New heads... New problem...
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Joined: Apr 2008
Posts: 91
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From: Stockton California
New heads... New problem...
Well I finally completed the overhaul on my 75. At first, it started out with just hopping up the motor a bit, but "you can't have that much power with that stock tranny", so I went ahead and bought a beefed up 700r4 and slapped it in there, but "what's the use of all that power when you have 2.80s in the back?", so i had my diffy rebuilt with 3.70's. Then FINALLY I was able to work on my motor, .477 lift cam, edelbrock eps performer manifold, aluminum water pump, edelbrock 64cc heads, and edelbrock carb.
Well everything was fine and dandy until I installed the heads. I go out to test em out and everytime I punch the gas my engine either dies or "hiccups"
. Thats only from low speeds, when I hit it at 30 it hauls *** with no problems. I feels like the engine is bogging down and I can't think of any reason why.
I'm thinking valve lash but I doubt that's the problem.
Any advice??
Well everything was fine and dandy until I installed the heads. I go out to test em out and everytime I punch the gas my engine either dies or "hiccups"
. Thats only from low speeds, when I hit it at 30 it hauls *** with no problems. I feels like the engine is bogging down and I can't think of any reason why. I'm thinking valve lash but I doubt that's the problem.
Any advice??
Instructor
Joined: Jun 2008
Posts: 105
Likes: 0
I just had the same problem with my 75. It truned out to be a timming issue alone with air/fuel ratio problem.. My first bet would be to check timming. But since it does it under part throttle i would count out the carb.
Drifting
Joined: Apr 2006
Posts: 1,911
Likes: 2
From: gold coast queensland
do you have your old carb or one you can burrow from a mate . at least thats only an hour out of your time to swap it and gives you a pretty conclusive answer in what direction to go next. i like your choice in parts but with all those parts and gearing are you at least running a 2500 stall so your motor doesnt fall on its face?
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Is the engine hot or cold when you experience this problem...or both?
Look at the carb choke adjustment first, then the timing, and depending on the carb type, it may need to be rebuilt.
Look at the carb choke adjustment first, then the timing, and depending on the carb type, it may need to be rebuilt.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Just tune like it should be done.
Congrats on the upgrades. There are plenty of us that get the "while i'm at it itis". But at least u have it running - and can diagnose it easier.
Just tune the ignition and carb like it should be. Plenty of info on setting the timing curve and then the carb right here in the archives (and stickies). Now if you have something thats not installed correctly like a missing vac line we won't see that here from the internet. But if u have any specific questions we'll be here for u.
IMHO it sounds carb related. Now a carb stumbles like a drunk when its too rich with fuel. And for the opposite it bogs when too lean. It sounds like your "hiccups" are a stumbling drunk - too large a pump shot or metering rods are too rich. I would have expected too lean with your new mods but we don't really know whats going on without and A/F meter installed.
Just like most everyone else here u went for the power mods before u learned how to tune the ign and carb - now u pay the price. Not sound like a crab as your more the norm than not. Just hope others take note of this before they dive on thier eng mods like it was a pot of gold (but really its a greanade).
Hope this helps,
cardo0
Just tune the ignition and carb like it should be. Plenty of info on setting the timing curve and then the carb right here in the archives (and stickies). Now if you have something thats not installed correctly like a missing vac line we won't see that here from the internet. But if u have any specific questions we'll be here for u.
IMHO it sounds carb related. Now a carb stumbles like a drunk when its too rich with fuel. And for the opposite it bogs when too lean. It sounds like your "hiccups" are a stumbling drunk - too large a pump shot or metering rods are too rich. I would have expected too lean with your new mods but we don't really know whats going on without and A/F meter installed.
Just like most everyone else here u went for the power mods before u learned how to tune the ign and carb - now u pay the price. Not sound like a crab as your more the norm than not. Just hope others take note of this before they dive on thier eng mods like it was a pot of gold (but really its a greanade).
Hope this helps,
cardo0
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Joined: Apr 2008
Posts: 91
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From: Stockton California
1 it was too rich, jetted up both prim. and second. and changed metering rods 1 step richer.
2 i know how to tune my car. I work for an auto restoration company and if I didnt, my boss builds high performance engines. So thats not the issue.
3 The carb I had bought with the car was a piece of ****, which was unknown to myself.
4 Now i run 4.98 0-60's.
5 My tranny has a 1650 stall and is locked up by hydrolics. (bought that way from a performance tranny shop).
So now eveything is fine except for my gas mileage! But that's to be expected.
Now all I need is a paint job, thanks for all the input.
2 i know how to tune my car. I work for an auto restoration company and if I didnt, my boss builds high performance engines. So thats not the issue.
3 The carb I had bought with the car was a piece of ****, which was unknown to myself.
4 Now i run 4.98 0-60's.
5 My tranny has a 1650 stall and is locked up by hydrolics. (bought that way from a performance tranny shop).
So now eveything is fine except for my gas mileage! But that's to be expected.
Now all I need is a paint job, thanks for all the input.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Good to hear u worked things out and all is well. I don't understand what u mean by it was too rich and u changed metering rods to 1 step richer - but all that matters is that u do and congratulations. With those parts u should have a car that makes a lot of pwr, fun to drive and very reliable.: :I didn't mean to bust your bubble but i would be honest to say i read of a new enthusiast at least once a week here that can't set his timing let alone tune his carb that dives into a big $$$ overhaul then can't even get the car to start.
I just want to get the word out that the place to start for performance is the timing/dist and then the carb. I wouldn't waste my time and effort with most others but i can see you are sincere and motivated to get it right. My personal guess is most novice mechanics are leaving at least 30hp in a bad tune on a stock motor and a lot more for a hi-po eng.
Thx for posting your results,
cardo0
Thread Starter
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Joined: Apr 2008
Posts: 91
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From: Stockton California
What I meant to say was it was running too lean. The classic booooog, then nice high end pickup. so i jetted up and metered down and all is good, except i'm running stock dist. because i ran out of money! All will work out in the end and yes, this car is a blast to drive! 0 - 60 in 4.98!
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