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Search found 827 matches

by travis
Mon Sep 16, 2019 4:56 am
Forum: Engine Tech
Topic: Port velocity vs cfm
Replies: 18
Views: 627

Re: Port velocity vs cfm

Imo, for 1hp/ci............ you’re way over thinking it. Yeah, I probably am. That’s kind of what I do #-o They are ported as far as I am going with them other than maybe a little clean up of some rough areas. They are going to the machine shop this week for a regular 3 angle VJ and a flat .040” mi...
by travis
Mon Sep 16, 2019 4:41 am
Forum: Engine Tech
Topic: Port velocity vs cfm
Replies: 18
Views: 627

Re: Port velocity vs cfm

After listening to all the ST interviews and reading everything on this subject I have come to the conclusion that you need a square round oval rectangle port with a mcs somewhere between the plenum and valve seat, a fast slow air speed with very abrupt long smooth gentle radius's with good cfm as ...
by travis
Sun Sep 15, 2019 8:56 am
Forum: Engine Tech
Topic: Port velocity vs cfm
Replies: 18
Views: 627

Re: Port velocity vs cfm

"I think this confirms the old saying that flow isn’t everything." "I could probably lay the short turn back and pick up some flow there, but on my other iron heads doing that killed a bunch of low lift flow (under .300-.350” or so) for big gains above .400”. " This move kill the velocity which is ...
by travis
Sun Sep 15, 2019 7:11 am
Forum: Engine Tech
Topic: Port velocity vs cfm
Replies: 18
Views: 627

Port velocity vs cfm

After reading some excellent real world info in this post, I’ve got some questions related to port velocity vs cfm... https://www.speed-talk.com/forum/viewtopic.php?f=1&t=840&start=30 From what I got out of that post, 2 ported OEM heads with nearly identical flow numbers, but one being much faster t...
by travis
Sat Sep 14, 2019 6:37 am
Forum: Engine Tech
Topic: lean on both banks...1999 C2500 Suburban
Replies: 30
Views: 1175

Re: lean on both banks...1999 C2500 Suburban

GARY C wrote:
Sat Sep 14, 2019 3:47 am
midnightbluS10 wrote:
Sat Sep 14, 2019 3:37 am
GARY C wrote:
Sat Sep 14, 2019 2:30 am


So now we can put nitrous on it?
LOL I wouldn't without at least a marine intake manifold and 8 real injectors.
I was thinking a 50 shot just to clean the plugs... :)
It would probably take a 200 shot to put this thing into the 15’s!
by travis
Fri Sep 13, 2019 8:48 pm
Forum: Engine Tech
Topic: lean on both banks...1999 C2500 Suburban
Replies: 30
Views: 1175

Re: lean on both banks...1999 C2500 Suburban

There was actually a multitude of problems that seemed to occur all at once. That’s part of what made this thing so hard to troubleshoot. I think the initial problem was a distributor cap failure, which caused a misfire, which killed several plugs and one of the O2 sensors. Then the fuel pump crappe...
by travis
Fri Sep 13, 2019 7:30 pm
Forum: Engine Tech
Topic: lean on both banks...1999 C2500 Suburban
Replies: 30
Views: 1175

Re: lean on both banks...1999 C2500 Suburban

This time it was the TPS. A $30 /)($&@!! TPS. I had tested it twice and it read perfect from closed to wide open throttle, no less! The TPS is the only thing left I hadn’t replaced, but I noticed as I got other issues fixed it had a completely dead spot at very light throttle tip in from a dead stop...
by travis
Thu Sep 12, 2019 1:05 am
Forum: Engine Tech
Topic: Low speed (1500-1800 RPM) driveability issue
Replies: 104
Views: 2050

Re: Low speed (1500-1800 RPM) driveability issue

That cam is listed as 2200-5800 rpm range, just FYI. You’re trying to operate outside of its listed rpm range. 235/249@.050 on a 107 lsa...lots of overlap and low speed reversion there for sure.

Maybe cruise in the next lower gear? :wink:
by travis
Wed Sep 11, 2019 2:43 am
Forum: Engine Tech
Topic: Finally figured out how to move some air on these heads...
Replies: 14
Views: 1044

Re: Finally figured out how to move some air on these heads...

I just read it...definitely some excellent info there! Makes me think that maybe I should just trim that one fast point a bit and call these heads done.
by travis
Wed Sep 11, 2019 12:50 am
Forum: Engine Tech
Topic: Tight lash camshaft questions
Replies: 31
Views: 1350

Re: Tight lash camshaft questions

Wasn’t the -097 Duntov in the FI 283’s like .012”/.018”? They have been around a while Nope...they were called "30-30" 's for a reason. The valve noise was enough to drive off most street racers...if it's that loud it must be fast. The 097 is nothing like the 30/30. The 097 was something like 228/2...
by travis
Tue Sep 10, 2019 6:26 pm
Forum: Engine Tech
Topic: Finally figured out how to move some air on these heads...
Replies: 14
Views: 1044

Re: Finally figured out how to move some air on these heads...

Tried way too hard more like :lol: These are very similar to the E7TE heads, except with a 69-70cc chamber. Supposedly with a .040” flat mill they end up around 62cc like a E7TE. I had already done a bowl blend/cleanup on the intake ports and the same plus ground out some of the smog hump out of the...
by travis
Mon Sep 09, 2019 11:10 pm
Forum: Engine Tech
Topic: Undercut vs straight stem valves
Replies: 5
Views: 506

Undercut vs straight stem valves

I was wondering what y’all’s opinions are between the 2. I’ve been reading that there are times when an undercut valve stem can cause turbulence in the bowl and cause reduced flow on a bench.

What kind of gains or losses have you guys seen between the 2?
by travis
Mon Sep 09, 2019 5:20 pm
Forum: Engine Tech
Topic: Finally figured out how to move some air on these heads...
Replies: 14
Views: 1044

Re: Finally figured out how to move some air on these heads...

One way to check how efficient a given amount of port area is in any Head is to keep in mind that a ideal perfectly streamlined orfice of 1sq inch will flow like 142 cfm at a 28" test pressure. In a perfectly perpendicular idealized port a 1.780" valve with its 2.396" square inch of area should flo...
by travis
Mon Sep 09, 2019 2:09 am
Forum: Engine Tech
Topic: Tight lash camshaft questions
Replies: 31
Views: 1350

Re: Tight lash camshaft questions

Wasn’t the -097 Duntov in the FI 283’s like .012”/.018”? They have been around a while
by travis
Sun Sep 08, 2019 7:34 pm
Forum: Engine Tech
Topic: Finally figured out how to move some air on these heads...
Replies: 14
Views: 1044

Finally figured out how to move some air on these heads...

D832E6C0-2C93-4F16-B431-A01B879A10AF.jpeg Can you use water jackets as an intake port? After yet another depressing flow bench session on these E5AE smogger 351w heads, it was decided that the 1.78” intake valve is just too small. These 2.125” valves should fix that. There’s about .030” between the...