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Discussion Starter #1 (Edited)
86 cam and head advice

Guys, Looking for some advise on what is known to work in these circumstances. Decided to do some clean up work on a dirty engine/bay/front suspension. One thing leads to another ... and the engine is on the stand. Has been trouble free for 55K miles. I'm the original owner. Thought I'd install it with a bit more power. It's and '86L '128 heads. I'm keeping the TPI and don't want to go through the trouble/expense to convert to or retro roller, so staying flat tappet. I'm installing the Edelbrock High-Flo base that I'll siamese/gasket match, SLP High Flow Runners, stock plenum that I'll port, 24# FIC Bosch III injectors (I can self tune), stock exhaust manifolds that I'll grind out AIR extensions and a 2.5" true dual SS exhaust.

What I'm looking for is a head/cam that is known to work with anything close to the above. Unless everyone with flat tappet blocks has gone roller! Or is there any chance I can get a reasonable power gain and stay with the '128 heads? I want to keep a decent idle and vacuum so I'm looking for something with good street manners and the TPI even with the High Flow base/Runners and bit of porting is going to limit my top to 52-55 hundred if I'm lucky, 5K is more likely I would think.

Let me know what y'all think, even if I'm dreamin'.:laughing:

Many thanks.
 

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Discussion Starter #3

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I'm running the same base/runners and ported plenum.
Went to 3.875 crank and 10.6 compression using Canfield race rite 210s. I would If you stay to stock compression and 350CC I would recommend either the Race rite 180s or the AFRs Grumpy mentioned.

I used 32PPH injectors and the 58MM TB. 58 MM is too big even for my cubes so you should be able to stick with stock until you change out the bottom end.

The 32 PPH definitely needs to be custom tuned.


I'm using the Hydraulic roller so can't offer much on the cam shaft..
 

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DC Crew
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http://www.airflowresearch.com/index.php?cPath=24_25

heads


http://www.summitracing.com/parts/CRN-114132/
cam

make a real nice combo but Ill point out that swapping to a 3.73:1 rear gear makes it even more effective
:agree:

I'm running that cam and similar heads - strong combo, still maintained great mileage, and a nice idle. :devil:

If you haven't bought runners yet, shop the forum classifieds (like thirdgen) there are some good deals to be had. I got a spanking deal on some TPiS runners from there.
 

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DC Crew
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Hey Ray, good info above, I just wanted to say I'm kinda shocked to find your car is stock. With the knowledge you bring to this place I figured you have been down this road many times. Good luck with the mods and enjoy the new beast you are creating.

One thing leads to another ... and the engine is on the stand.
Seems you got a case of the whileimatits. Sorry there is no cure.:laughing:
 

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Discussion Starter #8
Thanks for all the input, guys. Big help.
If you haven't bought runners yet, shop the forum classifieds (like thirdgen) there are some good deals to be had. I got a spanking deal on some TPiS runners from there.
Already have the runners, Dan.

Hey Ray, good info above, I just wanted to say I'm kinda shocked to find your car is stock. With the knowledge you bring to this place I figured you have been down this road many times. Good luck with the mods and enjoy the new beast you are creating.



Seems you got a case of the whileimatits. Sorry there is no cure.:laughing:
Steve, I've been fooling with the C4s since '85 mainly helping people with the electronic stuff that was a mystery to many gearheads back then. I've not done much in the way of engine work since I rebuilt my '68 ragtop back in '80 when I was in the Navy. When I bought the '86 new, I left it completely stock except for the SS True Duals I put on when I brought it out to England back in '90.

You're so right about the whileimatits. Just as well I enjoy tinkering with it as much or more than driving it!

Thanks again for all the help. I'm sure I'll be back with a load of questions.
 

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Discussion Starter #9
Told you I'd be back! For the AFR heads that Grumpy recommended, the smallest chamber size is 65cc. Should I be concerned about the loss of compression from my 58cc stockers? Can I use my stock center bolt valve covers with these, they seem to be compatible with both?

On the rockers Grumpy mentioned, will they fit under the stock valve covers? I'd rather not hack up the originals (drip tabs/baffles grinding/cutting). If not which valve covers will fit without modification to accessories?
 

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Told you I'd be back! For the AFR heads that Grumpy recommended, the smallest chamber size is 65cc. Should I be concerned about the loss of compression from my 58cc stockers? Can I use my stock center bolt valve covers with these, they seem to be compatible with both?

