Starting my engine build

[geezer#99]

Originally Posted by Mrturner1

I did a good bit of reading and looking at dyno sheets, and decided to fork out the extra 70 bucks and get an RPM Air Gap manifold instead of the Performer RPM I had. All the dyno tests I saw are showing a pretty significant increase in power at the same rpm range, I think it's because the air going in is cooler on the air gap. Less contact with the engine (the gap under the carb) means less heat, less heat is guuuuud I almost got it in black and changed the color scheme completely but I am goin for polished, or satin painted to match the block. That's a whole other project I'm going to tackle soon

If you plan on driving it when the temp is below 50F, you might regret the air gap choice.
You need heat in the intake when it's that cool out.
Could be a tuning nightmare for you.

[GRX]

Originally Posted by geezer#99

If you plan on driving it when the temp is below 50F, you might regret the air gap choice.
You need heat in the intake when it's that cool out.
Could be a tuning nightmare for you.

Good point. That intake totally eliminates the exhaust cross over. May mean having to keep your foot on the gas for 10 minutes or so to warm the engine before driving.

[Mrturner1]

This is what I got for the head bolts

[Mrturner1]

I've tried Home Depot, Riebes auto, Napa, and Harbor Frieght and nobody has a thread chaser. Would a clean head bolt with some brake cleaner do the same job?

[GRX]

That Permatex sealant should work. Pretty much same teflon pipe sealant the factory used.

A bolt may not fully clean the threads. I would use a tap if no chaser can be found.

[Mrturner1]

I found an engine block rethreader at an auto parts store for 40 bucks. If I can avoid using a tap or rethreader I'd like to, just to be on the safe side.

[Mrturner1]

Originally Posted by GRX

That Permatex sealant should work. Pretty much same teflon pipe sealant the factory used.

A bolt may not fully clean the threads. I would use a tap if no chaser can be found.

With a tap do you have to just be more careful because it's a harder steel than a chaser?

[ptc]

Originally Posted by Mrturner1

I've tried Home Depot, Riebes auto, Napa, and Harbor Frieght and nobody has a thread chaser. Would a clean head bolt with some brake cleaner do the same job?

Just use a tap like stated before, a 7/16"-14 thread tap. I just saw this thread and read thru the whole thing. I see youre in Colfax, I have a very good friend that lives there, builds boat motors. Looks like you have been to Tognottis for your parts too, the guys there are very smart and helpful. Ask all the questions of them you need.

I have a couple questions - Did you verify what the SBC heads you already had on the motor were? springs? valves? specs etc? It looks like the PO went to a pretty good effort on the rebuild using a LUNATI cam, thats not cheap stuff, already had a double roller timing chain thats probably good, does the chain feel loose? Your heads, springs, valves were probably sufficient for the cam that he already went through the process of 'building'. Do the heads look like any porting was done or any work on them at all? Maybe they are shaved? to get more compression? did you check the deck measurement or ask the PO?

Also with the PO going .040 over on the pistons, shows he wanted something a little more than most. The pistons are flat tops but 'doming' them is not the only way to get compression ratio changes. There are many things to check when you start decking heads and such, you have to figure gasket quench thickness, chamber volumes, piston deck clearances and many others. it really is 'rocket' science if you want it right and want it to go fast.

The air gap manifold will be a good upgrade as will the new carb. I dont get the 50F number mentioned, as you want manifold temps to be AS COOL AS POSSIBLE, thats why intercoolers are used on blowers to make them even COLDER. Theres been alot of input here for you to take in. Just beware that there is A LOT of information out there.

I didnt see in any of your first posts as to why you wanted to make alot of these changes to the motor? Did you have any baseline of information on its performance other than it has a 'lumpy idle'.... you may be going backwards in your enhancements if you dont know where you started. Does that make sense?

Chances are if the PO knew what he was doing and there isnt many miles on that motor, you are doing alot of work for nothing at this point. just saying.... please dont take any of this wrong.

Try and get a 'build sheet' from the PO if you can... you might be pleasantly surprised at whats in your motor.

[Mrturner1]

I'm not sure how to tell if there's any porting or decking done to the heads that were on it, but here's a pic of them. The springs and valves must have been sufficient because it ran great. I think you're right about the PO doing some work to the engine, but I was looking for more out of it than it had. I wouldn't be surprised if it was a nice little 300hp motor at all. Needed a stall converter bad but ran like you whipped it after 3000 rpm.

[Mrturner1]

Unfortunately I can't find the PO, and I didn't ask to much detail when buying the truck because I just didn't know better really. Wish I would've but after this build it'll be more like MY truck instead of driving someone else's build.

[Mrturner1]

It's kindof a weird mixture of parts that PO used when you think about it. That Lunati cam works in the 1800-6300 rpm range and needs 2300 rpm stall, but there's no stall converter, it does have a TH400 though. and it has long tubes with 2 1/4" exhaust which is a bit small for a cam that tall. Also has a performer intake manifold which is for bottom end grunt as well.

