350 SBC build--abnormal questions PICS!!

[Wrench]

You can use the stock distributor. The cam gear on the billet cam is sintered iron even though the cam is steel billet. I'm currently running a comp cams roller cam in my engine with the factory distibutor gear. If you don't believe me then call comp cams and they will verify it for you (that is what i did).

Thanks Scott, I was hoping you'd chime in on that one. It's one of the few things where there's so many varying stories I didn't want to make the call. I actually read the same thing on Hotrodders but wanted to hear from someone I knew would know .

My cam is the 8-500-8 from Comp, and I'm using a brand new Mallory distributor, so there's no wear pattern on it yet anyway.

 

[dyeager535]

Yeah, I'm running stock SBC distributor with my Crane roller cam too.

Next time it will be stock roller components though.

 

[76zimmer]

Yeah it would be interesting to hear some theory on it, although there is probably precedent in how race heads are finished. What do the chambers look like on some high end AFR's?

To me it would seem that airflow wouldn't make a huge difference, which is probably true regardless, but one way or the other has to have been proven to be more efficient, and racers are probably the ones that have tested it. I would think that any protruding edges, microscopic or not, would tend to be a problem.

This is a response from a friend who is a highly regarded cylinder head expert:


Polishing the runner causes the fuel to separate from the air especially in the turns as the fuel is heavier than air.

If the runner has texture to it, the air boundary layer stays active and keeps the fuel in suspension better.



I took a motorcycle that had like a chrome finished runner and just ruff textured it and the bike owner said it was faster and required less fuel!I

I always leave about a 36 to 50 grit finish on my intake ports



The exhaust can be very smooth but it really doesn’t show any improvement in power.

The only time it could possible make any improvement would be if the port velocity was too fast to begin with.

If you had a dry port with fuel being injected into the chamber {like some high pressure nozzle spray}

there would be maybe a 1 percent better flow!!!!!!!!!

 

[NateInChandler]

I have a 8-465-8 Comp cam in my 99 chevy vortec 383, specs are .560 .555 with 1.6 rocker and 210 218 duration at .050 with 1.6 rocker, im running the comp cams 1.6 roller rockers with beehive springs. I think you will like that cam. Mine pulls great from 2,000 or so to 6,000 or so. Im also using a stock dizzy gear..

 

[Wrench]

Yeah, the specs on this one are 206/212 duration at .050, .480/488 lift with 1.5 rocker (will eventually be running 1.6's) and 112 LSA. It's rated 1000-5000RPM, which is all it will ever see. I don't think I ever pushed my last engine above 3500.

The truck currently has 3.08 gears and 27" (I think, it's 275/55R15) rear tires, so I want to maintain torque. Cruise RPM is somewhere around 18-1900. 'Course, I also have a 3.73 diff that I swap in when I feel like it

 

[Wrench]

as many engines as i have rebuilt over the years, i have never seen 1 of those timing chain tensioners for a sbc, not even in the parts books..who makes it & where did you get it from...i'm about to actually build me a 383 & a 377, i figured since i'm robbing parts from 1 for the other and vice versa, that i would go ahead and have all machine work done and buy all the parts to put them both back together.

The tensioner is Comp Cams #5419 for the complete kit including drill template and #5417 for the kit without the template. I would not advise trying to install one without the template, it has hardened bushings to put your drill bits through which makes it really easy to drill square to the block. I paid about $60 for the complete kit with template, I think without is around $30. That's Canadian dollars too.

According to my machinist, the Buick Grand Nationals came with this type of tensioner installed from factory . . .

 

[Wrench]

Yeah, I'm running stock SBC distributor with my Crane roller cam too.

Next time it will be stock roller components though.

Yep, if I ever build another one of these it'll be a stock roller block. I'll just get it drilled and tapped for splayed mains and I'll be good to go

 

[blazin_blazer]

cool, thanks for the info.

 

[dyeager535]

According to my machinist, the Buick Grand Nationals came with this type of tensioner installed from factory . . .

I could be wrong, but I think all the 3.8's came with chain tensioners...but I'm too lazy to look it up.

 

[4X4HIGH]

I know that some of the vortec 4.3 V/6's had them stock.

 

[76zimmer]

I could be wrong, but I think all the 3.8's came with chain tensioners...but I'm too lazy to look it up.

I believe too....my 225 V-6 has one in it....thats a 68....precurser to the 3.8 231...

 

[Wrench]

Just fired it for the first time, poured some fuel in the carb bowl and it fired within a crank and ran smooth. I'm exhausted, been up since five this morning working on it. Bedtime now, will continue in the morning when I'm 100% conscious.

 

[Wrench]

Well .. . . been a while, had to leave it home for my road trip and back working on it now.

For starters, it was running nasty (barely at all) the next day, checked vacuum and was getting 5-7 inHg instead of the 18-20 I should be getting, did a compression check next and found that cylinders 1, 3, 4, and 6 are getting 185 psi, while 2, 7, and 8 are getting 0 psi. ZERO. Needle doesn't even move. Cylinder 5 I couldn't get at without removing the header, so I left it for the time being.

Zero pressure doesn't seem like a blown head gasket to me, particularly because none of the zero pressure cylinders are beside each other with the possible exception of 5/7.

Anybody see a pattern in that? 2 and 8 on one bank, 7 and maybe 5 on the other. Next step is pull the valve covers and check valve operation thoroughly.