Exhaust update and question

NateL

NateL

Member
I stripped the head to rebuild it, and thought I would try to improve the stock exhaust for now while everything is apart.. It had some abuse and I’ve sleeved the pipe to center the donut, and reshaped the flange to match better. Does anyone know if I have the baffle/deflector in the right way? I’m sure it is but the “front” stamp on it actually faces the rear‍♂️
 

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Something weird happened to the first photo
 

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S0updragon said:
I’m not sure but surprised that nobody has answered the question yet lol
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There was no way I was going to put that in the way it was. It had never been apart, that much I’m sure, I believe it was marked and installed incorrectly very long ago. have my van buttoned up, I have the baffle the opposite to what it was and it hasn’t boiled gas in the carb since ,easy hot starts now and I had these problems before.
 
Sorry Nate must have missed this one. It's a long time since I had one apart so the old memory is patchy, but something doesn't look right. Glad to hear you've got it sorted now,
 
Panky said:
Sorry Nate must have missed this one. It's a long time since I had one apart so the old memory is patchy, but something doesn't look right. Glad to hear you've got it sorted now,
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Thank you, the van was giving me fits the last few months, I parked it ,frustrated .then I snapped out of it , and rebuilt the entire top end , got in some fine tuning and it’s been running better than it ever has! sounds good, feels good, I’m stoked! ED241C43-2A0B-4BCA-8440-4121FBF660FC.jpeg
 
That's brilliant and looking good. I know the feeling they can be so frustrating but when they're up and running well................. :cool:
 
I dont know about my working Commer but this is my spare exhaust manifold showing the deflector plate position, deflecting to a hot spot in the middle of the inlet manifold, off a Hillman Minx :-

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NateL said:
Does anyone know if I have the baffle/deflector in the right way
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Its all to do with heating the inlet and depends on your motoring conditions(eg. racer or street), whether you need a hotter or cooler inlet manifold.

Plenty of reading on the subject here:-

https://www.rasoenterprises.com/engine-technology/40-carburetion/20-intake-manifold-heat
 
I think that confirms it, the one on Nate's manifold was fitted the wrong way round.
 
this was the way mine was originally but I can tell you absolutely and most assuredly that my van runs 1000 times better with the deflector flipped around away from the intake manifold, and I’ve had zero problems with boiling gas or hot starting. I’m running a Weber btw. Maybe the original carb needs help preheating ?
 
A flipped deflector gives a more free flowing exhaust (good) but a cooler running inlet manifold (not so good). If it works for you and the Weber though then fine:)

By the way, do you have the obligatory heat insulator under this carb?

I'm interested to find out if my deflector's been flipped now.
 
Yes, it’s had the phenolic spacer. I’ve noticed the fuel consumption has gone up since I redid everything. Not sure if it’s the deflector , or the valve timing and lash adjustments recently, doesn’t matter I’m happy with that trade off. It used to just stall out at stoplights after it got hot, boiled gas, hot starts etc. not anymore thankfully. I’ve been able to get back to the important stuff like new floor trims!
 

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NateL said:
I’ve noticed the fuel consumption has gone up since I redid everything.
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The intake manifold is now running cooler affecting (spoiling) the fuel vapourisation in there.
According to the article above, you need a heat source (hot spot or coolant heat) in the intake for street engines.
 
Hot intake charge for economy, cooler intake for a bit more power. There will still be a hot spot, as the manifolds are still joined, but not as much as before. I've gone to great lengths to get separate intake and exhaust manifolds (SU conversions) and the engines run much more efficiently than standard.
 
I have now read conflicting arguments/theories on this subject so well done for finding an acceptable balance with the Weber.
 
I know it's a bit of a minefield but I think that what ever works for you then forget the theory. For instance to get the SU I have on the Rapier engine in Harvey to run smoothly there are two springs on the piston and EP90 in the dashpot, a tuning expert would probably be horrified but it works and works well on my engine - and I get over well 30 MPG on a run. He is running a somewhat exotic inlet manifold though;)
 
I'm leaving mine well alone because a previous owner astutely fitted a Ford carb (gawd knows what model off) straight onto the existing joined-up manifold and it just works well, all year, on my standard iron 1725. I too get well over 30mpg, willing/brisk performance and no hot start problems(touch wood):)
 
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I know of another van with a Ford carb and that one runs well too. The then owner picked it up from a car boot sale, bolted it on and it's been on there ever since - well over 25 years :)
 
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