Don Terrill’s Speed-Talk

dfarr67 wrote: ↑Thu Aug 18, 2022 10:17 pm
My work truck is a 2019 K1500- engine is fine- starting to get a hate on for the trans tho.

Is that the 8 or 10 speed? What’s going on with it?

. " The 076 idle air bleeds should be fine." Based on what ? We don't even know the carb list number or what the original size IAB was. Are they screw in bleeds or pressed in? Most of these older carbs were pressed in bleeds. Have you seen a lot of Holley carbs with .076" IAB's ? Mor...

Perhaps the milder engine made more off-idle manifold vacuum which would pull more fuel through the transfer slots at low speed. Closing the secondary throttle should help by reducing the amount of air into the engine that must be satisfied by primary transfer slot fuel. If the lean condition persis...

I think the cruise slip with the converter is normal. My experience was similar with a Hughes 2000 stall in a 79 GMC C35. Big heavy trucks aren’t nearly as forgiving as hot rods at low speeds. Unless your goal is upper RPM HP I’d go back to the smaller carb. It should provide better response and fue...

I built a 383 for my Nova years back with late nineties vintage AFR 195 heads, 223/228 110/107 HFT cam and about 9.8:1. I ran the non-self tuning Holley 900 cfm 4bbl C950 TBI. No tuning issues whatsoever. I think you could run the 268 Voodoo or 274 Mega on a 108 without tuning issues.

One thing to keep in mind when modeling these lobes is whether they’re symmetrical or asymmetrical. For example I recently degreed a Howard’s HFT, 275@0.006”, 221@0.050”, 110 LSA. This cam dialed in at 106 ICL based on .050 opening/closing points which was also max lobe lift. This cam was symmetrica...

mt-engines wrote: ↑Thu Jun 24, 2021 9:59 pm How many of you guys have ACTUAL DYNO DATA on tbi heads?... because like most posts I see on here.. its just regurgitated hearsay at best.

I saw some chassis Dyno numbers 10-15 years ago over on third generation.org. I’ve never seen engine Dyno numbers.

I recently measured tapped lift vs valve lift with Comp 1.72 roller tip and ZZ502 rockers on a Mark IV BBC, and calculated actual rocker ratio through the lift curve. Cam lift Comp. ZZ502 0.006. 1.68. 1.17 0.050. 1.74. 1.68 0.100. 1.76. 1.69 0.200. 1.79. 1.75 0.300. 1.81. 1.79 0.330. 1.80. 1.78 The ...

Keep in mind the Chev big block is one of the most critical engines for a flat tappet cam break in, having a small diameter lifter and a very high rocker ratio. (1.7:1) Tread lightly, edm lifters if possible, soft spring break in, Gibbs BR oil, no idle, etc and cross your fingers. We use break in r...

Do some chamber work to lower the comp down to 9.6:1. We just did a 496 with semi closed chambers, flat tops...9.6:1, no port work, hyd. Isky cam and rpm intake...made 472HP and 548TQ. Cam is small 221@ .050. that sounds like a very sweet engine. the cam is probably one step up from what i’d want t...

I believe the Edelbrock pump is rated 6 psi.

I have a 79 C30 with about a 520 HP 496. Truck is 5600 Lbs. Has the huge 14 bolt full float rear end with 13” by about 3” wide drum brakes. It has thick, heavy 1 ton aluminum wheels with 265/75-16 10 ply tires. 3.73 gears, TH400 with stock stall converter. It will light the right rear at will and ru...

I had a 12” Hughes 2000 stall in a TH400 behind a worn out, but well-tuned, 468 in a 5600 Lb square body truck. That thing would flash near 3,000 at WOT and was real sluggish at part throttle. I bought a PDQ 13” heavy duty converter from a local trans rebuilder that flashes about 1,800 and is much n...

I tuned a fuel injected SB 400 in an early nova several years ago. The owner wanted to maximize fuel economy. We were on a level straight highway running 2000 rpm at 70 mph. I adjusted ignition advance from 35 to 50 degrees in 2 degree increments. There was no noticeable change in drivability, injec...

Jim, I don't have anything for start RPM in my software and it use IVC at the seat. What I get working backward for you engine and 181.9 psi. Is IVC 70.35 ABDC and with a 103 ICL that is 294.7 seat_to_seat duration. Stan This assumes the lobe is symmetrical. Many open faster than they close. I rece...