Thread: 540 vette street engine

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Hi u guys,
I was going to salvage the small block in my car, a '70 vette, but now I found out one of the cylinders is bad....so back to square 1.
I started about a year ago gathering parts for a big block chevy. I have the lower end for a 540 big block. I have a 4.25 eagle stroker crank, h-beam rods, small 10cc dome srp pistons and a gm gen VI bowtie block.
I want it to be very streetable and reliable with enough vacuum to operate brakes and the headlights, which also work off vacuum.
For the heads, I was going to get darts new pro 1, 310 cc but I have been looking at everything under the sun, including dart iron heads, merlin, stock oval ports. That would be cool to make it look stock, with a 540 lurking under the hood...
I guess my biggest questions on this motor are the heads and camshaft.
My rear end ratio is 3.36 and my car is not that heavy at 3200 pounds, current tranny is a 4 spd. I will be putting on hooker headers and a full mandrel bent 3" exhaust.
Thanks for your suggestions
Ed

Have you checked out the AFR 305's and 315's???? Erik brought them to my attention, some very good numbers!!!!

For a cam, I would think yours would be the ideal place for a mild hydraulic roller... Lots of good low and mid range power without giving up driveability and street manners..... Pat and Erik both do a lot of BBC work, hopefully they'll be along to provide all the good numbers....

well your engine builder should know what you want ?i could give you some numbers but you need to talk to the guy building it. i would run the small cc runner rect port head iron or alum that is up to you . roller or hyd roller cam ?

you may have header room issues with the raised port heads---work out the exhaust and cylinder head as a compatible package for your car

Yes, I am concerned about header fitment. One guy said do not worry, headers will fit even with raised ports on my car, but it is yet to be verified.

For heads, how about the GM "990" LS-6 service replacement head. It has the large open chambers 118cc with 325 cc rect intake ports. Does anyone know about this head?

AFR's, too much money and they don't sell em bare, that bugs me.

Yeah, the AFR's are a bit more, and they do sell them bare.... Have you looked at the Patriot Performance heads? They even made one for Chevy, think it's like a 325 runner???? They're also available bare or assembled....

AFR part no. 3050-1 is the 305 cc head as cast with no parts....

As for the header fitment, it would depend on how much the ports are raised and how much room there is with stock configuration ports... I've seldom used a set of "store bought" headers that didn't need at least some minor mods to fit.... Actually prefer buying the flanges and collectors, a bunch of mandrel bent tubing, and building my own..... More time consuming, but if it's done right you'll end up with a better set of headers that are sized and fit specifically to the car....

if the ports are raised any, the pipes won't fit thru the holes in the trans crossmember

Originally Posted by ekitch

Yes, I am concerned about header fitment. One guy said do not worry, headers will fit even with raised ports on my car, but it is yet to be verified.

For heads, how about the GM "990" LS-6 service replacement head. It has the large open chambers 118cc with 325 cc rect intake ports. Does anyone know about this .

yep i have used them they will work good for your build i would put 2.250 intake valves in them

Originally Posted by jerry clayton

if the ports are raised any, the pipes won't fit thru the holes in the trans crossmember

Guess I will have to make the exhaust fit!
Since it's going to be a custom exhaust anyway, I don't think this is a big deal. I was more concerned whether the headers hit the steering box or mech. clutch linkage.
I found a good deal on the darts 325 pro 1's, the exhaust port is raised 1/3 of an inch from stock.
And the other big question I have is the camshaft. Is it possible to run a mild solid roller without having to worry about it and which will give sufficient vacuum? I need at least 12 in Hg vacuum to operate the headlights on this car. I may also put on power brakes, but right now they are manual. I know there is a guy on ebay recently who built a 496 with an isky solid roller with 244 deg duration and it made 650 horse with ported factory heads.
Thanks for your time,
Ed

i have had to 548s on the street but did not make any vacuum but what do you want? you say you need vacuum but then you say the guy on e-bay makes 650 HP with stock heads ? 650hp is not that hard to get.you will get more then that with a 540 done right i have one i built that could run on the street for a guy that runs in the 8.50 in the 1/4 mile with no Nos but will not run your vacuum doors for your lights i have a customer that has a 70 vette454 with merlin iron heads used side pipes so the heads will fit not to big of a deal

Well the 350 in this car was not a barnstormer by any means..
I expect the big block to wake this car up...but I do not want to ruin the car at the same time.
I will probably be happy with 550-600 horse in that range with very good driveability and dependability, that's what I want.
Ed

hyd roller cam is what i would look at like erson 621 .238@050 621 .246 @050 on 108 or e120339 621 .254@050 .621 @260 on 110 hard to say if you will have much vac on this last one but it will rock