On the rockers Grumpy mentioned, will they fit under the stock valve covers? I'd rather not hack up the originals (drip tabs/baffles grinding/cutting). If not which valve covers will fit without modification to accessories?
the slight loss in compression is more than off set by much increased air flow rates, with the new heads and as a bonus the slight reduction in compression reduces detonation OR if used with a 383 stroker keeps the cpr nearer the original levels
with flat top pistons, but naturally you need to calculate the true cpr with and rotating assembly ,or head gasket or block deck height changes
l98 heads flow about 199/164cfm at .400 lift
AFR heads flow about 240/178 cfm at .400 lift
thats potentially easily 70 hp or more gained when combined with the new cam
remember to order the L98 plug angle heads
"SBC 180cc Street Heads, L98 angle plug w/heat riser, 65cc chambers, complete w/parts
[0918*]"

I don,t know if the rockers clear as Ive always strongly preferred tall valve covers,and/or never gave removing drip tabs a second thought,when using those erson rockers and yes IM well aware the darn windshield washer motor is in the way preventing use of tall valve covers until its modified or replaced on many c4 corvettes, or the valve covers are modified to clear
 

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Discussion Starter #11
the slight loss in compression is more than off set by much increased air flow rates, with the new heads and as a bonus the slight reduction in compression reduces detonation
That's what I was hoping to hear.:thumbsup:

OR if used with a 383 stroker keeps the cpr nearer the original levels with flat top pistons, but naturally you need to calculate the true cpr with and rotating assembly ,or head gasket or block deck height changes
No changes to the bottom here.


l98 heads flow about 199/164cfm at .400 lift AFR heads flow about 240/178 cfm at .400 lift thats potentially easily 70 hp or more gained when combined with the new cam remember to order the L98 plug angle heads
"SBC 180cc Street Heads, L98 angle plug w/heat riser, 65cc chambers, complete w/parts
[0918*]"
Yep, those were the ones I expected I'd need. Are the plugs angled at the same angle as my stockers, so I'll have no trouble changing plugs with the stock exhaust manifolds?

I don,t know if the rockers clear as Ive always strongly preferred tall valve covers,and/or never gave removing drip tabs a second thought,when using those erson rockers and yes IM well aware the darn windshield washer motor is in the way preventing use of tall valve covers until its modified or replaced on many c4 corvettes, or the valve covers are modified to clear
I guess I'll just have to wait and see. In the meantime maybe someone will let me know of a valve cover that will clear the wiper motor and still fit over these rockers. Otherwise I'll have to hack up the stockers. Can you verify that these AFRs are dual perimeter/center bolt, right?

Grumpy, I really appreciate the time you've taken to give me these pointers. I plan to follow your recipe and let you all know how I make out.
 

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I guess I'll just have to wait and see. In the meantime maybe someone will let me know of a valve cover that will clear the wiper motor and still fit over these rockers. Otherwise I'll have to hack up the stockers. Can you verify that these AFRs are dual perimeter/center bolt, right?
AFR's picture and Summit's website show the AFR-0916 as drilled for both style covers.

I've read that narrow body rockers will fit the center bolt covers (but cost a lot more), fortunately grinding down the drippers is an easy option.

http://www.corvettemagazine.com/2000/march/l98buildup/l98p7.asp
 

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Discussion Starter #13
AFR's picture and Summit's website show the AFR-0916 as drilled for both style covers.

I've read that narrow body rockers will fit the center bolt covers (but cost a lot more), fortunately grinding down the drippers is an easy option.

http://www.corvettemagazine.com/2000/march/l98buildup/l98p7.asp
Dan, Thanks for the info from Summit on the heads. I'm sure the 0918 will be the same.

I'd go the narrow body rocker route, if I was sure they'd fit under uncut stock covers, but I'd like to stay with Grumpy's formula. I just hope that PBM will ship USPS to my Military PO Box.

Please chime in if anybody has discovered a valve cover that will fit over 1.6 Full Roller Rockers and clear Wiper Motor/Compressor/Alternator.

Thanks again to all. I'd better get ordering!
 

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DC Crew
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I'd like to stay with Grumpy's formula.
Definitely! As he says he's done all the testing, so benefit from his knowledge.

Keep us posted, there's been several members who have recently been doing TPI builds. Definitely some big gains to be made without much effort or cost.

I'm sure the 0918 will be the same.
Yes, sorry I typed the wrong PN after comparing the 0916 & 0918 (just plug angle differences).
 

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Hey Ray if you want to not hurt your stock valve covers and want the look I'll send you my stockers for the cost to ship them. You can cut them up and make them fit and keep your originals.
 

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Hey Ray if you want to not hurt your stock valve covers and want the look I'll send you my stockers for the cost to ship them. You can cut them up and make them fit and keep your originals.
Steve, That would be fantastic! I just want to keep my originals if I ever go back to stock. I'd imagine that the drip tabs help to oil the original stamped steel rockers so I'd like to keep them for when/if the original heads go back on. I'll have to give you something in addition to shipping though. I'd need them to go USPS to 09469. Can I PayPal you or would you rather a check or what?

Thanks again, you're a true gent.:cheers:
 

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Discussion Starter #17
Ordered the 0918 heads and 114132 cam from Summit. 9/23 for the cam and 10/14 for the heads so I've got some time to get the rest of the whileimatits done.
 

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Discussion Starter #20
I've not heard anything back from PBM yet on whether they will ship USPS to my Military PO Box. Any thoughts on if the Crane 10759 would go well with this head/cam combo? Summit has them and they do ship to APO/FPO.
 
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