hartsmike

Possible scenerio: Older 350 Iron block bored .30 over, RV cam with vortec heads. Basic-general rebuild. What kind of HP and torque could be expected? Now, put in flat top pistons in place of dome pistons. Would compression be too high for pump gas?

dmccain

iTrader: (2)

Na run 93 octane. If you run headers and good exhaust and depending on cam selection 275-325 HP 330-380lb tq. I ran same setup, old style 350, flat tops,headers +3in exhaust with a Doug Herbert flat tappet cam best I remember 218 int 218 exh 465 lift flat tappet cam and it made probably 300-325 HP I imagine. It was stout

hartsmike

Was your set up with vortec heads? I am wondering since the flat top pistons increase compression so much if it would be worth the extra $300 to buy a set of used vortec heads or just have the old iron heads worked?

dmccain

iTrader: (2)

Yes vortecs. They are worth it. Your comp ratio shouldn't be over 10:1 if that much. Run a higher octane gas you will be fine

hartsmike

What kind of torque guestimate would you have with flat top pistons, vortec heads, aft market intake and quadraject?

hartsmike

I don't want to get into racing fuel..

dmccain

iTrader: (2)

Even my L03 with a hotter chip doesn't run good on 87 octane. Im not talking racing fuel just premium 91. Vortecs are a bolt on 30+ HP over almost any stock sbc head. Well worth it.

hartsmike

Thanks for all your help! My builder had mentioned going with flat top pistons for added compression and when I'd mentioned 305 heads he said compression may be out of pump gas range. So, I'd heard lots of good reviews on placing vortec heads on iron blocks and wondered if the extra 300 for set of used heads (cost me the same to work them as the iron heads) would be worth it if the flat top pistons were going to give the same added horsepower.

Night rider327

iTrader: (13)

Heads are where the power is... No other single part (other than nitrous or turbo/superchrager) will gain you as much as a good set of heads. The gain of a set of vortec heads will be in the 30-45 HP range.

Flat top pistons will rise compression and is a needed thing in a good "performance" engine, but just the gain from the compression alone will only be in the 10-20 HP range

You will be no where near "race gas" range. If your builder is tell you that, even with say small 305 heads... You need to find a new engine builder.

He does not understand Static vs Dynamic compression, cylinder pressure, role the cam plays on the pressure, quench height, timing, chamber shape, etc.

You can run 10.5:1 + with iron heads on 91 octane fuel with the correct cam, quench and timing.

hartsmike

So, in effect, I can do flat top pistons and vortec heads and remain on pump gas then? If we put a RV cam in for lower grunt (torque) will that alter it or will I have to have a loping cam to relieve some of that compression? (I've been searching the internet and reading forums all day) I'm wanting to build as much torque as possible without having to pour large amounts of money into it.

Night rider327

iTrader: (13)

Yes, build the engine with flat top 4 VR type 5 to 6 cc pistons, be carful on which pistons you buy... A lot of them has the short compression heights and sits the piston way down in the bore..

Fel pro 1094 4.100 x .015" head gaskets
Vortec heads
204/214@.050" cam, or 214/224 @.050" cam
summit stage II or III, edelbrock performer RPM, etc vortec intake
600-670 cfm carb
1-5/8" tube, 3" coll. headers
Good exhaust system
Total timing around 32* to 34*

You will have 350-375 HP, 400+ ft lbs torque

Run on pump 91 octane fuel all day, every day.

hartsmike

That's what I want!! Thanks!!

Thirdgen89GTA

iTrader: (5)

What you have described is essentially the B-Body iron headed LT1. Which made 260hp and 330lb/ft torque stock, and with tune and bolt-ons produced about 300-320hp and almost 400lb/ft maximum.

Add a more aggressive cam for more power as the B-body cam (same as L03, and L05) is pretty limiting. F-body cam is worth a good 20-30hp with out any real noticeable loss in torque. Go for a real aftermarket cam and you can make closer to 360hp or so.

