Budget Vortec Head Upgrade

[pjmoreland]

I installed a set of L31 Vortec heads on my 1979 3970010 block recently, and I couldn't be more pleased with the outcome. This engine has some serious punch now. The block is machined .060 over, and a previous owner upgraded to flat top pistons. The block has not been decked, which is a good thing when it comes to keeping the compression ratio at a reasonable level. In case anyone else is considering doing this upgrade, here is a list of the parts I used. I tried to keep the cost down as much as I could.

Here's a little video of it in action.

https://youtu.be/dh2woxXvRXE


Parts List

10239906 Vortec heads from a 1998 C1500 $140
CL12-242-2 Comp Cams XE268H cam & hydraulic flat tappet lifter set $189
PR7825312-16 BTR pushrods, .025 longer than stock $94
12499224 GM LS1 valve spring set $80
787-16 Comp Cams spring retainers $57
555-513002 Jegs intake manifold $140 (price went up since I bought it)
3/8 temperature sender from member A1971Blazer $45
1590 Comp Cams break in oil $50
2900 Comp Cams timing chain set $35
4605 Comp Cams cam lock plate $5
1003 Felpro head gaskets $80
ES72856 Felpro head bolt sets $38
MS98000T Felpro intake manifold & valve cover gasket set $51
TCS45121 Felpro timing chain cover gasket set $10
TR5/2238 NGK spark plugs $24
82180 Permatex ultra black RTV $6
6039 Mr. Gasket kickdown cable bracket $23
Total $1167

[cj847]

Great list of parts.

Just curious, why didn't you opt for the roller cam?

[pjmoreland]

Originally Posted by cj847

Great list of parts.

Just curious, why didn't you opt for the roller cam?

Because I'm cheap, and felt like this old engine wasn't worth the extra money of a roller cam. I did debate it, and it would help with durability and performance.

[i82much]

sounds good!

[pjmoreland]

Originally Posted by i82much

sounds good!

Thanks... at least what you can hear over my rattling windows.

[Steeveedee]

My understanding is that a roller cam is best at higher RPM. Anyone use a roller cam for a tow vehicle, which is all about low-RPM torque?

[MikeB]

Originally Posted by Steeveedee

My understanding is that a roller cam is best at higher RPM. Anyone use a roller cam for a tow vehicle, which is all about low-RPM torque?

Good for a little more "area under the curve" which means a powerband that is around 500 RPM wider. Roller lifters are quite heavy though, so valve train needs to be able to control them at higher RPMs.

Also, for the 010 block he would need a retrofit roller cam and lifters, which costs a lot more than flat tappet cam and lifters, or even roller cam and lifters for a 86-up roller cam block.

[i82much]

what heads were on it before?

[pjmoreland]

Originally Posted by i82much

what heads were on it before?

1968-76 3998991 307, 350 1.72int 1.5exh 75cc

The intake valves on the Vortec heads are quite a bit bigger at 1.94".

Based on the Summit Racing compression ratio calculator, my compression ratio went from 8.68:1 up to 9.77:1 based on a 4.060" bore, 3.480" stroke, .025" deck clearance (measured), .041 head gasket thickness, 6cc piston dome volume (a guess), and 75cc vs. 64cc combustion chamber volume. I was hoping for 9.56:1 for the compression ratio, which would have been the case if the cylinders hadn't been bored out, but it seems to run well on 91 octane. I can't hear any detonation, so hopefully I'll be alright. The carb is running a bit rich at the moment, and I have the timing set kind of low at 8 degrees. I will be playing around with settings over the next few weeks.

[ChevyRacefan]

Anyone that does this. a few things before you put them on your short block

1)open up the push rod holes in the head. he push rod will hit the head opening with any lift, and /or 1.6 rockers.
2) beehive springs will get you a little more lift before hitting the guide seal and top of guide.
3) 1.6 full roller rockers. this adds lift without having to have the heads machined, IIRC after .480 lift you are machining the heads.

G.M. gets 330 hp out of the 350 with low (by todays standards) lift.

[Rich72C10]

makes me think I should have went ahead and did that, instead of staying stock. lol

[57taskforce]

Originally Posted by Steeveedee

My understanding is that a roller cam is best at higher RPM. Anyone use a roller cam for a tow vehicle, which is all about low-RPM torque?

Yep, GM did in both the small blocks and big blocks. All the 96+ vortec truck engines were roller cam, as well as all the LS engines.

Op, nice work. I bet it runs light years better than it did before. I’ve got a vortec 350 block that I’m building up right now. I’ve got a set of aftermarket aluminum heads for it though. I’ve got 2 sets of good vortec heads sitting on the floor that I need to get built up and stashed in my shop for another day.

[ChevyRacefan]

Originally Posted by Steeveedee

My understanding is that a roller cam is best at higher RPM. Anyone use a roller cam for a tow vehicle, which is all about low-RPM torque?

G.m. did not add them to truck engines for high rpm.
Today's oils and metal on metal sliding movement don't jive.
It is also why the rockers on ls and up are not rockers sliding on a half ball .
I know the back and forth on this. but fact is oem's have bean counters that don't spend money unless it is needed. If a flatt tappet and ball type rockers would last and not fail. they still be in use.

[pjmoreland]

Originally Posted by ChevyRacefan

G.m. did not add them to truck engines for high rpm.
Today's oils and metal on metal sliding movement don't jive.
It is also why the rockers on ls and up are not rockers sliding on a half ball .
I know the back and forth on this. but fact is oem's have bean counters that don't spend money unless it is needed. If a flatt tappet and ball type rockers would last and not fail. they still be in use.

I added ZDDP to my oil, and I plan to continue doing this to try to address this wear issue.

