Help with 4 bbl carb riser I.D.

[too much stuff]

Can we get a positive I.D. on these? (carb to air cleaner) Short one for a 4x4? Any help is appreciated.
Eric

[too much stuff]

Someone must know the correct application of these. These are from 67-72s.

[special-K]

I never noticed any differences before this. I just checked my '71 C/30 and '72 K2500 and they are both the same...about 2 1/2" tall and both are small blocks. I have another one around from a '71 C/20 but pretty sure it will be the same. My guess would be maybe the short one is for big block(?) and maybe the tall one is a medium duty??

[sameyrasmea72]

That's a good question. Every V8 4 barrel (sb, bb, 2wd,4wd, 1/2ton,3/4 ton) i have every seen used the same spacer.

[sameyrasmea72]

Maybe the shorter one was for older BB (68-69) that had a high-rise intake?

[Indyuke]

I've always wondered what they're for except to provide clearance. I was talking with an old GM guy and he told me that the riser was for three reasons:
1) clearance for the linkages
2) prevents the carb from getting too hot by an air cleaner that sits so low it prevents cooling airflow around it
3) turns the intake airflow to hit the venturii straight down rather than allowing the air to "skip" across the top of the carb.

All those reasons sound pretty good, but I was wondering how much truth is in them. When I put a riser on, I notice a slight loss in power causing me to push the gas pedal in a bit more to get the same results. So is it really more efficient? What do you guys think?

[special-K]

Al those sound like good reasons. For linkage clearance the filter housing could have been designed to clear that w/o a spacer. So,it seems kind of silly. It does give a more direct breather location to help keep oil from puking up into the filter? They do act as a stack to bring a better volume of direct intake air into the venturi.

[mrein3]

I'm not in front of my truck right now with a tape measure but I'd swear my 4x4 spacer is just like the middle one. Which looking at the tape measure is a lot like what special-K described in his post.

[71 super]

Both of my v8 4x4 trucks have the taller spacer, both are 72 if that helps or matters, they are also the same height as the spacers on my bb trucks as well

[special-K]

That tallest one doesn't have a breather port,does it? My instincts say bigger truck on that one,maybe older? Maybe tall deck? Were those even 4bbl?

[too much stuff]

Tim, no hole in the tallest one. That was my thought also was a bigger truck. I think the holley were mainly on tall decks.
I have a big block spacer here that is 2 1/2" has the arrestor in line with a metal pipe into the valve cover.
My guess for the short ones was 4x4 since the engine sits farther back and it gets tighter to the firewall.
sameyrasmea72, the theory on the big block sounds good.
I will look at some others i have and see.

[oldgold70c10]

A tall spacer without a breather hole is what I am currently using with an air cleaner I pulled off a 68 1/2 ton with 327 at a salvage yard. Of course, there is no way of knowing if it was the original air cleaner or not, but it had a provision for the breather on the air cleaner itself. No damper door on the snout either.

[chipflyer]

I didn't know they were different either but I think I may need one of those short ones....

[teeitup]

I've had one of those shorter ones before WOW that sounds good doesn't it
Anyway I think the shorter one was on a 68 BB I parted if I remember right but remember Eric, I do drink some so I may be wrong.
I've never seen one of the bigger ones like that

[chipflyer]

I've had one of those shorter ones before WOW that sounds good doesn't it

Almost as bad as me saying I wish mine was shorter...
Seriously Randy, do you have an extra one of those?

Jeff

[teeitup]

None right now Jeff, we will have to look for one at the Swap meet