Engine for our 1969 GMC
 

So our 1969 gmc hasn't ran in about 10 years and I ran across a deal I couldn't pass up. It is an engine and transmission out of a motorhome (350) with 31,000 original miles:

Complete from air cleaner wing nut to oil pan drain plug.
Built April 1976
010 block
991 heads
th350

Going in:
1969 GMC 2wd
all new hd suspension
31x10.50r15 tires
3.73 rear axle

So the questions-
This engine appears to have low performance (duh) and small valves. I was thinking of using the XE256 from comp cams in it to boost performance (I already have the cam and lifters- new)
New heads are not an option, I'd rather run it as-is.
Maybe run headers? already have them off a parts truck as well, or maybe rams horns for original look?

Re: Engine for our 1969 GMC
 

If the engine only has 31,00 on it, I'd run it as is.
Valve cover, oil pan gaskets.

The first thing you might do is pull the intake to install new intake gaskets.Doing so you will be able to see the top of the engine, and most importantly it's condition. Hopefully it's clean. AND you'd be able to look at the cam to see if you have any flat lobes, or any going that direction...

I'm no fan of XE cams, at all.
I'm not familiar with 991 heads. Are there any other numbers on the heads???

Re: Engine for our 1969 GMC
 

3998991 casting for heads

Re: Engine for our 1969 GMC
 

Good cam and a good choice for a stock 350. Rather than use the red syrup assembly lube that comes in the kit I like to use this instead. https://www.speedwaymotors.com/Isky-...YaArL7EALw_wcB It's a moly based peace of mind that the cam will live through the break-in procedure. Follow the beak-in procedure to the letter as well as use a quality break-in oil during the break-in...

Re: Engine for our 1969 GMC
 

Apparently we're talking 307 cubic inch motor here...? I've no experience with the 307 so I retract my upper comment. I seen the 010 block and assumed a 350. Now with that said, that may be a very good motor regardless of the cubes. If that thing came out of a motorhome it may be a 4-bolt main block. heres a couple of links http://www.73-87.com/chevy_ids/sbheads.htm
http://nastyz28.com/threads/991-head...-or-no.213869/

Re: Engine for our 1969 GMC
 

its a 350, the 307 was the original motor in the GMC (long gone)

Re: Engine for our 1969 GMC
 

according to the link those heads are a 307 head. Again, that dnt make them a bad head, just a small valve head that wont flow to that cams potential. But if you already have the cam and lifter set it wont hurt a thing to go ahead and use them. It wouldn't hurt to call Comp Cams and bounce the specs off them and get their opinion as well. If your running a 4BBL and duels, I'd say go for it...;)

Re: Engine for our 1969 GMC
 

Did they make a 307 with 4bolt mains ?

Re: Engine for our 1969 GMC
 

no 4 bolt main 307. AFAIK the 4 bolt main is 350 up in a gen 1 engine SBC

Re: Engine for our 1969 GMC
 

Those crap small valve heads did find their way onto a handful of 350's from the factory. Mt stepson got a 1975 350 out of a trashed C30 and it has the same heads. Valves are only 1.72's. I'd start looking for different heads as they are going to be the limiting factor to ANY "performance" upgrade.

Is the block casting number 3970010?

Gary

Re: Engine for our 1969 GMC
 

Yes it is. I think it is factory ratedat 160hp and like 260ft lbs of torque. I was thinking that with the XE256 to promote cylinder filling and bringing up cylinder pressure it COULD be more fun to drive. I would like to get to 190hp and 300ft lbs.

Re: Engine for our 1969 GMC
 

Even with smogger 1.94 heads you could easily make a respectable 300hp.

Gary