1955blown sed del delema

[FAT ASS 55]

some time ago I started a face lift on my sedan delivery ive have removed a 350 and am installing a 502 blown with 2 holleys using a small distributer . I am trying to figure out how far forward the engine will have to be moved for valve cover clearance with out shoehorning this any more times than possible any help out there this evening:confused::confused:

[NickP]

Welcome aboard Fat A$$! Post some pics.

[chevynut]

Welcome to the site. Usually 1.5" forward will give you enough room to clear a stock firewall with no modifications. As you move the engine forward, you begin to introduce other problems like drag link to oilpan clearance issues and possible clearance issues in front of the engine.

[markm]

Agreed with above, however is a 502 a tall deck, if so if you intend to run taller than valve covers I would go with Ecklers 2.25 forward kit. I run a tunnel ram on a 408 BBC and appreciated the extra room for carbs and air cleaners.

[chevynut]

A 502 is not a tall deck block. If you're running a blower you could have other issues with it hitting the top of the cowl. If it was me, I'd drop the engine in and see where it sits the best, then build the mounts.

[NickP]

Agreed with above, however is a 502 a tall deck.


Ding Ding Ding - nope!

Stock Chevrolet V-8 Block Heights


Displacement Cubic Inches
Liters
Deck Height (inches)


302
4.9
9.025


305
5.0
9.025


327
5.4
9.025


350
5.7
9.025


350(LT5)
5.7
9.025


350(LS1)
5.7
9.240


364(LQ4)
6.0
9.240


383
6.3
9.025


400
6.6
9.025


396
6.5
9.800


402
6.6
9.800


427
7.0
9.800


454
7.4
9.800


502
8.2
9.800

[TrifiveRichard]

question NCW, isn't a 383 a 350 block (.30 over) with a 400 crank? Why would it have a deck height different from a 350? What am I missing? Also, isn't there a tall deck 427, generally a truck block? Dick

[Bitchin'57]

question NCW, isn't a 383 a 350 block (.30 over) with a 400 crank? Why would it have a deck height different from a 350? What am I missing? Also, isn't there a tall deck 427, generally a truck block? Dick
You can build a 383 two ways, the way you described, or by using a 400 block with a 350 crank and boring it .060 over.

[TrifiveRichard]

I believe the 400 bore (4.125) and 350 stroke (3.48) results in 373 cu in, close but has different performance characteristics. This generally results in a higher RPM (horsepower) motor, but typically less torque throughout the range, all else equal.

[BamaNomad]

Ding Ding Ding - nope!

Stock Chevrolet V-8 Block Heights



Displacement Cubic Inches
Liters
Deck Height (inches)


302
4.9
9.025


305
5.0
9.025


327
5.4
9.025


350
5.7
9.025


350(LT5)
5.7
9.025


350(LS1)
5.7
9.240


364(LQ4)
6.0
9.240


383
6.3
9.025


400
6.6
9.025


396
6.5
9.800


402
6.6
9.800


427
7.0
9.800


454
7.4
9.800


502
8.2
9.800




Of course all the 'std' passenger car big blocks have a taller deck than the 'small blocks'! :)

All of the 'big blocks' you posted/listed are so-called short deck (big) blocks; IIRC, there ARE big block configurations (for large trucks I think?) which have a taller than 9.8" deck... I believe that is what CN was referring to... ?

[BamaNomad]

I believe the 400 bore (4.125) and 350 stroke (3.48) results in 373 cu in, close but has different performance characteristics. This generally results in a higher RPM (horsepower) motor, but typically less torque throughout the range, all else equal.

And if you bore it 0.060", then you get close to '383' ci... which is what Bitchin was referring to... :) A very high-winding (larger) cube motor...

[BamaNomad]

question NCW, isn't a 383 a 350 block (.30 over) with a 400 crank? Why would it have a deck height different from a 350? What am I missing? Also, isn't there a tall deck 427, generally a truck block? Dick

1st question: It doesn't have a deck height different than the 350 engine... exactly the same.

2nd question: I believe there is such an animal as a 'tall deck 427'... so yes..

[markm]

Ding Ding Ding - nope!

Stock Chevrolet V-8 Block Heights


Displacement Cubic Inches
Liters
Deck Height (inches)


302
4.9
9.025


305
5.0
9.025


327
5.4
9.025


350
5.7
9.025


350(LT5)
5.7
9.025


350(LS1)
5.7
9.240


364(LQ4)
6.0
9.240


383
6.3
9.025


400
6.6
9.025


396
6.5
9.800


402
6.6
9.800


427
7.0
9.800


454
7.4
9.800


502
8.2
9.800



Read again I never said it was a tall deck I was asking a question because I was not sure. Pretty sure the 572 and bigger crate motors are based on tall deck stuff.

[markm]

A 502 is not a tall deck block. If you're running a blower you could have other issues with it hitting the top of the cowl. If it was me, I'd drop the engine in and see where it sits the best, then build the mounts.

The upper cowl issues come in to play with a tunnel ram, perhaps a blower too.

[Rick_L]

Traditional SBC engines were 9.025" block deck height.

I think the confusion may have come from some LS engines being adjacent in the list, they are 9.24" as shown.

Most big blocks are 9.80" as shown, including the 502. There are tall deck big block (10.20"). There were truck engines, 366" and 427", that were tall deck. The 572" GMPP engines are tall deck.

