Technical 6-71 Blown 355. First time start up procedures after sitting for a LONG time?

Hey Guys. A buddy of mine has offered me a smoking (pun not intended hopefully) deal on a 6-71 supercharged 355 SBC. He had it built by Long Racing Engines as a backup for a blown 55 he had (you may remember the trade deal he offered me last year for this car). It was built for street duty, so the internals are nothing special but should support modest boost levels (I'm thinking 6-8 should be good). Pretty sure it's a solid roller cam, but dude is 75 and has had so much stuff come and go he can't remember it all. He does recall it being a blower grind. Double hump heads, stainless valves, dual Carter AFB carbs. The issue is it was built over 15 years ago and never run. Externally it needs a good cleaning and some of the hardware has rusted. No biggie. It's been stored on an engine stand in his rec room the whole time, so it hasn't seen any extreme temperatures or potential rodent hi jinks.

I'm already expecting having to freshen up the carbs to work with ethanol blended gas before doing much more than test firing it. I don't see internal rust being an issue because of how it's been stored. I'll put a scope in the bores just in case. I've got the fuel system to feed it I think, at least for modest boost levels.

If I buy this thing, what do I need to do specifically to a blower engine to keep it happy on initial start up? We'd prime the oil pump beforehand. Where would I want initial timing? What's a good initial curve on the distributor?

Thanks as always.

 

Just an fyi,those aren't "camel hump" heads as they have accessory holes to mount brackets to the heads

 

Looks good,,,,definitely been sitting a while though .
But no problem,,,,,it should work just fine,,,,,,do the normal pre start stuff as always .
Pull the valve covers and squirt some lube on the rockers,,,,,,stuff like that .
Very interesting to me,,,,,,I like it .
You can read up on the blown pre start procedures,,,,,not really too complicated.
Good luck man,,,,,I’m hoping to see this fire pretty soon ,,,,,it should be awesome .

Tommy

 

Any way to identify them from the pics, or externally when I go and look at it?

 

I would pull the distributor and spin the oil pump with a drill to pump lubricant through the engine.... since it has sat that many years after being assembled

 

Definitely. It's probably sat dry, but I forgot to ask.

 

Quite a few double hump heads have been drilled and tapped. Pull a valve cover and get the casting number.

 

I'll do that when I go and look at it. Ultimately the Edelbrocks on my current engine may end up on it anyway.

 

There's nothing about having a blower that changes the starting procedure for an engine that's been sitting. You want to get the carbs ready to go, and full of fuel, before you start the engine. Around 15 degrees initial timing, 30 to 34 total, should work. Figure out what the cam is, make sure the lash is adjusted. If it's a flat tappet, it might be worth the time to pull things apart and put some fresh moly grease on the lobes and lifters. If it's a roller, just prelube the oil system, as mentioned, and squirt oil on the rockers etc.


The camel hump heads got accessory bolt holes/bosses for the 1969 model year, didn't they? they're still the same inside, just look different outside.

 

Good info as always Jim, thank you.

 

The passenger side head appears to have the cast triangle marking of a ‘71-‘76 head which I believe has 76cc chambers.

 

Yep, I was gonna say the same that there were some factory “camel hump” heads that got accessory holes...but squirrel beat me to it...

By the way...I have always wanted to build a blown small block about like that. Good luck.

 

True "camel hump" heads will have one of three casting numbers ending in either 461, 462 or 291, with the 291's being late 1967/68 production and the last ones, physically they appear the same as the earlier ones except the 291's will have a temperature sender hole.
Like was mentioned earlier, people have been known to drill them for accessory mounting but they most likely will be the 69 and later castings, possibly the 186, 292, 492, etc heads.

True camel hump castings.


The mis-identified later castings is what have confused the issue with people for years, having the much smaller hump. In all actuality they will be a better head as far as hp making just not the earlier "period look".
Your heads will most likely look similar to these:

 

Sounds like boost friendly compression won't be an issue then. He said it has stainless valves, so I'm wondering what size they're going to be.
My Edelbrocks are 64cc, so I may not want to use them then. I'm not looking for this thing to be a world beater, but it's gotta have at least 500hp to back up the looks at least a little.

 

Thanks DDDenny!!

 

L.R.E. out of Irving, Texas ??? Odd coincidence ? ( DFW's best/nationwide reputation ) IF so, they can probably give you some details. Ben, Max & crew.

Unfortunately Max Long, passed about 3 years ago. Bad deal. Especially awesome, engine builder. IF the same company .. he was the man that touched that engine .. the most.

Good luck with the start up.

 

Don't think it was that Long Racing Engines, I'm pretty sure this guy is east coast. Dave Long I think he said.

 

Make sure you check the oil in the blower before you start it.

 

^^^^^^^ding ding ding

 

I had a couple sets of these in the past... They were the #186 castings with the 65cc chambers and 1.94" intake valves with 1.50" exhaust....

 

Went over and checked it out yesterday. Found the build sheet. Needs a little this and that but it’s legit. Pretty much a done deal, just gotta get it home. Oil pan and blower are dry.



Sent from my iPhone using H.A.M.B.

 

More pics.



Sent from my iPhone using H.A.M.B.

 

Actually the humps did have them drilled/tapped accessory holes about 1967/68.....kinda rare to find.

 

If you feel like it, pull the blower and break the engine in with a single 4 barrel intake, at the least I would deeply under drive it on break in so the engine isn't pulling the load of the blower.
Make sure and set the timing to around 30 also, no need to detonate the thing during the 20 minutes, plus it'll build some heat so be prepared for that.
Nice engine by the way

 

That's a good idea. The top end is just sitting on the block, so I'd have to pull it off to put the gaskets under the intake anyway.
I should be able to figure out the drive ratio of the blower by counting the teeth on the cogs. I suspect it's already underdriven since it's a street engine.

 

Prices gone up in 16 years

Just a question, but is it # of teeth on the pulleys, or diameter that determines under/overdrive percentage? Maybe it’s related, but I always assumed it was the diameter of the pulleys.

 

Tooth count,,,,,,that’s a Gilmer drive belt .
If they were v drive belts,,,,it would be diameter of pulley.

Tommy

 

Here's a link to a blower drive ratio chart offered by Good Vibrations Racing, which is a great place to get parts and advice, they also have a preowned section that you can find pulleys and things at much cheaper prices.

https://goodvibesracing.com/Ratio_Charts.htm

I've bought several pulleys out of that section and the damn things look brand new.

 

Thanks Swade!!

 

Digging this back up. Weiand says the engine can be run with the blower belt removed, and it will "run adequately". So do you guys think I can break it in like that?
MY 55 is undergoing some surgery at the moment, so this engine looks like a Fall or Winter project most likely.