Another low budget 360 build

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That sounds pretty good. I will probably leave the cam at 0
Just cleaned up the cylinders and it looks like 004 over so I will go with standard bore 405s and a hone.
I will get pricing on head work this next week.
Again I want to thank everyone for all of the help
 
That's the way to do it. It'll be good.
 
nm9stheham said:
I actually worked out the numbers... The H405CP pistons are about .050" in the hole for a standard LA block and have 10 cc's worth of valve reliefs so are not high compression by any means. (BTW< the compression height is 1.675".) The OP's combo works out to 8.6 static CR with 72 cc head chambers, and 8.9 static CR with heads shaved to 68 cc chambers. Both of these numbers are with the .028" head gaskets.(I would not expect 65 cc open chambers; that is probably an NHRA minimum spec.)

Dynamic CR's will be 7.1 and 7.3 respectively with the Lunati 60402 cam. I can't see where the OP has anything to worry about with detonation at these levels and regular fuel and the mid 2000 rpm range stall TC.

Later on with closed chamber heads, there will be no effective quench with these pistons so that anti-detonation aid is out if the H405CP's are used. 63 cc closed chamber heads would push DCR to 7.7 with that cam so still has some margin against detonation although a cam change may be in order then, or aluminum heads would pretty much proof it against any such problems.

BTW, OP, I use the Pat Kelley calculator if you want to plug in numbers and see these results on your own.
Click to expand...
So it looks like I will be going with EQ Magnum cast iron heads after all.
You mentioned a cam change may be needed. Do you think the 60403 cam may work better for this engine set up? H405CP pistons, 028 head gasket. No decking of the block. Magnum Mopar EQ stage 2 heads and adjustable roller valvetrain.
 
Just running the numbers again:
- 405 pistons
- 62 cc head chambers
- .028" head gasket
SCR is now 9.3 and DCR with the 60402 cam is at 7.7. Changing to the 60403 cam barely moves the DCR needle; the 03's change to a smaller LSA mostly cancels out the modestly longer duration. You just move up the lower end of the usable RPM range and gain a bit on the top. Neither cam says "Danger, Will Robinson, detonation ahead!" to me. (Sorry that is from a 50 year old TV show LOL.)

But I always like to go for low RPM torque in my uses and driving, and let the chips fall where they may on ignition advance, so I am biased towards that. So the cam difference between those 2 is more what you want the engine use to be tuned too: a bit lower RPM torque for the street or a bit higher RPM for the track; not a lot either way. My comment on 'maybe a cam change' was more to have your mind staged to rethink things through with the smaller chambers.

I think I would just try it at this level with either cam and see if the detonation will not show up with the tuning on 87 octane. Just start lower on the ignition advance and work up. And you can always just change the head gasket later for not too much extra work or $$. Likewise for a change of cams.

I think you are going to be happy to have put the $$ in the heads; it just puts your engine up another step in capability..
 
nm9stheham said:
Just running the numbers again:
- 405 pistons
- 62 cc head chambers
- .028" head gasket
SCR is now 9.3 and DCR with the 60402 cam is at 7.7. Changing to the 60403 cam barely moves the DCR needle; the 03's change to a smaller LSA mostly cancels out the modestly longer duration. You just move up the lower end of the usable RPM range and gain a bit on the top. Neither cam says "Danger, Will Robinson, detonation ahead!" to me. (Sorry that is from a 50 year old TV show LOL.)

But I always like to go for low RPM torque in my uses and driving, and let the chips fall where they may on ignition advance, so I am biased towards that. So the cam difference between those 2 is more what you want the engine use to be tuned too: a bit lower RPM torque for the street or a bit higher RPM for the track; not a lot either way. My comment on 'maybe a cam change' was more to have your mind staged to rethink things through with the smaller chambers.

I think I would just try it at this level with either cam and see if the detonation will not show up with the tuning on 87 octane. Just start lower on the ignition advance and work up. And you can always just change the head gasket later for not too much extra work or $$. Likewise for a change of cams.

I think you are going to be happy to have put the $$ in the heads; it just puts your engine up another step in capability..
Click to expand...
Thanks, That's the main reason that I picked this cam is with the lower compression it may help with the engine pull sooner.
I'll work with the timing first
 
I am finally getting this engine together.
Ended up decking the block after all. approximately .006 off
Ended up going 30 over H405CP pistons.
Closed chamber EQ heads with 1.92 intake and 1.62 exhaust valves and 1.6 roller rockers.
MR gasket 028 head gaskets.
Lunati Voodoo 10200702 cam
Edelbrock LD340 intake and a Holley 650 carb
Hooker competition headers and dual 2 1/2 exhaust with a H pipe
Should run pretty decent but I don't see it being happy on 87 octane. Oh well
 
What's your static ratio and cam specs?
(Link?)
 
Voodoo Hydraulic Flat Tappet Cam - Chrysler 273-360 262/268 - Lunati Power

Cam specs with 1.5 rockers.
  • Advertised Duration (Int/Exh): 262/268
  • Duration @ .050 (Int/Exh): 220/226
  • Gross Valve Lift (Int/Exh): .475/.494
  • LSA/ICL: 112/108
  • Valve Lash (Int/Exh): Hyd/Hyd
  • RPM Range: 1400-5800

Lift with 1.6 should be 507 intake and 527 exhaust
I will confirm true ratio with a dial indicator

SCR should be 9.3-9.5
 
Play with a ratio calculator to find a head gasket thickness that will drop it below a 9.0-1 (8.5-1 would be great!) for regular grade fuel. Click here ---> Compression Ratio Calculator - Wallace Racing

I used a Cometic .075 thick gasket
to drop the current builds ratio fom 10.82 - 9.94.
This is not how I normally do things but it is for this particular build. The ratio will rise later on this engine with an introduction of (much) larger cam(s).
 
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Thanks for the information.
I will keep the compression up for now and see how it runs.
It will be a weekender so I can afford the higher octane fuel.
May swap out the head gaskets later if gas prices skyrocket again.
 
moper said:
I think either Comp is fine. The Lunatis recommend dual valve springs that require head work so if the heads are not going to the shop, I'd skip them. I have an '87 360 in my truck. All stock long block with the XE262, 901-16 springs, the MP windage tray, recurved distributor, MSD, Performer intake and Edelbrock carb, and cheapo headers. I did not rebuild anything, block's never been out of the chassis. It's a great all around package and pulls like a freight train off idle. I pull a car trailer and plow an 8' blade uphill when it snows with it. With the better pistons I'd go with the XE268 and the 901-16s. The stock rockers will work, but you will need to measure for, and order, custom pushrods to get the right preload so be prepared for that.
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You like that comp 's shaft? I've got an 86 W250 I'm gonna swap cams in over the winter. Went with a summit brand EDELBROCK PERFORMER equivalent and hate it. Pretty close to same combo you're running except it got new rings bearings etc when it went in along with a set of Indy reman heads. Haven't heard from anyone running that can in a truck but I've really been eyeballing the 268 version. What kind of preload did you have? I just put a set of new head gaskets in this weekend after Tstat stuck and blew one. Installed comp lifters to replace a ticking summit lifter and luckily came up with 065" preload with the comp stock length push rods I was already using. Thanks for any info you can give me on that cams performance and if youd rather have the 268 with a performer rpm intake and the 2.02 Indy heads. Thanks
 
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