84 4+3

There about. May change slightly once I final measure piston to deck. It is supposed to be zero deck but I think it'll end up poking out .001-.005 so may be closer to 11:1. Everything else is measured out so that is the only variable and I'll know once I get the block back.

skinny z

Take the actual numbers as you will. I used my heads and went with 10.5:1 with small tube open headers. Also went with a dual plane manifold. This is as it would be dynoed.
But comparatively speaking, his 20 HP loss is spot on.
And predictably, the torque is up below peak for the small cam.
That said, the larger cam would probably like a single plane intake and would easily go to 7000 RPM.

84 4+3

I am liking the curve on the smaller cam. I will be running it on a renegade... so more like a crossram which I would consider a single plane... The curves seem similar to the current setup which is nice with a larger torque peak, most likely caused by the overlap and LSA changes... Sheet below: (note the AFR readout is wrong, no sensor was used) But it would seem it is nudging me in the direction I want.

skinny z

Digging into it a little further:
With a target SCR of 11:1, that smaller cam puts the dynamic compression at 8.8:1 when installed on a 106 ICL angle. (Take DCR however you want however I've found a reasonable correlation between the DCR number and this range of SBC's. DCR doesn't apply evenly across all platforms or applications)
That may or may not play nice with pump gas and everyday driving. I'd say the tune would have be spot on.
I bet Fast355 or Orr have some insights into how this might play out.

@Fast355

@Orr89RocZ

Orr89RocZ

iTrader: (20)

I like cam 2. I dont like 277/231. Seems way fast for what the goal is. Unless its some kinda inverse radius special lobe that keeps acceleration rates in check

skinny z

The 277/231 came from the Jones catalog which has many seat values for a given .050 number. I just took a stab at it. This was kind of middle of the road.






FTR: A COMP HR is 276/224. .334" lobe.
The XFI is 274/224. .360" lobe.
I kind of use the XFI profile as a sort of benchmark when trying to stretch the boundaries as compared to the XR's. It proven to be a survivor on the street and track.

84 4+3

FYI he is calling the grind number 73353-75348 meaning it is closer to 292/233 than 277/231 I would think? I would assume that is the lobe it would be based on?

skinny z

Based on that then yes, the profile becomes much slower. That info is helpful.

73353:


Call it 290/231. (Using the % difference between seat and .050 timing.)

75348:


299/239 or thereabouts.

That'll certainly take a load off of the cranking compression / DCR.
Correspondingly, torque will be down some as well.
Now at 74.5° of overlap, that small cam is looking pretty big.
I'm no expert, (just a number noodler) but I'll say it'll like the 11:1 compression.
I ran 71° in a 355 with less than 10.5:1. It was very drivable, pulled well to 7k and still got decent mileage (with a lot a spark advance and lean AFR's). A 383 should handle 74 degrees without issue.

84 4+3

I'll also add for the 240/250: grind 75375-78560.

skinny z

For reference, here's how the "short" 231 stacks up against the "long" version. 290/231 vs 277/231.



Predictable.
And again, just for comparative purposes rather than output.

skinny z

75375



And I'll guess and say you meant 78360.



298/240, 300/250 .
Anyway you slice it, that's a big cam.

skinny z

His catalogue blurb for two categories of rollers both state "Using our proprietary Inverse Radius technology".
So your guess is as good as mine. Lobe lifts, .050, .200, seat timing seem to cross over on all levels. This is where that conversation with the designer becomes so important.

84 4+3

Yeah. I felt that cam would be a little too much... or a lot too much. The small grind seems to play nicely with the engine as intended currently.

Orr89RocZ

iTrader: (20)

73353 is same lobes i ran in my first turbo 400” afr 195 deal. Very mild and driveable. Done by 6000 with the small heads. Good mild driver cam
imo. On a 383 it may be alittle more noticeable but probably not a huge difference given same stroke. Id run that cam

Fast355

iTrader: (2)

I am still not 100% sure what caused my head bolt failure. It was suggested to me that it could have potentially been detonation. That being said, I have found ZERO evidence to support this.

