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Is this flagrant abuse of carb spacers???

Nikwho

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Okay,
First of all, I would like to say that this boat is not mine, and I'm not trash talking it at all! I've been looking to buy an old flatty v-drive. This particular boat that I've looked at has a Ford 390 FE engine. Not my first choice, but I appreciate the nostalgia of these engines.

I am morbidly curious, is this a common setup with these FE's? Or do these perform better and better the taller your stack of carb spacers get? :rolleyes:

IF I were to hypothetically pick up this boat, I was thinking that at least one layer of carb spacer would need to come off. Or, does this seem normal and is considered socially acceptable among FE enthusiasts? :D Perhaps it would get up into cooler air with some billet spacers between the carbs and scoop?

Also, while I'm prodding for Ford FE info, it seems to me that two 600 cfm cabs would be grossly over carbed for a 390" engine. Seems like something needing closer to 750 cfm worth of carb, than 1,200 cfm of carb? With all of the mildly built engines running so much carb, is it super common for all of these carbed boats to live SUPER fat?

Thanks for any insight!

Nik
 
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obnoxious001

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The racers used to do that with dual carb manifolds, look around at some of the older photos. I don't think there was a tunnel ram made for them. Not quite sure what they have going on there, but I agree it would be cleaner with the one spacer removed. It would also be interesting to run the boat before and after. In dyno testing, tunnel ram manifolds have proven to provide horsepower increases.

As to the size of the carbs, those should work correctly. You could try finding a pair of 450's if you wanted. I can't tell by the photo exactly what is on there. If the engine is tuned and jetted properly, it won't be super fat. Pull some plugs and look.
 

Nikwho

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Thanks for the info! Seemed like kind of a home made tunnel ram attempt. Then, I started looking for a proper tunnel ram for a 390 FE, thinking that an intake swap may be in order if I ended up with that boat. Then I realized that there aren't tons of options for those engines.
 

obnoxious001

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As I said, if you look around at old racing photos from the 60's, you will find that's how they did it. Lou Brummett used to run Louis Unser engines that way. That's why I suggested that you may want to retain one spacer for the old school look.
 

squeezer

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Just speculating here but there would be some tuning options with multiple spacers if the top spacer was the 4 hole type and fed to an open plenum type... The closed type might help keep the air velocity up which would compensate a bit for being over carbed... ???

(More of a question than a statement of fact.)
 

wsuwrhr

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Well...its a Ford.....so....I mean....you are surprised? :)
 

Nikwho

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Well...its a Ford.....so....I mean....you are surprised? :)
LOL. Few things surprise me. I have never been exposed to one of these FE engines. I honestly don't know what to expect. Seems that the general consensus is that this is sort of a standard setup.
 

wsuwrhr

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LOL. Few things surprise me. I have never been exposed to one of these FE engines. I honestly don't know what to expect. Seems that the general consensus is that this is sort of a standard setup.

Any engine designer that cant figure out that the component either needs to be a head, or needs to be a manifold, and not a combination of both, needs their own head examined. ;)
 

Rajobigguy

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What I used to do was too take any cheap aluminum manifold for the FE that I could find and then machine it down too accept a 351C manifold on top. that gave me a lot more manifold choices.
 

Nikwho

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Funny, I never bought the boat in question in original post, BUT I did just pick up another boat that is also abusing carb spacers, earlier this month! #carbspacerlivesmatter

This stockish 455 Olds surely doesn't need the carb this high to live its best life! But, nonetheless, it's got a single carb'd tunnel ram, with a spread bore to square bore adapter, plus a 1" phenolic carb spacer between that Quick Fuel carb and the heads! 😅 The boat runs pretty good, though. Took it out once. Ran an honest 62mph on GPS. And that was with this low buck 650cfm cast Quick Fuel Brawler carb! Can't imagine it was feeding this thirsty big block as much as it wanted!

I do have a 496 BBC build going on right now. If I can talk myself out of using all of the 496 parts in my '59 Chevy Apache, I'll be getting it installed by summer. Perhaps I'll throw the BBO in the '59 Apacge, just to have the only one powered by a 455 Olds! I imagine that this Olds would make a good street engine, with some changes.
20201230_150340.jpg
 

lbhsbz

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Google "2nd Order Harmonic" and "Joe McCarthy"

This was one of the most brilliant people I have ever had the pleasure of meeting...Vietnam vet, but led a less than healthy lifestyle and passed about 6 years ago. He played with Honda engines, built engines for Honda Racing in Canada, and spent more time on the dyno testing his designs than most folks who own dyno shops. He had his faults, but the data supports his work.

