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Discussion Starter · #1 ·
Back story......... running a 540 in my ‘66 nova. Motor is 900 hp 700 torque. 14 to 1 compression, cam is 777 lift. Dart block, dart heads.
car is tube chassi approx 2500 lbs. I’ve been running 9.60/9.50 index. I use limiting plates to slow it down. Best pass 9.18 with a limiter. Probably go high 8’s all out.
I want to make life easier so I want to rebuild motor and run lower compression and a hydraulic roller cam.
I know I’ll go slower, I’m okay with that. Might run 10.60 index and brackets.
I’m looking for advice. Has anybody done this with success?
what kind of pistons to run on 91 octane. What cam? Could I use the existing roller cam with pump gas and change it later.?
 

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I feel with the right combo of parts you could make very close to the same HP with what you have already. Should not be very difficult to run those times at that weight. If you are gonna make this a track only car I would stay with a solid roller. I rarely have to adjust valves on mine.

As far as the rest some of the experts will probably be more help than me.
 

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I built my 582 BBC specifically to use pump gas to save a little on fuel. I actually use 100LL Av Gas. The air port is 3 miles from me and convenient. 10.5 compression pistons 1.5MM/3 MM rings. Autotech shelf pistons. They are 4032 alloy. Molnar rods and crank. .800" lift cam, 284/292 cam. makes 800+ Hp at 6700. Low 9.30 @ 3150. E Z Plate restrictor plates to run 6.40+ 1/8. Starting line RPM 4200, shift 6500. over 250 passes so far, no issues.

I went bigger cubes to offset lower compression.

Solid roller is more reliable/consistent and not much effort to maintain with good quality valvetrain.

Soften the head chambers and run a thicker head gasket might lower the compression some. You can run Av Gas at 12.5 compression and a little RACE GAS Concentrate octane booster. 4 ounces to 5 gallon. MMT and 100LL love each other.

My next engine will be a 496 12.5 compression for Av Gas.
 

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Discussion Starter · #4 ·
Thank you to both of you. I think I might try to stay with the solid roller cam. Just change the pistons out.
 

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Did a 540 at 10.51cr AFR 335 heads OTB Mech roller Made 829 HP .ran 9.66 at 138MPH in 71 Nova full street trim 3750#.Also did 565 at 10.3 cr ,more agressive cam .Made 896HP both on 93 octane..Not getting into the technology why but avoid using Airplane fuel,Go E85 if it is available in your area .
 

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I run 10:70's in my pump gas combo in my wagon. My car is 3310 empty and 3510 with me in it, so I am sure it would run 10.50's in your car. I also dont have a ton of converter because I street drive it a whole bunch. The only non ethanol stuff local to me is 90 octane, so thats what I set it up for. I love just running down the street to get gas and dont see myself ever doing anything but a pump gas combo

I have a 9.8:1 GM block 468 combo
It has out of the Brodix BB2plus heads with a comp 680 lift solid roller and comp lifters. The solid roller hasn't given me any trouble on the street and while I check lash 3 or 4 times a year, I really only adjust an exhaust lash occasionally

GM forged crank
Crower I beam rods
SRP pistons
Crower stainless rockers
Howards stud girdle
Brodix intake that was machined down to keep everything under my 2-1/2" hood
Holley 950

Brutally simple combo that you could probably do for less money with some parts substitutions. Combo made 634HP at 6400 rpm and 580 ft-lbs at 4900 rpm.

I run an 8" 4200 converter and I footbrake the car.

I love the pump gas set up, I havent put new springs in it in 5 seasons of use and it goes to cruise ins, lacrosse games, ice cream runs, etc. I had concerns with consistency due to pump gas variations, but that was unfounded and the car is easy to dial. It is probably overkill for a 10:70 set-up...but again it is consistent and low maintenance.
 

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Discussion Starter · #8 ·
Thanks for all the help. I'm going to swap out the pistons for a 10 to 1 compression ratio. I will leave everything else the way it is. I hope the cam will be okay as the cam specs say "for a 12 to 1 compression and higher motor"
I'm going to leave the roller cam in it and see how it runs.
 

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My engine is a pump gas 615 BBC. Static compression is 11:1. I run 93 octane super unleaded from the corner gas station by my house. Almost all of my runs are at 38 degrees total timing depending on the weather. Never had any problems. I have splashed some race gas in the tank before and it did not make one bit of difference.
 

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My 555 is 10:1. Goes 5.80's on 93 around 3,550 with a PG on 28's. It is a SR... Lift is .750/.730 on a 108 274/277. No doubt your 540 could make 900+ on 93 with some changes.
 

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My 555 is 10:1. Goes 5.80's on 93 around 3,550 with a PG on 28's. It is a SR... Lift is .750/.730 on a 108 274/277. No doubt your 540 could make 900+ on 93 with some changes.
Dude that is a sick combo. That motors gotta be making close to 900hp.

Unless it was a "daily driver" or something Im driving 10,000 miles a year I would stick with a solid roller all day. No special oils, no bs. Cam goes up, lifter goes up, valve opens... if not, something is broken.
 

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My 555 is 10:1. Goes 5.80's on 93 around 3,550 with a PG on 28's. It is a SR... Lift is .750/.730 on a 108 274/277. No doubt your 540 could make 900+ on 93 with some changes.
Whats the rest of your combo? What Heads are you running, any kind of work? Who's piston & cam. No doubt a very strong package.
 

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Dude that is a sick combo. That motors gotta be making close to 900hp.

Unless it was a "daily driver" or something Im driving 10,000 miles a year I would stick with a solid roller all day. No special oils, no bs. Cam goes up, lifter goes up, valve opens... if not, something is broken.
I'd think going almost 119 it has to be around 900 maybe a few more. I'd fought fuel issues and never had the 60' all that great.
The SR has been awesome. Springs and check lash.
Whats the rest of your combo? What Heads are you running, any kind of work? Who's piston & cam. No doubt a very strong package.
Foxwelll did some work on the Edelbrock 340 heads. They flow really good down low/mid and 400 at .700 lift. Straub did the camshaft.
Pistons are heavy I believe, they're JE/SRP box, Scat crank. Edelbrock 7075 with 2 box AED 750's. It's been a good combo and a lot fun cruising/racing.
 
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