HotRod 2 Posted December 19, 2020 Hey. Dose anyone know, if I put a comp cams big mutha thumpr cam in my 351c 2v with standard iron aussie heads into my f100 with power brakes. Will I need a vacuum pump and reseviour to keep my pressure up. Truck also has e4od trans and vacuum holley if matters??? Share this post Link to post Share on other sites
bear351c 10,260 Posted December 19, 2020 I'm running a Comp XE274H in the 351, with no real issues. Standard brakes, rear disc conversion, new master cyl, ( all overhauled.) Doesn't exactly stop on a dime, but it's a 2 tonne 40 year old Falcon. 2 Outback Jack and Free.51 reacted to this Share this post Link to post Share on other sites
gerg 10,871 Posted December 19, 2020 Vac might be a bit average at idle, but a couple of stabs on the throttle and the over-run will likely charge the vac booster enough for assistance. These cams perform best in the midrange, so that's where the best vacuum will occur.Sent from my CPH1920 using Tapatalk Share this post Link to post Share on other sites
HotRod 2 Posted December 19, 2020 Yeah cool. That was the alternative cam if was going to be a mission. Already got a shiny us booster that was trash. Didn't want to cause another headache with the brakes. Do you no if I would need adjustable roller rockers for the thumpr? Cheers bearing and Greg. Share this post Link to post Share on other sites
gerg 10,871 Posted December 19, 2020 Yeah cool. That was the alternative cam if was going to be a mission. Already got a shiny us booster that was trash. Didn't want to cause another headache with the brakes. Do you no if I would need adjustable roller rockers for the thumpr? Cheers bearing and Greg. I don't know the exact specs of your cam but I assume it's around the 0.550" lift am I right? I think hydraulic lifters and bolt-on rollers will be fine. Stock steel rockers don't like much over 0.500".These cams are designed to have a racy-sounding lope about them without needing all the race hardware that goes with race cams. Though I would at a minimum, upgrade to stiffer springs that are over 100lbs on the seat. Mine spec'd in at 115.One accidental trait of these cams is that they have a pretty good midrange, due to having a short duration but lots of overlap from a narrow LSA, making them pretty good towing cams. Sent from my CPH1920 using Tapatalk Share this post Link to post Share on other sites
HotRod 2 Posted December 19, 2020 Yeah its 0.500 lift. Cool i have the edelbrock performer rpm with I believe should also help the old girl go pretty good too. But only have a holley 600cfm carby. Thinking about getting a 750cfm. Only plan on chunking around town in it.. Share this post Link to post Share on other sites
HotRod 2 Posted December 19, 2020 Ment over .500 lift... Its the 32-602-5 comp cams.. think its 109 with .534 lift not sure of the separation.. Share this post Link to post Share on other sites
gerg 10,871 Posted December 19, 2020 Yeah its 0.500 lift. Cool i have the edelbrock performer rpm with I believe should also help the old girl go pretty good too. But only have a holley 600cfm carby. Thinking about getting a 750cfm. Only plan on chunking around town in it.. Performer RPM might be a bit peaky for it, I honestly reckon you'll be better off with a stock 4 barrel or a normal Performer dual plane. If you already have it, I guess it will work but with no exhaust crossover, it will run cold and need to be a bit rich. The 750 carby would be a good choice if your engine is making upwards of 300hp. Otherwise, the 600 will work nice. Just looked it up, duration at 0.050" is 242/257 and 107 lobe sep. But advertised is 294/312, meaning very gentle ramps for use with standard valve gear. Sent from my CPH1920 using Tapatalk Share this post Link to post Share on other sites
HotRod 2 Posted December 19, 2020 Hey, its 8k3. It has the small hole for dizzy and longer block, and is black haha... was supposedly out of an xd and put into my f100.. when I got it it had a terrible knock, found it was the lifters. Took a look at the cam and it was toast. So started looking for new cam and opened a can of worms with the aussie heads.. yeah I already have the rpm intake.. Share this post Link to post Share on other sites
gerg 10,871 Posted December 19, 2020 Hey, its 8k3. It has the small hole for dizzy and longer block, and is black haha... was supposedly out of an xd and put into my f100.. when I got it it had a terrible knock, found it was the lifters. Took a look at the cam and it was toast. So started looking for new cam and opened a can of worms with the aussie heads.. yeah I already have the rpm intake.. What's the issue with the Aussie heads? Are you worried about too much compression? Or was there some confusion about 2V/4V ports?Sent from my CPH1920 using Tapatalk Share this post Link to post Share on other sites
HotRod 2 Posted December 19, 2020 Yeah , the compression is one. Block at mechine shop now getting .030 over. Would have gone for flat top pistons but the oz heads have small combustion chambers. Think I need 11cc dished pistons (not 100% still) then the valve springs and valve lockers , then rocker arms if wanted the thumpr cam.. I started arse about face when I got the truck. Motor wasn't running so been chasing my tail and have caused myself other dramas like the msd I get for the cam that was in it can't take a roller cam coz of the gear. So staying with hydrolic flat tappets. Wanted to put a stroker in it but the trans i just had rebuilt and new quick2 us shift computer is not as strong as was expecting, but good enough if was just what it started as before cam was toasted... few expensive lessons in this one haha.. 1 gerg reacted to this Share this post Link to post Share on other sites
