teamzr1
Supporting vendor
It was all in the COMP MAGNUM CAM I selected for a 327 CI engine with long tube headers
LSA is only 110 so will be a choppy idle
Good power from 2,000 to 5,500 RPMs
Exciting day - rebuild of 78 coupe
- Thread starter johng
- Start date
It was all in the COMP MAGNUM CAM I selected for a 327 CI engine with long tube headers
LSA is only 110 so will be a choppy idle
Good power from 2,000 to 5,500 RPMs
johng
CCCUK Member
Went for a drive today. When cruising it's a similar volume to the old exhaust but a nicer tone. The old system used to drone a bit. When you put the pedal to the metal it sounds more like a machine gun! Performance wise it doesn't feel much different, if anything it accelerates a little slower. I've still got the original Quadrajet on the car, which I need to fit a new top gasket to anyway (when I stripped it down last year I noticed the gasket was a bit damaged but didn't have a spare at the time). Whilst I've got it opened I'll check the float height and the Adjustable Part Throttle setting, from what I've read they are the only simple changes you can make. You can't really put bigger jets in the late model Quadrajets, they already have big ones.
teamzr1
Supporting vendor
You have access to a wideband O2 sensor to place into the end of the exhaust and AFR meter to measure ?
If using E5 or E10 gas, for non WOT I would adjust carb for non WOT at like 14.4:1 and for WOT like 12.5:1 AFR
Monitor for engine knock and adjust to reduce that with carb or timing
If using E5 or E10 gas, for non WOT I would adjust carb for non WOT at like 14.4:1 and for WOT like 12.5:1 AFR
Monitor for engine knock and adjust to reduce that with carb or timing
Forrest Gump
CCCUK regional rep
I decided on a Magnum cam when I built my 383, nice to see you rate them too. An old design and single profile but still seem popular. I used a build spec from David Vizard who has dyno’d hundreds of cams, if he likes the Magnum, that’s good enough for me!
Do you think those HP figures from the Comp Cams software look a little optimistic despite the great cam? Virtually 400hp from a motor with stock-ish heads, dual plane intake, medium compression and not particularly high revving?
johng
CCCUK Member
Unfortunately I don't have a way to measure my AFR and as things seem to be going I could really do with one. I've always thought that my engine was unmolested, I got lots of history with the car and there's no mention of anything being done to the engine, plus all the original parts were still attached to it (even though several didn't actually work).
However, following some email conversations with Lars Grimsrud (the acknowledged Quadrajet guru on the US forum) I've stripped my carb with the intention of first making sure everything was set up correctly and then raising the float height and Adjustable Part Throttle to richen the mixture slightly. First I found that the aluminium plug above the APT adjuster had been removed and the APT was already set high. Then I discovered that the arms that the primary rods hang from were bent upwards (raising the rods even higher) and lastly the rods that are fitted are a lot smaller than standard. Since all of these things richen the mixture, I don't really understand how come the car has always started and run fine and generally returns around 17mpg (UK gallons).
Does anyone know where I might get some replacement primary rods in the UK? I can get them from the US, but for some reason postage costs for these tiny items is a ridiculous $70 (+ 20% import VAT).
antijam
CCCUK Member
I've bought parts from QuadrajetParts.com in the States (who incidentally are very helpful) and in all cases the postage was $28.80. Admittedly this was four years ago but shipping costs of $70 does sound excessive.
I've found that swapping primary jets on the Quadrajet - even by one size makes a very significant difference in economy and stable running.
I've found that swapping primary jets on the Quadrajet - even by one size makes a very significant difference in economy and stable running.
teamzr1
Supporting vendor
These online websites be a help ?
quadrajetpower.com
www.carburetor-parts.com
carbkitsource.com
Quadrajet Power, Your One Stop Quadrajet Shop
Quadrajet service, parts, kits, restored originals
quadrajetpower.com
Rochester Quadrajet Carburetor Parts
Carburetor kits, parts and manuals
Carburetor rebuild kits and parts for automotive, marine, farm and industrial
carbkitsource.com
antijam
CCCUK Member
If a seller won't ship to the UK they will quite often ship free to an american address. If so it can be worth using MyUS. They will give you an address in the States to have the parts shipped to and then they send them on to you. Their business being solely shipping they can negotiate very favourable bulk rates with the major shipping services - check the rate for your package on their website. I've used them several times - they're very efficient and it's free to join. Even if the internal shipping in the States isn't free it can still be worth using MyUS.
teamzr1
Supporting vendor
How about this one of these in the UK, or maybe they could point to where your parts can be bought
www.etsy.com
www.corvettekingdom.co.uk
www.woolfe.uk
www.summitracing.com
www.jegs.com
Quadrajet - Etsy UK
Check out our quadrajet selection for the very best in unique or custom, handmade pieces from our car parts shops.
Q-Jet Carburetor, Choke & Rebuild Kits :: Corvette Kingdom
www.corvettekingdom.co.uk
RPC Performance Parts for American Vehicles - John Woolfe Racing
Performance parts, OEM and Aftermarket parts for American vehicles
www.woolfe.uk
JET Performance 201010 JET Quadrajet Metering Rods | Summit Racing
Free Shipping - JET Quadrajet Metering Rods with qualifying orders of $109. Shop Carburetor Metering Rods at Summit Racing.
JET Performance 201941: Quadrajet Primary Rods Carburetor Metering Rod - JEGS
Get the Best Performance with JET Performance Quadrajet Primary Rods Carburetor Metering Rod 201941 parts at JEGS. Shop Now at the Guaranteed Lowest Price!
johng
CCCUK Member
That looks good, how does the import VAT get paid? I can't see any reference to it on their website
antijam
CCCUK Member
Great - hope it goes smoothly for you. Where MyUS can be really useful is when you're buying from several different suppliers. If you get all your purchases sent to your US address MyUS will consolidate them into one shipment before sending them on. This can really save on international shipping costs.
