Don Terrill’s Speed-Talk

I build quite a few 750VS carbs for street cars. Start with a 3310 of any vintage, replace the body with the Proform unit (which has the primary only referenced vac tube) and fit a secondary block for ease of jetting change. They always drive great and rip tyre, especially on something with less tha...

FWIW I had one of these 9381 carbs from new on my old SBC combo and could never get it to run properly. A forum member here and fellow Australian said he could fix it (and had done so on the same model carb previously) so I sent it off to him. He pressed a restriction into the booster feed to improv...

cjperformance wrote:Hi, just 2.5" as a choke then straight out to 3".

Thanks, I'll try that next time !

I do the Falcon tri ys - cut off the 2.25 collector back to 2.5 then step out to 3, they work better like that with a full system than just going straight to 3". This is what I have found also with the VN/VK pipes. Consistently make more torque with 2.5" at the tertiary rather than 3.0&qu...

Don't bother with the Weiand intake, it won't cover the ports without welding and getting valve covers off will drive you mad.

TBS sell a nice intake, large port, tented plenum etc.

JMHO

You might try measuring the skirt on that piston. ' They have been known fold in under heavy load. Could have added to your piston rock. Once the thing hit the head and pinched the ring, it was doomed. Yes, had a look at the skirts and yes, they have moved in, no breakages but the top ringland of a...

PTH was 0.032" however it did have fairly generous piston to bore clearance which would make this a bit closer with piston rock. This is the problem^^^^^^ With old design pistons with lots of skirt clearance , I'd set the PTH clearance at 0.045" on your aplication. Yep, definately going t...

My Two cents worth : The pistons hit the head, distort the ring land, ring is stuck, burning gasses melt the ring lands, oil contaminates the chamber, detonation and pre-ignition finish the game. Which was the PTH clearance? PTH was 0.032" however it did have fairly generous piston to bore cle...

When running all the fuel thu the blower, it screws the fuel toward some cyls. and away from others. So when you leaned out the rich cyl.(which was getting other cylinders fuel - plus its own) to stop it from blubbering, it starved the lean cyl. And the end result. IMHO SDave Yes, quite possible. I...

Well I was going to suggest if it's going lean on the back end of the track you might check with your carb tuner and consider reducing the hi speed bleed size. Fueling blown alky with carbs, at anything other than very modest boost, is a tough deal to get to give a consistent result. Runs hard 3-4 ...

I see detonation pock marks clearly on the right hand pstons top around the area of the part number and such. Surly your spark plugs must of showed this if viewed thru a mag. Yes it does, but it is only this one cylinder. Do you know about where on the track it lost the hole? 1000ft, or sooner? I t...

MELWAY wrote:Sounds like its fairly close ,,,an engine dyno with egt could help find out exactly what is going on

True, if you weren't so far away I'd give you a days work !

Was it ever put on a dyno the check a/f ratio and egt ? Also what size venturi are carbs and what size jet are you running Mixtures were checked on a chassis dyno before racing, was left rich. Car has an AFR meter, initially wouldn't register due to being too rich but leaned it out to 0.75 Lambda. ...

BTW Not that I have ever seen a good alcohol carb (firestorm alert) but are you sure they are purpose built "alcohol" carbs. Pins: yeah they do that when this happens. Heat and distortion. Probably still has the stock street pin clearance though. I'm afraid to ask but what are you using f...

Yeah I remember being there. No money to buy the stuff I should be using, but always seemed to find the money to bore it and replace the pistons, rings, bearings and gaskets when it took a dump. Sometimes I was that lucky and that's all it was. Sometimes I wasn't, and it was the crank or rods, and ...