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Big Block Chevy Questions

 
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JeffBoy
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Joined: 18 Oct 2005
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PostPosted: Tue Oct 18, 2005 11:22 pm    Post subject: Big Block Chevy Questions Reply with quote

hey everyone im looking for some opinions on a 454 swap ima do on my 79 camaro.

here are some motor specs : stock crank, rods, 9:1 comp, just got the heads back with oversized valves (2.19, 1.8Cool, hyd. cam with .5 inch lift, 1.7 rockers, performer intake, 750 carb

any advice or answers to the following questions would be really helpfull.

is a 750 carb enough for this motor?

can i use my small block motor mounts?

i have oval port heads and just got hedman headers and noticed they are circular, if i use the right gasket will i be ok? or are all hedders circular?


im going to weld up my own exhaust system (no cats) i have some 2.5 inch pipes, or is that too restrictive? mabye 3 inch?

has anyone hooked up an engine oil cooler and actually noticed the difference? i wanna try to keep my stock radiator


the rest of my drivetrain is a 700r4, and a 3.73 10 bolt. i really dunno how long my tranny will last against a big block

thanks!
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SMOKEmUP
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Joined: 30 May 2002
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1979 Chevrolet Camaro

PostPosted: Wed Oct 19, 2005 9:24 am    Post subject: Reply with quote

Quote:
is a 750 carb enough for this motor?
According to the airflow calc yes. I think it will be a good starting point.

Quote:
can i use my small block motor mounts?
Yes. I know someone who used them because that's what he had at the time. They were intended to be used as a temporary solution. I don't think he ever replaced them.

Quote:
i have oval port heads and just got hedman headers and noticed they are circular, if i use the right gasket will i be ok? or are all hedders circular?
I'm pretty sure they'll be fine. Check with hedman for the correct header for your application.

Quote:
im going to weld up my own exhaust system (no cats) i have some 2.5 inch pipes, or is that too restrictive? mabye 3 inch?
Check out torque tech. I think they make a system in 2.5" or 3" for your car.

Good luck with a 700R4. Let us know how long it lasts.
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Hanz
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2003 Dodge Ram

PostPosted: Wed Oct 19, 2005 10:10 am    Post subject: Re: Big Block Chevy Questions Reply with quote

JeffBoy wrote:

can i use my small block motor mounts?


The motor mounts are the same, but at least in Ist gen Camaros, the motor mount brackets (that bolt to the frame) are different, the small block sits higher and something (I believe bellhousing or distributor) hits the firewall. Go to the dealer or yearone and see if they have brackets for one of the last years a Camaro had a BB, and double check my info that they are different.

As far as the exhaust, 3" is monster, hard to install, takes a lot of room underneath, and for your motor and application I don't think you need it or would even enjoy it. Hanz

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JeffBoy
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PostPosted: Wed Oct 19, 2005 4:17 pm    Post subject: thanks for the replies so far Reply with quote

yea i did some more research and yea the big block mounts are lower for alittle help with clearance.

my boss had to hammer the firewall when he had this motor in a truck a long time ago. but engines sit back more in trucks. its ok im ready to take a BFH to my firewall.

i bolted the heads on today, and lifters,pushrods, and rockers. mabye ill get to the manifold.
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pitontheprowl
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Joined: 20 Oct 2005
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PostPosted: Thu Oct 20, 2005 10:26 am    Post subject: Reply with quote

Jeff,
I am not much for the high dollar rat motor, but I love my little gas guzzlin' mouse. I am running a 4 core stock radiator, a transmission cooler, and oil cooler on my 79 Blazer. I did not use the oil cooler or filter relocation kit until the rebuilt mill had about 1500 miles on it. I did not want to deal with the chance of a clog in the cooler. After intalling the cooler, and twin filter relocation kit, my engine temp. dropped about 15 to 20 degrees. I am sure that the total 12 quarts of oil in the system helps out too.
Also the round port headers should work on the oval port heads with out a problem. You may want to do some port matching to blend them together for a smoother flow.
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JeffBoy
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PostPosted: Thu Oct 20, 2005 5:16 pm    Post subject: Reply with quote

wow 12 quarts in insane, did you have a high capacity pan? i have the stock depth pan, but its all different shaped to fit in my camaro, i also got a double remote filter and a big oil cooler, im using it for my trans right now but when i put the motor in itll be used for that. i picked up a smaller oil cooler from pick n pull for 5 bucks.