HotRod 2 Posted December 19, 2020 Had to put fuel line , pump, reg to new tank to get started then new tail shaft and cross member to try get it to move. Had trouble with the tuning on the computer for the e4od trans so took to the auto shop. Spent a shit load rebuilt box new computer b&m shifter and box still not tuned coz of the cam now.. replaced all brake booster coz vacuum problems but got from states and was crap , so had old one reco'd and replaced all braks , brake lines ect while there but still had a miss. Checked lifters and they were toasted, checked cam and the lobes were f#@k'd bad. One for the garage wall.. so rebuilding bottom end replacing oil pump and yeah.. the heads.... Share this post Link to post Share on other sites
HotRod 2 Posted December 19, 2020 Haven't got to the stock 77 f100 diff yet.. Share this post Link to post Share on other sites
gerg 10,871 Posted December 19, 2020 Yeah , the compression is one. Block at mechine shop now getting .030 over. Would have gone for flat top pistons but the oz heads have small combustion chambers. Think I need 11cc dished pistons (not 100% still) then the valve springs and valve lockers , then rocker arms if wanted the thumpr cam.. I started arse about face when I got the truck. Motor wasn't running so been chasing my tail and have caused myself other dramas like the msd I get for the cam that was in it can't take a roller cam coz of the gear. So staying with hydrolic flat tappets. Wanted to put a stroker in it but the trans i just had rebuilt and new quick2 us shift computer is not as strong as was expecting, but good enough if was just what it started as before cam was toasted... few expensive lessons in this one haha.. Yeah I learnt that lesson hard when I bought my "reco" 302C which hadn't run yet. My workmate convinced me to strip it anyway and lucky I listened. 4 out of 8 rods and pistons were installed backwards (would have destroyed the crank in minutes). Engine was filthy inside like they'd built it in a garden shed. Oh and one piston was pressed onto the rod backwards. The dizzy was rubbish, the oil pump was a cheapo that used to get a stuck relief when cold (blowing oil filters off). All I can say is... Build it once, build it right. Had to put fuel line , pump, reg to new tank to get started then new tail shaft and cross member to try get it to move. Had trouble with the tuning on the computer for the e4od trans so took to the auto shop. Spent a shit load rebuilt box new computer b&m shifter and box still not tuned coz of the cam now.. replaced all brake booster coz vacuum problems but got from states and was crap , so had old one reco'd and replaced all braks , brake lines ect while there but still had a miss. Checked lifters and they were toasted, checked cam and the lobes were f#@k'd bad. One for the garage wall.. so rebuilding bottom end replacing oil pump and yeah.. the heads....I would guarantee almost with 100% certainty that the wrong oil was put in. Modern oils are not designed to be run in flat-tappet engines. Older oils contained good amounts of ZDDP("zinc") additive to provide the required coating on high pressure parts like cam lobes and lifters. They started reducing it a lot when it was found that this additive destroys catalytic converters.Trust me, I killed 2 cams in 70,000km. I don't take any chances now.Your only options are: Find a street oil with around 1500ppm of zinc, but they are getting hard to find. Penrite makes some.Use a race oil like Fuchs Titan, but these need changing at half the km a normal oil does due to much lower detergent content (this causes sludging otherwise).Use a conventional mineral oil but use a Zinc additive like Rislone or any break in lube that contains zinc. This is what I do but even at that, my valves are still noisy. I put it down to a couple of loose hydraulic plungers as I have already looked at the faces and they look perfect. Some clevos are just noisy.Sent from my CPH1920 using Tapatalk 1 bear351c reacted to this Share this post Link to post Share on other sites
bear351c 10,260 Posted December 21, 2020 Agreed. If you haven't machined the block, buy your pistons first. Most engine builders will ask for them, as they measure them first to decide which is smallest/largest and adjust the tolerance on the boring machine. Definitely use a Zinc additive or Zinc oil. If you have the Eddy Performer, run with it, it will work fine for a daily. If you buy flat tops, you might have to run her on 98 PULP, which can be pricey. I ground a relief chamfer on my 302 heads, and it runs fine, on 95 but doesn't really enjoy 91 unleaded (pings). As it's a weekend cruiser, I only run her on 98. "Black" block is a later XD-XE Clevo, and has a different size dizzy shaft, earlier "Blue" block dizzy's wont fit. 1 gerg reacted to this Share this post Link to post Share on other sites
HotRod 2 Posted December 21, 2020 Sweet. Going to order the thumpr k-kit from summit and get back onto the pistons.. thinking the srp302432 ones.. 1 bear351c reacted to this Share this post Link to post Share on other sites