Meet the man who makes Man-a-fre in­duc­tion set­ups like new again.

The Man Who Makes Man-a-fre Set­ups Look Like New

Hot Rod Deluxe - - Contents -

“Man-a-fre? That’s the kind of in­jec­tion setup they had on the yel­low Mil­ner coupe in Amer­i­can­graf­fiti,” Bob Hansen said. As a film buff with a movie theater in his base­ment and a car buff with a ’55 Chevy gasser in the garage, Hansen knows these kinds of things.

How­ever, it’s likely that no one knows as much about Man-aFre carburetor in­jec­tor sys­tems as Dave Petersen of Wauke­sha, Wis­con­sin. Dave has re­stored Man-a-fre set­ups for small-block V8s and Man-a-fre di­rect-port-in­jec­tion sys­tems de­signed for Chevy big-block V8s. One of the lat­ter units is a rare After­burner in­jec­tion sys­tem; and Petersen has also re­stored what is con­sid­ered the rarest After­burner that was de­signed for the big-block Chevy V8.

The After­burner fea­ture was a pre­cur­sor to to­day’s di­rect-port ni­trous ox­ide in­jec­tion. Fuel bosses were pre-spot­ted by the fac­tory, and op­tional After­burner so­le­noids and plumb­ing were of­fered to in­ter­ested buy­ers.

Ac­cord­ing to Kip Pull­man’s Amer­i­can Graf­fiti blog (kip­samer­i­can­graf­, the yel­low chopped Deuce coupe used in the movie was pur­chased in the Los An­ge­les area by the film’s pro­ducer, Gary Kurtz, who paid about $1,300 for the ’32 Ford. The blog says it was al­ready chopped, but not fin­ished, and needed both me­chan­i­cal and cos­metic work. The film’s trans­porta­tion man­ager, Henry Travers, took the car to a cou­ple of North­ern Cal­i­for­nia shops near the film­ing lo­ca­tions to get the needed work done. Johnny Franklin’s Muf­flers in Santa Rosa in­stalled an early Man-a-fre small-block in­take with four Rochester two­bar­rel car­bu­re­tors.


The name Man-a-fre meant the in­jec­tion sys­tem, de­vel­oped by Robert Pa­trick, was “free from man­i­fold pas­sages.” Con­ven­tional man­i­folds don’t dis­trib­ute fuel equally to all cylin­ders. To help com­bat this prob­lem, Pa­trick de­cided not to use a con­ven­tion­al­type man­i­fold. In­stead, he used a plate that four car­bu­re­tors could be mounted on.

Pa­trick started in At­lanta and had the plates made by dif­fer­ent foundries. Some early 1962 cast­ings, like the one on the movie car, had “MAN-A-FRE. MFG. CO. AT­LANTA 3, GA. PAT. NO. 2,896,597 OTHER PATS APL’D FOR” cast into them.

By 1963, a man named Harold Graves had re­fined the cast­ings a bit and moved Man-a-fre to Canoga Park, Cal­i­for­nia. Some kind of pub­lic­ity cam­paign must have been car­ried out, be­cause the Man-a-fre In­jec­tor Car­bu­re­tion sys­tem showed up in ad­ver­tise­ments and ar­ti­cles in a num­ber of hot rod­ding pub­li­ca­tions. Speed­me­chan­ics (Dec. 1962 and Feb. 1963), Hop-up, Cus­tom

Rod­der, Speedand­cus­tom (Jan. 1963), Car­craft (Oct. 1964), Pop­u­larhotrod­ding (May 1966), and HOT ROD (July 1968) all ran sto­ries about the sys­tem. It was also fea­tured in Petersen Pub­lish­ing’s Ba­sic­fu­el­sys­tems Spotlite Book and the Cus­tom­rod­der Hand­bookno.4.

The main part of a Man-a-fre kit was the alu­minum plate that locates the four car­bu­re­tors di­rectly over the in­take ports to achieve per­fect fuel distri­bu­tion and max­i­mum per­for­mance. With the 9-pound plate and four two-bar­rel car­bu­re­tors in­stalled, there was one carburetor bar­rel for each cylin­der of a V8.

