Just bought a 68 chevelle, when push on it , don't have power it should I ck time it's ok I think could be carb it has a street avenger on it and a air gap intake motor sounds good on idle. I just bought it machine shop in Boston built motor.
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Just bought a 68 chevelle, when push on it , don't have power it should I ck time it's ok I think could be carb it has a street avenger on it and a air gap intake motor sounds good on idle. I just bought it machine shop in Boston built motor.
Air gaps work best @WOT after warmed up thoroughly.
At least, that's my experience.
Which machine shop? Bostons about 60 miles from me, maybe I know them?
Did they give you a build sheet? Do you have any specs on the internal parts? what pistons, camshaft, springs?
Could be they only built a driver with a "small" cam.. but without any specs, you'll have to do some digging to find out what is there.
Does it get great gas mileage?
If it does, then that's your answer: it wasn't built for power
See, here's another example of marketing hype sucking money out of your wallet. If the motor you're building or buying is intended to be used 100% at the drag strip, great, use an intake manifold you want to and experiment with it. But if the motor is to be used on the street, DO NOT USE AN AIR GAP INTAKE. A street driver needs the heat of the motor up into the manifold to heat the fuel charge so that is will begin to separate into a fog of mixture that the motor can burn. When the mixture is cold, it goes into the motor as big clumps of fuel separated by equally big clumps of air and big clumps of fuel will not burn.
Since you didn't spec out the parts or build the motor, you have no idea of the relationship between the static compression ratio and the cam timing or anything else about the motor, so unless you are willing to tear the motor down and measure everything, get used to continuing problems like this.
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I know it got me puzzled I think the carb is a 770 dual line. I think I need to get the air gap off there and put a performer intake on it. He said spent 2 k on transmission but it needs a stall converter on it. I think carb is vacuum secondary's, needs to be manual I think
Ken-----------look up Holley site for pics/discreptions of carbs--vacume seconaries are easy to tell from mechanical sec. look in the carb and work the linkage to wide open-if sec throlle plates open its manual------
should be a "list" number across front of chole housing---------the 770 is a vacume sec carb and was a very good unit
For what it's worth, if you're running this on the street daily and use an auto trans.
Stick with a vacuum secondary carb.
Again, for what it's worth - my point oh two.. etc. etc. etc. yada yada yada.
I took the valve cover off today it does have roller rockers on it , an is very clean in there don't believe it's been run none since he built it . The back sight glass on carb fuel level is to high will that make her run wrong the front is ok right at bottom back is at top
usually the back float level is set a little higher than front so fuel won't slosh to the rear ucovering the main jets--------
How about checking the list number on the front of the choke tower??????and did you check to see if the sec opened manually????
Yea it is a vacuum secondary's. It got a little backfire thru carb when pushing on it can't figure it out, is there anyway of telling if I got a hydrulic cam or a flat tap pet. Cam is a little big I guess when I idle brakes are hard , put a vacuum gauge on her today an at idle got 6 on gauge. It needs a stall convertor just don't have the power it should have. Will a set of aluminum heads bring her around,
The carb backfire was very typical of what I experienced with the air gap intake. A smaller carb helped, but only a performer intake fixed it.
Ken, Tech gave you good advice in his post above:
Until you know the facts of your motor, either by going back to the shop that built it for the specs, or tearing it down (pulling the heads) for some precise measuring, you're going to be throwing good money away on pieces & parts in a gamble that might yield a little bit better performance, might make things worse or stay the same. Picking the right parts is a science based on knowns, and once you know your engine you can invest your money wisely in parts and pieces that you can feel confident will give good results.
Good luck to you, and hope you have fun with the new to you Chevelle! Oh, and if it popped back through the carb, even a little, you may have just identified one of your problems.
Can I take the timing chain cover off an get the #s off front of cam and that tell me wat cam is in her
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Maybe, but cam grinders usually stamp the cam on the rear journal. I suspect that's because when you stamp into the face of a piece, it raises the numbers/letters that you're stamping, causing that material to stand proud from the face of the journal. It might be that when you would then bolt a timing gear onto the face of the cam, she might run a little lolly-gagged due to not sitting on a perfectly flat face. I really have no idea, that's the best I can come up with. I think in recent years, they have begun to etch the number into the front face rather than stamp it, because it does not appreciably raise any of the material.
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No I can't find any info the guy that had it built passed away and his brother I got from don't know
Ken,
If you search through TechInspector1's posts (there's a bunch!!) you're going to see over & over again that choosing components for best fit to your wants & needs all starts with the deck height and gasket thickness, compression ratio (piston specifics, combustion chamber design/head selection), which guides the cam selection, which guides the intake & carb selection which all together leads to a predictable power output in the rpm range where you want it. When you start
swapping things around in the later stages without first knowing the answers to the first key pieces (squish & compression ratio) you're rolling the dice and may well be burning $100 bills one after another, throwing your money away. Here's one recent post from Tech that I really liked - http://www.clubhotrod.com/chevy-big-...tml#post558088
There's a few other guys that hang around here that can give you good guidance too (love Glenn Sexton's engine build posts, too!!), but if you want to know the who/what/where/when of getting your engine to the place you want it you cannot go wrong listening to Richard, IMO.
Why don't you just get and post for me the list numbers on the carb???????? And I will then tell you jetting/timing info for baseline trouble shooting and tune---------I have asked for it twice already and now 3 times
80770-1
1402 that's the #s carb
3 different websites I checked, don't see those numbers...???...??? this is one of them, I see a 80780?
Holley Four Barrel Carburetor List Numbers, Stock Jet Sizes, CFM, and Stock Power Valve Ratings | Hot Rod Reference
Also see Holley Carb Numbers | Holley Carburetors
I found out a little more about motor build not a lot but some it does have hyd lifters an hyd roller cam still don't know lift on cam but sounds like somewhere around 600 lift A buddy of mind has a set of dart pro one heads think I could use them an run pump gas
Well took car dn to shop are taking 396 out an putting in a 454 with arf heads on it he said make 600 hp. Going to put 396 on shelf car problay worth more with it in there, but we will see he said 454 had 1 PS seal in it
There's no substitution for cubic inches!
what does 1 PS in it mean?
And having the 396 on the side, not being hurt, will pay dividends somewhere in the future.
one piece rear crank seal---
Yea crank seal , he said 600 hp out of 454 on pump gas can he do it ??
Decided to go with a stroker 489 using Callie's rotating assembly with afr heads he said should be around 700hp on pump gas , this car had air on it an I have the heat an air assembly box out of a 68 chevelle if anyone needs one excellent condition