That being said my 383 is very well tuned with SFI. I did find the quench/chamber caused a weird burn/soot pattern on the pistons. The 383 is getting opened up from 0.041" to 0.053" quench from the Felpro 1003 head gaskets going on to it. I will know more on how that turns out when I get it running. I am also replacing the Rhoads lifters with stock GM lifters. They literally work too well and had my DCR at about 9.5:1 at low rpm and the knock sensor would occasionally pickup enough to pull 1-2° of timing. The frequency was few and far between though and was often caused on light throttle tip-in with a locked torque converter in overdrive under 1,500 rpm.

No signs of engine destroying detonation. #3 has some thread sealer I was disolving with brake clean that spilled out on to it, which is the weird white spot. I cannot say I have ever seen pistons that had spots with NO carbon buildup on them. I stuck a bore scope in this when it had 500 miles on it and it looked much the same.

skinny z

Head bolt failure? When did THAT happen?

Now this could be interesting. Plenty of talk on the effectiveness of a tight quench and what tight actually means.
.040" has always been my target but where that figure comes from I can't actually say. Maybe Vizard?
Now I've a build decision to make as to whether to use my my go to head gasket at .026" x 4.100" (Clevite/Reinz 5746) and a .008" PtH clearance for .034" or back off a little and use the .039" x 4.080" gaskets I also have on hand. That'll open up the quench to .047". Either way, one is tight beyond familiar territory for me although several have suggested it's be fine in my case, or open it up to a less than best gap. But best compared to what?
Compression would move from a fairly iron headed high of 10.4 to a more user friendly 10.12:1. Subject to change should I get into dressing up the combustion chambers (which need some work).

Your results may demonstrate the value here.

skinny z

Both the 73353 and COMPs XR288 lobe come in as "mild" on the simulation aggression index. The 288 was a long liver too as it survived between two engines seeing 7k. Peak was about 6500. It wasn't until I pressed well used parts back into the build that things went wrong.

Orr89RocZ

iTrader: (20)

your pistons kinda look like my bbc pistons burn pattern. They say a good burning chamber has carbon staining across 90% of the surface area. Might be fuel dropping out of suspension, idk. Theres a decent thread discussing some of it

https://www.speed-talk.com/forum/vie...hp?f=1&t=66074

84 4+3

I seem to recall Vizard stating the quench should be tight enough that "the chamber will knock down the carbon on the piston crown." But I too could be remembering wrong... .034 is tighter than I would go on mine... I'm shooting for about .038 with piston where it ends up and gasket compressed thickness.

Though I may add... what is the rule of thumb with gasket bore size... having a 4.030 block it seems you could run a 4.030 gasket but it seems most opt closer to 4.1... is that because it's just widely available or what.... I was planning on making sure it was big enough to not shroud any of the chamber uncompressed as that seems to be a good idea...

Orr89RocZ

iTrader: (20)

Want thegasket bore to be bigger than the chamber in the head. Often chambers are larger than the bore, so you dont want gasket exposed

Fast355

iTrader: (2)

A few weeks ago on the head bolt failure. Then I was sick with Covid. Just now feeling well enough to put it back together. I found the failed head bolts while I was starting an intake swap. 2 bolts completely broken, 1 stretched to the point it was finger tight and a 4th bolt had a broken washer under the head of it. That was on the driverside. Still have the passenger side to pull apart.

ThIs engine has pulled my van and travel trailer from Fort Worth, TX to both Padre island as well as to Durango, CO via New Mexico so far. Never missed a beat in those miles moving ~12,000 + lbs. Towing in 3rd gear at ~2,850 rpm @ 70 mph on flat lands it manages 12-13 mpg. In the mountains it sat at ~10 mpg. Some of those climbs were fairly long, hard pulls.

FWIW I was also told by some self proclaimed experts that the tightly gapped upper rings would butt while towing and they would score the cylinder walls and rip the pistons apart. I will be pulling the passenger side apart today or tomorrow, but the driverside had no signs of rings butting. No scoring of the cylinder walls indicating butted rings. There were people saying I needed 0.028"+ of ring gap for an 11:1 small block. Which is nearly double what this engine was built with.

