73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Performance => Topic started by: English on June 10, 2015, 10:33:20 AM
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Some opinions please!
Truck needs some love in the engine department. I'm wondering which direction to take. I either have a blown head gasket or a cracked head. Also my vacuum gauge tells me I have worn valve guides. It's a 350, 165hp
Wondering what the pros and cons are of replacing/rebuilding the heads vs swapping in a long block. Also I'd like to install the Comp 12-300-4 (because of my existing motor has the heads and manifold off, I might as well put the cam in; and if I'm putting a new block in, I might as well put the cam in the new engine before dropping it into the truck).
Working out the costs, going down the new long block route costs an extra £1,000. And changing the cam *might* void the warranty (over here the warranty will be upheld by the vendor, it's not worth sending a block back across the pond to GM).
What are the pros of using a new long block, and what are the cons of using my existing block?
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When I got my truck the engine is completely unknown with unknown mileage.
All I did was put new heads, cam, lifters, and push rods in. I haven't done a compression check yet but the truck runs amazing for what it is and doesn't blow any blue or black smoke ever. But the amount of money I've put into it so far I could have saved a few hundred more and dropped a new long block in.
To be honest with the cheapness of a long block these days it really doesn't make much sense to toss a bunch of money into an older block.
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^^^ agreed.
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Right, after a whole lot of thinking I've decided to go for a new long block 8)
A lot of money, but I'm hoping it will be a "wise" spend that adds value to the truck. And the old girl is in otherwise such good condition that I think she deserves it.
Question- it'll be the 350/260 that I'm getting. I've read up a whole lot on the 260 vs the 290, and the 260 sounds much more appropriate as it has better low down torque. But... would it be a good idea to swap the cam out before the block even goes in? It would be the Comp Cams 12-300-4 that I'd go for. I've been reading Rich Weyands threads, and the 12-300-4 sounds ideal, but at the same time I'm wondering if the benefit would be worth it over the stock 260hp, as pretty every thread I've read about the 290hp concludes that it's a rev-hungry low torque set up.
Should I swap the cam out straight away, or see if the stock 350/hp is good enough as it is?
I have Flowmaster true duals, Edelbrock Performer intake, and Holley 570cfm carb. Unfortunately I can't use the Comp Cams dyno software as my laptop is a Chromebook and my work PC blocks it. If anyone fancies plugging in some numbers on my behalf I'd be very grateful!
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+1 for the long block.
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+2 for long block
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Yeeeeeah I'm going for the long block already! Now wondering about the cam
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If you want bone stock, as close to original, as you can get, don't add performance parts. If you want extra HP or extra torque or to use existing parts that you stated above, then you will have to make sure they are applicable to the new long block.
Also, alot of long blocks come with a warranty, the moment you pop ONE bolt loose that's not required for final engine assembly then your warranty is void. If your ok with that then that's ok, but if you like to retain the warranty, consider finding a company that builds long blocks with customer request parts. That way you can tell them what you have and what you want and then you win both ways.
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It's a tricky one. On the one hand I don't actually need the truck to be *fast*, but on the other hand I don't want to drop a new motor in and be disappointed with it's performance. On the flip side, I don't want to spend out on changing a cam if it's not necessary (the company that sells the block can swap the cam, but would charge 3-4 hours labour, is that right?), and risk the warranty in the process.
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I would run the new engine for a while, then you can find exactly what you would like to improve, if anything. That and I wouldn't want to void any warranty you might have.
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There are a number of companies that build engines per customer request. You could call a few up, tell them what you want, price around a bit. I bought my short block from a company called ATK Performance Engines. They build short blocks, long blocks, performance turn-key engines and can add curtain parts you want so you don't have to add them your self. Since they are assembling the engines, the work should be covered under there warranty. Most shops like this use stock parts for stock engines and well as popular performance brands parts. It's gonna take some shopping around but you should be able to find what you want.
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There are a number of companies that build engines per customer request.
