Steve, Think you're right. The object being to slow the Fuel/air down after it leaves the carb and before it impinges on the manifold plenum bottom and seperates. I've seen polycarbonate manifolds with little rivers of fuel running down the intake runners. Doubt if that burns very well.   

Frank/Rebop

Bristol, In ( by Elkhart) 

Am I confused (happens a lot anymore)? - isn't the spacer suposed to be made with the 4 holes matching the carb baseplate bores and then opening up and tapering away as air leaves the carb? This seems upside down to that concept.

On the other hand - I sure can see the advantage of smoothing the edges of the air entry into the manifold too. Seems like you need two transitions - one out of the carb - and one from the open plenum into the manifold passages.  

 
 Steve Metzger       Tucson, Arizona

Thanks Billy and Charlie... That's what I needed to know. I'll continue on. There is a good used Barry Grant Mighty Demon 750 CFM blow thru carb with mechanical secondaries on Epay that I think I'll go for to top things off.

Rono

  Ron Lane,  Meridian, ID

Definitely match the intake to the spacer opening and put a radius on the transition from the carb to the runners. You can epoxy the recessed portion and carefully file it flat. I'd use either an open or divided gasket between the spacer and manifold - you can trim your four hole into a divided or open gasket. It really won't make a whole lot of difference which gasket you use.


Lawrenceville, GA

Ron, on the slotted intake i would go with the open gasket otherwise the 4 hole could rip out between bores and peices go through your motor with no support under them.

Ted/John, just thinking about the blowthrough scenario, could it be that being open, the manifold is slightly charged but when the valve opens the air has to search for that open valve and you have the air going all sorts of directions fighting and bumping into itself to get to whichever valve is open. whereas in a direct 4 hole combination, each runner has a full charge and is ready to enter the cylinder as soon as the valve opens? I guess an 8 hole (2-4bbl) would be optimal if it was the case.

55 Vicky & customline

58 Rack Dump, 55 F350 yard truck, 57 F100

59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?

Continuing on with my blower motor project, I've elongated the holes in my "B" intake and since this will be a street motor, I went with a Quick Fuel 1" tapered hole phenolic carb spacer (P/N 300-4150-1) that I will use with either a Holley 4150 HP or double pumper carb. I'm a little confused on the spacer gaskets (which ones to use where), to weld in or epoxy fill the gaps left under the gasket and if I should try to do any additional port matching. Here are a few pictures of whatI have going on.

 

 

Rono

  Ron Lane,  Meridian, ID

thanks for the info guys!

1956 F-100 in the works.

If the engine is just going to be a steady state cruiser and never see over 3500 rpms, then a four hole spacer under the carb will give the best lowend torque numbers.  If you want additional passing gear performance, then the tapered spacer design shines.  With the aluminum heads, torque increase is substantial so the tapered spacer design would work out to be the best overall.

Lorena, Texas (South of Waco)

Hadn’t thought of trying the tapered spacers upside down; holes on the bottom instead of the top.  Down the road when there is a four hole intake back on the dyno, I’ll give that scenario a whirl.  At this point, I’m even thinking two tapered spacers with the open cavities matched up together and the holes themselves at the carb and the intake.  Lots of possibilities here when talking about combinations.

Lorena, Texas (South of Waco)

Based on the results that Ted got from my engine, I would start with the HVH 2" tapered spacer. But and a big but, every engine is different and what works for one combination may not be good for another. I am old school and always had my doubts about dyno tuning, but I am convinced that if Ted had not taken the time to try different combo's, I would have a 385 HP engine instead of a 415 HP engine. From my experence with stock cars, I would have stuck a four hole spacer on it and called it good. Dyno time and a good tuner is dollars well spent, it might take a seasons trips to the track trying different things to find what you can in a day on a dyno.

Glen Henderson



Freedom is not Free

Letohatchee, AL