spacer or not?

[manoa matt]

Here are some articles to explain differences between open spacers and spacers with multiple holes:

http://www.circletrack.com/enginetech/c ... index.html

http://www.gnetworks.com/v4files/barryg ... images.pdf

http://www.nhra.com/dragster/1999/issue ... ology.html

http://www.automedia.com/Carburetor_Spa ... 080701cs/1

[mbouse]

cool. that was what I thought i asked about in the beginning... thanks for the articles written by an obviously non-Fiat Spider nut.

so, if i understand how our webers are made, and how the intake is designed... a two holed spacer will not necessarily redistribute the mixture away from the center of the intake....and not change the majority of the mix hitting just the two center cylinders, right? or did i misunderstand?

[racydave]

Besides the butt-dyno testing, you would need facilities to bench test the flow. What would Guy Croft do??? I do not think you will re-direct the flow, At best maybe a better atomization? And the results may vary according to what warms up, and what doesnt. Direct injection is the coming thing...

[manoa matt]

I agree with racedave. The carb spacers are too cheap to necesitate renting a dyno for an hour. Luckly you only have two choices it's either open spacer or two holes. Although, if we go by history and the evolution of fiat parts, then... why did Fiat switch from the dual plane manifold to the single plane manifold??...MORE POWER. Therfore if the single plane "open" design provided more power for double barrel progressive carbs, then the single hole open spacer should be the better of the two spacer designs. Luckily if you bought the two hole you can make it a single hole.

Croft usually only uses 45 DCOE sidedrafts, because they provide 2-3% more power than 45 IDF's. So I don't think he would care about a carb spacer for a double barrel single carb. Although he does briefly mention single carbs for more low end torque.

[mbouse]

i believe you have your cronology backwards in that the dual plane two litre manifold was preceeded by the single plane 1800 manifold.

everyone knows the fully stock US '79 & early '80 were the worst performers of the big bumpers. and reverting to a single plane 1800 manifold is one, highly recommended performance enhancer.

at least the '80 came stock with a two hole spacer, the '79 prolly did too. the replacements i got are one large "oval" hole.... so i am gathering i am about to make my butt-dino smile

[manoa matt]

The 68-73 models used vacuum operated secondaries which needed a dual plane manifold.

[mbouse]

Fiat edge-E-cation. thanks.

i received my 5mm spacers from that E-Bay source. Man, they must be individually hand cut, cuz they sure don't line up when stacked. gonna have to glue 'em together and file 'em for a clean fit.

[racydave]

Krinkel paint will fill the gaps1

[So Cal Mark]

how many are you going to stack up? are they phenolic or aluminum?

[mbouse]

two total, and no... they are not aluminum.

this winter i am buying some aluminum and making a 1.75 or 2" spacer which will be next year's experiement.

[manoa matt]

Mike,
Is your butt dyno happy? Did you notice any improvement? Worth the effort?

[mbouse]

daily distractions have kept me from going the full distance. I used a spare intake manifold and some brackets to clamp the two spacers together. I used some non-hardening gasket goop (Dave...that blue stuff) to seal between the two spacers.

after the goop set up, i have begun to file the center hole flush. seems that these spacers are not identical, and there is unevenly rough surfaces in the opening. once i smooth that out, and eyeball the center hole to match the intake i will proceed to the next step.

which, of course, will be to pull my carburetor and check the clearances then install the spacer. this weekend sounds like a great time to get all that done.

at the same time, i am swapping my intake for a gasket matching ground and polished intake manifold. that should match up with my gasket matching ground and polished head!!

butt-dino reports next week.