Ahem, permit me to draw your attention to my username sir. I'm in the land of your forefathers! Not quite so easy over here I'm afraid. There are a few places that do builds, but they're way out of my price bracket. The company that I'm planning on getting the longblock from want £300 just to change the camshaft. That's with an engine that's not even in a vehicle!
I think I live in the wrong country :'(
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There are a number of companies that build engines per customer request.
Ahem, permit me to draw your attention to my username sir. I'm in the land of your forefathers! Not quite so easy over here I'm afraid. There are a few places that do builds, but they're way out of my price bracket. The company that I'm planning on getting the longblock from want £300 just to change the camshaft. That's with an engine that's not even in a vehicle!
I think I live in the wrong country :'(
I didnt forget, I just wasn't sure how you were planning on getting or doing all of this so I just threw the ideas out anyway. Some of it may or may not be useful.
On another note, my mother was born is Sydney, Australia. So I'm half part of the people who got kicked out of the land of my forefathers.
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I would try the 260 before swapping in a cam. Especially if it will void the warranty.
The 454s of the era of our trucks were only 230hp, but they were also 380tq. The 260hp 350/5.7 should move the truck around quite respectably especially considering that the truck has a manual transmission.
And as an additional thought I'm predicting English will soon be wearing Levis, cowboy boots, a New York Yankees baseball cap, and listening to 80s Southern Rock........once you've been bitten by the bug......
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There are a number of companies that build engines per customer request.
Ahem, permit me to draw your attention to my username sir. I'm in the land of your forefathers! Not quite so easy over here I'm afraid. There are a few places that do builds, but they're way out of my price bracket. The company that I'm planning on getting the longblock from want £300 just to change the camshaft. That's with an engine that's not even in a vehicle!
I think I live in the wrong country :'(
I didnt forget, I just wasn't sure how you were planning on getting or doing all of this so I just threw the ideas out anyway. Some of it may or may not be useful.
On another note, my mother was born is Sydney, Australia. So I'm half part of the people who got kicked out of the land of my forefathers.
Ah sorry, I thought you had assumed I was in the US.
Everything's do-able over here, just a lot more expensive. For example, the same long block that costs $1500 from jegs is going to cost me $2800.
Apologies for the Botany Bay thing, I think people got kicked out just for stealing apples, cor blimey guv'nor!
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I would try the 260 before swapping in a cam. Especially if it will void the warranty.
The 454s of the era of our trucks were only 230hp, but they were also 380tq. The 260hp 350/5.7 should move the truck around quite respectably especially considering that the truck has a manual transmission.
And as an additional thought I'm predicting English will soon be wearing Levis, cowboy boots, a New York Yankees baseball cap, and listening to 80s Southern Rock........once you've been bitten by the bug......
Haha, I'll confess right now that I bought a Kansas album purely to listen to in the truck :-[
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And as an additional thought I'm predicting English will soon be wearing Levis, cowboy boots, a New York Yankees baseball cap, and listening to 80s Southern Rock........once you've been bitten by the bug......
Hahaha, only thing is that hat would be better suited if it was a faded, vintage Chevrolet type with a few wear spots and a small tear in the bill.
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There are a number of companies that build engines per customer request.
Ahem, permit me to draw your attention to my username sir. I'm in the land of your forefathers! Not quite so easy over here I'm afraid. There are a few places that do builds, but they're way out of my price bracket. The company that I'm planning on getting the longblock from want £300 just to change the camshaft. That's with an engine that's not even in a vehicle!
I think I live in the wrong country :'(
I didnt forget, I just wasn't sure how you were planning on getting or doing all of this so I just threw the ideas out anyway. Some of it may or may not be useful.
On another note, my mother was born is Sydney, Australia. So I'm half part of the people who got kicked out of the land of my forefathers.
Ah sorry, I thought you had assumed I was in the US.
Everything's do-able over here, just a lot more expensive. For example, the same long block that costs $1500 from jegs is going to cost me $2800.
Apologies for the Botany Bay thing, I think people got kicked out just for stealing apples, cor blimey guv'nor!
It's all good. I just wasn't sure how much MORE expensive it will be. By the way, one of my favorite TV shows of all time is or should I say was your Top Gear.
