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Can't get tires to spin easy or power brake

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Chase Marose

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Hey guys, I have a 74 d100 custom long bed, and I am having a hell of a time getting this thing to power brake or chirp the tires, I'm running 295/50/15 Hercules tires on the back, I have a 9 1/4 inch rear end 4.11's with posi. The motor is a bored out 360 with kb Pistons 107's and a comp thumper cam. It has a 727 tranny with a 2000 rpm stall and the heads are cast iron 2.02 1.60 ported out. I'm running a 670 street avenger carb and when I try to power brake foot full on brake and throttle I rev 1800 rpm without even trying to start spinning the tires. The motor performs well in the 2500 and up range but off the line full throttle it hesitates a little bit. With a stall and that low of rear end what the hell is going on? Is my combo wrong? Any help is awesome for me no judgements from me, just want to know what to do to make this into a tire burning machine
 
You know tire burning is wasted energy and shortens tire life?
Now seriously what is you timing set at?
Have you checked engine vacuum?
What did you use for the intake manifold?
The tourque converter stall seems low for the cam and gears.
 
My timing is set at 18 initial and 36 total vacuum advance unhooked, I can't adjust my advance in the canister worth crap if it's hooked up like this it will read 55 total timing. I'm using a strip dominator intake, I did a little reading and found it is a 3500-7000 range. So I'm thinking an edelbrock performer rpm air gap would be better 1500-6500 rpm. I originally had 2.73 gears in a 8 1/4 rear end and I just swapped the hole rear end I found from someone and that's when I had a 2500 rpm stall installed. I was wrong about it being 2000 stall. Is the intake what's killing all my low end power?
 
Actually gonna go with the weiand stealth intake, I've never been a fan of edelbrock
 
The intake definitely is not within the application range. I would stay with a dual plane intake. It will give a better off idle response. The rpm range of the performer intake should be OK
What is idle rpm and at what rpm does timing go full advance?
Also what exhaust has been installed?
 
All very good questions and answer's from "7Mopar" . The only other thing I would ask is what "size" cam are you running and what's the power range ? If you have a cam that's to big for your application and doesn't even think about kicking in until say 2500 Rpm's then that also is going to kill your bottom end .
 
Cam is 2000-6800 rpm the single plane intake I have is 3500-7500 so I'm going to go with a weiand stealth idle to 6800. My idle rpm is around 850 in gear, timing goes full advance around 2700 rpm. I thinking going with the dual plane will be a lot better considering my 2500 torque converter with 4.11 rears
 
You hould be fine with the converter you have. Check cam and timing. You stated you have 36° all in unhooked?
 
Yes 36 vacuum advance unhooked. It advances too much so I unhooked it 55 all in hooked up is too much I couldn't turn it down to 50 without cutting out initial timing
 
Are you still using the factory distributor? The vacuum can maybe adjustable. There are also plates to block total advance if need be.
If we knew what the vacuum reading at idle is and what changes occur getting it to road speed we would have a better idea what the engine likes and also if the timing at idle is within range.
Your cam sheet should give some ideas as what to expect.
 
Just my two cents , but first things first . Get rid of that darn intake . It's not doing you any good on the bottom end . Then go from there .
 
Here's the cam sheet give me any pointers

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The 107° lobe separation does nothing for bottom end power. Your truck weighs approx 3800 lbs.
With out a cam change to something closer to 110° separation you will have a lot of tunning, trial and error to get thing right. The more weight lost the better.
Your carb is going to be a pain to adjust due to lack of vacuum at idle and just of idle
 
Also I personal would not use a vacuum secondary carb with your present cam. But I don't care for vacuum secondaries on anything.
 
Chase Marose said:
U think the weiand stealth would be a better route bear?
Click to expand...
To me they both have there pro's and con's over each other and either one would be a good choice over what you have now . Now this is just my opinion . The Weiand stealth intake would give you just a little bit more bottom end torque over the Edelbrock air gap . But like I said it would be marginal . The air gap design I like because it separate's the runners from the engine with gives you a cooler denser fuel mix which has been proven to make power . It should also ( by design ) give you better mid RPM torque and power over the Stealth . Now I think price should also be in the equation because if your like most of us , your on a budget . And you don't want to just keep throwing money at it and "hope" it works . I just did a quick search on Summit and the air gap is about $100 more then the stealth . So all that being said . Personally I like the air gap better but if money was an issue then I'd go with the stealth . But if I did buy the stealth I'd try it as is and see how it performs but eventually ( judging by what I see in it's design and me being me ) , Id be installing about a one inch spacer or notching the divider to equalize both sides of the intake . I'm willing to bet that , that would improve the stealth intake quite a bit over what it is as is . Sorry this post ended up be longer then I expected but I like giving reasons why or why not I'd use something .
 
7mopar said:
The 107° lobe separation does nothing for bottom end power. Your truck weighs approx 3800 lbs.
With out a cam change to something closer to 110° separation you will have a lot of tunning, trial and error to get thing right. The more weight lost the better.
Your carb is going to be a pain to adjust due to lack of vacuum at idle and just of idle
Click to expand...
Nothing against "Chase" , but the only thing I like about the thumper cams is the way they sound .
 
The Thumper has its place. Just do not figure where they think it is a streetable cam form the information given and that is not much.
 
Hey Chase . You are going to let us know what the result's are when or if you change your intake , aren't you ? I'm betting it's going to be like night and day , if you do .
 
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