MODMUSTANG

Well I am new to the forums here and new to Big Blocks. I just finished a Modular OHC mustang build up and am now helping a bud with his BBC build up for his 79 Camaro.

I have been reading up for a cpl weeks on here and it seems like a great forum!

Currently we have:
Block = 3999289 With stock internals
Heads = 338781 With stock valvetrain
Weiand 7554 Intake Manifold (can be found Link
Holly 750 double pumper
Also have an Erickson Cam but don't have the specs on it right now

We are going to attempt to hand port the heads, at least a good gasket match. We also have a set of headers that are probably going to have to be massaged to fit.

I have a ton of questions. Our goal is to have a NA budget strip car (non-competitive).

With the parts that we currently have what kind of compression ratio are we looking at?

What's an estimation of power output when staying with the stock parts ported and given that we have the right cam for the application?

I am pretty sure he has enough money in his budget to pick up a set of pistons and connecting rods to raise the compression. We aren't sure of what kind of rpm the stock valvetrain will go up too though.

Any thoughts comments or advice would be greatly appreciated!

Thanks,

mongse

iTrader: (2)

Good choice on the heads. Not sure if you got them on purpose or not, but they're a very good open chamber iron head. BTW, I think they're 336781s.

If you need to look up BBC casting info, mortec.com is the place to go.

Heads:
336781.....73-85...oval...OPEN...454, 118cc chamber, 256/114cc ports

Block:
3999289....454.......71-79...2 or 4 bolt, some "CE" replacement blocks had four bolt main caps

Stock compression should be fairly low. High 8s with a flat-top if I were to guess. Get a set of domed pistons in the 10-15cc range and it'll be a nice setup.

MODMUSTANG

Do you know what kind of cam would work best if we did get 10-15 cc domed pistons?

I noticed that even with the pistons in the link below that It will only yeild about 10.4:1 compression. pistons
Is there any reason we can't run a higher compression?

And we actually lucked out on the heads. Didn't get them on purpose. Got a running 454 for 650 the other weekend.

mongse

iTrader: (2)

Damn, nice deal indeed.

I'm sure you could run higher compression, but 10.4 on an all-motor BBC will be pretty nice on the street.

Not sure on a cam. Might want to give a couple cam companies a call (Cam Motion, Isky, Comp, etc). If it were me, I'd go with one of Isky's 270 cams. They should be on their site (somewhere). You can also get some good ideas on here:
http://www.enginecombination.com

Best of luck.

69rat

the weak point on bbc heads is the exhaust. you said you were gunna port them yourself, i heard the key to good flow numbers is working the exhaust ports so work them over really good.

MODMUSTANG

Thanks for the link! I will register today and check it out.

Thanks for the advice. We have another set to practice on incase something goes wrong.

mongse

iTrader: (2)

Good site and well setup. I know the guy that runs it and there's a pretty good variety of BBC setups on there from drag to street.

Wise idea. I hate porting iron heads.

Firechikn

iTrader: (15)

I'd suggest stepping up the valve springs a little. Try to find the specs on the cam and get springs to match. Also a set of decent lifters would help on your rpm.

MODMUSTANG

Cam is a Erson E120421.
Specs are
296 IN
296 EX

228 @.050 IN
228 @.050 EX

Lift .542 IN
Lift .542 EX

Lobe Center 111 Degrees.

Can I use this cam on a stock motor with the oval port heads without PTV contact or valve spring bind?

MODMUSTANG

Any ideas if this is a good cam for a stock block, ported 781 heads?