[Rick_L]

Back to the original question about how far forward you mount the engine, you basically have 3 basic choices.

If you place the BBC with the back of the engine in the original location, you'll have serious firewall mods to do. But more room for the oil pan and front of the engine.

If you move the engine 3/4" forward, you'll have minor firewall mods, you'll have to be picky about the oil pan (Milodon has one that fits), and you'll still have a bit of room for the accessory drive. This is probably the most common setup used.

If you move the engine 2-1/4" forward, then your firewall will clear nicely, you'll have to have a modified oil pan or a dropped center link, and you'll be crowded in the accessory drive/radiator area.

markm's comments about the tunnel ram and blower are also worth considering. Also the blower drive might be a problem at the front.

It's all a balancing act. Kind of like stepping on a balloon. Each choice lead to more choices. There is no "right" way.

[NickP]

Of course all the 'std' passenger car big blocks have a taller deck than the 'small blocks'! :)

All of the 'big blocks' you posted/listed are so-called short deck (big) blocks; IIRC, there ARE big block configurations (for large trucks I think?) which have a taller than 9.8" deck... I believe that is what CN was referring to... ?

I'm uncertain what anyone intended by their retort/reply/post. All I did was to find a chart on the web that listed what was shown. Simply adding information. Yes, there are taller deck heights within the GM platform.

[markm]

I have three of the cutout BBC pans, might part with one of interested.

[chevynut]

IMO 2.25" forward is unnecessary to clear the heads and valve covers (unless they're really tall valve covers) and it reduces the space everywhere else by an additional 3/4" that's not needed. But it may be necessary for the blower to clear....I don't know. As I said, 1.5" will eliminate problems with the heads and valve covers using a stock firewall. Some guys have claimed to put a BBC in the stock location without modifyng the firewall, but I don't believe it.

For reference, here's some pics of my 502 in my Nomad at 1.5" forward. The engine also sits a bit higher than stock and is at a 5.5 degree angle to clear the C4 steering rack so it's not a perfect comparison. At the stock height and angle there will be more clearance. The firewall was previously "massaged" to fit a BBC 1/2" forward. You can see the dents in the driver's side corner, near the master cylinder holes, and the passenger side setback was enlarged upward to clear the valve covers of a 427 I previously had in it at 1/2" forward.

8375

8376

8377

Here's the driver's side looking straight across the firewall with the engine 1.5" forward. The passenger side is further back.

8378

[chevynut]

I still say the best way to deal with the issue of engine placement, especially with tall valve covers and a blower, is to put it together and drop it in. Then determine how far forward you want to go. I'd even install the headers and accessories to make sure they clear everything.

[markm]

I don't run super tall valve covers, but mine are taller than those pictured above, the result is about the same clearance shown above. I have things 2.25 forward.

[bigblock]

I've read a lot of opinions on engine placement, as I will be installing a L88 blown I'm very interested in all you guy's that have all already did this or are working on it now. I will be using a set of M/T 427 valve covers, I will also be using the original frame. I love to be able to upgrade to C4 but the$$ is going to be spent on sheet metal. What about the dist. clearance? CN you are right about seating the engine in the compartment for the final location and checking clearance.

[markm]

At 1.5 to 2.25 dist clearance on firewall is a non issue. My access is tight at 2.25 forward due to tunnel ram carbs and linkage, not firewall.

[chevynut]

My custom firewall is only set back 2.5" and the distributor clears the firewall by about 1/2". The stock firewall is set back 4" in that area. I do have to remove the upper intake to remove the distributor. These pics show the distributor clearance with the engine 1.5" forward. At a 4 degree engine angle the clearance would be greater.

8393

8394

[bigblock]

CN what headers are you using ? I've been a hooker man on all my cars.

[chevynut]

CN what headers are you using ? I've been a hooker man on all my cars.

bigblock, those headers are made by Earle Williams Classic Chassis Works.

http://www.williamsclassic.com/#!__products/other/vstc10=headers

I tried a couple of sets of Hooker Competition headers and didnt' like them. Turns out these tri5 headers work fine with my C4 setup. I did modify the #5 and #7 tubes mostly for looks.

8396

8395

I also cut off the 3-bolt header flanges and welded on v-band clamps.

8397

[Bitchin'57]

Having installed a Roots blown engine before (in another make/model), I agree with the others, the only way to know what clearances you have (and don't have) is to put the engine AND trans in there, with the headers on. You are going to want that engine/trans set as far back as possible, because your space for an electric cooling fan setup will be taken up by the 3" belt drive. I predict you will have to build a custom radiator support with a kickout towards the front several inches in order to make room for an electric fan. OR, build a four sided sheet metal spacer between the radiator support and the back of the radiator, and mount the electric fan(s) inside the spacer. Please don't be tempted to just mount the electric fan(s) in front of the radiator, as you'll lose about 20% efficiency. You will need all the cooling you can get with a blown big block.

[markm]

At 2.25 forward, with am l-88 short water pump I have room for a 70 GMC pickup with AC fan and with a custom shroud I run 170 on 100 degree days. One of the coolest rung cars I have ever owned.

[bigblock]

CN,B57,and markm, thanks for your reply, and input, I all most forgot about the 3in belt. Thanks

[bigblock]

CN,B57,and markm, thanks for your reply, and input, I all most forgot about the 3in belt. Thanks CN that's some nice work!!:)