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Discussion Starter #1
It went better than expected. Only thing is the rear three cylinders on each side had the headers glowing red with the rear two on each side worse than the others. It is a 383 with a 671 blower. The timing is locked out and right now is at 28 degrees. Fuel is a mix of 100 and 91 octane for an average of 94. As I got the timing under control some of the color went away but was still red. Temp came up to about 205 when my timing light vibrated off and into the engine compartment :eek: Shut the engine down to retrieve it (all is OK with it luckily) then after checking for leaks etc.. Fired it back up to finish breaking in the cam (breaking in on outer springs only)Temp came back up after another 15 minutes of it running at 2000 rpm idled it down to 800 rpms and it purred like a kitten.
I need to get the carbs richer I think? They are Edelbrock 1407's I'm not a carb guy at all. I can assemble an engine as I did with this one but when it comes to carbs I give em a pass to the experts. Any suggestions?
Thanks and a pic of the engine
 

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what is your intial timing? I have read on here that not enough intial timing can cause your headers to glow like that while breaking in the motor? Hopefully that didnt take some of the shine off of your coated headers...

Awesome looking motor you have there....I bet is sounds way cool:cool: :)
 

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I would look at blowerdriveservice.com. BDS has a tech section that might help you out. It looks like they say the problem is either not enough initial timing or too lean.
Chris
 

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If all seems well at idle but it gets hot at 2000 RPMs I'd think the intermediate circuits of the carbs are lean. That is controlled by the air bleeds and can be corrected. I intentionally run my intermediate circuits lean to keep the plugs cleaner riding around the pits but that's just me. I'm not real carb smart but the guy who does my carbs is and I got his number..LOL.
I think if the timing was way off it would get hot at alll engine speeds. RM
 

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Discussion Starter #8
69NovaSS said:
what is your intial timing? I have read on here that not enough intial timing can cause your headers to glow like that while breaking in the motor? Hopefully that didnt take some of the shine off of your coated headers...

Awesome looking motor you have there....I bet is sounds way cool:cool: :)
The timing advance is locked out. It is at 28 degrees so I guess you could say that initial is 28 degrees with no advance.
It took the shine off the rear three cylinders on both sides :(
I knew it could do that, just wishing it wouldn't though. Hence the mixed fuel to lift the octane. I really believe the hot cylinders is from a lean condition. Once it fired I had it at 28 degrees within 30 seconds and it still stayed red just not as cherry as when it first fired.

Thanks for the kind words on the motor.
 

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Discussion Starter #9
Real McCoy said:
If all seems well at idle but it gets hot at 2000 RPMs I'd think the intermediate circuits of the carbs are lean. That is controlled by the air bleeds and can be corrected. I intentionally run my intermediate circuits lean to keep the plugs cleaner riding around the pits but that's just me. I'm not real carb smart but the guy who does my carbs is and I got his number..LOL.
I think if the timing was way off it would get hot at alll engine speeds. RM
I think you're right about the intermediate circuits being lean. Just need a carb guy and dyno to straighten it up.
 

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You haven't tried any timing higher than 28°? What's the compression of the motor? I would think that you'd want in excess of 40° at idle to get the exhaust temps down.
 

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Discussion Starter #11
Mike Goble said:
Why only 28° advance? This could be a big part of your red header problem.
Well, I was told by Hampton to run it at 30 degrees with pump gas. Should it be more or less? When it first fired it was at 60 degrees advanced when I hit it with the light. In the mist of trying to bring up the idle screw, running the light, and noticing that both carbs had the rear plug out for the brake vacuum (wondering how the hell I missed that earlier), I twisted the distributor and it settled in at 28 degrees. So I left it to tend to the trans fluid, checking water level, leaks, etc...

I'll be the first to say that I'm not the keenest on timing or carb issues. Hampton said to fire it at 30 so I went with it. I have no problem defering to those that know better than me. I also realize there are a lot of opinions out there. What I will do is look for someone that knows these carbs, blowers, and has a dyno. Any suggestions Mike? Thanks
 

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Discussion Starter #12
Mike Goble said:
You haven't tried any timing higher than 28°? What's the compression of the motor? I would think that you'd want in excess of 40° at idle to get the exhaust temps down.
No, nothing higher yet. Overall compression is 8.5
Cam is .553in .569ex on a 112 lc running duration is 280in 295ex
 

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How long did it run with vacuum ports unplugged?.....that would lean it out.
This is kinda like comparing apples to oranges but on my 350 with a mini blower I'm running 24* advance at idle and my exhaust temps are signifigantly less than at mid or higher rpms (36* total advance). I have an exhaust gas temp gauge so that's how I know. in my case the idle circuit is probably too rich.
Have you checked how much vaccum you have at idle... above the blower.
 

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It seems to me that a blower motor would have unusual timing requirements to operate efficiently on the street. When you're making no boost, which is about 95% of the time, you're driving an 8.5:1 compression motor with an cam that's too large on fuel that burns too slow. The timing requirements for this operation would be markedly different from being under 10# of boost, which will raise the cylinder pressure to something equivalent to 14:1 compression.
We've used a couple of the MSD boost retard modules on blown cars with great results, a huge increase in pre-boost torque with enough retard to keep from detonating at high boost. We even have one customer who runs a full vacuum advance setup on a blown 355 that he drives everyday.
 

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Discussion Starter #15
shawn63 said:
How long did it run with vacuum ports unplugged?.....that would lean it out.
This is kinda like comparing apples to oranges but on my 350 with a mini blower I'm running 24* advance at idle and my exhaust temps are signifigantly less than at mid or higher rpms (36* total advance). I have an exhaust gas temp gauge so that's how I know. in my case the idle circuit is probably too rich.
Have you checked how much vaccum you have at idle... above the blower.
Shawn it wouldn't run and kept stalling. It back fired once and I saw the light smoke puff out the holes so I quit until I plugged them.
I have not checked the vacuum other than what the boost/vacuum gauge showed at 2000 rpms and that vacuum was from below the blower.
 

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I think I would question running a locked dist. on a street driven car. I use a MSD timing computer which I've set to begin advance at 1200 rpm and its all in by 2800. I also have a boost retard setup; 4* retard under boost....note my little blower only makes 6psi.
 
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