Intake runner length and header primary length can be optimized to get crazy power gains....most that are stacking spacers are seeing these gains by accident...but if you understand the theory behind it, it can be perfected. Packaging on a big cube engine is a bit rough.
 

mash on it

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Google "2nd Order Harmonic" and "Joe McCarthy"

This was one of the most brilliant people I have ever had the pleasure of meeting...Vietnam vet, but led a less than healthy lifestyle and passed about 6 years ago. He played with Honda engines, built engines for Honda Racing in Canada, and spent more time on the dyno testing his designs than most folks who own dyno shops. He had his faults, but the data supports his work.

Intake runner length and header primary length can be optimized to get crazy power gains....most that are stacking spacers are seeing these gains by accident...but if you understand the theory behind it, it can be perfected. Packaging on a big cube engine is a bit rough.

Chrysler utilized/preferred the third harmonic... back in the fifties.
Tunnel ram intakes benefit from this.
Second harmonic is difficult to package with long intake runners.
Fourth harmonic runners would be rediculously short.
Supposedly possible to gain 3psi intake pressure (boost) if conditions are right.
Theoretically, @ 5500 rpm, I would need a 15.xx" intake runner, from valve to bottom of throttle plate. A tunnel Ram would be close, and could be tuned.

I'm not an engineer, nor did I stay at a Holiday Inn in Nashville.

Dan'l
 

lbhsbz

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Chrysler utilized/preferred the third harmonic... back in the fifties.
Tunnel ram intakes benefit from this.
Second harmonic is difficult to package with long intake runners.
Fourth harmonic runners would be rediculously short.
Supposedly possible to gain 3psi intake pressure (boost) if conditions are right.
Theoretically, @ 5500 rpm, I would need a 15.xx" intake runner, from valve to bottom of throttle plate. A tunnel Ram would be close, and could be tuned.

I'm not an engineer, nor did I stay at a Holiday Inn in Nashville.

Dan'l

It was years ago...and I've got no idea where my notes are...but I discussed his principles for the 2nd order harmonic on the 496 I was running at the time...intake runner length needed to be somewhere around 26" for a 6000rpm peak IIRC... If you're on Speedtalk, he posted there back in 2013 before he passed....and also on HondaTech. He was involved in the Hondata Bonneville car and a few other salt cars too.

I didn't give the guy much consideration until I had to help him install a 90 gallon diesel tank under the bossman's toyhauler...that he designed to be held in with a grand total of (4) 1/4-28 bolts. I told him he was nuts until he showed me the math and I realized that those 4 bolts had tensile strength of 1790lbs each, which would give us a safety factor of close to 8X. The only reason he chose this size is because it's what he had on hand...otherwise, if weight was a consideration...he said he'd order some #6 screws. That's when I started paying attention to the old man.
 
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Nikwho

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Google "2nd Order Harmonic" and "Joe McCarthy"

This was one of the most brilliant people I have ever had the pleasure of meeting...Vietnam vet, but led a less than healthy lifestyle and passed about 6 years ago. He played with Honda engines, built engines for Honda Racing in Canada, and spent more time on the dyno testing his designs than most folks who own dyno shops. He had his faults, but the data supports his work.

Intake runner length and header primary length can be optimized to get crazy power gains....most that are stacking spacers are seeing these gains by accident...but if you understand the theory behind it, it can be perfected. Packaging on a big cube engine is a bit rough.


Oh my lord! What a rabbit hole I just traveled down! I googled what you suggested and spent the past 5 hours getting caught up on the theories that he spoke to, regarding tuning to the 2nd, 3rd and 4th order harmonics, and immersing myself in naturally aspirated 2.x liter Honda drag racing intake drama!! Wow... Very interesting, though!
 

lbhsbz

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Oh my lord! What a rabbit hole I just traveled down! I googled what you suggested and spent the past 5 hours getting caught up on the theories that he spoke to, regarding tuning to the 2nd, 3rd and 4th order harmonics, and immersing myself in naturally aspirated 2.x liter Honda drag racing intake drama!! Wow... Very interesting, though!

Be sure not to google "lotus" along with that name if you don't like drama...lol
 
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