Hello, To start with some basic info: My engine is a stock 350 (1991) mated to a T5 with 3.73s at the back. My current carb is an older Holley 1850 (came with the engine) adapted to the stock aluminum spread bore manifold. My understanding (or lack of it) is that the use of an adapter plate costs performance and that an intake with a higher rise will typically offer better performance? The goal (until someone tells me otherwise) is to "match" the carb and intake. I could go looking for a QJet but lets assume I'm sticking with Holley for the moment. OK, so I was expecting to pick up a Performer RPM but, as it turns out, it's not available for '87-'95 engines. From what I've read on this forum the basic perfomer does not offer much over the stock intake aside from no longer needing an adapter between the it and the carb. Weiand offers the Action + in a square only as well as a square/spread version. Would it be correct to assume that the square/spread is a compromise? Weiand's "Stealth" boasts a wider operating range (0-6700rpm). Summit also lists the Holley "street dominator" and a cast iron hi-rise offering from GM. ????? Which way to turn? Sorry this is so long winded. Any practical "from experience" advice would be well appreciated. Thanks, Jon

 

The goal is to match the cam and the intake. The carb is matched by size to the engine size & RPM; carb type by transmission type with some influence from what you'll be using the car for.

Until we get more details about your engine, the intake type discussion is moot. Need to know cam details, what heads you're running, and it wouldn't hurt to know more about the exhaust.

From what you have given, it's safe to say you don't have the right carb. The q-jet wouldn't be much different/better.

 

Thanks Five7. The cam is stock as are the cast iron heads and the T5 manual transmission. The only mods to date are Headman headers that collect to a 3" pipe back to the muffler and the 3.73s in the diff. This is a street only car. A mild cam and heads are scheduled for Feb 2009. Not so much a cost issue as I want to really work out all the bugs with the car before proceeding to real mods. I've gone from a Holley replacement spread bore to the 1850 square bore that's on there now with a noticable loss of performance. What I was getting at with "matching" the carb to the intake was the supposition that the adapter plate is costing me power. Is this all in my head and simply a tuning issue?

 

It's probably part tuning, and probably part that the 1850 is the cheeeeeepest thing Holley sells that has 4 holes, so it has the bottom-line of everything. The least efficient boosters, most notably.

You can no doubt improve it quite a bit with tuning; but in the end, it's still going to be a rock-bottom low-bid universal replacement POS.

The adapter might or might not have anything to do with it. If it's a one-hole spacer (one gigantic hole), it will generally tend to favor high-RPM performance somewhat (4500 RPM + ) , at the expense of low-RPM torque and driveability (3000 RPM - ). Hard to predict accurately in a specific case, but in general, that's how they tend to behave.

It's pretty easy to get a manifold that will direclty replace your stock one, but has the other kind of flange (most have BOTH flanges, actually). The Edelbrock Performer, the ZZ4 one from GM, whatever Holley/Weiand is selling these days, are all like that.

What "replacement spread bore" did you have? You might be WAY ahead to fix that up and put it back. Or maybe not.

 

When my engine was put in the garage installed a Holley 80555C. I kept going back with complaints that it was running too rich and hard to start in warm weather. By the fourth visit (after a couple of blown power valves and re-jetting) they decided to rebuild the 1850 and put that in instead. As far as the spacer is concerned the behaviour you described it is exactly what I'm experiencing. Are any of the Holley spread bores any good or do I need to find a Rochester to stick with my current intake? Otherwise, my expectation was to switch to a square bore intake so that I can move up to a higher end Holley. Thanks, Jon

 

I'd suggest rebuilding the 80555, and following the Holley tuning instructions in the "sticky" at the top of this forum.

Most likely, that will produce an AMAZING difference in how it runs. Although, out of all the possible Hlley spreadbores, that's pretty low on the list of "good" ones; it's vacuum secondary and has a metering plate. Probably an emissions replacement model. The one to get is the 6210; you can find em on eBay from time to time, sometimes even factory refurbs from Holley.

 

Not sure if If can get the 80555 back. I looked up the 6210 on the Holley web site but they don't give a great deal of info as far as features go. Would there be any pros/cons to buying 6210 vs a 4150 based carb (aside from the additional cost of changing the intake)?

 

Look it up on eBay, and check out the pics.

