Speed-Talk is running on www.Speed-Talk.com

IMPORTANT: Update your bookmarks to https://www.speed-talk.com/forum/
(Right-click the URL and select "Bookmark this link")

Search found 12250 matches

by MadBill
Tue Dec 01, 2020 12:57 am
Forum: Engine Tech
Topic: 0.006" valve clearance in new DOCH CAMs - Too tight?
Replies: 17
Views: 587

Re: 0.006" valve clearance in new DOCH CAMs - Too tight?

Some historian in the ranks probably has the details, but back in the mid-fifties, Corvette road racers with the factory race cam (xx097?) were having trouble with burnt exhaust valves. Better materials didn't help much, but opening up the exhaust lash did; the hot clearance was going negative, hurt...
by MadBill
Mon Nov 30, 2020 4:40 pm
Forum: Engine Tech
Topic: 0.006" valve clearance in new DOCH CAMs - Too tight?
Replies: 17
Views: 587

Re: 0.006" valve clearance in new DOCH CAMs - Too tight?

Since the exhaust valve is much hotter than the seat, it will grow in relative diameter and thus 'climb' the latter's 45° slope, offsetting some of the valves linear expansion.
by MadBill
Mon Nov 30, 2020 12:07 am
Forum: Engine Tech
Topic: 0.006" valve clearance in new DOCH CAMs - Too tight?
Replies: 17
Views: 587

Re: 0.006" valve clearance in new DOCH CAMs - Too tight?

I see European makers offer new billet cams for my DOCH application (Fiat original twin cam). They suggest valve clearances as low as 0.006" and typically no more than 0.008". This seems awful close to me. Factory clearance was 0.016/0.020". What would be the acceptable clearance range? One cam mak...
by MadBill
Sun Nov 29, 2020 9:48 pm
Forum: Engine Tech
Topic: Inline 4, parallel cat converters in 4-2-1
Replies: 3
Views: 211

Re: Inline 4, parallel cat converters in 4-2-1

I'd say from a performance standpoint, as far back as it takes to allow the unrestricted portion upstream to match the desired box volume. For emissions though, too far back/too cool could be the final straw re failing; it would depend a lot on the test parameters and the engine calibration in 'test...
by MadBill
Wed Nov 25, 2020 12:23 am
Forum: Chassis / Suspension / Body
Topic: aerodynamic drag and body style
Replies: 7
Views: 391

Re: aerodynamic drag and body style

It's not uncommon for a car's optimum qualifying setup to be high downforce, but needing to be 'trimmed out' for the race, since the former's high drag leaves the car a sitting duck in traffic on a long straight.
by MadBill
Tue Nov 24, 2020 11:19 pm
Forum: Engine Tech
Topic: Big Issues with Cylinder Pressure (DCR)
Replies: 118
Views: 2767

Re: Big Issues with Cylinder Pressure (DCR)

In my stock 1970 Z28, I checked the aircleaner snorkel temperature at 60 MPH on a 70° F. day. It was 125°, good for a theoretical 5% HP loss vs. ambient.
by MadBill
Tue Nov 24, 2020 1:20 pm
Forum: Chassis / Suspension / Body
Topic: Question - Improved Camber Curve
Replies: 44
Views: 857

Re: Question - Improved Camber Curve

Oops! How the (bleep) did we end up way over here? :? :lol:
by MadBill
Tue Nov 24, 2020 12:05 am
Forum: Chassis / Suspension / Body
Topic: Question - Improved Camber Curve
Replies: 44
Views: 857

Re: Question - Improved Camber Curve

The broadcast cockpit data readouts from current Formula 1 cars show as much as 6 Gs deceleration at high speed. :shock:
by MadBill
Mon Nov 23, 2020 12:07 am
Forum: Engine Tech
Topic: Big Issues with Cylinder Pressure (DCR)
Replies: 118
Views: 2767

Re: Big Issues with Cylinder Pressure (DCR)

David Vizard says that 200 cranking psi is a good max target for a hot street engine on premium pump gas...
by MadBill
Sun Nov 22, 2020 11:53 pm
Forum: Chassis / Suspension / Body
Topic: Question - Improved Camber Curve
Replies: 44
Views: 857

Re: Question - Improved Camber Curve

David Redszus wrote: Thu Nov 19, 2020 11:59 am Forgot to mention tire grip and vehicle weight transfer as affecting brake balance.
Also downforce and thus maximum braking force diminishing with the square of the speed as you slow...
by MadBill
Sun Nov 22, 2020 11:42 pm
Forum: Chassis / Suspension / Body
Topic: cheap chassis to save drag racing
Replies: 34
Views: 2820

Re: cheap chassis to save drag racing

The easiest way is to click on the Attachments tab below the Post Reply box, then on the Add files box, which will take you to your computer's picture folders. Find the folder and the pic you want, left click it and hold, drag it to the message box and drop it. Done!
by MadBill
Sat Nov 21, 2020 5:40 pm
Forum: Engine Tech
Topic: Piston pin "end play" ? How much is ok ??
Replies: 19
Views: 824

Re: Piston pin "end play" ? How much is ok ??

A single 1/8" one would do, but tricky to machine and it would have to be chamfered to lock the clips in place.. :-k
by MadBill
Sat Nov 21, 2020 2:43 pm
Forum: Engine Tech
Topic: Piston pin "end play" ? How much is ok ??
Replies: 19
Views: 824

Re: Piston pin "end play" ? How much is ok ??

Surely 1/8" clearance turns the pin into a tiny, patient battering ram? :?
by MadBill
Thu Nov 19, 2020 10:20 pm
Forum: Engine Tech
Topic: Nylon fuel lines
Replies: 20
Views: 819

Re: Nylon fuel lines

The best Copper line ( easier to work with ) might be an option to consider where you mentioned running the steel line ?? Mark H. Copper tubing is dangerous in applications subject to vibration such as on a vehicle, especially in a use carrying fuel. It can work harden and crack. Not good! 2X for w...
by MadBill
Sun Nov 15, 2020 10:07 pm
Forum: Engine Tech
Topic: Steel Main cap material
Replies: 28
Views: 1623

Re: Steel Main cap material

Making caps or making stepped dowels?