Cus­tomers could buy the plate with built-in in­jec­tors or with stan­dard carburetor mount­ing pads. If they did the lat­ter, they could add in­jec­tor car­bu­re­tors that worked just like the built-in in­jec­tors. Man-a-fre could also sup­ply mod­i­fied car­bu­re­tors if the cus­tomer wanted them. It also of­fered the After­burner set­ups and all the nec­es­sary in­stal­la­tion com­po­nents such as cus­tom­made ball-bear­ing link­ages and fuel blocks.

The first Man-a-fre sys­tems were de­signed for the 265-283327 Chevy small-block V8s, but Graves said all the ac­ces­sories could be adapted to any en­gine, and the in­jec­tors could be used with any carburetor or man­i­fold. Man-a-fre could sup­ply stock GM Rochester two-bar­rel car­bu­re­tors or Rochesters that were spe­cially mod­i­fied with trimmed arms and built in After­burner in­jec­tor noz­zles. Graves pre­ferred the large, 3-inch-di­am­e­ter Rochesters (13⁄ 4- inch bore size) used on 1957 Pon­ti­acs, to which he added cus­tom arms so they could work when close to­gether. He would also spe­cially mod­ify carbs with built-in in­jec­tors. A bal­ance tube that was cast into the plate pre­vented any one cylin­der from scav­eng­ing off too much fuel.

Graves also re­worked Oldsmo­bile Rochester car­bu­re­tors (11⁄ 4inch ven­turis) and Chevy truck car­bu­re­tors for use with the ManA-fre sys­tem. The four truck car­bu­re­tors pro­vided a to­tal of 7.50 square inches of ven­turi area. Graves also sup­plied carb adapters to mate the big carbs to smaller bases, and the cost was only about $8 back then.

The lack of tra­di­tional man­i­fold pas­sages kept the height of the en­tire setup very low. Even with the four car­bu­re­tors mounted

and air clean­ers at­tached, ev­ery­thing fit un­der the hood of a Corvette with­out any clear­ance prob­lems. The sys­tem looks great, and hood­less cars like the Mil­ner coupe show it off to its best ad­van­tage.


Whether it’s those looks, the in­ter­est­ing his­tory, the me­chan­i­cal in­no­va­tion, or the rar­ity, Dave Petersen has what he de­scribes as “a Man-a-fre fas­ci­na­tion.” He has col­lected and re­stored dif­fer­ent types of Man-a-fre set­ups, re­searched facts about the com­pany, dug up old mag­a­zine ar­ti­cles that ex­plained Man-a-fre con­cepts, hooked up with a for­mer Man-a-fre em­ployee named Tim Bow­man, and taken to heart Bow­man’s wish that he share his knowl­edge of the sys­tem with other en­thu­si­asts and col­lec­tors.

“It’s a pas­sion pro­ject,” Petersen ex­plained. “A Man-a-fre is some­thing I saw when I was a kid, and I just be­came fas­ci­nated with them. The small-block-chevy ver­sion—just the straight small-block ver­sion with­out the After­burner—was re­ally the start for me, but to find an orig­i­nal big-block Man-a-fre with After­burner that was put in a duf­fle bag in 1969 and kept there 47 years made it spe­cial.”

Petersen bought his first small-block-chevy Man-a-fre setup at a swap meet and his first big-block-chevy Man-a-fre with After­burner off ebay, but says he first learned about the lat­ter on an in­ter­net fo­rum, through a chat line where users were talk­ing about all kinds of me­chan­i­cal topics. Later, when it showed up on ebay, he re­al­ized it was the same one and bought it.

That big-block Chevy Man-a-fre sys­tem with After­burner has its orig­i­nal 1958 Pon­tiac large-bore Rochester 2G car­bu­re­tors. Petersen’s re­search re­vealed that Harold Graves would buy the car­bu­re­tors new in the box, stow them away and then, as he built an in­jec­tion sys­tem, pull the “fresh” car­bu­re­tors out and do the in­ter­nal changes nec­es­sary for the par­tic­u­lar in­jec­tion setup. “This sys­tem was built and pack­aged in 1967,” Petersen discovered.