I think being part Aussie is where my rebellious side may come from, I got kicked out of class a few times when I was in school for being, as my grandma so wonderfully puts it, a cheeky buggah.
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I would try the 260 before swapping in a cam. Especially if it will void the warranty.
The 454s of the era of our trucks were only 230hp, but they were also 380tq. The 260hp 350/5.7 should move the truck around quite respectably especially considering that the truck has a manual transmission.
And as an additional thought I'm predicting English will soon be wearing Levis, cowboy boots, a New York Yankees baseball cap, and listening to 80s Southern Rock........once you've been bitten by the bug......
Haha, I'll confess right now that I bought a Kansas album purely to listen to in the truck :-[
Nah, you want Marshall Tucker Band....
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You know, if you're over in Jolly Old, the warranty might not be worth bugger. In which case, getting the 350/260hp long block and swapping in a 12-300-4 or 12-230-2 cam might be worth it. If you do that before it is run AT ALL, you don't even need to change out springs or lifters.
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I would try the 260 before swapping in a cam. Especially if it will void the warranty.
The 454s of the era of our trucks were only 230hp, but they were also 380tq. The 260hp 350/5.7 should move the truck around quite respectably especially considering that the truck has a manual transmission.
And as an additional thought I'm predicting English will soon be wearing Levis, cowboy boots, a New York Yankees baseball cap, and listening to 80s Southern Rock........once you've been bitten by the bug......
Haha, I'll confess right now that I bought a Kansas album purely to listen to in the truck :-[
Nah, you want Marshall Tucker Band....
Or some Molly Hatchet and some Outlaws too.. Can't forget The Allman brothers or Lynard Skynard also!!
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You know, if you're over in Jolly Old, the warranty might not be worth bugger. In which case, getting the 350/260hp long block and swapping in a 12-300-4 or 12-230-2 cam might be worth it. If you do that before it is run AT ALL, you don't even need to change out springs or lifters.
There's that idea too.
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You know, if you're over in Jolly Old, the warranty might not be worth bugger. In which case, getting the 350/260hp long block and swapping in a 12-300-4 or 12-230-2 cam might be worth it. If you do that before it is run AT ALL, you don't even need to change out springs or lifters.
Do you have any torque/hp curves saved from when you were cam shopping? Any chance of posting them here or in a PM, as I'm unable to download the Comp Cams dyno software.
I've spoken to the vendor and they offer their own 12 month warranty. I think they'll be happy to swap the cam for me and maintain the warranty, so might be going down that route.
Edit- Whoops! Just read your previous post and I'm following the hyperlinks now, I think your fullsizechevy.com post has all the info I need, thank you
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Okay here's another question...
I'm in discussion with the vendor about swapping the cam. He says to check if there are any other parts that are required to be changed with this cam (like springs). I've been on the Comp Cams website and it says if I have "self aligning rocker arms" I need an additional rocker arm kit to go with the cam.
So, does a brand new GM350/260 have self aligning rocker arms? The kit costs more than the cam!
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I put the 12-300-4 in a nearly new 350/290 (same as 350/260 except for the cam) and the only thing we replaced was the lifters, because they had bedded in. You can put the 12-300-4 or 12-230-2 in a new 350/260 GM engine with no other changes -- not even lifters as long as the engine hasn't been run yet.
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(http://i58.tinypic.com/zk0ghs.jpg)
Yeeeeeeeeeeeeeeeah!
Ordered on Monday, arrived Thursday. Not bad, considering I'm on the other side of the Atlantic! Now just waiting for the shipment of long blocks to arrive at the vendor's...
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12-300-4. I think you'll love it.
That cam is also very educational: it will teach you what tires cost if you're not careful.
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12-300-4. I think you'll love it.
That cam is also very educational: it will teach you what tires cost if you're not careful.
Then I should be a freakin doctor lol.
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12-300-4. I think you'll love it.
I flamin' hope so! I think I've read all your posts across various forums, thanks for sharing your experience.