This all makes me kindof curious about the rear end. Maybe I'll get lucky and it'll have 3.73's in it haha the mystery-mobile

[Mrturner1]

Originally Posted by geezer#99

If you plan on driving it when the temp is below 50F, you might regret the air gap choice.
You need heat in the intake when it's that cool out.
Could be a tuning nightmare for you.

This is interesting. I really wanted to get an air gap but a tuning nightmare doesn't sound fun. Can I ask how the tuning would come into play? I do see how warming it up could be a little tougher, but I have electric fans on a switch so I could leave the fans off for a few minutes. Would that work?

[Coley]

By the last pic of those heads....I think those are pretty good 'old school' heads.
I think those are called '186' casting heads...similar to the 041 heads.
Those were mostly found on the higher hp small blocks in the '69 and '70 years.
The upside of those heads (if they are the 186 casting) is that they have the higher compression 64cc chamber (vs. 76cc std. in the trucks) and the front accessory holes which are needed for the factory mounting of our alternators, a/c, etc.
Are you having those rebuilt or just re-using them?
Are the 2.02" intakes or the 1.94"?
Coley

[Mrturner1]

Originally Posted by Coley

By the last pic of those heads....I think those are pretty good 'old school' heads.
I think those are called '186' casting heads...similar to the 041 heads.
Those were mostly found on the higher hp small blocks in the '69 and '70 years.
The upside of those heads (if they are the 186 casting) is that they have the higher compression 64cc chamber (vs. 76cc std. in the trucks) and the front accessory holes which are needed for the factory mounting of our alternators, a/c, etc.
Are you having those rebuilt or just re-using them?
Are the 2.02" intakes or the 1.94"?
Coley

Like camel humps?? I'm actually putting these on the shelf and installing a set of Pro Topline heads with 2.02's and 1.64's on them. As far as the ones I took off, I'm not sure what the valves or springs are, but they were paired with a Lunati 285 Bracketmaster 2 cam so they are most likey pretty decent. If they are good heads, I have a nice head/intake/cam and lifter package I need to find a home for. That's too cool of stuff to just sit around the barn

[GRX]

Have blocked off the exhaust crossover on a few of my engines. Mostly Pontiacs. It does make a profound difference. That crossover was put there for a reason. Heat under the plenum helps with cold starting, fuel atomization - basically helps even things out in varying conditions on a street driven vehicle. If you are only interested in acceleration and don't mind waiting for it to heat up on cold mornings, don't sweat it's absence.

[Mrturner1]

Originally Posted by GRX

Have blocked off the exhaust crossover on a few of my engines. Mostly Pontiacs. It does make a profound difference. That crossover was put there for a reason. Heat under the plenum helps with cold starting, fuel atomization - basically helps even things out in varying conditions on a street driven vehicle. If you are only interested in acceleration and don't mind waiting for it to heat up on cold mornings, don't sweat it's absence.

I definitely want it to be more than just a fast accelerating truck, enough to give up a few hp anyway. I think if I got done with all this work and it was a PITA to drive in any way I'd be disappointed

[Mrturner1]

I didn't get to do much today, spent a lot of time running around for parts but I did find a 7/16 tap, so tomarrow ill be able to start. I'm really excited about how this is going to turn out

[swamp rat]

If your chasing threads with a tap you need to buy a bottoming tap not a starting tap, starting taps have a tapered start, a bottoming tap only has maybe one thread that is tapered, this will clean the threads in blind holes, probably $10 at my local hardware store. Open the link:

https://www.google.com/imgres?imgurl...lxCbUQ9QEIIDAA

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[Mrturner1]

Looks like I got a plug tap

[GRX]

Bolts have a taper at the end so that helps. You can easily grind that down to a bottoming tap if desired. Usual precautions to prevent over heating and de-burring apply.

This is a great project for you. Make a list of what needs to be done and go through it in your mind a few times before starting. Do not rush. Take your time, reassess after each step, & pay attention to details.

[Mrturner1]

I was taking a look at the heads that came off, and the number on them is 3991492. They have 2.02's and 1.60's, and a spring stout enough to run that Lunati that has .455 lift. After reading a bit about them, they look to be pretty nice heads. I'm definetly happy with the heads I got to replace them, but a cool find anyway

[toolboxchev]

Originally Posted by Mrturner1

I didn't get to do much today, spent a lot of time running around for parts but I did find a 7/16 tap, so tomarrow ill be able to start. I'm really excited about how this is going to turn out

Yea be careful with that thing, you can bore through a blind hole with it if your not careful.

[Mrturner1]

Originally Posted by toolboxchev

Yea be careful with that thing, you can bore through a blind hole with it if your not careful.

What's boring through a blind hole?

[Mrturner1]

Here's the numbers on the heads. Any idea what the bottom one means? And how do I check for decking or porting?

[toolboxchev]

Originally Posted by Mrturner1

What's boring through a blind hole?

Its a hole that has a bottom. I never thought that a tap would cause problems, I broke though the cast on my intake manifold in the thermostat bolt hole by going to deep.

I had to put a helicoil insert in there and now it leaks unless I do a real good job sealing the threads.