The man who bought it was from west­ern Iowa. He used it on a Corvette he raced for a year and a half. Then, in 1969, he went in the ser­vice and was sent to Viet­nam. “That’s when the Man-a-fre went into a duf­fle bag,” said Petersen. “When he came back from Viet­nam, he was go­ing to put it on the big-block in his ’57 Chevy, but he never did that. So, there it sat in his duf­fle bag for all those 47 years. And then, I got it.”

Due to the Man-a-fre’s “in-the-bag” stor­age, it had re­mained in very good con­di­tion down to the orig­i­nal, never-touched-up Chi­nese Red paint on the carburetor bases. “Noth­ing had been or has been changed at all,” Petersen pointed out. “The parts that you see on it to­day are al­most all orig­i­nal parts. The only ex­cep­tions would be the ther­mo­stat hous­ing, the tem­per­a­ture switch, and one clip. Out­side of those, ev­ery sin­gle piece on this setup is the orig­i­nal piece re­stored back to work­ing con­di­tion. I don’t know if this could have been done if it hadn’t been stored so well for all those years. When I got it, the Man-a-fre was 100 per­cent com­plete, un­touched, and ab­so­lutely beau­ti­ful.”


Petersen says it is hard to de­fine how long it took him to re­store the first Man-a-fre. “There were days when I spent lots of time just track­ing down peo­ple who knew about these sys­tems, and I think that do­ing that was one of the most fas­ci­nat­ing parts of the pro­ject. In fact, that’s how I wound up get­ting in touch with Tim Bow­man. Back in Fe­bru­ary, I was on the phone with Bob Kunz, a carburetor guru from the St. Louis area who’s been re­build­ing car­bu­re­tors for 42 years. He gave me Tim’s email and told me that I should send him a mes­sage.

“Tim emailed back, ask­ing if I could send him a photo. I sent him a cou­ple of pic­tures, and he sent me his phone num­ber and told me to call him in Penn­syl­va­nia. When we talked, Tim says to me, ‘See those welds? I did those 50 years ago out in Canoga Park, Cal­i­for­nia.’” It turned out that Bow­man had worked for Harold Graves and had done the fi­nal assem­bly on the man­i­fold that Petersen had pur­chased!

“Tim rec­og­nized his work, be­cause each man­i­fold they made was lit­er­ally a cus­tom job. He would put them to­gether, pack­age them up, and ship them out,” Petersen ex­plained. “And Tim not only be­came a good friend through the tele­phone calls and emails, he also was the one who be­came in­stru­men­tal in help­ing me to un­der­stand some things about Man-a-fre, be­cause it was all new to me when I started. He gave me a lot of de­tail that I could not have found any­where else. Some of the old mag­a­zines—two es­pe­cially—are good in ex­plain­ing the ba­sic premise of the sys­tem, but Tim’s in­side knowl­edge goes way be­yond even those. That’s the part he shared will­ingly with me. The only thing he asked in re­turn for his help was that I pass the in­for­ma­tion I learned onto any­body else who was in­ter­ested, So, I’m thrilled that he helped me.”

Petersen’s Man-a-fre fas­ci­na­tion didn’t ebb af­ter he fin­ished restor­ing his first big-block-chevy Man-a-fre with After­burner, in Au­gust 2017. He im­me­di­ately be­gan restor­ing an­other big­block-chevy Man-a-fre with an­other type of After­burner sys­tem de­signed for the big-block Chevy.

Ac­cord­ing to Dave, some peo­ple say his third unit was never made. “I can tell you, they talked about it and showed a pic­ture of it in the Jan. 1965 Hop-up mag­a­zine ar­ti­cle,” he pointed out. “This is the ‘rarest’ big-block-chevy Man-a-fre in the sense that Man-a-fre as­sem­bled it us­ing four spe­cially built 1957 Rochester 2G large-bore car­bu­re­tors. Work­ers capped two out­lets on the After­burner up­per fuel log, run­ning a cop­per fuel line to each in­jec­tor placed into the choke-plate shaft open­ing on each of the four car­bu­re­tors. They arched the in­jec­tor down­wards, spray­ing fuel di­rectly into the ven­turis.”

