Because the Poms adhered to the need for equal firing intervals, and would not adopt a 180 degree crank?
mad_signtist,
Aug 8, 11:41am
Thanks for the advice guys. Going to see engine builder tomorrow and will have a yarn with him
mrfxit,
Aug 8, 1:24pm
Get a basic weight check of each part cross referenced with full sets of components done & go from there. Shouldn't cost to do that bit.
the-lada-dude,
Aug 8, 5:43pm
Yes and no, . It is impossible to balance an inline engine in motion, by adopting a 180 * crank on a twin . all you do is transfer some of the rotary balance to another plane .
sr2,
Aug 8, 6:52pm
A bit off topic (apologies to the OP) but I’m currently building up a retro Holden 6 and with the advent of cheap digital scales I’m DIY balancing the pistons and rods- currently building a jig for weighing each end of the conrods. Have to say that the stronger Starfire rods I’m using still look like they could do with at the least some linishing to remove some obvious casting stress raisers, any suggestions?
jmma,
Aug 8, 10:26pm
Yah progress :o)
sr2,
Aug 8, 10:43pm
Point taken - thanks. (Update coming soon).
elect70,
Aug 9, 1:07pm
Get them crack tested after linnishing smooth & shot peened . just in case Luckily for me while building my chargers 340 they found stress crack in 2 rods necks so biffed them
mrfxit,
Aug 9, 1:58pm
Did you grab the Starfire flywheel as well 13kg verses about 16kg (16kg I think for std Holden 6). Made my old 186 a little more responsive
supernova2,
Aug 9, 4:26pm
Yep, Ive still got my old letter balance scales with the felt pen markings to center pistons etc. Used a glass of water for the weight, match to the lightest and grind away. Still got a pipette somewhere too, and 3/4 of a Ford cam off-set dowel kit. Ah the things we used to do - usually in the dead of night as well!
mad_signtist,
Aug 10, 2:11pm
Putting new rods etc in so have decided while the engine is in bits for a small amount of money I may as well just get it balanced too.
mrfxit,
Aug 10, 2:50pm
Good call. Noting that it's a mixed bag of various motors, then anythings possible. Did you get the Starfire flywheel, the 6's love them & everything still bolts up std
jmma,
Aug 10, 5:17pm
Wrong person, that was sr2 with starfire rods. For his Vauxdon :o)
sr2,
Aug 10, 8:06pm
Standard Red 6 Flywheel is 10.6 Kg and XU1 was 8.6 kg (both with the early lighter crank). For the, Blue/Black 6 and Starfire 4 the Flywheel was 8.6 kg (with a heavier counterbalance crank).
I’m running a 186 X2 cast flywheel that I’ve machined down to 6.8 kg although I’m running the heavier 3.25†Comodore counterbalance crank with the mains ground down to fit (here’s hoping it clears the block!). At 60 thou oversize the old 186 X2 will be a 208. I’m a bit too busy to update the Oldschool blog but should get around to it next month.
Here’s a quick peek at the dummy mock up engine.
Xcelent !. should be more of it . all the power as you know is in the cylinder head, . I can show you where & how and give you the critical dimensions to modify
The biggest engine make or break is the CAMSHAFT choice .
sr2,
Aug 11, 2:06pm
I've always looked at the overall combination of components, the weight and gearing of the vehicle and most importantly how it's going to be driven.
Final cam specs are yet to be confirmed but I'm not going too wild, the venerable old Holden Red always struggled with torsional vibration over about 5700 and I want something that's still an easy drive. I'm looking at something like Auckland Cams Stage 3 Hydraulic.
It's all good retro fun and so different from the 135i race car!
the-lada-dude,
Aug 11, 5:52pm
Basically, . all the parameters are worked back from Intake valve size. 46 mm would be as big as you would want to go, . but on your head this would mean moving valve guide centres etc . no point as you won't be running individual runners and you are looking at 7500 +
tell me your IN val size, . looks like it is only 35 > 36 mm ? then gas flow beyond 9 mm lift drops away badly ,. if you do NO head work, your going to be stuck with dreadful gas reversion at lower rpm if you open the overlap up beyond 40 > 50 * so MID range grunt is want you will probably want and I bet only achieve. a high lift cam won't give extra power because of lift, but the extra lift is only there to allow the valve more time to decelerate from usually higher ramp velocity, and ramp velocity is limited by the follower diameter ( assuming a flat tappet ) confused ? . haha that's just the beginning
my choice would be the >>> 875 <<< you can see the acceleration is much quicker than STD by the 0.50 " figure and the 112 LSA will pull the overlap back a bit . the >>>> 309 <<<< is too much
sr2,
Aug 11, 6:22pm
The head is an original stage 3 Yella Terra (got to keep it period).
the-lada-dude,
Aug 12, 10:48am
Ah, well that will help . give me the INTAKE valve head diameter, induction and exhaust system you intend to use
sr2,
Aug 12, 3:22pm
44mm inlet and 38mm exhaust valves. Triple HS6 SU’s on a Speco manifold. Headers have 38 mm primarys, 44 mm secondarys and a 51 mm collector. Exhaust will probably be 57 mm.
emmerson1,
Aug 12, 4:41pm
My second car was a 1.3 mitsi. It spent a lot more of it's relatively short life at 6000rpm or above than the 327 I had a few years later. It would make it to 8500 (no electronic limiter), but sounded really bad.
the-lada-dude,
Aug 12, 5:54pm
Shit ! more than I thought . ok, valve seat throat should be 39.6 mm venturi bowl no more than 40.5 mm ( this is the area by the valve guide boss , which really should be pencil thin ) after that 37,5 mm for at least 3 " and then slowly increasing to the port face ( a guess is maybe 38 > 39 mm ) are the rockers 1 : 1.5 or 1.6, 1.7 peak flow will be at 11 mm or .440 "
you will still have intake gas reversion and robbing because of the manifold , which means a lumpy idle so ok the >>> 882 <<< will do the job, but a bigger rocker ratio of 1.6 and LSA of 112 would be the deal, you have over 60 * O/L with this cam which a fair bit for a streeter . check the head gasket fire ring and see if there is any more room to modify the chamber around the IN valve
at a guess with out doing the #'s, the exhaust looks reasonable and I suppose it is 3 - 2 - 1 and the length from cyl head to collector will be 36 " ?
have you an estimated HP output ? my guess is 221 at the flywheel . hurry up and get it going !
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