Report - Edelbrock Thunder AVS

[Buzz]

Initial reaction: VERY impressed!

I finally got tired of the constant tuning and fiddling with recurring hard starting, poor running and plug fouling issues and ditched my second Holley carb. In its place, I took a chance and bolted on a new Edelbrock Thunder AVS with adjustable secondaries. This is not intended to be a knock on Holley carbs, but in my experience with two of them, I would have them running great at times, but it just never lasted very long - the same old issues just kept coming back.

Truthfully, I wasn't sure what to expect, and I'm happy to report the difference is night and day. The car starts instantly, hot or cold and unless its been sitting for more than a day or two, I don't even have to touch the gas pedal. The slightest turn of the key and she fires right up. It feels uncannily like a car with EFI now - squirt gun throttle response and absolutely no bog or hesitation on acceleration from any speed. I've often read that Edelbrocks may run well, but Holleys make more power. I have no way to measure, but possibly due to the improved throttle response, the car actually feels faster now.

Re the recent hot start thread, I began having serious hot start problems with the old holley, so I put louvers in the hood, added a heat shield under the carb and insulated the fuel log and lines from the mechanical pump. Those changes made a huge difference. Still had recurring cold start gremlins, though.

One other little discovery I made was that the big 16 X 3" drop-base air cleaner was shrouding the carb and baking it in hot air on long drives to the point where there was a noticeable drop in performance after a few miles. The hood louvers do a great job venting hot air from the engine compartment, but the big, deep air cleaner was neutralizing their effect. When I switched back to a smaller flat base filter, that problem went away.

The old Holley heat shield won't fit with the Edelbrock carb and its plumbing, and I have not yet insulated the fuel lines but so far there's no sign of any problems. I got a 1/2" phenolic spacer but I am waiting on some longer carb studs before I can do the install. For posterity, I will also add a heat shield when I put on the spacer.

I am very happy with my new carb.

[Gaz64]

Good to hear.

Edelbrocks are very underestimated carbs.

They have way more going them than most think.

[letsboogie351]

I might be wrong here but I am led to believe that Edelbrock took over "Carter" and that their carbs are based on the carter carbs. In my opinion Ford enginges responded better when equiped with a carter carby

[Bobcat]

Buzz ... which Ebrock did you get ... the 800 cfm unit ?? My Holleys are driving me crazy . Can get them to run at top end , but bottom end suffers or just the opposite . Or worse yet ... I finally get it all right and then it`s out of tune after several hundred miles . Just curious as I may try one . I`m running a 482 engine and am wondering if this carb is big enough or intended to run on big blocks .

[Gaz64]

Originally Posted by letsboogie351

I might be wrong here but I am led to believe that Edelbrock took over "Carter" and that their carbs are based on the carter carbs. In my opinion Ford enginges responded better when equiped with a carter carby

Yes, correct.

The Edelbrock Performer carb is a Carter AFB.

The Edelbrock Thunder AVS is a Carter AVS.

Both made by Weber.

[Buzz]

Bobcat, I had the same problem. Getting my Holleys to run well in one range always seemed to cause problems in another area.

I chose the 650cfm carb. I have a stroked small block and most calculators showed that to be adequate for my displacement and RPM range. The overwhelming majority of my driving is on the street so satisfying throttle response and driveability are my priorities. I think the 800cfm unit is recommended for big block applications.

One of the neat things about these carbs is the adjustable secondaries. I haven't played with mine yet as I'm just plain tickled by the way it runs as is.

[Bobcat]

Buzz .... thanks . I`ll talk to Ebrock Monday as I do track the car some , but if the partial throttle response is nice and crisp , it will be a big improvement . At VIR recently , times suffered as the part throttle ( can`t go WOT in the middle of a turn ) was horrible . The "cure " was to go one gear lower and rev the crap out of the engine and have to shift as I came out of the corner . How did the throttle linkage and fuel hook ups compare to what the Holley requires ?
BTW , you said the hood louvers helped let the heat out .... I thought they were to keep the front end down on the high speed roads down there ???

Bob

[jhv48]

Ed carbs are known for crapping out on hard cornering. I had the Thunder AVS on my first Cobra. Never could get it to flow right on corners. Go over to FFRcars forum and do a search on Ed carbs. Not many good remarks.

Call ProSystems and tell him what you want. He will build a DP that will solve your problems.

