Cam choice- LT1 or summit 8800?

[Hipster]

I had several 70s and 80s engines that I pulled apart that had thin waffer steel gaskets. All the 305s had them.

Not doubting you guys just never seen it, all the ones I've torn down had coatings, If that's still considered a shim type gasket I stand corrected. never measured thickness on stuff coming apart.

 

[L31MaxExpress]

Not doubting you guys just never seen it, all the ones I've torn down had coatings, If that's still considered a shim type gasket I stand corrected. never measured thickness on stuff coming apart.

The 305s had a small bore specific 0.018" compressed. Wish they were still available to buy for the small bore small blocks.

 

[Hipster]

I have run nearly 9:1 dynamic with iron heads and pump gas without issues with good quench. You will never do it with GMs crappy dished piston design though. GM engineers shot their foot off using them rather than a D-shaped dish that matched the chamber. They have learned though. Modern stuff has some crazy piston designs.

Calculators can be useful tools as guideline. Well thought out, pro-prepped heads, working with the porter to spec out a replacement cam(there really isn't a better person to confer with, Elliot?), exquisite machine work and attention to detail can make the impossible on paper and commonly accepted guidelines....possible. Don't leave yourself out that you go the extra mile and have the tuning skills.

The 305s had a small bore specific 0.018" compressed

HG gasket bore often gets overlooked. Many are .080. Again flirting with the upper edge of what's streetable the small differences matter.

I often look at head/lift limited classes and Mopars. Some engine architechures are notoriously head handicapped up to and including race prepped heads. They turn out numbers, dyno pulls, track times that on paper look ridiculously not possible with head numbers they achieve as compared to commonly accepted Chevy numbers. They often get into less talked about subjects like fuel distribution balance through the intake the while porting. There's more to it than the sum of the parts and numbers derived from calculators. Op kinda describes goal of wanting wanting a relatively problem free, jump in and go cruiser, but other aspects of the build indicate otherwise. Anybody's that built a smog motor in the 70-80's knows you can shove a cam in a few degrees advanced to bump low end cylinder pressure on an 8.1 engine,, and still have daily driver reliability.
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[Erik the Awful]

Kinda funny the program lists optimal LSA at 107. I think I hear Vizard laughing, and damn right you need to be careful what the internet weirdos link to and promote.

Yup, that's his formula. I know you're not a fan. I caveated that it's not a spec for a truck cam, but I'll accept his formula for a max power build. Fair point that the DCR might be high for iron heads. I'm still learning that stuff. It's only been in the last few years that engine builders have really been opening up on the engine math. For the longest time we hobbyists were always told that the secret to being a top-notch engine builder was just to "blueprint your engine". Dirty dogs.

Intl45 has already stated he's using flat-tops and not factory dished pistons, so that's a plus.

 

[L31MaxExpress]

Yup, that's his formula. I know you're not a fan. I caveated that it's not a spec for a truck cam, but I'll accept his formula for a max power build. Fair point that the DCR might be high for iron heads. I'm still learning that stuff. It's only been in the last few years that engine builders have really been opening up on the engine math. For the longest time we hobbyists were always told that the secret to being a top-notch engine builder was just to "blueprint your engine". Dirty dogs.

Intl45 has already stated he's using flat-tops and not factory dished pistons, so that's a plus.

Tight LSA like that needs a very well designed exhaust system, a loose converter and deep gears to work well. Mine runs hard when you get up on the converter but just cruising around it is not happy until 1,500 and its only 218/228 @ 0.050. For what I am using it for 219/219 @ 0.050 on a 112 will make it a lot happier.

 

[Hipster]

Yup, that's his formula. I know you're not a fan. I caveated that it's not a spec for a truck cam, but I'll accept his formula for a max power build. Fair point that the DCR might be high for iron heads. I'm still learning that stuff. It's only been in the last few years that engine builders have really been opening up on the engine math. For the longest time we hobbyists were always told that the secret to being a top-notch engine builder was just to "blueprint your engine". Dirty dogs.

Intl45 has already stated he's using flat-tops and not factory dished pistons, so that's a plus.

Not necessarily for or against anything, different situations and applications call for different things. Form follows function. You can talk the fisherman out of going with a Cigarette boat to deep sea fish in , you can talk a hardcore biker out of chosing a 10" over hard tail to tour the USA on, but I've seen many a guys turn nice streetable classics into nearly race ready nightmares they themselves don't want to go anywhere in. BFE @ 2am and no high test available is not when you contemplate if you overbuilt for the intended use. Totally get it, if a little power is good more is better and off you go chasing numbers and end up in a place you didn't set out ever go to, but people get hung up in it. I have in the past. Sometimes it's figuring out where you want to be and a stopping point.

