Don Terrill’s Speed-Talk

If I hedge a bet that the motors exh valves are next to each other per cylinder would I loose? Lose. Fiat 124 Twin Cam, Hemi head, 2nd ever belt drive after the Pontiac OHC 6. It might be the pics, but to me it sure looks like there's overhang in the cylinder and/or chamber. What do you mean with o...

Asking for a fella on another forum. His Fiat twin cam head gasket blew under load in an uphill. The fire rings of the gasket in all 4 cylinders are crushed flat as if hit by the pistons, all the way around. Piston contact was ruled out though due to the size of the bores in the gasket. Detonation? ...

How do you determine when the intake and exhaust valves need to be opened and closed.how lobe profiles affect things. for different purposes and parts used. I would like to know how to spec a cam and tailor the events for my usage. Any rules of thumb? I know there is alot of variability in how you ...

The paddle would be more like MAP since it creates a restriction and then gets moved by the pressure difference that is created. Then the paddle position can be directly translated into air velocity since the paddle position will be a result of the pressure drop, and the flow will be the pressure d...

The MAF measures flow, not mass. Whether you're in Miami or Denver, the MAF sees the same volume of air though the mass of air is very different. Air/fuel ratio is mass of air to mass of fuel, not volume. The O2 sensor gives a readout of the amount of oxygen in the exhaust gases which gets translat...

The MAF measures flow, not mass. Whether you're in Miami or Denver, the MAF sees the same volume of air though the mass of air is very different. Air/fuel ratio is mass of air to mass of fuel, not volume. The O2 sensor gives a readout of the amount of oxygen in the exhaust gases which gets translat...

A fellow needs aux shaft bearing sleeves that press into a bore in the block. Replacement parts are not available.

Is this something that could be custom made at reasonable cost? Source?

Thanks for helping!

Has anybody ever accurately measured real Vac numbers in a cylinder at speed. There's plenty of graphs etc out there with pressures v degrees of rotation but I haven't seen real numbers for the vac side. Not surprising when the vacuum could be less than negative 1 PSI I guess considering the pressu...

It would be better discussing this in more accurate terms regarding cam timing than seat-seat perhaps? Maybe overall lift, duration @ .050"? When I messed about with the Lotus TC, cams rated around 300 deg were more race than street suited. Cheers Steve Steve, this is the cam the fellow has on...

Im curious what list are you browsing? 34* is the basic for 8V TC, which lift 12mm and works with the standard springs :) IMG-20210527-WA0054.jpg -juhana Juhana, I'm not understanding your post. A fellow Fiat guy is building a 16V 2L twincam. Wants to make 200+HP. Bought CAT 280 seat to seat cams. ...

OK. Thanks. Kinda makes sense. So, how is this done in a hi-po 16V build? A shorter IN cam duration will result in high DCR unless ICL in the 114+ range is used, which would result in way less lift, overlap at TDC. Right? Would a 16V head with a 280deg seat to seat IN cam perform similar to a 300deg...

Does 16V head, typically, need less cam duration than 8V head to provide similar torque, peak HP characteristics?

Browsing cams for 8V vs 16V Fiat twincams, it seems 16V cams have way less duration than 8V for a stated application.

What engine?

^^ ???

Since when does rod bolt torque have anything to do with bearings?