Fast355

iTrader: (2)

That is the reason I changed mine. I noticed the GM 0.028" were just ever so slightly overhanging into the chamber. I either missed it during initial assembly (unlikely) or the gasket deformed when it was crushed pushing the fire ring into the chamber (more likely). The 1003s 4.166 bore is what Lloyd Elliot scribed the cylinder head casting with when he performed the chamber work.

skinny z

What brand is that bolt? What is the torque spec?
One thing I intend to do is reuse my ARP head bolts. They've seen two go rounds of head swaps ( maybe three) but it may time for replacements.

Fast355

iTrader: (2)

JEGS @ 70 ft/lbs. Having had both the JEGS and ARPs in hand, the JEGS were possibly some grade of ARP. They clearly stated Made in the USA.

The bolt failure may even be my fault given I did not know to 60 grit sand the bottom of the washer where it contacts the heads. Then again if it was a known problem the JEGS instructions should have stated to watch for this.

skinny z

I had this discussion on another forum too and the consensus was all over the map. From what constitutes too tight (someone was in the 20's!) to what does it matter.
https://www.speed-talk.com/forum/vie...hp?f=1&t=65624
22 pages!

There are still a few cards in the air here. It may be that after going over the heads, they may need another pass on the mill. But that still won't address the clearance issue, just the compression ratio.

Fast355

iTrader: (2)

I after cleaning the head as much as possible with a straight razor scraper, I straight edged my head for warpage, cleaned the MLS remnants off with 600 grit wrapped around a straight 2x4 lubricated with WD40 after letting brake clean work on it. It came out stained but clean. The 1003s will brinele the head but I do not see that as a problem as it will hold the head gasket in similar to o'ringing the thing. AFR and others call for the 1003s as their head gasket of choice for their aluminum heads.

I also discovered I unknowingly bottomed out an intake bolt and cracked a small piece of the head casting. IMO there is still plenty of material where the intake bolt threads in. I will throw a little PTFE sealer on that intake bolt to prevent an oil leak and send it. The intake that is going on is cast iron base anyway. In some research I discovered that the factory Vortec intake bolts are designed to bottom out in the Vortec head to prevent the OE plastic gasket carrier from being over crushed. The updated gasket design also has aluminum spacers to further prevent this. I am using paper gaskets 0.120" thick. The paper gaskets probably crush beyond what an OE or updated OE style gasket would. I ground the tip of the intake bolts to prevent further damage to the head castings. This engine has definitely been a steep learning curve in Murphys law using aftermarket parts.

Orr89RocZ

iTrader: (20)

i always use studs now. Much nicer than bolting

thats heavy boost gap on something like that. Typically .0065-.0070” gap per inch bore is what i use for heavy boost. Na usually .0045-.0050” per inch bore which would be closer to .018”

then again its always better to have slightly too much ring gap than not enough lol

Fast355

iTrader: (2)

From memory its 0.016 upper and 0.018 second per Weisco specs for a Street small block.

Ring gap is a double edged sword. Too narrow and the rings butt. Too wide and you sacrifice VE and Compression with added blowby all of which decrease power and efficiency. Blowby contaminates the oil in a shorter interval and eats bearings from fuel/moisture/carbon contamination, especially running on E85.

The ring seal is very tight in this engine with minimal blowby. I checked both PCV function and intake gasket sealing. With one PCV port blocked the engine had minimal blow by exiting the second PCV port, building slight pressure in 30 seconds. Adding a fixed orifice LS PCV with the vent still blocked off created a strong crankcase suction of about 5-6 in/hg in about 30 seconds. That being said I do not have a crankcase vent plumbed for fresh air inlet. It has a PCV valve on one side and two header evac check valves behind the cats. One in each exhaust pipe. It pulls a consistent 6-8" of vacuum on the crankcase at all loads and rpms.

skinny z

FelPro 1255?





