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406 Engine Build...What do you think?

15K views 117 replies 11 participants last post by  lhmurphy 
#1 ·
I have a 509 casting, 2 bolt main block bored to 4.155. I'm using a Scat 9000 Series crank, 6 inch scat rods with ARP cap screws, ARP main studs, Probe forged -14cc reverse dish pistons, with blueprint cylinder heads that have 195cc intake runners and 2.02 int. and 1.60 exhaust valves....The cam is a roller thumper cam that has .513 and .498 lift, 227 and 241 duration at .05...also using comp retro fit roller lifters, trick flow 1.5 roller rockers, and Comp chromoly pushrods, Comp dual valve springs, 670 street avenger with 68 primaries and 74 secondaries, .35 pump shooter...What do you think of my setup??
 
#4 ·
I was looking for the 14cc reversed dome pistons on Probe's website. All I found was 15.0 reversed dome and 22.5 reversed domed for 400 ci engines. I hope you have the 22.5 reversed dome or your compression is going to be too high at 10.476 and a DCR of 9.068 with a .015 head gasket. With a .039 gasket your compression will be 9.924 and DCR will be 8.598. But then your Quench will be .064 which is best to be .040.
 
#10 ·
I'm with Mr. Minter, I don't see a 14cc dish piston for the 400 block from Probe. If you have such a piston on hand and intend to use them with 64cc chambers, the SCR will be on the order of 10.6:1.

With a 6" rod, the wrist pin will be pushed up into the oil ring, something that I will not build. You won't see a nickel's difference in performance between a 5.7" rod and a 6" rod and you don't have to crutch the ring land to prevent snagging.
 
#18 ·
The kit I bought was said to have a static compression of 10.3:1 with 64cc combustion chambers but that's not the issue...I just want to know how you think it will run...using the six inch rod moves the piston higher in the bore for when my cam closes so I don't lose as much of a stroke
 
#19 ·
And also mister this motor has been running pretty good for the last 3 years and I never hear any pinging...I just posted so I could see how accurate these forums are and if I would really wanna join...so that's why I posted this to see how many people would chime in about compression and say it wouldn't run 15 minutes or idle smooth...looks like my test is done:)
 
#24 ·
I will make a mathematical statement:
440 horse power is possible with a 670 cfm carb but highly unlikely.If the engine dyno tests at 440 horse power and the carb actually flows 670 CFM then that engine is close to perfect tune.
As far as that small cam working in your engine,it too is possible if all the other specs you gave are accurate then your total timing has to be very low and or your fuel is very good quality.
If you have very good fuel then that engine would make power at a very low RPM and it would build the power very quickly,,,tire melter
 
#39 ·
The rod doesn't affect the stroke one damn bit, the heads may have been purchased from blueprint, but they do not cast heads- find out where the heads were cast and what they are, likely offshores but that doesn't mean they won't work there are some good offshore heads. A lot of people also sell World or Dart heads under their own name so it could be those too.

the compression is too high for pump gas. it can be made to run buy pulling out timing, running it cold, and running it a hair rich, but it will be down on power compared to if you ran less compression and tuned it right.

Also, on a side note, while thumper cams are sold purely for sound and they do deliver on that respect, they have way too much exhaust duration for most heads. Oddly enough though the smaller one will work well with older heads like camel humps as the overlap can help make the most out of a restrictive intake port- at 195cc's your ports are likely not restrictive until the upper RPM's though and the excessive overlap is costing you power and probably giving you some major reversion at low rpm.
 
#34 ·
I just posted so I could see how accurate these forums are and if I would really wanna join...so that's why I posted this to see how many people would chime in about compression and say it wouldn't run 15 minutes or idle smooth...looks like my test is done
Did you hear the one about the TROLL that walks into a bar with his head up his *** ........:rolleyes::rolleyes:

Tom
 
#37 ·
Just give me your opinion please about why my compression is too high? Do u mean too high for pump gas? Or too high for my cam? Just looking for help and not looking to post jokes...I apologize for my earlier comments if they offended anyone who is part of the hot rod forum and part of this post
 
#40 ·
I think the rod does effect stroke bc a 6 inch rod compared to a 5.7 will reduce piston velocity which will make it able to run slightly higher compression...the castings are made overseas but blueprint does the valve job and puts their parts on them...they claim it's their own casting
 
#42 ·
Well, you can think it all you want but you're wrong. It doesn't affect it a little, or kinda, or slightly, or a lot, or maybe, or anything else. It doesn't affect it at all.

As for piston velocity it does affect it SLIGHTLY, plot out the piston travel though and you'll see how little that "slightly" is. It will help a little on induction but its not a miracle worker.

Track the casting numbers and marking to find out who/what cast those heads. There are some good offshore castings, and a lot of crappy ones too.

BTW, are the heads aluminum or iron? Have a picture of the chamber?
 
#41 ·
And I've seen this same cam in a 350 with 4 valve relief pistons (stock) that had 64cc combustion chambers, 2.02 1.6 valves, and not sure but I believe he had 416 casting heads built to those specs, and he had a 670 avenger and a high rise single plane intake, and his motor ran very smooth and you could rev it to 6000 pretty easy...sounds crazy but I'm not joking...he had 3.73 gears and a 700r4...pretty impressive for a cheap build
 
#44 ·
Well, after a quick look at those heads while they're not spectacular they're not too bad, and they could actually benefit from some valve deshrouding. that's good for you on two accounts. You can increase the marginal flow a little bit, AND by taking out a few cc's you can also drop your compression to something that is a bit more pump gas friendly allowing you to run a decent coolant temp, good carb tune, and optimal ignition timing.

Your power will come up across the board.

You don't need to get crazy so a grinder and a few reglite cartridge rolls should be enough, 3-4cc's can make a pretty big difference when you're right on the edge.
 
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