I'm getting the 350/260 as opposed to the totally unsuitable 350/290, but I'd still like to take the opportunity to stick the "torquiest" (is that a word?) cam in there before the engine goes into the truck. A lot cheaper to do it beforehand
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Indeed. It's about $1000 labor (local shop rate $75) to change the cam after the fact.
Ask me how I know. <sigh>
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Hey, English. When you get it all together, you will probably find with that cam that when you have your foot in it that the stock TH350 (Your trans is a TH350), right?) will hold gears too long. You will probably want to move shift points down about 500 rpm to get back into the beef of that torque curve sooner.
If you find that to be so, I have the weight you need to modify the governor to do that. Half-hour job. I have one extra because I got a pair of them with another governor I bought for parts. So, when it's all back together, let me know, and if you want to drop those shift points let me know and I'll send it to you. No charge. Stuff like that is easier for others to find over here, and it does nobody any good sitting in my parts bin.
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Wow, thanks for the offer, that's very kind of you. She's a manual though so no need.
Spoke to the vendor today, still going to be a few weeks before the blocks arrive. Very frustrating!
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A container full of engines has finally arrived 8)
Taking the truck to the garage this afternoon for the swap. Fingers crossed it all goes smoothly
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Awesome!
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Whoa! Didn't realise it had been so long since I last posted here! I've had a hectic few weeks.
The new engine has been fitted, after the camshaft swap, without any problems (apart from the mechanic grumbling how hard it was to get into the engine bay- he normally works on drag cars!).
I'll admit I wasn't overly impressed with the performance at first, but I'm wondering if it just takes a while for the engine to break in, plus I don't think the wide ratio manual gearbox does it any favours. It feels a lot better now it's got a couple of hundred miles under it's belt. Feels just a little bit boggy at times when accelerating, I plan on spending more time tinkering with the carb. Initial timing is at 12 btdc.
But overall I'm happy with it, the best thing is being able to start first time, and it's so smoooooth!
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Adjust the accelerator pump: https://www.youtube.com/watch?v=k-Nx5HEzvlY
Advance the timing further. I am running that same engine at 17*BTDC with no knocking ever. Timing is almost a horsepower adjustment: more timing gives you more horsepower, right up until knocking. This is why modern cars have knock sensors -- so they can run the timing right at the edge. If you get knocking, back off two degrees at a time until the knocking goes away.
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Adjust the accelerator pump: https://www.youtube.com/watch?v=k-Nx5HEzvlY
Advance the timing further. I am running that same engine at 17*BTDC with no knocking ever. Timing is almost a horsepower adjustment: more timing gives you more horsepower, right up until knocking. This is why modern cars have knock sensors -- so they can run the timing right at the edge. If you get knocking, back off two degrees at a time until the knocking goes away.
Perfect! The pump cam is what I was going to look into, but I didn't know I could change the pump nozzle as well. The video recommends I use a 25-30 size nozzle, whereas my carb (570 avenger) has a 31. Time for some more parts, thanks for the tip
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Just had a thought- are the pump nozzles and cam kits available on the shelf in the US? My old man is on holiday there at the moment, if he could pick the bits up it would save a few dollars
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That's the sort of thing we usually get mail order here.
You can also order it over the net and get it shipped to the local store, then go pick it up. So you could order it shipped to some O'Reilly's, Advance, or Autozone store he is close to and have him go in and pick it up.
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How's that for a quick turnaround- 'phoned the engine parts place on Monday morning, and the bits turned up today!
Got a 25 and a 28. Fitted the 28 tonight and went for a short drive, feels much better
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OK, now you know you gotta try the 25, right? That engine pulls a ton of vacuum, even compared to stock, and most engines people put a Holley on is cammed for horsepower and has a weak vacuum, so you gotta try things to get the tune squared away. If less is better, even less could be better still....
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If less is better, even less could be better still....
I'm sure that quote sounds vaguely familiar...
Yeah I'll try the 25, I'm just doing it one step at a time. Will see how the 28 goes for a bit first.
Then I'm gonna have to look into the pump cam
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IIRC there's a set where you get all the different flavors of pump cam in one kit.