I have an Edelbrock C357 manifold drilled for three bolt and four bolt carbs (five threaded holes). Unfortunately, the existing bolt patterns do not match the small base Rochester 2GC carbs that I want to use. The manifold in on the motor and has a nice patina. I'd like to leave it in place if possible. I can get adapter plates from Automation Rochester Carburetor Service in Great Falls, Montana for $55 each. http://hotrodcarbs.com/images/largeparts/IMG_0723.jpg But I would prefer to find a cheaper solution. One option that comes to mind is filling the existing threaded holes with JB Weld or a similar product and then drilling and tapping to the 2GC pattern. Can anyone offer another solution?
I drill the holes out to 7/16 and tap it 1/2 and screw alum. all thread in the holes with loc-tite, cut them off and redrill.
If you redrill, make sure the butterfly's dont hit in the middle of the bores, I'm pretty sure they will
The mismatch is very close. Another option is elongating or drilling out the holes so the carbs fit over the studs. Any opinions?
if you dont want to remove the manifold then modify your carbs. You could make an adapter plate just as easy as drilling the manifold. its a carb, the tolerances dont have to be great, as long as the sealing surface is flat.
yule16met>>>You could make an adapter plate just as easy as drilling the manifold.>>> Yeah, what yule said --- out of nice flat pieces of hardwood from the precut hardwood bins at Home Depot or Lowes. Work great. Jack E/NJ
Heck, you could even get phenolic spacers for $19.99 each for a total of $38.98 each and still be way under the other price you gave, and have a much cooler set up, { literally } TR
The Edelbrock C357 (p/n 5419) is still available new in the 4-Bolt (or the p/n 5418 3-Bolt) pattern. I always suggest using new if they are available. If you are looking for a patina'd look, I've had customers who have sprayed their intakes with oven cleaner to smut that "to new of casting". BTW - our aluminum adapter plate @ $55.00 each does come with the studs , gaskets and hardware as pictured, so it is not just the plate your are receiving... and as noted on our site, there is a discount for multiples of 3 or more. If you need an insulator, we have those also. (A phenolic spacer is a not an adapter). JB Weld - When you tighten the carb base down to the intake manifold it will not hold.
You need to READ my post Larry, no one said a phenolic spacer is a adapter. The two items can be used together as I stated by adding the two prices together. I'm not trying to hurt you or your business, I dont even know who you are. The O/P " prefers to find a cheaper solution ", and said so. I simply gave another HAMB member a "choice", this is AMERICA still right? I'm glad more than anyone here, that another American product is being made for us here on the HAMB. Many members here dont want anything to do with Speedway parts, so the playing field is completely even for you and the original poster. I'll be the FIRST to wish you much continued sucess with your company, but please dont try an insinuate I dont know a adapter from a spacer just because you didn't actually quote me. I hope you sell 50% more spacers this year than last, Have a nice day sir, TR
After thinking over all the options I did it the way Danny G suggested. I could not find aluminum allthread so I used aluminum bolts from McMaster-Carr. Machine shop results with home shop tools and techniques. If there is enough interest I will put up a thread during tech week.
now will a new gasket and the carb base completely cover the other holes? or are they bottomed out so it wouldnt matter anyway?
I was initially concerned about that too. The gasket and carb base fully cover the one remaining hole in each flange. I checked all three holes and they are not drilled through to the air runners. If I have a problem I have four aluminum bolts left over from my box of ten. But I think I will be OK.
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