1255's fitted to an RPM Air Gap unported or gasket matched. .120" thick. (Could measure the crushed thickness for verification)

Fast355

iTrader: (2)

Edelbrock 7215

They closely match Lloyds intake port work and I matched both the OEM truck intake and now the marine intake ports to that gasket. It was not a perfect match, but these pictures were of the worst one. The OEM truck intake was terrible and the ports were twisted and offset the start with. I threw an OEM style gasket against it for comparison after getting a close match to the 7215s. I will also add I had 3 OE lower intakes on hand and had already started clean up before I stopped to get those pictures. The other 2 OE intake bases were even worse than this one. To get power out of a vortec truck intake the manifold needs some heavy rework even using 1255s with a stock port head. The marine manifold is much better in this respect and it is easy to see why bolting a factory marine intake on adds the power it does. Not only is the injection setup moved out of the plenum, but the manifold base has larger, much cleaner and more consistent ports.





i

Orr89RocZ

iTrader: (20)

The actual ring design, material, tension, and location on the piston along with bore hone job quality and break in procedures will be far more important and influential on leakdown/blowby/etc than just gap number alone. A top ring thats way further down from the piston crown should technically run cooler and not be subject to thermal growth as much as a ring closer to top, and therefore get away with smaller gap.
i’ll take a very slight loss in performance over grooves in the cylinder wall from butting rings any day. I’ve butted them on a boosted motor at .022” i think it was on a 4.125 bore.

Fast355

iTrader: (2)

OEM gasket vs Lloyds head work just for reference. The heads and ported truck intake far outflow the as delivered OEM Vortec stuff.

Fast355

iTrader: (2)

Bigger bores definitely need a wider gap. As far as an OEM engine is concerned. A 5.7L Vortec upper ring is considered in spec all the way down to 0.009 end gap per the FSM. GM says the stock engine will run and hold up with the rings that tight in an OEM application. That was also out of the Marine manual for the ~300 hp Mercruiser/Volvo Penta variant. Whipple makes a blower they claim goes on a stock engine and will work. Definitely a wise idea to regap those rings with a blower in a boat. I would not feel safe running 10# of boost in a marine application with rings that could be 0.009" gap as designed and built. Then again I would not run the stock pistons in that application either. They have a tendency to create detonation anyway. The GM chili bowl dish does not provide any meaningful quench effect.

skinny z

Here's the same gasket compared to an untouched RHS Vortec port.

Fast355

iTrader: (2)

Now picture those heads under a stock truck intake. Definitely would not run to the added potential of those heads.

skinny z

There's certainly more in your ported Elliot heads than there is in these.
But the question is, at the risk of running this thread completely off topic, would cutting up the head and intake at the gasket surface mess up what's purportedly a decent port to begin with?

Fast355

iTrader: (2)

Now this is just my opinion. Gasket matching will not hurt the port flow or efficiency. Bowl work and valve work is a large perentage of the airflow gain in porting. That being said if the port is not efficient to start with it would be a mute point doing either. That is to say bowl, throat, pushrod pinch, CSA and short side radius need to be well designed for the port to work well.

I think it would not be hard to make ~550+ with these Lloyd ported heads. They flow just shy of 300 cfm @ 0.600 and increase all the way to 0.700 the highest lift tested. They flow over 240 cfm @ 0.400 too. The best of the factory OEM cathederal port LS heads (243/799) only flow 220-230 cfm @ 0.400 and 240-250 cfm @ 0.600-0.700. Those heads can make 470+ in stock form.

skinny z

I've read too that gasket matching does little if there's not an alignment issue to begin with. A little more investigating on my part with the heads and intake in place will tell the tale.
As for these heads, they're upgraded version of OEM Vortecs so not a bad port to start with. These have a 2.02/1.60 valve set and 170cc (out of the box). RHS sells them as 270CFM@.500" but that's on an unrealistic 4.200" bore fixture. They eventually ended up with a better valve job, some bowl and SSR work too. At about 175cc (yet to measure after porting) they flow about 255 @ .500" on a 4.030" bore so CFM looks good relative to port size (230@.400"). They look to be very efficient.
That said, the small size and lack of additional porting, most notably the pinch I would think, leads them to fall off past peak flow. Not much but it's not the best case where flow should remain at least undiminished as the valve is opened further.
Still, I'd say good for a solid 450 HP in dyno trim. Sims show more but I'm not getting ahead of myself. Looking for a 6000 RPM HP peak.