Dave’s restora­tion of this “rarest” Man-a-fre After­burner de­sign was com­pleted in De­cem­ber 2017, with spe­cial thanks to the folks at Zinc, Inc. in Slinger, Wis­con­sin, and to Huth Ben Pear­son In­ter­na­tional, LLC, in Hart­ford, Wis­con­sin, where the ve­loc­ity stacks were done. “A lot of peo­ple say that they never made them this way,” Hansen em­pha­sized. “But they did.”

Amaz­ingly, this “rarest-of-all” Man-a-fres was also in stor­age for many years. It was in the hands of a racer from Wash­ing­ton State, who socked it away for 40 to 45 years. No one can deny that it’s in the right hands now, be­cause Dave Petersen has re­stored it to new.


> It’s au­to­mo­tive art and his­tory—en­gi­neer­ing beauty and per­for­mance!

> Af­ter be­ing tucked away in a duf­fle bag for 47 years, here’s the very well-pre­served orig­i­nal and “rare” big-block-chevy Man-a-fre di­rect-port in­duc­tion sys­tem with After­burner unit.

> Spe­cial thanks to Tim Bow­man for teach­ing me the cor­rect ad­just­ment of orig­i­nal brass floats. Tim worked for Harold Graves at Man-a-fre 50 years ago and built this very unit.

> The orig­i­nal “rare” big­block-chevy Man-a-fre with After­burner sits next to an orig­i­nal small-block-chevy Man-a-fre sys­tem.

> Thanks to the folks at Huth Ben Pear­son In­ter­na­tional for their help fabri­cat­ing new ve­loc­ity stacks.

> That’s the orig­i­nal Chi­nese Red paint ap­plied in 1958 on those throt­tle bod­ies.

> Ev­ery­thing in its place, i.e., the orig­i­nal ball­bear­ing linkage and fuel lines. > The re­stored “rare” ver­sion of the big-block-chevy Man-a-fre di­rect-port in­duc­tion sys­tem with After­burner unit (left) next to the “rarest” After­burner ver­sion (right).

> The four rub­ber fuel lines run from the lower fuel log to feed the four 1958 Rochester 2G large-bore car­bu­re­tors. The eight orig­i­nal cop­per fuel lines run from the up­per fuel log and feed the two in­jec­tors lo­cated di­rectly into the ports be­neath each of the four car­bu­re­tors when the driver ac­ti­vates the After­burner so­le­noid above 4,000 rpm.

> This close-up view shows the eight orig­i­nal cop­per fuel lines.

> Thanks to the folks at Zinc Inc. for the new dichro­mate plat­ing on the 1957 Rochester 2G large-bore car­bu­re­tors on the re­stored “rarest” ver­sion of the big-block-chevy Man-a-fre di­rect-port in­duc­tion sys­tem. Look closely at the ex­pert en­gi­neer­ing and clear­ances of the up­per and lower fuel logs, fuel lines, and linkage for the four 1957 Rochester 2G large-bore car­bu­re­tors.

> The “rarest” ver­sion of the big-block-chevy Man-a-fre di­rect-port in­duc­tion sys­tem with After­burner unit feed­ing four in­jec­tors lo­cated in the choke-plate shaft open­ings and arched down­ward.

> Restora­tion has be­gun on the big­block-chevy Man-a-fre with the “rarest” ver­sion of the After­burner unit.

> The top view of the re­stored “rarest” ver­sion. Tim Bow­man, who worked at Man-a-fre 50 years ago in Canoga Park, Cal­i­for­nia, ex­plained how to prop­erly set up the throt­tle linkage for in­stant and smooth op­er­a­tion.

> Harold Graves liked to use mon­strous Rochester two-bar­rel car­bu­re­tors from hot 1957 Pon­ti­acs, which have a bore size of 1 ⁄34 inches and pro­vide the ul­ti­mate in street and strip car­bu­re­tion. Graves mod­i­fied the ven­turi clus­ter assem­bly bore and in­stalled a fine-wire dif­fuser shown here. You’ll also see the in­jec­tor tip set in each choke-plate shaft open­ing. The modificati­ons are shown here on the two front car­bu­re­tors; sim­i­lar modificati­ons were done to the rear two car­bu­re­tors as well.

> The busi­ness end of the mod­i­fied 1957 Rochester 2G car­bu­re­tors: the largest bore (13⁄ inches) throt­tle bod­ies.

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