Truck avenger carb size

juggernaught

I had a mc 2100 1.08 carb on my amc 360. The ofroading was actually very good and had no complaints. Now that I have rebuilt and recam'd the motor along with some head work, I am looking to wake up the street driving a little. The old carb was definetly lacking any power in the mid to upper rpm's. The holly t/a 670 may be larger than I really want to go. Would I see performance gain by just up grading to the 470? I have been told that one reason the mc 2100 works so well is that it gets very good atomization being that it is only about a 300-350cfm carb. This makes me wonder if maybe a t/a 470 wouldn't be a better choice (over the 670). Is any one running a Holly truck avenger on a amc 304/360? Another possibility is getting a mc 2100/2150 with a larger venturi.

ironman_gq

your going to need the 4bbl intake to use a truck avenger carb. I have a 600 on my 304 and it works great for anything on or off road so I would think that a 670 shouldnt be too large for your 360 as long as everything is tuned properly. Being a 4bbl they act like a smaller 2bbl until you put the throttle down and open up the secondaries so a 600cfm carb acts like a 300 or smaller cfm carb until your engine needs more and the secondaries open.

juggernaught

I have little doubt that a 600 or 670 would work ok. What I am wondering is that given the fact that the little mc2100 that I and many people swear by for off roading works so well, partly because of the fact that you can get excellent vacuum/atomization at low/idle rpm's.Would this also be truer with the smaller 470 truck avenger carb (vs the 670)? What can I expect going from a 2bbl/300cfm carb. to a 4bbl/470 or 500cfm carb? I am looking for: Low idle crawl uphill No low idle accel lag Off camber operation A moderate improvement in street perf.

ironman_gq

more power should be expected. Check the primary venturi size compared to your stock 2100 and see which ones are close I dont know if the 470 will be larger or smaller but if they are the same then you should be able to expect your throttle response to remain pretty much the same if they are smaller same deal if they are much larger then you may lose low end throttle response. I would see which carb is closest to your 2100 as overall CFM is only important at WOT with the secondaries open otherwise you only pull what the primaries will let you.

juggernaught

I have seen the CFM of a motocraft 1.08 2100/2150 stated as many as three different amounts. Still not entirely sure which is the "correct" number. Somewhere between 250 to 350 CFM.

ironman_gq

I would say tat going up to the 470 wont make a huge difference in your top end power but could help your low end by actually having less flow at part throttle 470 *1/2= 235CFM without secondaries opening. I cant find the venturi sizes for the truck avenger carbs but they are probably around 1-1.25" for the 470-670 carbs. I would call Holley and find the one that has the closest primary venturi size to the 2100 (probably the 670)

juggernaught

So if the mc2100 venturi size is 1.08 and max cfm is approx. 300, then a truck avenger 470's primaries alone would be almost equal to the mc2100 total avail. cfm with the primaries stil avail. for mid-top end. Sounds like more than just a slight improvement. Or am I missing somethig?

ironman_gq

the truck avenger primaries should theoretically flow 235CFM the 670 335CFM and the balance will come in as the engine needs it by opening the vacuum secondaries.

jinpdx

ironman_gq wrote
the truck avenger primaries should theoretically flow 235CFM the 670 335CFM and the balance will come in as the engine needs it by opening the vacuum secondaries.

Correct, the primarys and secondarys are the same size. I don't think there will be much, if any, gain with a 470 on a 360. I would use a 670 and rejet it. I run a 670 on my 401, and the throttle response will snap your head back.

juggernaught

Thanks