Fast355

iTrader: (2)

From memory those are about what was on the Sledgehammer 350. It made about that with a 224 @ 0.050 roller cam even with the stock Vortec dished pistons.

84 4+3

Thread is totally on topic. The fun truck is a 383 L31 so I appreciate reading all this... I will say I didn't touch that intake but wish I had... truck is fun though, mostly torque. It'll run upstairs but doesn't really like it. It is what I learned from when building the top end package currently in my car. And What I want to learn more from (and here too) while doing my 383.

On the ring gap in marine applications, I do have to ask... You could theoretically run tighter ring gaps since the engines run cooler to begin with no? Talking raw water cooled here... most of my raw water cooled engines struggle to hit 150 degrees even under the heaviest of loads. I know it wouldn't be that much of a change but could potentially be noticeable no?

skinny z

Yeah. Sometimes a thread can get away but if everyone's on board then there's more to learn.
As for the marine deal, the coolant temps at the point of measurement may or not be indicative of the temps on the piston crown. Thinking marine, I tend to think of sustained RPM at peak torque. That's the highest cylinder pressure isn't it? Pressure equals heat.

Fast355

iTrader: (2)

My take on that is a colder bore will not expand as much, meaning the ring has even less room to grow. Cold bores but hot rings from the constant heavy load.

As for my 383. It is also happiest up to 5,600ish. Chassis dyno shows it makes peak at 5,600 and carries well up to the limiter I had set at 6,200. I have messed with timed acceleration runs and it accelerates best shifting at 5,500. Has to be because of ~500 ft/lbs of torque it makes in the midrange. Anyway my shifts are now 5,500 with a 6K limiter. I may revisit this with the marine intake if the engine is pulling much more airflow at ~5,500 rpm.

84 4+3

Well, I've just spent some money. I went along with cam #2 from jones. Excited to eventually get the next mill together!

skinny z

Nice.
Do you have lifters?
And are you going with one of those PAC springs?
FWIW, I asked Mike to spec out something for my 357.
Smallish heads. Peak HP RPM at 6k. Carry to 6500.
4000 stall. Drag racing primarily and the street will be what it is.
His reply:
​​​​​
Here's what I would recommend.
Cam#: SBC, HR72360-73360-108
232/236@.050"
.360"/.360" Lobe Lift
.576"/.576" Valve Lift, w/1.6 rockers
108 LSA
Interestingly, this is exactly the same spec for my earlier proposed 383 with the same at HP peak.
I find that just a little bit odd.
It'll have to be sorted out in our next conversation.

84 4+3

yes, i've been sitting on a set of morel 7717s. And yes, I'm doing the whole package from mike. I like the idea of the beehives.

As for your cam... same heads as the proposed 383? I could see that influencing things no?

skinny z

Yep. Same heads.
Originally Mike had spec'd a less aggressive pair of profiles (.340" lobes) and spread the LSA to 110. This was in his street performance category recommendation form.
Then I requested he take the "street" out of the equation and he came up with the result above.
When I asked for a recommendation for the 357 ( the only thing changed was the CID) I went straight to the drag racing form on his website.
Two CID's. Same spec.

84 4+3

Yeah. That does seem a little odd... but then again I'm far from an expert.

BadSS

Did you specify a specific or the same stall speed converter for both engine sizes?

skinny z

The 383 was spec'd with 3500 stall. The 357 at 4000.
Both builds looking for peak power at 6000.
Looking back through my notes, the 383 came in a 10:1. The 357 at 10.4.
Sims do show the 383 peaks at 6000 but falls off quickly past that. The 357 is flat from 6000 to 6500.

It'll be part of the discussion going forward. One thing to take into consideration is those heads on that CID are considered a little on the small side. From what Mike has explained about his methodology is that this greatly affects the cam result. It might also explain why the 383 drops off abruptly.
It may just be that the slight difference in compression and stall speed come together enough to have two CID's but similar cam specs..

BadSS

I was guessing there was at least a stall speed difference - makes sense now.