Engine Wizards...advice needed!
Thread Starter
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Joined: Sep 2011
Posts: 57
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From: Midlothian Texas
Engine Wizards...advice needed!
Ready to upgrade the existing top end, and have been thoroughly reading the forums.
My Possible top end changes on stock 1981 bottom end:
*Vortec heads - mildly ported/stock valves/milled to 60cc. Already have ready for the machine shop.
*1.5 or 1.6 stamped roller rockers
*Lunati 60103 or xe268 kit -k12-242-2
*Edelbrock Vortec air gap intake
*Not sure on Head Gasket thickness
*Would like to stay on 92-93 octane if possible.
I know there are some mods to the heads to get them to work with the cam. I will probably let the machine shop lower the guides during the valve job.
I plan to stay with stock converter until my 200r4 swap mid next year.
Any advice on chosen components, or things to watch out for, would really be appreciated.
Thanks,
Jeff
My Possible top end changes on stock 1981 bottom end:
*Vortec heads - mildly ported/stock valves/milled to 60cc. Already have ready for the machine shop.
*1.5 or 1.6 stamped roller rockers
*Lunati 60103 or xe268 kit -k12-242-2
*Edelbrock Vortec air gap intake
*Not sure on Head Gasket thickness
*Would like to stay on 92-93 octane if possible.
I know there are some mods to the heads to get them to work with the cam. I will probably let the machine shop lower the guides during the valve job.
I plan to stay with stock converter until my 200r4 swap mid next year.
Any advice on chosen components, or things to watch out for, would really be appreciated.
Thanks,
Jeff
Drifting
Joined: Dec 2004
Posts: 1,714
Likes: 42
From: Austin Texas
Jeff, I just installed the xe268h and I love it. However, I will tell you that it really pushed against the stock converter on my th400. (I plan on the 2004r upgrade as well down the line)
I bit the bullet and put a 2800 converter in and it was great. But my rear gears were 3.08 and it was still a dog. Changed to 3.55 and the cam works real well and a 2004r will be better.
The cam sounds great to me too with a noticeable lopey idle.
What I am saying is that you will love the proposed changes to a stock set up. However, not matching the converter and rear end may keep you from realizing the power. What are your rear gears?
I bit the bullet and put a 2800 converter in and it was great. But my rear gears were 3.08 and it was still a dog. Changed to 3.55 and the cam works real well and a 2004r will be better.
The cam sounds great to me too with a noticeable lopey idle.
What I am saying is that you will love the proposed changes to a stock set up. However, not matching the converter and rear end may keep you from realizing the power. What are your rear gears?
Last edited by johnt365; Oct 27, 2011 at 04:39 PM.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Vortecs are a great pick - make sure the porter knows what they're doing - it doesn't take much on the Vortecs and 90% of the work should be on the exhaust port. Why are you milling them to a 60cc chamber? Honestly...I would install the Vortecs untouched. I don't see the value in higher lift with the Vortecs given the flow numbers - but you're better off buying upgraded Vortecs from Scoggins-Dickey or another source vs. paying someone to do it.
Might as well do 1.6 rockers and have the shop drill out the pushrod holes as required. Keep in mind the Vortecs require self-aligning rockers. This will affect your cam choice for sure.
You'll know the required head gasket thickness once the heads are off and you have the deck height.
Premium unleaded is good to about 10.2 with ideal quench.
Might as well do 1.6 rockers and have the shop drill out the pushrod holes as required. Keep in mind the Vortecs require self-aligning rockers. This will affect your cam choice for sure.
You'll know the required head gasket thickness once the heads are off and you have the deck height.
Premium unleaded is good to about 10.2 with ideal quench.
Thread Starter
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Joined: Sep 2011
Posts: 57
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From: Midlothian Texas
Thanks for the comments!!
John: I was expecting exactly what you experienced with the setup.
Billa: 60cc should get me 9.5 -10.2CR depending on gasket and deck height. I think. As you mentioned, I won't know until I pull the old heads.
I paid $100 for the heads, prior to knowing much about Scoggins-Dickey.
I am only cleaning up the intake ports. Removing the ski jump on the exhaust and clean up.
I'm expecting $220 for Valve job, $30 for Junk yard valave covers and stock rockers. That is until I get some 1.6 rockers.
John: I was expecting exactly what you experienced with the setup.
Billa: 60cc should get me 9.5 -10.2CR depending on gasket and deck height. I think. As you mentioned, I won't know until I pull the old heads.
I paid $100 for the heads, prior to knowing much about Scoggins-Dickey.
I am only cleaning up the intake ports. Removing the ski jump on the exhaust and clean up.
I'm expecting $220 for Valve job, $30 for Junk yard valave covers and stock rockers. That is until I get some 1.6 rockers.
Le Mans Master
Joined: May 2002
Posts: 5,084
Likes: 786
From: Lebanon Township New Jersey
I have a Vortec type RPM Air Gap manifold under the stock hood on my 77. It fits with a drop base air cleaner, not with a stock air cleaner. One thing to keep in mind is that the RPM Air Gap for Vortec heads is a square bore carb type only. I'm using a 3/4 inch thick adapter on mine to work with a Qjet carb. Even that fits under the hood, but it is very close. I can't use a wing nut on the air cleaner because it hits the hood.
Thread Starter
Advanced
Joined: Sep 2011
Posts: 57
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From: Midlothian Texas
Thanks Again!!
I'm pretty confident a RPM air gap will fit under the hood. Current is stock GMCFM with 3/4" squarbore adapter + Edelbrock 1406 + drop base air cleaner. Still quite a bit of room to the bottom of the hood.
I'm pretty confident a RPM air gap will fit under the hood. Current is stock GMCFM with 3/4" squarbore adapter + Edelbrock 1406 + drop base air cleaner. Still quite a bit of room to the bottom of the hood.
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Racer
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From: Bowling Green Kentucky
Le Mans Master
Joined: Mar 2008
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From: Oxford MA-----You just lost the game!!!!
I have a Vortec type RPM Air Gap manifold under the stock hood on my 77. It fits with a drop base air cleaner, not with a stock air cleaner. One thing to keep in mind is that the RPM Air Gap for Vortec heads is a square bore carb type only. I'm using a 3/4 inch thick adapter on mine to work with a Qjet carb. Even that fits under the hood, but it is very close. I can't use a wing nut on the air cleaner because it hits the hood.
You can pretty much stick whatever you want, within reason, under an L88 style hood, just something to think about.
Scott
Anything less than a 3" element has real impact on power output.
Le Mans Master
Joined: Dec 2006
Posts: 5,557
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From: Oquirrh Mountains
St. Jude Donor '09
Factory Vortec heads are only good for 0.450" lift so check to see you have adequate clearance. To gain more room for additional lift you need to add +.050" keepers and/or replace the stock positive seals with umbrella seals and/or machine the guides down for additional clearance.