| Author | Message | ||
| Randall Booth (Randall)
New member Username: Randall Post Number: 29 Registered: 1-2003 |
Anyone ever see or try installing a fan in the engine compartment? I was just wondering if an 8" fan blowing air up out of the compartment would help at all. | ||
| Dan B. (Dan_the_man)
Junior Member Username: Dan_the_man Post Number: 86 Registered: 9-2002 |
My 79 glows. noticable at night, not too bright. Car runs great. | ||
| Paul Newman (Newman)
Intermediate Member Username: Newman Post Number: 1063 Registered: 12-2001 |
I get that starvation problem on a hard turn too. Without trying to address it, Ive been told its a characteristic of the car. The FI solved this. If there is a fix, let me know and Ill do it. I havent changed my pump jets yet but plan to this summer. Definately change them, you will see a gain just as the mains help when up sized. | ||
| John_Miles (John_miles)
New member Username: John_miles Post Number: 27 Registered: 7-2001 |
On the subject of accelerator pump jets, what sizes are people running? The diagram shows a metering bushing in addition to the jets themselves. Both are calibrated parts with stock apertures around 0.050" if I remember correctly. I haven't messed with mine yet, since the tops have to be removed from the carbs to get to them. Is it true that fuel starvation in corners has more to do with undersized pump jets than the floats' orientation and level? | ||
| Paul Newman (Newman)
Intermediate Member Username: Newman Post Number: 1061 Registered: 12-2001 |
JRV, explain how the air correctors (which are for high speed mixture) and emulsion tubes will have any impact on transition from idle to main circuts. The air correctors WILL NOT change that. I would look at the accellerator pump jets to "cover" the hole between the two circuts. That is one of its purposes anyway. The stock accel jets are too small and a performance gain will be found by changing these as well and most likely fix the lag too. | ||
| JRV (Jrvall)
Member Username: Jrvall Post Number: 597 Registered: 11-2002 |
>>If the main circuit enrichment is significantly different from the idle circuit, the transition between the two circuits becomes very noticeable,<< AC Jets & Imulsion Tubes! | ||
| John_Miles (John_miles)
New member Username: John_miles Post Number: 26 Registered: 7-2001 |
Given you were at 55/135 before and upgraded to 60/140 (if I understand your post), have you checked to see if you are going too rich on the transition from idle to main? I'd have thought you'd go 55/135 to 50/140, not 60/140 It seems to prefer richer idle jets with richer mains. If the main circuit enrichment is significantly different from the idle circuit, the transition between the two circuits becomes very noticeable, in the form of a lurch or discontinuity in throttle response. It definitely does better with the 140/60 combination than with 140/55, although I'm still not convinced I'm running the whole thing unnecessarily rich. I'll probably go through a couple tanks of gas on this combination before making any further comments, though. | ||
| Matt Lemus (Mlemus)
Intermediate Member Username: Mlemus Post Number: 1392 Registered: 8-2002 |
Hans, it was fun. You need to move to So Cal. When are you coming back? | ||
| Hans E. Hansen (4re_gt4)
Member Username: 4re_gt4 Post Number: 773 Registered: 4-2002 |
Tom: Mine were gone when I got the car. Don't frankly know the pros and cons. I've had a couple of experienced F-mechanics crawl around and pronounce that they can't see any ill heat related effects. I do worry a bit about 'heat soak' in the summer - hot headers, hot motor, high ambient. So I open up the engine cover when parked to allow a little convection air flow, particularly around that cramped front header. But nothing looks like it has been hot. There is even a soft rubber covering to a wiring harness going to the starter that is still soft and pliable. I'd think that if there were a zillion degrees in the area that this piece of rubber would have hardened or burnt. Life of headers? I've not a clue. Mine look OK, but..... Ask Peter Rychel. He's had experience welding up 308 headers. PS: Matt - I'll never forgive you. <jk> BTW, seriously bummed that I couldn't have done that new year's day thing. | ||
| Ken (Allyn)
Member Username: Allyn Post Number: 654 Registered: 10-2001 |
My steel headers didn't glow; just the SS ones. | ||
| Paul Newman (Newman)
Intermediate Member Username: Newman Post Number: 1051 Registered: 12-2001 |
Mine were already gone tom and it sure makes it easier to remove the header when they are less bulky. I would think removing them would prolong the life of the headers. Prevent them from becoming brittle. Mine dont glow either and Im running 55 idles and 140 mains. | ||
| Tom Bakowsky (Tbakowsky)
Junior Member Username: Tbakowsky Post Number: 159 Registered: 9-2002 |
Have any of you removed the heat sheilds on your cars? I was thinking of doing this to increase the life of the header. Of course I'll have to make a heat sheiled for the air flowmeter base and near the alternator. Just wondering if it's a good idea or should I just leave it and wait for the rattles to appear? | ||
| Philip Airey (Pma1010)
Junior Member Username: Pma1010 Post Number: 91 Registered: 7-2002 |
John Given you were at 55/135 before and upgraded to 60/140 (if I understand your post), have you checked to see if you are going too rich on the transition from idle to main? I'd have thought you'd go 55/135 to 50/140, not 60/140 Philip | ||