[MikeB]

Originally Posted by ChevyRacefan

Anyone that does this. a few things before you put them on your short block

1)open up the push rod holes in the head. The push rod will hit the head opening with any lift, and /or 1.6 rockers.
2) beehive springs will get you a little more lift before hitting the guide seal and top of guide.
3) 1.6 full roller rockers. this adds lift without having to have the heads machined, IIRC after .480 lift you are machining the heads.

G.M. gets 330 hp out of the 350 with low (by todays standards) lift.

All good advice. I would add that quench height (deck-to-piston clearance + gasket thickness) should be ≤.050", and probably closer to .040" for better quench. However, in the OP's case, he is already at 9.77:1, so he would need new dished pistons, a D-shaped dish being preferable.

FWIW, in the past I have used GMPP LS6 beehive springs with CompCams #787 retainers and #648 locks installed at 1.750" to work with an additional .050" lift at valve.

[pjmoreland]

Originally Posted by Rich72C10

makes me think I should have went ahead and did that, instead of staying stock. lol

I do miss the look of the original valve covers with the perimeter bolts.

[Rich72C10]

Mind reader! ...you answered one of my questions in my head - could I keep my stock valve covers. I really like the look of my stock engine bay.

At Cars & Coffee yesterday a friend said to me, you engine is way to clean - you need to drive this truck more! LOL

[ChevyRacefan]

Originally Posted by pjmoreland

I do miss the look of the original valve covers with the perimeter bolts.

They make adapters if you have to have the old look.

[Big Kev-O]

I did a similar build with Vortec heads and a Edlebrock 2116 intake. I used the Eddy 7235 intake gaskets similar to your Mr Gasket 136G. Engine ran like a champ for first couple thousand miles than started idling rough, fouling plugs and smoking out the tailpipes. Changed the gaskets thinking maybe I messed up the install, same results. After searching the web I discovered this was common issue Vortec heads when paper/felt style gaskets are used. Lots of builders recommend steel rubber impregnated gaskets found in the Felpro MS98000T kit so i gave them a try. Problem solved.

So if you start smoking check your intake gaskets.

[pjmoreland]

Originally Posted by Big Kev-O

I did a similar build with Vortec heads and a Edlebrock 2116 intake. I used the Eddy 7235 intake gaskets similar to your Mr Gasket 136G. Engine ran like a champ for first couple thousand miles than started idling rough, fouling plugs and smoking out the tailpipes. Changed the gaskets thinking maybe I messed up the install, same results. After searching the web I discovered this was common issue Vortec heads when paper/felt style gaskets are used. Lots of builders recommend steel rubber impregnated gaskets found in the Felpro MS98000T kit so i gave them a try. Problem solved.

So if you start smoking check your intake gaskets.

Thanks for the heads up

[MikeB]

Originally Posted by Big Kev-O

Engine ran like a champ for first couple thousand miles than started idling rough, fouling plugs and smoking out the tailpipes. Changed the gaskets thinking maybe I messed up the install, same results. After searching the web I discovered this was common issue Vortec heads when paper/felt style gaskets are used. Lots of builders recommend steel rubber impregnated gaskets found in the Felpro MS98000T kit so i gave them a try. Problem solved.

So if you start smoking check your intake gaskets.

I used GM 89017465 intake gaskets with a Weiand 8121 manifold. No issues at all after 3K-4K miles. I think they are the second or third version made by GM. In fact, there may even be a later version!

I've read where it's very important to follow the manifold torqueing procedures.

[57taskforce]

The Manifold torque and sequence, is essential with the vortec heads and intakes. That’s why so many of the vortec small blocks had issues from the factory with mixing coolant and oil. The factory supplied gaskets and torque procedure were wrong, resulting in the manifold being over torqued and killing the gaskets.

[bry593]

Regarding intake gaskets, the intake screw torque must be followed or the gaskets squeeze out on the ends. That 8 bolt intake design is not one of GM's crowning achievements.

A good thing about the late model valve covers is that they don't leak. The center bolts distribute the clamping force most evenly to the flange.

$45 for a temp sender with 3/8 npt threads?

[pjmoreland]

Originally Posted by bry593

Regarding intake gaskets, the intake screw torque must be followed or the gaskets squeeze out on the ends. That 8 bolt intake design is not one of GM's crowning achievements.

A good thing about the late model valve covers is that they don't leak. The center bolts distribute the clamping force most evenly to the flange.

$45 for a temp sender with 3/8 npt threads?

It is a stock AC Delco temp sender that member A1971Blazer machined down to fit the smaller port in the Vortec heads. The other option would be to mount the temp sender in the thermostat housing, but I prefer to have it in the stock location.

https://67-72chevytrucks.com/vboard/...=726700&page=3

[i82much]

Originally Posted by pjmoreland

1968-76 3998991 307, 350 1.72int 1.5exh 75cc

The intake valves on the Vortec heads are quite a bit bigger at 1.94".

Based on the Summit Racing compression ratio calculator, my compression ratio went from 8.68:1 up to 9.77:1 based on a 4.060" bore, 3.480" stroke, .025" deck clearance (measured), .041 head gasket thickness, 6cc piston dome volume (a guess), and 75cc vs. 64cc combustion chamber volume. I was hoping for 9.56:1 for the compression ratio, which would have been the case if the cylinders hadn't been bored out, but it seems to run well on 91 octane. I can't hear any detonation, so hopefully I'll be alright. The carb is running a bit rich at the moment, and I have the timing set kind of low at 8 degrees. I will be playing around with settings over the next few weeks.

thanks. i have heard the vortec heads are a nice step up even over the older high performance heads, so i'm sure the improvement over the 307 heads is substantial!