motor mods 79 350

scott · January 19, 2002

im looking to do some hop-ups to my recently aquirred 79 blazer

anyhow its got a 350 and an auto

i do some light towing but its mostly a daily driver and light mountain toy

what do u guys recomend as far as motor mods?

i was thinking headers cam intake

any particular brands?

probably going with edelbrock for the intake but not sure on anything else

looking at holley and demon carbs

what kind of cam specs should i be looking at?

remember i want to keep fairly decent mileage

looking for low end grunt

btw botom end was recently rebuilt 030 over but everything else is stock under the hood

thanx scott

SoMnDMAX · January 21, 2002

I have a few questions for you-

What gear ratio? Light towing- how much ###? 4x4, correct? Have the heads been rebuilt?

Dalma · January 21, 2002

I had a 79 Chev truck with the 350 motor. Here are some things I did to get a bit more power out of her.

Headers and decent exhaust system are needed.

Good dual plane intake such as a Edlebrock performer.

Decent 650 cfm carb.

Cam much like a Comp cams 268 HE

makes a good baseline combo.

Eric Bryant · January 24, 2002

Well, the Vortec heads combined with the Edelbrock manifold and some decent headers (don't forget a good exhaust system - dual 2.25" pipes would be good) should definitely do the trick. If you've got the valvesprings to support it, the Comp Cams Xtreme Energy cams work great as they open and close the valves very quickly, minimizing overlap - this is good for maintaining good low-end power. I'm sure someone at CC can recommend the right cam for your application.

76BBSub · January 24, 2002

You came to the right place...

First, intake...hands down, the Edelbrock Performer is the best value. I've put these on a few cars/trucks, always with great results.

Second, headers...DynoMax CeramCoat are the best bang for the buck. For around $200 you get a nice set of ceramic coated long-tube (low-end torque) headers. Shop around and you'll see this is a great deal, the coating alone is usually over $100.

As for the cam, I would call Comp Cams with all your info and ask them. The 268H is a bit extreme for most automatic transmission vehicles with stock torque converters. This cam doesn't really make power until 1500-2000RPM, which would make it a dog off the line in your truck. Think about a Comp XE256H, which is what I have in my '76 Suburban 454. This cam makes great low end power, works with stock torque converters, has a nice idle, and will definitely pull much higher and harder than your stock cam. You will need new lifters and springs to support this cam, but any new cam needs new lifters, and you should install new springs anyway after 30K miles or so with a new cam.

The weak link will probably be your carb and ignition systems. they have alot of calibrations engineered in for emissions controls. But, not alot you can do to stay emissions legal. The intake is CARB emissions legal if you get the EGR version, the headers can be ordered with AIR tubes (I think). Comp has legal cams. This can be done, and enjoyed!!

Jeff

scott · January 25, 2002

oops sorry guys maybe i wasnt specific enuff

im not sure what gears i have in it but im fairly sure theyre stock runs about 2000 rpm at 65-70 mph with 33" tires if that helps any

i was actually looking at comp cams they have some specifically ground for 4wd................... anybody have any experience with these?

was looking at the smallest one in the summit catalouge i dont have it right handy tho so i dont know the part #

ok to define "light towing" every now and then i might pull a trailer <old pop-up camper based> loaded with a couple dirt bikes or one street bike and every once in a great while i pull my dads 22' ski boat

i was kinda thinking the edelbrock performer also for the intake

i have a performer r.p.m. on my camaro now its good for that purpose but too high r.p.m. <i.m.h.o.>for the blazer

what about carbs?

has anybody out there had a holley they didnt have to play with constantly?

or a demon that got good mileage?

anybody tried edelbrock carbs?

any thoughts on them

oh yeah emissions arent a concern in my area <lucky me>

jeff mentioned that my ignition might be a concern

care to elaborate on that? anything i can do other than putting in a hotter coil?

i got a little windy here sorry bout that

thanx all

scott

Eric Bryant · January 27, 2002

For carbs, I'm still a big fan of the Quadrajet. If I was in your position and had the money, I'd be very tempted to pick up the Edelbrock Q-jet. If not, find a good junkyard core and throw a rebuild at it. The Q-jet works very well when properly tuned - it's just kinda tough to learn how to tune on, and they're not the easiest carb to work on. You've probably already got a Q-jet under the hood, so the cheap way out is to pick up a $25 rebuild kit and the $60 Edelbrock tuning kit.

I've got some generic "RV" cam in my van that I believe has 214/224 degrees of duration at 0.050" lift. It seems to work well for towing and has good all-around drivability.

As far as the intake goes, the Edelbrock Performance dual-plane works pretty dang well. Once again, I'm running this on my van, and it seems to work well.

Someone else already mentioned the Dynomax coated headers, and I'll second that recommendation. Regardless of your header choice, I'd really have to suggest that you get something that coated, or else they'll look bad immediately and rust out in short order.

76BBSub · February 21, 2002

Ignition

Your truck should have the HEI distributor, that was the ignition they used in '79. This is a really good setup, except that the stock coil and module are not really good above 4000 or so RPM, depending on the age of the stuff. I found that the HEI distributor on my '76 Suburban had no mechanical advance due to the weight sticking. The second time this happened I bought a new Accel HEI distributor. It's a great value, for about $115 you get a new distributor with adjustable vacuum advance and a mechanical advance tuning kit. It also has a new cap, rotor, and hi-performance module. The only other thing you need is a coil, I used the Accel Super Coil HEI with great results. This made a tremendous difference in the performance of the truck. I didn't realize how bad the old distributor was until the new one was installed. If you think your current distributor is in pretty good shape you can buy the module and Super Coil and install them in your old distributor. I can suggest some timing curves to start with if you choose to buy a new distributor, or even if you want to recurve your existing one.

Jeff