Cam and roller rockers
Thread Starter
Heel & Toe
Joined: Dec 2017
Posts: 19
Likes: 0
From: Canada
Cam and roller rockers
Hey guys once again!!
I have a 77 l48 with a 600 quick fuel, intake, dual exhaust with headers and a 2500 stall I’m on a budget and was looking for just a little more pep nothing crazy. I was planning on getting a comp cam xtream energy cam and lifter kit with roller rockers (parts below) how do you think will affect the car and has anyone done anything similar if so let me know! All feed back is highly appreciated thank you!!
I have a 77 l48 with a 600 quick fuel, intake, dual exhaust with headers and a 2500 stall I’m on a budget and was looking for just a little more pep nothing crazy. I was planning on getting a comp cam xtream energy cam and lifter kit with roller rockers (parts below) how do you think will affect the car and has anyone done anything similar if so let me know! All feed back is highly appreciated thank you!!
Burning Brakes
Joined: Sep 2017
Posts: 1,219
Likes: 364
From: Tolland CT
That is a mild cam choice but should work fine as long as the rest of your valvetrain is set up for it.
For a mostly stock motor I am sure those rocker arms will be ok but that is one of the areas where I usually spend a few more bucks to ensure that you are getting quality. Scorpion makes a decent product at a decent price.
For a mostly stock motor I am sure those rocker arms will be ok but that is one of the areas where I usually spend a few more bucks to ensure that you are getting quality. Scorpion makes a decent product at a decent price.
Last edited by PainfullySlow; Dec 22, 2017 at 06:16 PM.
Thread Starter
Heel & Toe
Joined: Dec 2017
Posts: 19
Likes: 0
From: Canada
My engine is completely stock other than the modifications listed above. If that is a mild can do you think I should bump it up a notch maybe to this guy?
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
Scorpion is an excellent product all right but hardly a "few bucks more". A quick search on Summit shows three times the cost compared to those roller tips ($98) you want, at $280. Not money well spent. Could be used instead to purchase a better ignition system to go with your set-up.
Melting Slicks
Joined: Dec 2009
Posts: 3,195
Likes: 632
From: Thunder Bay
Any HEI including (probably) the one you already have, with the advance curve optimized for your application. Do a search on this forum to find out what the curve should look like and how to achieve it. It can be done with a stock HEI, although its a lot easier if you spend $500 on an aftermarket distributor.
Drifting
Joined: Aug 2015
Posts: 1,939
Likes: 476
From: NSW, Australia
C3 of Year Finalist (track prepared) 2019
My engine is completely stock other than the modifications listed above. If that is a mild can do you think I should bump it up a notch maybe to this guy?
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Race Director
Joined: Mar 2016
Posts: 14,154
Likes: 7,941
From: Napa Valley California
Keep in mind that full roller rockers may not fit under your stock valve covers so you may need to add the additional cost to your upgrade. Crower makes a nice set of stainless full rockers that may fit under the stock covers, but they are pricey.
Burning Brakes
Joined: Oct 2012
Posts: 1,152
Likes: 252
The issue with adding a cam to an otherwise stock L48 (and written in the thread about 5 below this one) is that with the stock heads and pistons the CR is really low. Select a cam that will keep the dynamic compression as high as possible otherwise you might end up the moving the peak rpm higher up in the band without much of a net HP increase.
If it were me I would increase the CR also. The cheapest and easiest way to do that is with used 58cc L98 heads.
Last edited by Dynra Rockets; Dec 23, 2017 at 08:59 AM.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
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From: Cool Northern Michigan
Had a 1976 L-82, 4-sp
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From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Burning Brakes
Joined: Sep 2017
Posts: 1,219
Likes: 364
From: Tolland CT
Budget can quickly get out of hand. As was mentioned, if you are doing a cam and roller rockers it is quite likely that you will need new springs and push rods. If you are doing that you may as well do a thinner head gasket. Cost quickly spirals from there.
My advice would be to keep the HEI which has served many engines with much higher HP well. Do the head gasket and your cam/rockers/springs and call it a day.
My advice would be to keep the HEI which has served many engines with much higher HP well. Do the head gasket and your cam/rockers/springs and call it a day.
Pro
Joined: Dec 2003
Posts: 676
Likes: 36
From: Usa
Hey guys once again!!
I have a 77 l48 with a 600 quick fuel, intake, dual exhaust with headers and a 2500 stall I’m on a budget and was looking for just a little more pep nothing crazy. I was planning on getting a comp cam xtream energy cam and lifter kit with roller rockers (parts below) how do you think will affect the car and has anyone done anything similar if so let me know! All feed back is highly appreciated thank you!!
I have a 77 l48 with a 600 quick fuel, intake, dual exhaust with headers and a 2500 stall I’m on a budget and was looking for just a little more pep nothing crazy. I was planning on getting a comp cam xtream energy cam and lifter kit with roller rockers (parts below) how do you think will affect the car and has anyone done anything similar if so let me know! All feed back is highly appreciated thank you!!
My 73 currently has a ZZ4 crate engine and I would say my 77 with the above mentioned mods performed just as well as the ZZ4.