I'm not sure what "features" might be of concern... ?? It's a manual secondary (double pumper) spreadbore 650 CFM unit, designed to DIRECTLY drop onto a factory manifold and hook up DIRECTLY to all factory stuff (fuel line and choke for example) on a late 60s - very early 70s 327, 350, 396, 402, or 427. It'll work on a 454 (I've had one like that) but it's a bit small, they spec its big brother 6211 for that. It's easy to get Q-Jet-like gas mileage out of it, with Holley-like performance when you stand on it.

Pros = gas mileage, fits your manifold without an adapter, can be had cheeep

Cons = can't think of any offhand, besides you don't have one yet

http://motors.shop.ebay.com/Parts-Ac...d7db?_rkw=6210

 

Thanks for going to the effort of the link. I looked at that and some other stuff which led me to a listing by AllState Carburetors. There was a tel # so I called. The gentleman I spoke to had a refurbished 6210 ready to go (I never thought to ask if he had a Q-Jet) but after asking about the particulars of my car he recommended going Edelbrock. I said "all the racers in ThirdGen that know their stuff pan them". He said "racers yes, but for a car with only a couple of hundred horses you'll get better throttle response from the Edelbrock". Your thoughts?? Thanks, Jon

 

I disagree.

I don't care for Edelbrock carbs, for a number of reasons. First and foremost, they're square-flange; so they don't solve the problem you have right now. Second, they have just about the crappiest fuel line arrangement possible; they REQUIRE you to hack your factory steel line and put rubber into the pressure side of the system.

If he dislikes Holleys that much, I wouldn't trust his rebuild.

One of the factory refurbs from Holley would be a better bet than somebody like that.

 

Got it!! Now, I'm afraid I got us a bit off topic. Back to intakes. I've read alot of postings here and my impression has been that the Performer RPM is a reasonable choice for stock to somewhat modified. If that's so, could it not be modified to fit my engine (I'm making the assumption here that the ports to the heads are the same and the only difference is the angle of the center mounting bolts)? Alternatively, Weiand offers the action plus for '87-'95.

To be honest, I think I'll most likely buy a 6210 and stick with the stock manifold for the moment, but I'm trying to educate myself.

Thanks, Jon

 

If you have a "stock" 91 350, then Performer RPM is probably not a good idea; your heads are the "swirl-port" design, with this huge lump cast into the intake port runner to promote "swirl". The factory did that for low-end torque and fuel mileage. With those heads there, anything you do that de-optimizes the motor's low-speed properties in order to improve high-RPM performance (like a larger intake...) is likely to result in a net LOSS of performance.

For a replacement intake, I'd suggest just the regular Performer, or the equivalent Weiand/Holley. I believe both are available in a dual-flange (square and spread) design; I know for sure that's how the Performer is.

And yes, you could very well change out the carb on the existing stock intake, and change that later, if you want.

 

Your least-cost NEW performance intake for 87-95 heads is the following:

http://store.summitracing.com/partde...6&autoview=sku

It's the Weiand Action+Plus for 87-95 bolt pattern heads with Summit's logo stamped on it instead of Weiand's.

It will take a Qjet/spreadbore carb, or a squarebore carb (Holley) with a $5 adapter plate. No compromise putting a squarebore carb on a spreadbore intake EXCEPT for a factory 4-hole Qjet intake- that's a bad intake to put anything on except a QJet.

$5 adapter plate you'll need for your Holley:

http://store.summitracing.com/partde...5&autoview=sku

The adapter plate is only needed to prevent a big vacuum leak near the (more narrowly spaced) secondaries when you use a squarebore carb on a spreadbore intake. Use an open spreadbore/Qjet gasket under the plate and a regular square Holley gasket over the plate.

 

Thanks for the links! Since it doesn't say otherwise, I'm assuming that this is a low rise style that will fit under the stock camaro hood?

 

Yes it is. Little taller than stock (any performance intake will be) but not a problem fitting everything under the hood. Height is about equivalent to a base model Edlebrock Performer intake, since this intake is Weiand/Summit's direct competitor to the Performer.

 

Thanks again Damon. I called a local reseller and I can have the Action Plus for $164.00 and I don't have to worry about shipping and duty (customs brokering would take a good $60.00!). So, I'm just waffling over natural or polished finish (ah, decisions..decisions..). While I like the idea of a new carb to go with it I'm going to buy a wideband O2 instead. I want to learn to get as much as I can out of the Holley 1850 before moving on.