i better head to the store i only have 5 quarts lol
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pitontheprowl
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PostPosted: Fri Oct 21, 2005 5:11 am    Post subject: Reply with quote

Eight quarts in the pan, one in each filter, and two in the lines and cooler. All this and it shows 1/4 quart low on the stick. I am firm in the fact that oil is the life blood of your beast, keep it happy. Smile I am using a B&M Supper Cooler. The fun part was trying to keep oil filter/cooler hoses from meeting with the After Burner headers. Wink
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96capriceMGR
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1996 Chevrolet Caprice

PostPosted: Fri Oct 21, 2005 8:01 am    Post subject: Reply with quote

You guys want to be careful engine oil most certainly can be overcooled, it is designed to work best at 180+ and needs to reach those temps to evaporate off the condenstaion and the fuel dilution that carbs WILL cause. Not saying don't use a cooler just saying do some with some thought to keeping the oil warm there are bypass thermostats for this that send the oil right back to the motor till warm then through the cooler.
Also consider ANY length of plumbing is a restriction and extra parts are just something more to potentially fail. My cars came with factory oil collers as at least options many of us drop electric fan on temps signifigantly and some go with 20degree cooler stats these negates the need for the cooler so some guys delete it and gain the oil pressure that was lost to the extra plumbing. If still a little too warm for comfort a synthetic oil adds a safety margin.
With 12 quarts in a system I would probably look to delete the cooler to keep the oil warm enough to get rid of fuel and water and be able to run it 10K+ between changes, if the water and fuel are allowed to accumulate though 12 quarts could be overly contaminated within a couple thousand miles. Oil anaysis is cheap, consider sending in a sdample if you want to see how well your setup is really working.
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pitontheprowl
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PostPosted: Sat Oct 22, 2005 4:59 am    Post subject: Reply with quote

Yes, lack of operating temp. will cause condensation to "milk" the oil. My problem is, well I have rebuilt and repaired several engines that had synthetic oil run in them their entire lives and I am not impressed nor would I ever run a synthetic in any one of my vehicles. Second, the bypass for the oil system is built into the oil filter adapter that is on the block, that was removed and replaced with a "non"bypass adapter. "DO NOT REV A COLD MOTOR WITHOUT A BYPASSed ADAPTER!!!" It will blow your oil filter apart due to the thickness of cold oil.
Depending on what part of the country you live in will depend on how you build your engine and what type of cooling systems you should use. My truck was built to haul, not for show. Majority of my heavy hauls happen in our summer months and here in Texas it gets pretty dam hot. Hence forth the big oil cooler and bigger tranny cooler.
If it makes you feel better, on a 105 degree day in bumper to bumper traffic my truck will only get to 194 degrees, this was a 265 mile one way trip with a load. But for the most part it runs 186 year round.
My question is, "How do you get almost 400,000 miles out of a small block chevy?"
Valvoline VR1 changed every 2,000 miles reguardless of what it looks like. Wink
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JeffBoy
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PostPosted: Sun Oct 23, 2005 8:50 pm    Post subject: update on big block Reply with quote

heres an update for anyone is is interested.

since i have the "clamshell" engine brackets i didnt have much option for using frame mounts. they offered a "high performance" mount, however they lifted my engine about an inch, and i would have to drill new holes to mount them. so i just replaced what i have. (stock small block mounts.

the big block oil pan from summit cleared everything fine. the motor dropped right in with no firewall problems. low profile valve covers were a must to clear the power brakes.

the hedman full length hedders were SUCH a tight fit. but they did fit with the exception of moving a brake line over alittle.

right now the problems im dealing with is the flexplate. the factory only backed 454s with th400s. so the bolt pattern does not match up with a th350 or 700r4. also big blocks flexplates are externally balenced. where small blocks are internal. so i have to find a externally balenced flywheel, that has the bolt holes for a th350/700r4.

the next problem is the fact that i do not have a low rise manifold, and i have to adapter for spread bore to square bore. this puts my carb about 2 inchs over the hood WITHOUT an air filter.
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Hanz
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2003 Dodge Ram

PostPosted: Sun Oct 23, 2005 9:58 pm    Post subject: Re: update on big block Reply with quote

JeffBoy wrote:
heres an update for anyone is is interested.


right now the problems im dealing with is the flexplate. the factory only backed 454s with th400s. so the bolt pattern does not match up with a th350 or 700r4. also big blocks flexplates are externally balenced. where small blocks are internal. so i have to find a externally balenced flywheel, that has the bolt holes for a th350/700r4.