| Matt Lemus (Mlemus)
Intermediate Member Username: Mlemus Post Number: 1390 Registered: 8-2002 |
I stand correct Hans. I forgot to mention that mine do not glow as well. | ||
| Hans E. Hansen (4re_gt4)
Member Username: 4re_gt4 Post Number: 769 Registered: 4-2002 |
Actually, Matt, that's what the Prev Owner said he got with a heat gun pointed at the headers. I'm not sure where he was getting the reading from with the shields installed. He was reading 1600 deg before. FWIW, my headers show no signs of glowing in the dark - at idle, after a hard run, or at any other time. Just cold dark steel. OK, so not so cold. But dark. | ||
| Matt Lemus (Mlemus)
Intermediate Member Username: Mlemus Post Number: 1387 Registered: 8-2002 |
Hans Hansen told me that if you remove the heat shields, it drops the engine compartment temp by 900 degrees. | ||
| John_Miles (John_miles)
New member Username: John_miles Post Number: 25 Registered: 7-2001 |
Thanks VERY much for the reassurances. I can now sleep.  The 140 mains really did make a significant difference, on further driving. They feel stronger, but the progression from the idle circuit is much more obtrusive. Not hiccuppy like it was before, but not smooth either. I've got some 0.060 idle jets coming from Pierce Manifolds even as we speak... more later! | ||
| Bruno (Originalsinner)
Member Username: Originalsinner Post Number: 895 Registered: 5-2002 |
Mine were as Ken described. | ||
| Ric Rainbolt (Ricrain)
Member Username: Ricrain Post Number: 395 Registered: 2-2002 |
My 308 GTSi has the stainless headers (US spec), and they glow at idle. Not noticible in the daytime, but starting at dusk you can see a dark orange glow. My engine analyzer showed the mixture to be almost spot on. | ||
| Ken (Allyn)
Member Username: Allyn Post Number: 645 Registered: 10-2001 |
My SS glow, but only in the dark. A nice cheery dull orange, which is normal. When I was running lean it was a very bright orange you could see in the day; not good! | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 354 Registered: 5-2002 |
Yes they glow. Exhaust temps are something like 1200F plus, the header are insulated. You should be able to start to see a glow at about 1000F. They should glow. I bothered me too the first time I saw it. | ||
| John_Miles (John_miles)
New member Username: John_miles Post Number: 24 Registered: 7-2001 |
So... I just managed to track down an interesting problem on my carbureted 308GTB. A few days ago, I started hearing a funny metallic whistling/rustling noise when the engine speed passed through the 3000-4000 RPM zone. At first it seemed to occur only during acceleration, but eventually the noise became audible when revving the engine in neutral. It wasn't very loud -- my mechanic couldn't even hear it until I told him exactly what to listen for -- but it didn't sound good. Pulling into the pits(*) at night and opening the hood revealed something I hadn't noticed before -- a dim orange glow around the inspection ports of the rear exhaust headers, visible through the slightly-oversized openings in the heat shield surrounding the ports. I immediately jumped to the conclusion "exhaust leak," but the mechanic pointed out that those headers were intended to get pretty hot for emissions-control purposes, and argued in favor of driving around a little more to see if the whistling noise got worse or changed. I wasn't crazy about that idea, so tonight I pulled the airbox off to check the intakes, choke covers, and vacuum lines carefully. All seemed OK. What I did notice, though, was a large dead leaf curled around the alternator belt. After removing the leaf and putting everything back together, the noise seems to have gone away entirely! However, that still leaves me with the question of the glowing headers. I've never noticed that before -- not that I've looked specifically for the condition -- and it seemingly doesn't have anything to do with the noise I was hearing. The plugs looked OK, if a bit 'hot and lean' (I'm running the BP5ESes recommended in the last Forza service column). Two of the idle-mixture screws on that side were actually adjusted beyond cylinder cutoff -- only about 1.25 turns out, while the rest were around 2.5-3 turns out. I corrected this, but it didn't have any effect on the glowing headers. Since I was in there anyway, I took the opportunity to richen up the main jets from 135 to 140. AC jets were left at 200; idle jets were left at 55. This, also, did not have any effect on the headers. The drivability hiccups I'd seen with 140 mains prior to the recent Weber rebuild job seem to be absent now, but I can't really tell if there was any increase in power beyond possibly a slight improvement in midrange response. Certainly nothing like what I saw going from 130 to 135. Our club dyno session scheduled for March 1 should put this question to bed once and for all. The more pressing question is: are the dim-orange headers anything to worry about? Who here, especially owners of carbureted cars, has noticed anything like that? Should I be expecting cracks to develop? I've heard that 308 headers are getting very expensive and hard to come by, so I'd really rather not damage mine. But it's not clear what, if anything, I can do to stop the glowing. (*) For what it's worth, the smog pumps are sitting in a box courtesy of the previous owner. I haven't installed them since this is purely a track car that is never driven on the street. |