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1.75" Headers?

Aegis43 said:
I can't post pics in this forum with my level of membership. You can tell by the number of times I've posted vs how long I've been on this forum that I'm very not hard core.
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I sent an e-mail.
Aegis43 said:
That being said, I'm definitely not interested in mild steel painted. The ones on it now are Hedman Elite pn 69830 long tube ceramic coated, 3" collector. The port shape is very much round. The exhaust port shape on my heads is sometimes called rectangular, but they're more square-ish. They're sweet headers.

For new headers, I'd prefer ceramic coated or stainless. I guess my budget would be around $600 to replace them with right ones.
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If you have those headers I don't think you will see much gain, I would keep them. You already have long tubes, which are WAY better than shorties or manifolds for both torque and power. If you want more power just install a larger dual 3" exhaust. Yeah you could potentially see some small gains with larger tubes, but I think the exhaust is more restrictive than your headers. I am currently building a dual 3" exhaust for my ole 388. Same story, built a big block for the regal, sold my big block truck, want another big block, but not ready yet, 388 sitting there, so I plopped it in the blazer. :waytogo:

Aegis43 said:
It has a 700R4, 1800 stall (stock?), 33" KO2s and 3.42 gear. It's my daily driver. Half hwy miles. Off road is forest service roads. Zero rock crawling. I'd like to switch to 3.73 gears someday, but priorities, and $1000+, you know ...
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As for what you want to do, it depends on what you want out of it. A 225@ 050 with a 112 LSA is not that out of the question for a truck if the gearing and converter match, which they currently do not. But if you get a different converter and maybe gears it can certainly perform much better. What is the carb? What is it doing right now you are not happy with?

shady said:
Personally I'd change the cam to something more truck like.
Way easier than a gear change, and makes more sense in the end.
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Says the guy with a 236/246 @ 110 cam with 4.56 gears in a 6800 lb burb. :thumb: You didn't take your own personal advice, I like your style better than your advice. :haha:
 
..... Which is why I'm going to a 3500 stall lol
:thumb:
And the cam may not stay that way forever.
It was just that I couldn't afford to change it after spending $17k with my friendly ck5 parts supplier :haha:


And, 7.4L helps lol.
 
Also, I was thinking 350.
385 may have enough in the bottom to stay happy with the cam in a truck. :dunno:
Was Just thinking that changing gears is expensive and SUCKS lol. I'd rather change a cam any day.
 
shady said:
Personally I'd change the cam to something more truck like.
Way easier than a gear change, and makes more sense in the end.
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Definitely the wrong cam for a Blazer. Worked great in the Camaro. Really needs both.

Someday, hopefully, I'll rebuild the original 5.7 that came out of it and put it back in.
 
folkenheath said:
I sent an e-mail.

If you have those headers I don't think you will see much gain, I would keep them. You already have long tubes, which are WAY better than shorties or manifolds for both torque and power. If you want more power just install a larger dual 3" exhaust. Yeah you could potentially see some small gains with larger tubes, but I think the exhaust is more restrictive than your headers. I am currently building a dual 3" exhaust for my ole 388. Same story, built a big block for the regal, sold my big block truck, want another big block, but not ready yet, 388 sitting there, so I plopped it in the blazer. :waytogo:



As for what you want to do, it depends on what you want out of it. A 225@ 050 with a 112 LSA is not that out of the question for a truck if the gearing and converter match, which they currently do not. But if you get a different converter and maybe gears it can certainly perform much better. What is the carb? What is it doing right now you are not happy with?



Says the guy with a 236/246 @ 110 cam with 4.56 gears in a 6800 lb burb. :thumb: You didn't take your own personal advice, I like your style better than your advice. :haha:
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It has a Performer AirGap, not an RPM, and a Q-Jet 750. It's just kind of sluggish at cruise if I get on the gas. From a stop light it gets going fine. I don't drive it like it's a muscle car. Also, it doesn't have a tach, so I can't really tell you at what rpm it wakes up.