Are you talking about torque converter bolt pattern? Use a 350 converter.

JeffBoy wrote:
the next problem is the fact that i do not have a low rise manifold, and i have to adapter for spread bore to square bore. this puts my carb about 2 inchs over the hood WITHOUT an air filter.


You don't need a 1" thick adapter, you can use a sheet metal plate, look in catalogs and you will find it. You can also get a drop down air filter. But I think your problem is still in the motor mount brackets, if you skip this step I don't know why you would, here's a link-

http://cgi.ebay.com/ebaymotors/Chevy-Camaro-70-81-Big-Block-frame-mounts-396-427-454_W0QQcmdZViewItemQQcategoryZ34202QQitemZ4583579037QQrdZ1QQsspagenameZWDVW

Hanz

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JeffBoy
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PostPosted: Mon Oct 24, 2005 9:01 pm    Post subject: big block Reply with quote

well the motor mounts turned out fine. if they were any lower my hedders would have no chance in clearing.

tomorrow i will find out if i finally got the right flexplate. no parts stores can find one with the dual bolt pattern. i finally spent way to much money on a completely unnecessary NHRA approved b&m blah blah flexplate. so hopefully itll be the right part.
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87calais
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PostPosted: Tue Oct 25, 2005 12:02 am    Post subject: Reply with quote

In theory you could have used a 400 flywheel..... They're both external, and the small block should be dual pattern...... or just taken a normal one that was 168 tooth, and your old one, and had it balanced the same... but, as they say, water under the bridge
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Big Dave
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PostPosted: Fri Dec 16, 2005 9:23 pm    Post subject: BBC engine swap Reply with quote

I think I am to late to offer any advise this time arround, but I can't help myself.

Clam shell engine mounts come in two flavors four hole on chassis or three hole. None of them are designed for the big block so the engine is 1.25" to far back and 0.625" to low from what the Chevy engineers had in mind. Year One and similar third party resto guys offer correct (reproduction OEM) chassis and block engine mounts for most cars.

Header pipes are all round welded by robots to offer the greatest number of engine chassis fitments per model so the round pipe to the square port isn't an issue. Keeping them sealed will be because they generally use 1/4" mild steel plate and then grind it flat reducing the thickess even more. I recomend Percy's Seal'd for Good dead soft aluminum header gaskets and Mr.Gaskets sure clamp lock washers to keep your ARP SIX point header bolts properly tightened.

GM Parts uses Edelbrock for their (bowtie performance) heads and intakes.
I say by pass the middleman by buying dirrect from your favorite vendor an Edelbrock Air-Gap dual plane round port manifold and order it for the spread bore if your going to use the 750cfm Rochester QuadrJet that Chevy initially used on their 325 and 350 HP big blocks. Order it with a square bore if you are using a Holley 750 cfm (Chevy sold the 460 horse LS-6 over the counter equiped with a 785 cfm Holley dual feed double pumper. Suprisingly the smaller 450HP L-88 427 shipped with an 850 cfm).

Every Chevy PU truck mfg in the last twenty years which shipped with either HD cooling, or a trailering package left the factory with an oil cooler installed which installs above the spin on filter with an addaptor. Parts to install one on your BBC would only have to be modified for length should you get one for a song (possibly a little dance too depending on where you live) from your automotive recycler (or as I like to call 'em Junk Yard).

I have written enough about the 700R4 and Big Blocks. The problem you encountered was a Metric problem not a 350/400 168 tooth flex plate interchange. The bolt circle for the mounting holes are different between the Metric stuff and "real" BBC stuff. But at least your B&M blah blah is of higher quality than the stamped steel stock piece, and will last for years longer than the explosion proof certification will (they expire).

Exhaust pipe diameters are more a matter of personal taste than for any real performance gain. 2.5" dia pipes are the largest diameter ever installed by any of the big three. Most performance cars had 2" pipes, some had 2.25" pipes but only the Hemi, and Corvettes came front to back with 2.5" pipes. That said; the only restriction on larger diameter pipes is ground clearance and noise level. Keep in mind Cat usually ships their engines with 6" diameter pipes and 14"x52" round mufflers, chromed or stainless. I personally think it's just a bit much having coffee can size exhaust pipes on the street. When you race you uncap: the rest of the exhaust system is just dead weight.

BIG DAVE
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