remember). There should be vacuum in there not a pressure build up. So Im guessing the valve is lunched.

Anyway,it looks like the motor needs a rebuild so I was just hoping to get a few opinions from people out there that have rebuilt GEs themselves on what parts they recommend,brands, any weaknesses to look out for, parts I should replace, parts I should reuse,prices etc etc

I will be doing the assembly myself (my old mans a mechanic) and I really dont want to spend anymore than 4gz. What Im hoping to get out of it is a fairly tough and reliable motor that goes fair hard. I dont expect it too be cheap but thats the budget. Everything else is already sorted so I just want the motor done so I can thrash it without worrying about it dying.

Anyhelp is appreciated :2thumbs:


I tried search and got nada

[riojin]

4gz!

you can by an already built running setup for that. how much power you want? just wanna use stock stuff?

cheap easy rebuild - piston rings, upper and lower bearings, gaskets


cheapish tough streetable motor - id also get some toda 260 cams, larger jets for your carbies, head port and polish, toda valves and valve springs

[Jonny Rochester]

Take the spark plugs out and compression test the motor. Then you know if the motor itself is good or not. If you have over 120psi on all 4, the motor is sort of good enough to run. If you have 150psi on all 4, the motor will run fine. If you have 170psi on all 4 that is excelent.

For the inake side of the motor, silicon is not good enough. Fuel eats silicon. You have to use a different sealant, like the stuff they use for 2 stroke motorbikes. It's fuel resistant. One brand is called Three Bond I think.

If the carbies or not right, you will get a backfire or a flame thrown out one throttle. Be sure there is not air leaks between the carby and the manifold, or between the manifold and the head. Again, silicon is not good enough!

[terryo]

there are a number of detailed differences between big port and small port engines, so you need to work that out before doing any shopping.
all of the commonly needed parts are readily available. they are not prone to burning valves unless someone set the clearances far too tight. they are prone to piston ring land wear and bore wear (both taper and ovality) , so its rare to find a block & pistons that will just accept rings.
the early 86kw 40mm cranks (40mm big-end size) have a tendency to have knocked out bearings which often ends up with con-rod damage.
I agree, a compression and oil pressure test before you start is a good idea.
other than that, its what you see is what you get.
for parts see www.roadandtrack.net.au

[TopSecret]

Find the workshop manual for the 4age online (Toymods has it) and follow every direction to the letter. I built my 4age using only that manual and it was with no doubt the best choice I made.

Little things like lightening the flywheel and having the crank balanced etc. are good little mods to do while its all apart and make it super revvy. :2thumbs:

ACL gear for the rings, pistons, gaskets is what I used for my own and all of it was excellent quality IMO.

[static]

Cheers for your replys guys, i always appreciate good no bull information. The motor is in the car and running atm. in fact Ive been driving it daily for the past two weeks so its not quite on death row. But I do have a history of thrashing motors till they die so Id like to get on top of this one before I end up stuck on the side of the road begging workmates for lifts to work like has happened in the past.

It is a smallport motor and Ive tapped a thread into the final injector port and loctited a nut in there to prevent it from blowing out. I havent had the carbs tuned yet but they generally run pretty clean for twin carbs although sometimes depending on conditions you do get the occasional crackle or pop from the carbs under low load (ie driving around the carpark). Ive also got a straight through exhaust (no mufflers,two resonators or hotdogs) so it backfires fairly consistently whenever you come off the gas.
I have noticed a ticking or knocking noise coming from the back/top of the motor when idling. it can be quite loud (you can hear it from inside the car). Something else that has been bothering me is that when I first installed the motor it would start out rough and then rev hard all the way to over 7000rpm. Now it runs a bit better down low but wont rev beyond 5500-6000rpm. It seems to rev fine up to there and then suddenly breaks down as if its valve bouncing or the dizzy has shit itself. It almost sounds like its hitting a rev limiter.
Thats where the motor makes all its power...its poo

[static]

my bad...just read my thread,its a big port