I'm really becoming convinced the biggest improvement will come from gear change. I mean, with the 700R4 and 33s, at 70 mph with 4.10 gear, it would be turning 2045 rpm (not counting converter slip). It'll probably get BETTER mileage than it's getting now. Just need to start saving up the coin.
 
Aegis43 said:
It has a Performer AirGap, not an RPM, and a Q-Jet 750. It's just kind of sluggish at cruise if I get on the gas. From a stop light it gets going fine. I don't drive it like it's a muscle car. Also, it doesn't have a tach, so I can't really tell you at what rpm it wakes up.

I'm really becoming convinced the biggest improvement will come from gear change. I mean, with the 700R4 and 33s, at 70 mph with 4.10 gear, it would be turning 2045 rpm (not counting converter slip). It'll probably get BETTER mileage than it's getting now. Just need to start saving up the coin.
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By all means put some gear in that thing to give the power band a chance to do what it is supposed to do.
Your cam specs aren’t crazy big ( even though the amount of lift is high for a SBC grind ) with the duration only being in the mid-twenties - things aren’t considered to get in the healthy range until upwards of 230 and beyond.

With your grind numbers and good flowing heads plus a 3.75” stroke ( BTW, what length rod did you go with and how deep did you cut the pistons for valve clearance ? ) that motor should make fairly nice midrange torque.
Keep the motor happy by gearing it properly and you just might find that this motor combo is very effective with no need to make plans for a replacement. It’s not radical but just starting to borderline being healthy and interesting - allow the surrounding parts to compliment the motors power band and enjoy it even in a truck chassis.
 
Truth is higher lift and shorter duration is the way. Modern cam grinds are all headed that way as some of the derelict users finally are getting away from flat tappets, now that they’ve been out 60 years…
 
tarussell said:
what length rod did you go with and how deep did you cut the pistons for valve clearance ?
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Scat 5.7 rods. Sealed Power H869CP piston. That piston is designed for sbc stroker. We checked piston to valve clearance and it was .1" Engine spec'd out at 9.91 cr
 
Bent77 said:
Truth is higher lift and shorter duration is the way. Modern cam grinds are all headed that way as some of the derelict users finally are getting away from flat tappets, now that they’ve been out 60 years…
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Hmmmm, as every engine I have is still flat tappet.
BBC, SBC, Cummins, Buick V-6
 
76zimmer said:
Hmmmm, as every engine I have is still flat tappet.
BBC, SBC, Cummins, Buick V-6
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He did say modern.
None of what you have can be considered modern.
Don't get me wrong I am still holding on to my dinosaurs.
 
Aegis43 said:
It has a Performer AirGap, not an RPM, and a Q-Jet 750. It's just kind of sluggish at cruise if I get on the gas. From a stop light it gets going fine. I don't drive it like it's a muscle car. Also, it doesn't have a tach, so I can't really tell you at what rpm it wakes up.

I'm really becoming convinced the biggest improvement will come from gear change. I mean, with the 700R4 and 33s, at 70 mph with 4.10 gear, it would be turning 2045 rpm (not counting converter slip). It'll probably get BETTER mileage than it's getting now. Just need to start saving up the coin.
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That intake is also a choke for that engine, along with the small exhaust, everything between there is stout, from heads back out to headers. I would only put a regular performer on a bone stock engine. The RPM version is better pretty much everywhere in the entire useable RPM range.

If you want to do a test, 3rd gear at 70 MPH should be around 2600 RPM, try driving on the freeway in 3rd gear. That should make it a lot more peppy a low throttle without a downshift as a test. It won't affect the other driving because your axle gear didn't change, so you can't compare regular acceleration, that will be better with a gear change.

What is your ignition timing at 3K with the vacuum advance unplugged? 4k? 5k? 2k? idle?

What is the timing with the vacuum advance plugged in at 2500 RPM?

Trying to get a sense of your ignition curve.

Is the vacuum advance plugged into full manifold vacuum? or ported? (that engine will not want ported)
 
I haven’t had to do any work to those engines so I kind of disregard them for this discussion of us old farts not using roller cams.
 
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