Thread Starter
Heel & Toe
Joined: Dec 2017
Posts: 19
Likes: 0
From: Canada
I have high rise valve covers so rocker clearance is not an issue. I’ll most likely keep the stock HEI ignition system as many have said its more than sufficient. Sounds like it’s a good idea to go for the kit with springs, would a timing chain be necessary as well? Does anyone know the stock head gasket thickness? I think I’ll order a .015 shim gasket to bump up the CR just a little. Does anyone recommend a certain head gasket? Can I reuse the stock pushrods that’s what I was hoping to do. What do you guys think about this cam kit?
http://www.jegs.com/i/COMP-Cams/249/K12-242-2/10002/-1
http://www.jegs.com/i/COMP-Cams/249/K12-242-2/10002/-1
Race Director
Joined: Mar 2016
Posts: 14,154
Likes: 7,941
From: Napa Valley California
There are tools you can purchase to determine your needed pushrod length. Buy one and determine if you need longer pushrods. If you are beefing up your cam and springs, I would suggest purchasing better than stock pushrods. Follow the manufacturers suggestions by calling their customer service and talking to their techs.
The HEI you have will work great for your application.
Make sure your new cam and distributor gears and compatible.
Again ask the manufacturers techs.
You have to remove the timing cover, chain and cam gear to swap out your cam, so replace the chain and both gears while inside. Upgrading to a good set will keep things together for years without worry.
Increasing the cr by replacing the head gaskets with thinner ones is a great idea.
If you pull the heads you might as well get them checked out before you put them back on.
The HEI you have will work great for your application.
Make sure your new cam and distributor gears and compatible.
Again ask the manufacturers techs.
You have to remove the timing cover, chain and cam gear to swap out your cam, so replace the chain and both gears while inside. Upgrading to a good set will keep things together for years without worry.
Increasing the cr by replacing the head gaskets with thinner ones is a great idea.
If you pull the heads you might as well get them checked out before you put them back on.
Last edited by OldCarBum; Dec 23, 2017 at 12:21 PM.
Racer
Joined: Nov 2017
Posts: 289
Likes: 32
I have high rise valve covers so rocker clearance is not an issue. I’ll most likely keep the stock HEI ignition system as many have said its more than sufficient. Sounds like it’s a good idea to go for the kit with springs, would a timing chain be necessary as well? Does anyone know the stock head gasket thickness? I think I’ll order a .015 shim gasket to bump up the CR just a little. Does anyone recommend a certain head gasket? Can I reuse the stock pushrods that’s what I was hoping to do. What do you guys think about this cam kit?
http://www.jegs.com/i/COMP-Cams/249/K12-242-2/10002/-1
http://www.jegs.com/i/COMP-Cams/249/K12-242-2/10002/-1
That's a great street cam but it would do its best with a 10 to 1 compression ratio and lower rear gears like 3.55's.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,170
From: Hermosa
The stock shim head gasket in the 77 is .017” thick. You Will net no gain by going with a .015 felpro shim gasket.
The stock heads on the 77 are complete junk IMO, so you gains may not be what you are expecting.
The stock pistons have a 17 cc dish volume for any of your CR computations.
My 77 is pushing 440hp with 10.6:1 CR and the stock HEI , no issues, so you can save some money there.
The cams you are looking at have too much duration for what you have in a stock motor, it’ll make for a very lazy bottom end and then little gain up top due to the head flow limitations.
Something in a 256 to maybe 262 advertised duration Is more realistic.
The stock heads on the 77 are complete junk IMO, so you gains may not be what you are expecting.
The stock pistons have a 17 cc dish volume for any of your CR computations.
My 77 is pushing 440hp with 10.6:1 CR and the stock HEI , no issues, so you can save some money there.
The cams you are looking at have too much duration for what you have in a stock motor, it’ll make for a very lazy bottom end and then little gain up top due to the head flow limitations.
Something in a 256 to maybe 262 advertised duration Is more realistic.
Last edited by REELAV8R; Dec 23, 2017 at 01:07 PM.
Thread Starter
Heel & Toe
Joined: Dec 2017
Posts: 19
Likes: 0
From: Canada
So can those modifications be made without taking the heads off if new gasket aren’t going to get me anywhere.
Also a cam recommendation would be highly appreciated I can’t find anything with decent lift and a duration like that.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,170
From: Hermosa
http://www.lunatipower.com/Product.aspx?id=1982&gid=287
This cam might suit your CR and application. The real CR for the L-48 is about 7.7:1. the 76cc heads run up to 80 or so cc's.
Even this cam would be a lot happier at 8.5 CR vs what the L-48 offers.
The next step down is this cam in the voodoo line and may actually be the best choice.
http://www.lunatipower.com/Product.aspx?id=1981&gid=287
For comparison the stock specs for the L-48 are:
@ .050
Intake - .390 lift / 195 duration
Exhaust - .410 lift / 202 duration
112 LCA
You loose plenty of CR and DCR with these heads and piston combo.
This limits the cam choices quite a bit due to low cylinder pressure.
You can use this calculator to compute your DCR.
https://www.jeepstrokers.com/forum/calculator/
your deck clearance is .025 if the engine is still stock.
This cam might suit your CR and application. The real CR for the L-48 is about 7.7:1. the 76cc heads run up to 80 or so cc's.
Even this cam would be a lot happier at 8.5 CR vs what the L-48 offers.
The next step down is this cam in the voodoo line and may actually be the best choice.
http://www.lunatipower.com/Product.aspx?id=1981&gid=287
For comparison the stock specs for the L-48 are:
@ .050
Intake - .390 lift / 195 duration
Exhaust - .410 lift / 202 duration
112 LCA
You loose plenty of CR and DCR with these heads and piston combo.
This limits the cam choices quite a bit due to low cylinder pressure.
You can use this calculator to compute your DCR.
https://www.jeepstrokers.com/forum/calculator/
your deck clearance is .025 if the engine is still stock.
Last edited by REELAV8R; Dec 23, 2017 at 02:24 PM.