My stock stroke mild 360 build ;)

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250 psi! I hope that’s a typo. Or you poured oil in the cylinders.
Not a typo... I just did another test right now. Plugs left out over night, engine cold, carb off manifold. 250psi in all cylinders.

it has a small cam.... engine doesn’t like any more than 10-12* initial timing or it’ll detonate. I only use pump 91 CA crappy gas.

here’s a picture, 1&2. All the rest read the same, my gauge is good, unless I’m an idiot and I’m reading the gauge wrong...

what can I do? Lol.

speed pro hyper pistons, .003 from top of deck, speedmaster 65cc heads.

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Well I read up on the build and that cam and those heads should math to around 10.4:1 right? Something ain’t right. I’d start thinking about head gaskets.
 
Well I read up on the build and that cam and those heads should math to around 10.4:1 right? Something ain’t right. I’d start thinking about head gaskets.
Yea I’m around there, sounds right. Like I mentioned earlier, I’m down for a solid lifter cam. Maybe I could go the next step up. Engine runs pretty dang good as is though. I’m happy with it, has good power. Suppose I could do a thicker head gasket.
 
Well you need to do something if you want to run that thing on California’s pump crap 91 octane. 250psi is race gas territory. Or you can pull all the timing out of it and that’ll just make it lazy.
 
Well you need to do something if you want to run that thing on California’s pump crap 91 octane. 250psi is race gas territory. Or you can pull all the timing out of it and that’ll just make it lazy.
Okay check it out. Another old school racer friend of my dad came by the house and recommended a Holley 650 double pumper. “Get rid of that crap vacuum secondary” is what he said, and try a double pumper. “You’ll love it”.

My brother had one on the shelf, we rebuilt it today and I installed it..........What a difference!! I cannot believe how GOOD this engine runs. It’s a totally different truck, totally transformed it! And I thought that 750 Vacuum secondary ran good.

I mean like the guys said earlier in this post, it’ll throw your eyeballs to the back of your head. It woke this thing up man!! I don’t get it!???

I don’t want to change a damn thing now!!

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[1] Backfiring on decel. Probably carb too rich at idle. [ It is a Holley, right? ]

High vac on decel pulls extra fuel from the idle cct. Rich mixture burns slower & with your low init timing, mixture is probably still burning when exh valves open...
Lean mixture also burns slower. Air leakage [ gasket failure ] into the headers/exh at the heads can also cause backfiring, but I think rich mixture more likely.

[2] High cranking pressure. Simplest, cheapest is to try is retarding the cam 6*.
 
What did you gap the rings to? The reason I ask is I had a very similar motor, strong as an ox but ended up running hot and leaking oil like crazy. I let it go with .020 gap and ended up knocking the top off of one of the pistons. They run best the day before they pop!
 
What did you gap the rings to? The reason I ask is I had a very similar motor, strong as an ox but ended up running hot and leaking oil like crazy. I let it go with .020 gap and ended up knocking the top off of one of the pistons. They run best the day before they pop!

Used the manufacturers recommended spec, the step above ‘moderate performance’ as they list it. .0045” per inch of bore diameter.

But I think I’m gonna change the cam after all. Need a little more overlap. This one builds too much cylinder pressure..It does say not to be used with anything over 9:1, I’m at 10.5:1..so it was a mismatch from the get go. . I’m gonna take @rumblefish360 ’s advice and cam the **** outof it. LOL
So Rumble, would ya mind recommending a nice solid lifter cam? :)
 
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But I think I’m gonna change the cam after all. Need a little more overlap. This one builds too much cylinder pressure..It does say not to be used with anything over 9:1, I’m at 10.5:1..so it was a mismatch from the get go. . I’m gonna take @rumblefish360 ’s advice and cam the **** outof it. LOL
So Rumble, would ya mind recommending a nice solid lifter cam? :)
I gave up recommendations on cams.

To many opinions chime in. While different thoughts are welcomed, it always turns into ether a overload of opinions and information and/or a pissing match.
Someone who has been there and done that will chime in, then someone will say they did it with less cam, but fail to mention there combo is nothing like yours, next *** clown steps up with a calculator, and it goes on and on.

I have often given my thoughts and tips on camshaft selection.

And yup! One or two *** clowns pop in and you re read the top paragraph again.

speed pro hyper pistons, .003 from top of deck, speedmaster 65cc heads.
The wife’s 360 has the .030 oversized flat top Federal Mougal 5cc relief pistons set at zero deck with a .028 Cometic head gasket and TF heads running a Comp Hyd. roller (224@050) with 1.6 rockers.

Runs on 93, I haven’t tried 89 yet. Coming soon.

Running a knock of MSD, OOTB, which is freaking exactly the same inside! With 20* initial. I will add 18* stop bushings later along with a spring change out yet to be determined.

I don’t like this distributor in this particular set up. I’d rather go backwards to a recurved OE unit.

Have you thought about a thicker .050 head gasket?
You’ll still retain a good quench while taking a slight drop in the static ratio.

Research a cam with what @AJ/FormS would call a crap cam. Just be prepared for a Novell on the subject. Freaking guy can make your eyes bleed. But there’s a lot of good information that he can dish out on the subject but I just don’t wanna bother with rewriting like AJ and like I did years ago. It’s actually pretty simple.

AJ, nut shell it!
 
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I don’t know what is that matter with you guys… my daily driver is 14:1 compression….300psi cranking pressure… runs on 83 octane…. 5:13 gears … drive it cross country in the winter…it’s all in the tune
 
What did you gap the rings to? The reason I ask is I had a very similar motor, strong as an ox but ended up running hot and leaking oil like crazy. I let it go with .020 gap and ended up knocking the top off of one of the pistons. They run best the day before they pop!
I have heard that before...:)
 
I don’t know what is that matter with you guys… my daily driver is 14:1 compression….300psi cranking pressure… runs on 83 octane…. 5:13 gears … drive it cross country in the winter…it’s all in the tune
What is it a diesel? :)
 
Well I read up on the build and that cam and those heads should math to around 10.4:1 right? Something ain’t right. I’d start thinking about head gaskets.
Yea. Head gasket time. I’m thinking felpro 8553pt with a reported compressed thickness range of .048-.051. Maybe I could go with a thicker cometic, but I thought I need a special machined finish?
 
MLS gaskets do need a different finish on the decks and heads for a proper seal. That being said I’ve run them on engines that have never been machined and not had problems. 60-80 ra for standard type gaskets and 20-30 ra for mls gaskets.

How to prepare an engine surface for gasket installation.
All you’d ever want to know and more.
 
I built basically the same engine a few years ago for a 78 powerwagon, with a np435 3.55 gears and 28" tall tires.
360 Mag, KB 107 pisons, Eldebrock 58 cc mag heads.
The cam I used was a Comp HR262, that cam had a great sound, and pulled fantasitic in the old truck.
The reason I used the cam was to bleed off compression.
Ended up with tons of bottom end torque, and decent power on the top end. It was a really all around engine.
I ended up with 10.81 static, but 8.71 dynamic, with around 175 psi. It would run pump gas fine, but when I pulled a heavy trailer I would always dump in 5 gallons of 110.
This is what comp said the cam would act like on their desktop dyno, the engine basically acted the same way.
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wouldn't that cam preserve compression for strong bottom end or am i thinking of a different cam?
what was the duration...220'sh?
 
wouldn't that cam preserve compression for strong bottom end or am i thinking of a different cam?
what was the duration...220'sh?
Pay attention where the intake closes, you can gain compression, or bleed it off.
 
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