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77C3

77C3

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2 You're 10
Dec 2, 2012
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Manitoba
VetteCoins
603
Car
1977 C3
So my 77 has about 90,000 miles on it and has less than 5psi difference between all cylinders, right around 90psi. I want to get a little more performance out of the engine. The question is that the motor is pretty healthy and burns no oil, it could benefit from new valve seals though. I want to add a cam so I would take care of the valve seals at that time. Has anybody done this on an older motor? I would like a new crate, but the budget doesn't allow that at this time. Would you pull it and re-ring and re-bearing it. Thanks.
 
77C3,

In many ways, engines are a fine balance, and components age together. If you make an improvement in one area, without dealing with likely age deterioration throughout the rest of the engine, you will be stressing the older components.

That would be akin to building up your upper muscles for rock-climbing, without making sure that your legs were ready.

I'd wait on the cam change until you can go through the short block too.
 
i am in the same boat with my 76. it has 97000 on it and runs and performs very well considering the age. i don't see any point in messing with my old L48 because of the one thing leads to another deal. i have brand new long tube ceramic headers in my family room because i can't get the manifolds off without pulling the heads. like i say get too far in and i might as well swap out the motor. so my plan is to build up a goodwrench 350 with a roller, heads, etc and just plunk him in. the 350 is $1600 and i should have under $3500 in it when done.
:seeya:
 
My '75 has had some upgrades to the intake, carb and the addition of roller rockers. It also has a set of headers. With the stock 3.08 rear and 2.48 first gear of the THM400 with the stock 2200 stall of the converter, it's probably more of a dog off the line now than it was originally as the torque curve is further up the rev band; brake stand it to 2200 or so and it takes off like a scared rabbit...but who wants to drive like that. What I'm trying to say is if you change where the engine performs you may have to change rear gears, torque converter etc to make use of the new found power. And I agree that beefing up the top end with a soft short block will lead to more trouble.
 
Case75 said:
My '75 has had some upgrades to the intake, carb and the addition of roller rockers. It also has a set of headers. With the stock 3.08 rear and 2.48 first gear of the THM400 with the stock 2200 stall of the converter, it's probably more of a dog off the line now than it was originally as the torque curve is further up the rev band; brake stand it to 2200 or so and it takes off like a scared rabbit...but who wants to drive like that. What I'm trying to say is if you change where the engine performs you may have to change rear gears, torque converter etc to make use of the new found power. And I agree that beefing up the top end with a soft short block will lead to more trouble.
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greg, did you do a recurve on the distributor ? having full advance in around 2800 rpm should correct that. it will feel like you have gained some hp the factory initial timing is retarded by about 4 degrees. the stock HEI distributor has a mechanical advance of about 20 degrees. a timing light with the advance feature will tell everything. :D doug.
 
buckhorn76 said:
greg, did you do a recurve on the distributor ? having full advance in around 2800 rpm should correct that. it will feel like you have gained some hp the factory initial timing is retarded by about 4 degrees. the stock HEI distributor has a mechanical advance of about 20 degrees. a timing light with the advance feature will tell everything. :D doug.
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Funny you should mention this Doug as I've been reading up on recurving. Unfortunately I don't have access to a timing light. I think I need to adjust the floats in the carb as well; I've got a hesitation if I hit the gas while turning a corner in town. Lots of little things to get right to bring out an engine's full potential. I'd love to get it on a dyno and really tune it in good.
 
If you don't mind spending a few dollars, Eric Jackson is the guy to send your carb to. Welcome to Vintage Musclecar Parts Professional Carburetor Restoration Service He will restore it perfectly and actually runs it on an engine before returning it. I had the original Holley from our COPO Chevelle done by Eric. Over the years, I had sold the carb and eventually bought it back. A lot of parts like the choke linkage were missing and other stuff had been changed out. Eric restored the carb with all the correct parts and it came back looking like it was right out of the box from Holley. I think he is back doing Quadrajets as well. I still have two 4346 Holleys that he restored and they too look like brand new. A carb restoration isn't cheap but, to me at least, it is well worth it. Nothing more aggravating that a messed up carb.
 
Keith Tedford said:
If you don't mind spending a few dollars, Eric Jackson is the guy to send your carb to. Welcome to Vintage Musclecar Parts Professional Carburetor Restoration Service He will restore it perfectly and actually runs it on an engine before returning it. I had the original Holley from our COPO Chevelle done by Eric. Over the years, I had sold the carb and eventually bought it back. A lot of parts like the choke linkage were missing and other stuff had been changed out. Eric restored the carb with all the correct parts and it came back looking like it was right out of the box from Holley. I think he is back doing Quadrajets as well. I still have two 4346 Holleys that he restored and they too look like brand new. A carb restoration isn't cheap but, to me at least, it is well worth it. Nothing more aggravating that a messed up carb.
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Thanks for the tip Keith. I checked out the site. My original Quadrajet is in a box in the basement; the previous owner replaced it with a 750CFM Edelbrock Performer (Carter AFB). I think it's too much for the small port heads of the L48; I was thinking of changing it to a 650 CFM Edelbrock Thunder series (the old Carter AVS). I might actually get better throttle response. I'd sell the 750CFM.

Greg.
 
If you ever get to use a well set up Quadrajet, you won't want anything else. With the adjustable air valve in the secondaries, it can be tightened up for smaller engines so that you don't over carb the engine. Quadrajets are a little more involved to get set up but are some nice and smooth when they are and good gas mileage is a nice side benefit. If you want someone to set up a Q'jet for your application, this is the guy to see. SMI CarburetorSMI- Sean Murphy Induction
 
Keith Tedford said:
If you ever get to use a well set up Quadrajet, you won't want anything else. With the adjustable air valve in the secondaries, it can be tightened up for smaller engines so that you don't over carb the engine. Quadrajets are a little more involved to get set up but are some nice and smooth when they are and good gas mileage is a nice side benefit. If you want someone to set up a Q'jet for your application, this is the guy to see. SMI CarburetorSMI- Sean Murphy Induction
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absolutely right keith, the q-jet has powered some awesome gm products and flows air as an " on demand " basis. unless the previous owner of greg's car gave him the intake for the q-jet, i don't think he can use it. i think he has a square bore set up currently. greg, is your quadrajet for sale ?
 
buckhorn76 said:
absolutely right keith, the q-jet has powered some awesome gm products and flows air as an " on demand " basis. unless the previous owner of greg's car gave him the intake for the q-jet, i don't think he can use it. i think he has a square bore set up currently. greg, is your quadrajet for sale ?
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You're right Doug, I have an Edelbrock high rise with a square bore. The original cast iron intake was kept for awhile but his wife through it out along with one of the cast iron exhaust manifolds. I did get one manifold in the sale and I have the original cowl induction air cleaner complete with lid and rubber seal. It won't fit with the high rise intake. I may be interested in selling some pieces.

One reason I'm looking at the Thunder carb is the adjustable secondaries. You can adjust them on the AFB but you have to drill holes in the weights. Who wants to get into that...:eek:

Greg.
 
One reason I'm looking at the Thunder carb is the adjustable secondaries. You can adjust them on the AFB but you have to drill holes in the weights. Who wants to get into that...:eek:

right on greg, poking a hornets nest is only fun for a little while. :rofl:
i am mulling over whether or not to pick up a spare carb, let me know in the future if your carb will be for sale. the 75-80 q-jets are the same. :seeya:
 
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