Mounting a Rochester on a Square bore intake?

[angelorayhurst]

I have a 78 c1o Blazer that has a 350 crate engine with a Holley carb and Edelbrock Performer rpm intake that is square bore. I would like to put a rebuilt Rochester in. Is there a good adapter I can use for this? What are the pros and cons? Would it be best to just get a Edelbrock Performer intake and just forget the adapter? I would like to save a few coins and time, but would it be worth it. Also which adapter is best if I go that route. The engine is stock with dual exhaust if it matters. Thanks in advance for any info..

[Corts60]

You can't fit the spread bore rochester on a square bore. The secondaries are much larger and need the room to open. Even if someone does make an adapter, the restriction would be very inefficient. I would just buy a spread bore manifold personally.

[88Jimmy4x4]

http://www.summitracing.com/parts/EDL-2692/?rtype=10

no problems, people do it all the time....go for it

[mopar346]

I would get a spacer as well as the adaptor andflow them together to make it work as well as possible. I would also consider a wood spacer for heat.

[88Jimmy4x4]

seriously though its best not to use an adaptor and get the right carb for the right manifold

[Dead Parrot]

Since you mentioned cost as a factor, unless there is something wrong with the existing carb/manifold or they are an obvious mis-match for your planned driving habits, it would probably be cheaper/easier to tweak your existing setup rather than buying new stuff.

I switched from stock manifold and Q-Jet to the Performer manifold and 1405 Performer carb years ago. I switched because every Chevy Q-jet I have had, has leaked out the front casting plug at some point. The only maint. the 1405 has needed is de-gumming the step-up pistons and cylinders every couple of years. I gained about 1 mpg from the switch. There may have been a small improvement in performance or it could have been 'new stuff has to be better' anticipation. One advantage of the 1405, it took about 5 minutes to swap to a leaner set of rods when I took a trip to a 9000' high part of Colorado.

[INSIDIOUS '86]

Why? Just why?
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[angelorayhurst]

The Holley carb is in bad shape...I have a rebuilt Rochester from a friend..Also I have always had great experiences with Rochester carbs..I have never ran a adapter tho..So thought I would see if people have had any experience with them..I usually would get a performer intake but my time and budget is pretty tight right now..Are there any factual reasons in not running a adapter..How many people have had good or bad experiences with them?

[angelorayhurst]

Has anyone done this?

[C30trailerspecial]

A: I wouldnt bother with a holley on my truck ( I have enough tuning issues with them on my mopar) and

B: just get the correct intake manifold, trust us on this one

[88Jimmy4x4]

from searching internet, most recommend not to do it but those that did say only adaptor really worked was the 2" thick Moroso 64960

http://www.summitracing.com/parts/MOR-64960/?rtype=10

[Keith Seymore]

1) Wilson Manifold should have an adapter as well. Probably a bit more pricey than the Summit version

http://www.wilsonmanifolds.com/

2) I use a Wilson adapter to hop back and forth between a Holley Dominator and a 950 Holley, which have different size mounting flanges. (Dominator for "all out"; for class racing I'm restricted to using the smaller Holley). So I'm not morally opposed to using a carb spacer/adapter.

3) What's the specific problem with the Holley? They are really pretty easy to work on.

4) Is it a vacuum secondary or a mechanical secondary?

K

[mopar346]

Holley's are very tuneable, virtually anyone can make them work right with a little effort. Q-jets on the other hand can be very tempermental after an overhaul. They are great carbs when right but a "friend's rebuild" might concern me, cause I don't know your friend, it may be Barry Grant. The Moroso piece takes into account the spacer and the flow I was referring to, just make sure it mates up to the intake smoothly and might even smooth the joint on that. As long as the carb works fine that will work. I wouldn't be opposed to it, but like Keith said I'd just fix the Holley.

[angelorayhurst]

The Q-jet was rebuilt by recarbco for his 80 truck to pass smog..For the price of those adapters I can find a used intake on craigslist..I was looking at a Holley contender that is really comparable to the Edelbrock performer..Both have dual bolt patterns..So I'm going to get a intake instead and mount the Q-jet..Then the Holley will go on craigslist..Thanks for all the info..If no ones done it, there's usually a reason!! Although I read on g body forums a guy said they run em..Even the cheap Mr Gasket 1, with no problems..

[mopar346]

PLenty of people do it, do yes a compatible intake is generally a better route.

[Keith Seymore]

Originally Posted by angelorayhurst

Then the Holley will go on craigslist...

PM sent -

K

[C30trailerspecial]

Originally Posted by angelorayhurst

I was looking at a Holley contender that is really comparable to the Edelbrock performer..Both have dual bolt patterns..

and so long as the flange is for a spread bore. there is alot of manifolds that have the dual bolt patterns but only a square bore flange,

Im running an eddy performer with spread bore flange along with a 1" four hole phelonic spacer, & Im using a gasket that blocks off the heat cross over keeping the carb nice and cool with a little tuning (and Im no expert) its running real nice

[74 stepside]

Wouldnt it be easier and cheaper to just rebuild the holley or get someone to do it if you dont know how?

[angelorayhurst]

I prefer the Rochester carbs for gas mileage and performance..So the Holley is coming off and will be rebuilt by my buddy who wants it..I only wanted to know if a adapter was a good way to go? If anybody had ever ran 1..Seems most have said its not a good idea..So I may just change the intake or throw caution to the wind and attempt the adapter..I appreciate all the info and if I didn't have the Rochester then repairing the Holley would have been the best solution for me. I will post results when I do (even if it turns out bad lol) Thanks again for all the input and looks like I've started a carb war. I really don't have anything against the Holley carbs, but just have always preferred the Rochester. They have always been reliable for me and less maintenance.

[88Jimmy4x4]

I talked to a buddy of mine about this today and he says it will be no problem. He has built alot of engines, mild to wild so I trust what he says....for whatever its worth.

[angelorayhurst]

Ok, so I went out and bought a adapter. The cheapest 1 I could find was the Mr Gasket (15 bucks and change o'reilly). The adapter fits great and works great thus far. Truck starts right up and runs without any hesitations. This kit is for both applications, square bore-spread bore or spread bore to square bore. I would recommend getting longer bolts for the rear mount for my application though. So thanks for the help and input. If there are any problems down the road I will post. Thanks again!

[88Jimmy4x4]

Originally Posted by angelorayhurst

Ok, so I went out and bought a adapter. The cheapest 1 I could find was the Mr Gasket (15 bucks and change o'reilly). The adapter fits great and works great thus far. Truck starts right up and runs without any hesitations. This kit is for both applications, square bore-spread bore or spread bore to square bore. I would recommend getting longer bolts for the rear mount for my application though. So thanks for the help and input. If there are any problems down the road I will post. Thanks again!

great....glad it worked