 

[L31MaxExpress]

Not neceesarily for or against anything, different situations and applications call for different things. Form follows function. You can talk the fisherman out of going with a Cigarette boat to deep sea fish in , you can talk a hardcore biker out of chosing a 10" over hard tail to tour the USA on, but I've seen many a guys turn nice streetable classics into nearly race ready nightmares they themselves don't want to go anywhere in. BFE @ 2am and no high test available is not when you contemplate if you overbuilt for the intended use. Totally get it, if a little power is good more is better and off you go chasing numbers and end up in a place you didn't set out ever go to. Sometimes it's figuring out where you want to be and a stopping point.

I agree with most of that. I can say without a doubt, 95% of people on this board wanting something peppier than the stock engine would be absolutely ecstatic with how the L31 I built runs. That 1987 G20 van screams with that ubber basic 350, is decent on fuel and once the Proflow 4 ECM is pulled off will run like GM put the thing there from day 1. The engine is quiet as can be internally, idles smoothly with lots of vacuum, carries great oil pressure, broke in without any drama, it does not burn oil, and just flat runs great overall, PF4 ECM hiccups aside. When the P59 goes on it with a knock sensor I am not afraid to tune it to run on 87. Sure it has an aftermarket intake, throttle body and headers on it, but most of the internal engine is production GM engineering in some form or another and just works. I have spun it to the fuel kill at 6,000 rpm numerous times and it is silky smooth all the way up the rev range and just does not stop pulling until it is bouncing off the rev limiter.

 

[Erik the Awful]

Yup. When I plug WCJr's engine parts into the spreadsheet it specs out a 108.4 LSA, but I have a 112 LSA Lunati cam in it and it tows like a champ. The spreadsheet was built to do the math on a max-power LS engine effort. I just find it really handy for optimizing quench and compression ratio. I can also plug cams into it and see the difference in the cam profiles and how they affect DCR.

 

[International47]

The 8.21 DCR is pretty much aluminum head territory and much higher than the 7.54 or whatever it was that was posted previously, which I thought sounded rather low for 10.3ish static with short duration cam. Big negative on doable on pump gas. .028 drops static to 9.8ish static according to my calc's @ Wallace with no quench and can be in the detonation danger zone so .028's are not a good option either. If you have to back up timing to get it to run your killing power so not a best case scenario either.

I've done 10.5 iron headed. It needed some race gas mixed in to run right. 10.+ iron headed on pump gas ford, chevy, or mopar is not typically doable even with quench. Every pro head porter I've dealt with has told me to stay out of swirl port heads at anything beyond a minimal bowl blend and cleaning up casting boogers. Kill the swirl effect, or too much cross sectional area in the wrong place and it's not hard to end up where an untouched head moves more air with better cylinder filling/combustion efficiencies etc.

Kinda funny the program lists optimal LSA at 107. I think I hear Vizard laughing, and damn right you need to be careful what the internet weirdos link to and promote.

Wow, this thread is starting to expand way beyond my experience/comprehension.

I'm a bit worried that now I've created a problematic motor.
the thinnest gasket from cosmetic I see on thier site is .023, so not much of a difference.

I would have assumed that the .40 overbore on a stock block and the summit flat top pistons(1.560 compression height) would have created only a slight increase in compression, as its not a dished piston anymore.
I was thinking that adding the stock cam (LT1) to a stockish block would have created a stockish engine build, IE the roadmaster, iron head LT1 had 9.6:1 compression ratio.
But it appears that I was wrong.

The head porting amounts I followed, were to the 3rd cut from Charles Servedio videos ( another internet wierdo?), where he flow tests his porting changes.

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[International47]

I just realized that in my previous numbers I didn't override the cylinder bore. Here's the sheet with correct numbers and a 117* ICL. Note that the "Optimum LSA" is for max power, and not necessarily a good truck engine.

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This info is starting to become more than I have learned in the past.|

I believe I grasp the differences between static and dynamic compression, but am unable to see the end result effect, or the negative result.

I was thinking that the almost stock nature of the parts used ,would result in a engine that would be stock like in power, reliability and tuning. Maybe resembling something closer to a LT1 cammed, 1995 Roadmaster, iron head LT1?

Has my choice of parts/machining creating an unsuitable or unrealible combonation?