[cdnus]

I've had two pro systems. The first was so bad I returned it to Patric & after checking he admitted they had missed the program & sent me a totally different & larger carb.
2nd. carb ran great when accelerating really sucked on cruise. I have spent many hours modifying the circuits & now have it I believe, as good as it can be.
When I called Patric on the second carb & even offered to pay for another not expecting anything for free, I was told that was all they had ( program wise ) & I was on my own.
This is not meant as criticism of pro systems, more as information that not all their carbs are as advertised "bolt on & go"

Craig

[tcrist]

Talk to some circle track guys. They always used to have this problem. I seem to remember something about adding a longer vent tube or something about a cross over tube of some sort on the carbs.

If you are buying street carbs instead of race setup carbs, that could be the problem.

Just a thought about something that I remember from my past. Not that I ever used it because I don't race.

[Buzz]

Bob, I have a cable throttle linkage and the E'brock hooked right up with minor adjustment. The plumbing was easy - inlet options on either side. I installed a new inlet log with a pressure gauge port and of course a new filter. I used the same adjustable pressure regulator I had with the Holleys.

They say the louvers also vent underhood pressure and keep the front end down at speeds around 160mph, but I'll have to take their word for it! The fastest I've managed down here is close to 140. I've taken it over 130mph three times now - very early in the morning while eeeeasing around potholes and watching out for goats, horses and a family of pigs that frequents the area. Huge adrenaline rush but I don't think I'll be doing it again.

As far as fuel delivery under hard cornering goes, one thing we have in abundance here is corners. We just completed a new National Tennis Center near a sports stadium not far from where I live and there is a nice section of new, flat, unused road that winds through the undeveloped area. I also installed a new oil pan and I've run it hard around the little "test circuit" to see how the oil pressure holds up. The pressure is fine and so far the carb works flawlessly in the turns.

I realize there's a lot of brand loyalty with Holleys, but the way I see it is these companies care about their bottom lines and as long as I pay my money, I don't owe them anything else. Plus, they have legal teams to defend their names, so they don't need me for that.

I'll use what works for me and if the Edelbrock develops problems or turns out to be a disappointment, I will report back.

[Wbulk]

If you look on the left side of the carb you will see this. Magneti Marelli is an Italian Company that's a subsidiary of Fiat Group. Weber is part of Magneti Marelli.

[Bobcat]

Buzz ... thanks for the feedback . I`m still thinking on the carb change and will be talking to Ebrock tomorrow . From what I can find over on some other forums , the Holleys make more power , but the Carter/Ebrock are the more drivable carb ... general statement .

cdnus ... I had to send my first Pro Sytems carb back also as it was pretty much undrivable on the track until I hit 4000 rpm ) and a handful on the street . To Patrick`s credit , he built another unit ( smaller ) at no charge and I now have it on the car . Haven`t driven it yet as the temps are over 100 to 102 now , but I don`t have a warm and fuzzy feeling as I have to have the idle mixture screws almost 3 turns out to get it to idle . Before changing air bleeds , I need to talk to Patrick . Actually , I have a stock Holley that works better than what I had .

[cdnus]

Thanks Bobcat
I am relieved to know that I'm not the only one that has had serious problems with Pro Systems. Helps to restore my confidence big time.

Craig

[Dirty Harry]

I bolted an Edelbrock 600 on my small block and adusted it once and have not touched it in 18 years. Great on cold starts and not bad on hot starting. Easy to buy, no maintenance, and no leaks. Money well spent, I'd say. IF the Holley makes 10 more horses, I'd be surprised.

[Bobcat]

cdnus .... I think what a lot of people miss here ( me included ) is that ProSystems builds a race carburetor . I may work ok on the street , but is really intended for the race track . If you look at the build sheet where the mods are listed , it seems to me that they are heavily weighted towards competition ... and that`s ok , as Pro says they build race carbs . I was just hoping it would have worked better in my application .

Bob

[cdnus]

Bobcat
I believe the wording on their sight has been changed & some models eliminated.
When I ordered my first carb they were offering non-race carbs with hi-performance. I had very specific discussions about the application for my use with Patrick. Mainly street use, mileage important as I do many long day trips, in fact he did some mods to increase mileage that totally did not work & I had to reverse.
Good luck with your second carb, I hope it works well for you, as I am sure my case is unusual. I have a permanently installed O2 meter, so I am constantly aware of the performance of the carb. After many changes to my second carb it is now very good.

Craig

[cdnus]

Just checked their site & according to information below they still build street carbs..

"We specialize in designs for programs starting at 400 h.p. (thats a great power level for any respectable street machine) and we have built carburetors as large as 2600 cfm in flow.

By specializing in only race and high performance street designs we not only helped ourselves grow into a strong, innovative and self reliant company, it also helped our customers by giving them a company that really knows and understands their needs and how to get results from their programs. "