another cam question

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n8ling

n8ling

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So, I've aquired some goodies over the last couple months, and of coarse have more questions.I have a 76 360 .30 over fresh bottom, heads have been lapped and spec'd, I plan on running 3.73 rear end w/ 245 60 14 tires. The last couple of weeks a performer alum edelbrock intake,and 770 cfm holley street avenger carb have basically fallen in my lap. I am still unsure how lumpy I can get with the cam, and now if I will be over carbed. oh yah elec ignitionas well. I would like the car to be mean on the street, possiblely a few passes on the track, not far on the hwy,but would still like to get to a show and shine or two. One other concern is swapping the (74 swinger) rear assembly for a 70-73 light and bumper assembly. Thanks N80
 
I'm running a Mopar purple shaft with a 284/284 duration with .484 adv. lift in my 340. It had a pretty good lope and was still pretty friendly on the street. You may need a bit of a stall on the converter, but it treated me pretty well.
 
If your bottom end is a stock rebuild then the compression is down in the weeds and you would be best to stay with a smaller cam or you won't have any bopttom end.

I would recomend one of the modern fast ramp cams from Comp, Crane, Hughes or Lunati over one of the old school mopar purple shaft cams.

The 770 carb is likely going to be too much carb for street driving.
 
Thanks for the replies, by the way the 3.73????? are 3.55 . Now about the 770 carb, could it not be jetted down, And i think the cam will be comp cam 20-417-3 211\227 @110deg if you guys now about this combo let me know
 
You can jet a big carb down, but a carb that is to big won't receive a very good signal from the engine so it won't be as efficient as the correct sized carb.
 
The motor is spec'd @8.5 comp...30 over with flat top pistons. I suppose the comp wont rise much with out the heads shaved or rods.I just want a weekend warrior to burn some gas in
 
I don't believe you will have any problems with a street avenger vacuum sec. carb. Really hard to overcarb with One. Mopar used an 800 TQ on the 340 and got good results with that one. That is one of the good things about them. They are street friendly. That 284/484 cam is a good one for a 360 with 10 to 1. But with 8 to 1, the 280/474 or the 272/455 are good street choices from Mopar. There are other good ones out there too. Good luck, Terry.
 
FWIW,

1. You can get 3.73 gears from the after market if you want them.

2. When you use a carb that is too big you wind up jetting UP. The reason being is that the air velocity through the venturi of the carb is slower creating less signal to pull fuel, resulting in the need for bigger jets. And, the opposite holds true too if the carb is small you jet down. For example; On my 360 if I am using the 600 cfm carb I had to jet down to 64's from the stock 69's and when using the 725 cfm Road Demon I had to go up to 78's from the stock 76's.

3. You can't compare an 800cfm TQ to a 770 Holley to make a judgement on carb size. The TQ has tiny primaries and huge secondaries and on a stock 340 the secondaries (vs the holley have the same size primaries and secondaries) never opened all the way. The reason for this size of a carb was to provide addequate capacity for race classes that required the use of stock carbs.

IMHO, if you have the 770 try it but if you are going to buy something and the car is primarily a street car stay with something in the 650 range.

4. the cam you are looking at will be a good choice but you may want to consider the XE262H (p/n 20-222-3). This is one of the new technology fast ramp cams that has approximately the same duration but quite a bit more lift. I am using the XE268H cam and my 360 puls clean from below 1500 rpm and is super strong from 2-6K rpm.
 
Thanks dgc333, That's what I was hoping to hear. Thanks for the info, and comparisons.......Seems I dropped 800lbs on my hand at work so now theres some stand still time on things for a bit, but more info means more knowlegde
 
Holley 4160 carbs and TQ's have vacuum accuated secondaries. Square flange (4160) and spread bores operate on the same principle..manifold vacuum. Vacuum secondary carbs lend themselves well to street duty and are more forgiving on smaller engines. My point entirely. Terry.
 
n8ling said:
Thanks dgc333, That's what I was hoping to hear. Thanks for the info, and comparisons.......Seems I dropped 800lbs on my hand at work so now theres some stand still time on things for a bit, but more info means more knowlegde
Click to expand...


800lbs.... I have one word for you..... OUCH!!!!!!
 
Sounds similar to my "Oooppsss, got zapped by 750VDC." Cooked knuckle anybody?
 
those pistons must be way down in the clynders to just get 8.5 to 1 out of a flat top i have a .030 over 360 with speed pro forged flat tops and it makes about 10 to 1
 
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