This is all crank numbers, not wheel numbers.

hartsmike

My goal is to make as much torgue as possible as simple as possible and cheap as possible. I realize that with increase in HP comes a gain in torque. I know a lot of folks like the Holly and Edelbrock carbs but I want to stick with the quadrajet. It is a spread bore not a square bore so I'm looking for an intake that will work with it and vortec heads..

Lotta info out there but just not answers to my specific questions. So, thanks guys!

Night rider327

iTrader: (13)

About your only 2 options

http://www.summitracing.com/parts/ed...make/chevrolet

http://www.summitracing.com/parts/pf...make/chevrolet

Or use an adapter plate like this... And run a square bore intake, one of these adapters and your Q jet carb

http://www.summitracing.com/parts/edl-2692

Night rider327

iTrader: (13)

What specific question? I answered all that you asked.

"What kind of HP and torque could be expected" As I said 350-375 HP, 400+ ft lbs

"What if I used Flat top pistons"... Best thing to use, but just the pistons alone will only gain you 10-20 HP

"Would compression be too high for pump gas" No

"would be worth the extra $300 to buy a set of used vortec heads or just have the old iron heads worked?" Yes heads are the single most power making item... Vortec heads will make 30-45 HP more than any other factory production head

"So, in effect, I can do flat top pistons and vortec heads and remain on pump gas then?" Yes

"If we put a RV cam in for lower grunt (torque) will that alter it or will I have to have a loping cam to relieve some of that compression?"
I told you what cam size to go with... No such thing as an "RV" cam to an engine builder. I relay on numbers in degrees and inches to know the size of cam.

You can not, and will not get any more specific answers than that...

Night rider327

iTrader: (13)

The build list I posted in #11 I have built many times, and in fact very close to what I'm using in my daily driver S10.

1988 S10,
350 bored .030" over (355)
Speed pro/sealed power flat top 4 vr 1.56" compression height pistons.
.025" deck heights
Scat 9000 cast 3.48" stroke crank
Scat 5.7" rods
fel pro 1094 head gaskets
10.25:1 compression.
216/228 @.050" cam with 112 LSA.
.484"/.512 lift
1.6 ratio roller tip rockers
Vortec heads w/ modded spring retainers, howards 1.25" springs
Edelbrock performer vortec intake.
1" open spacer plate
Edelbrock 600 cfm carb
Hooker headers
Dual 2.25" exhaust

Will run on 89 octane but in middle summer 90+ degree weather I heard it ping a time or two, so I just run 93 octane pump gas and never had any probs.

hartsmike

Hey Nightrider, no, thanks for your help and input.. I was referring to there is a lot of info out there on other forums and such just that that info wasn't covering my specific questions. But, you and couple other posters on here did. Thanks man.

Night rider327

iTrader: (13)

Oh ok, cool deal. Just a slight misunderstanding. You are very much welcome

hartsmike

Hey Knight rider, or anyone else who wants to chime in, do I need the adapter to run the/this performer intake? ( http://www.summitracing.com/parts/ed...make/chevrolet )

Thanks so much for the help guys!

jokerZ71

If you are really worried about the compression,using a D cup,or,reverse dome piston is a good idea.It has all the benefits of a flat top as far as burn goes,while providing some volume to lower compression.A good choice in hyper pistons is a KB-193 from KB Pistons.This is a 12cc D cup piston with a 1.561" pin hgt.With a quench of .040,it will set your compression close to 9.6:1. With flat tops & over 10:1,cam choice will be very critical,especially with an RV type grind.Most of these close the intake valve very to early to build cylinder psi for power/torque at lower rpm.You can get into trouble quik with 10:1 & too small of a cam. Cooling & the tune need to be optimized as well to prevent problems.

jokerZ71

IDK if your using a flat tappet cam,or,considering a roller,so,there will be some difference.We've used the Comp XR264 roller(212/218 @ .050 .487/.495 lift) in 3 different Vortec builds with the KB-193 pistons,LS springs & Comp 787 retainers.Only 1 of these engines saw dyno time.It put out 375 HP/420 ft/lb.For a flat tappet,you will need to raise the duration slightly.Maybe 5 to 10*.

hartsmike

Thanks for the input! I really appreciate it!!