Author Topic: The pure stock quest for 11's continues  (Read 14762 times)

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Offline notabiker

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Re: The pure stock quest for 11's continues
« Reply #75 on: August 08, 2017, 08:00:54 pm »
Very impressive times,are you still using the stock vacuum secondaries in the carb or have you converted to mechanical linkage ?, My 428 back in the day liked the vacuum operated secondaries much better. opening up the rear part of the carb too soon just spun the tires. Funny 48 years later i still remember it running its best with the stock jets 66 front. I put in 68s for a while thinking the jetting was for smog not performance WRONG .It ran better with 66s in the front. Cant remember what had in the back  .
1969 ram air 428 mach 1
1966 GT 350
1968 chevelle ss 396 375 HP
1988 mustang GT
1991 saleen W 5 lb vortec supercharger
2002 Lightning PU
82  hatch back drag stang, 10.5 tire heads up small block class ,no power adder 377 windsor
1987 427 Cobra kit car

Offline 428 CJ hardtops

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Re: The pure stock quest for 11's continues
« Reply #76 on: August 16, 2017, 12:19:08 am »
Very impressive times,are you still using the stock vacuum secondaries in the carb or have you converted to mechanical linkage ?, My 428 back in the day liked the vacuum operated secondaries much better. opening up the rear part of the carb too soon just spun the tires. Funny 48 years later i still remember it running its best with the stock jets 66 front. I put in 68s for a while thinking the jetting was for smog not performance WRONG .It ran better with 66s in the front. Cant remember what had in the back  .
Still run vacuum secondary's with a quick change spring kit .Stock front jets a 2 sizes smaller than stock rears  .On a chassis dyno on a cool day it liked that .When its hot I should probably drop 2 more in the rears .
Got my head gaskets today ,new cam (same as the current one but not wearing down like the current one )will be in next week .New heads and rockers also (bit more compression).Get the cam coated on the lobes and hopefully by labor day everything changed and making time trials before the Pure Stock race in Michigan September .Hope the 11's will finally happen.
had many 428 CJ and SCJ cars over the last 30 years.I currently own a 68 1/2 coupe and a 69 R code SCJ Coupe and a 70 R code SCJ Cougar Eliminator .I am looking for a 70 428 coupe if anybody knows of one for sale.

Offline crossboss

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Re: The pure stock quest for 11's continues
« Reply #77 on: August 16, 2017, 05:16:07 pm »
Very impressive times,are you still using the stock vacuum secondaries in the carb or have you converted to mechanical linkage ?, My 428 back in the day liked the vacuum operated secondaries much better. opening up the rear part of the carb too soon just spun the tires. Funny 48 years later i still remember it running its best with the stock jets 66 front. I put in 68s for a while thinking the jetting was for smog not performance WRONG .It ran better with 66s in the front. Cant remember what had in the back  .



Again, I agree. My old heap ran the best with 64/74 jetting. It especially liked the leaner tuning at LACR. When I raced it with 66/76 jets it was about a 1-2 tenth difference, however it ran about 1 mph faster. It also did not like a double pumper or larger carb. The OEM 735 worked the best. That said, it just 'felt' snapper with the 64/74 set up.
<My old C.J. heap  aka  S-B Racing!
Current lifelong project: 1969 Mustang Fastback/FOX chassis, Powered by a modern Can-Am 494 (Boss 429), Kaase headed, Autolite 1425 cfm 'B' Inline carb, 6 speed, 4 wheel discs, ala Trans-Am style--Whew!

Offline 161854

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Re: The pure stock quest for 11's continues
« Reply #78 on: August 17, 2017, 10:11:19 am »
  The small jetting is thanks to the "truck booster" used on the primary side of an otherwise 780 CFM carb. The straight leg and "skirt" really pull fuel so the smaller jet is used versus a 72 normally used in a 780.
68 1/2 CJ FB San Jose white/blue "C" stripe Foulger Ford
 66 GT350 Hertz SFM 6S 477 white/ blue side stripes 1  of 18
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Offline crossboss

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Re: The pure stock quest for 11's continues
« Reply #79 on: August 17, 2017, 12:06:36 pm »
  The small jetting is thanks to the "truck booster" used on the primary side of an otherwise 780 CFM carb. The straight leg and "skirt" really pull fuel so the smaller jet is used versus a 72 normally used in a 780.



Randy,
You are correct. That is why I prefer the OEM 735 CJ carb over any other Holley.
<My old C.J. heap  aka  S-B Racing!
Current lifelong project: 1969 Mustang Fastback/FOX chassis, Powered by a modern Can-Am 494 (Boss 429), Kaase headed, Autolite 1425 cfm 'B' Inline carb, 6 speed, 4 wheel discs, ala Trans-Am style--Whew!

Offline 161854

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Re: The pure stock quest for 11's continues
« Reply #80 on: August 17, 2017, 03:01:40 pm »
    Scott,
       You have to be careful . The 735 can "over carburate"  if the primary "sees" too much vacuum.  Bottom line the carburetor that gives the best performance is the one to use. I know that sounds more simple than it really is.
68 1/2 CJ FB San Jose white/blue "C" stripe Foulger Ford
 66 GT350 Hertz SFM 6S 477 white/ blue side stripes 1  of 18
3 magazine covers- Car Craft July '77,  Modified Mustangs Feb '11 , and June '14 Mustang Monthly
'78 F350 Oleynik racecar hauler

Offline crossboss

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Re: The pure stock quest for 11's continues
« Reply #81 on: August 17, 2017, 09:01:00 pm »
Randy,
Yes, I should have stated the best OEM 735 Holley on/for a 428 CJ. Also, the 735 seems to work better on a Boss 302 too. I also like to use the Autolite/Motorcraft 4300/4300-D carbs on my 351 Windsors, as they have performed exceptionally well too…for me.
<My old C.J. heap  aka  S-B Racing!
Current lifelong project: 1969 Mustang Fastback/FOX chassis, Powered by a modern Can-Am 494 (Boss 429), Kaase headed, Autolite 1425 cfm 'B' Inline carb, 6 speed, 4 wheel discs, ala Trans-Am style--Whew!