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| FREQUENTLY ASKED QUESTIONS |  |
1. What is your turnaround time?
Head rebuilding and porting is generally in the 4-6 week range, depending on season and complexity of port work. Winter is the busiest time for us and late summer is a little slower. Ported intake and exhaust manifolds usually follow the same turnaround time as heads.
2. Why should I sent my heads to GHP when my local engine builder says he can rebuild my heads?
That's simple, Quality work, well maintained quality machines and personal pride to do the job right. Click on this link to see multiple errors on a set of heads that recently passed thru GHP's shop.
3. Do you do 3 angle valve jobs?
Yes, and more. Most factory heads came with 3 angles, and it's necessary to have 3 angles to do a proper valve job. Depending on the casting and its application, the valve seats are cut with 3, 4, 5 or even 6 angles on our Sunnen VGS-20 head machining center. Radius cutters that blend a radius into the valve seat are also used.
4. I am using MLS head gaskets, the manufacturer recommends a very smooth head surface finish. Can you do that?
Yes, GHP's state of the art CBN/PCD surfacer is capable of producing very straight and smooth surfaces for applications such as yours.
5. Why do you ask for so many details about my car on your car-info-form?
We build heads or manifolds to work with YOUR car and its intended function. Installing race heads that flow huge quantities of air at high valve lifts will not work on a mild cammed heavy street car. Heavy cars/light cars, low gear ratios/high gear ratios, big cams/small cams, all have different requirements for optimal performance in THEIR application.
6. Do ported heads, intake or exhaust manifolds require a change in carburetor jetting?
Generally, yes. A larger jet size is usually needed for best performance. Its best to start slightly rich and lean the air/fuel mixture till best performance is obtained.
7. Can you flow test my heads and evaluate them?
Yes. We will flow one intake port and one exhaust port on our computerized Superflow 600 flow bench for a nominal fee, examine your heads and give you a call with our recommendations.
8. I have original Buick 455 Stage1 heads, can I have them ported?
Sure, we can port them. But for several reason's, I would strongly recommend that we start with a standard valve size head (non-Stage1) and convert them to Stage1 specs in the rebuilding process.
- Previous valve seat grinding on your Stage1 heads removed metal and lowered the valve seats further into the chamber, making it difficult to obtain the correct valve installed height.
- You can sell the original Stage1 heads for alot more money to a collector than what the conversion process costs.
- Sunken valve seats are not the best situation for superior air flow. Converting standard heads to Stage1 specs (which includes machining the new larger valve seats at the correct original height) allow proper valve stem installed height, which is critical in a non-adjustable valve train.
9. What is the casting number for a Buick 455 Stage1 head?
Stage1 heads carry the same casting number as a standard 455 head. In fact they are the same head, except Buick installed larger valves and unshrouded the combustion chambers around the larger valves. Click here for Buick casting numbers.
10. Do Buick GS's have better heads, intake or exhaust manifolds than full size Buicks?
No, all components are identical and interchangeable with in a given year. Exception being the Stage1 heads which received larger valves in the same casting head.
11. Can Buick 1967-69 400 & 430 heads be converted to Stage1 Specifications?
Yes, Stage 1 valves can be installed and the combustion chambers unshrouded to Stage1 spec's (455 bore). In fact, any Buick 400/430/455 small valve head can be converted to Stage1 specifications.
12. Do you recommend using the 430 'big port' heads?
Some castings of the early 430 heads did have a larger intake port. These heads can work out well when combined with GHP's level 3 or lower porting. Be aware that these early heads are prone to cracking, so finding good cores may be difficult.
13. How do you stop the exhaust crossover passages from heating up the intake manifold?
There are several ways to do this. Some applications can be blocked with a simple cup plug or blocked intake gasket, but the best way is to fill the passages with molten aluminum so that the hole/passage is filled flush within the exhaust port. This not only keeps the intake cooler, but increases exhaust port flow by eliminating unwanted and flow robbing turbulence caused by the passage.
14. Will plugging the exhaust crossover affect proper choke function?
Yes. Blocking the hot exhaust gases from heating up the intake will not allow the factory choke to open quickly enough. Most owners disable the choke and manually maintain their idle for the first 1-2 minutes with their foot on the gas pedal. Other options are manual or electric chokes.
15. Can I run my cast iron heads (originally designed for leaded fuel) on unleaded gas?
Maybe. Cast iron exhaust seat surfaces tend to work-harden with use. Heads that were broken-in and run for many thousands of miles on leaded fuel may very well survive a long time on a diet of unleaded fuel, IF valve temperatures are kept normal, and the engine is not run too lean. Some manufacturers used more nickel in their cast iron, which makes it stronger/harder. But when a valve job is performed, new metal is exposed. Even with a high nickel content cast iron, this newly exposed metal lacks hardening and needs to be work-hardened again with a mixture of leaded race fuel or a good lead additive for several thousand miles. The best solution is to install hardened valve seat inserts. This is only needed on the exhaust seats. Click here to learn more about valve seat recession
16. Do your Shootout exhaust manifolds produce as much HP as good headers?
No. A good header will always produce more HP than an exhaust manifold. Most manifolds cannot create the scavenging effect that headers can. Shootout exhaust manifolds are for class racers required by rules to use original manifolds or car owners that want it to look original, have better performance and not have to deal with leaking, ground scraping headers.
17. What is the purpose of polishing the combustion chambers?
Polishing the combustion chamber removes and reduces possible 'hot spots' that can cause detonation. This is especially helpful for pump gas engines.
18. Can I just get my heads rebuilt to stock specs for my concours restoration?
Yes, we can control ourselves enough to not port every head that comes in here :-) and can refurbish your heads to be like new.
19. My exhaust manifolds were leaking, when I removed them I found that they were installed with no gaskets. Should I use gaskets?
Many cars originally had their exhaust manifolds installed without a gasket. Two freshly machined surfaces seal up very well and last a long, long time. But after 30+ years of service the manifold surface tends to erode and warp, causing annoying exhaust leaks. A gasket may work for a while, but the best solution is to have GHP machine the manifolds flat again. As long as the head exhaust port sealing surface is in good shape, they will seal up just fine.
20. Do you knurl valve guides?
No, GHP never knurls valve guides. Knurling is not a durable fix for worn guides. We only use solid or thin wall bronze valve guides and hone them to insure straight, properly sized valve guides with correct surface finish for oil retention.
21. I want .060" milled off my cylinder heads to reduce chamber cc's. Do I need to mill the intake manifold also for proper fit?
Milling the heads this much will affect intake manifold alignment on most engines. Usually, I try to mill the intake side of the head instead of the intake manifold. This way any intake will fit on the heads and you don't end up with an 'odd-ball' intake that will only fit on these heads.
22. I am ready to send you my heads but they have some rusted, broken off bolts in the heads. Is this OK?
Yes, that's fine. Restoring broken off bolts is not a problem for us. It's better to let us fix them (straight and correctly located) on our Bridgeport mill, than to try and drill them out yourself. Many times that only results in crooked and incorrectly located bolt holes.
23. Will you test my heads for cracks?
Yes. Every cast iron head is cleaned and magnafluxed before any further work takes place.
24. My exhaust manifold has a mounting bolt ear that is broken off. Can you repair that?
In most cases, exhaust manifolds can be repaired with building up a new ear with our spray welding process and remachining.
25. Will ported factory heads negatively affect my cars streetablity?
No. In most cases you will not notice any difference over stock heads until you floor the car and allow the heads to breath and make more power. GHP cylinder heads are customized to your application, heavy cars with mild gearing and tight convertors need smaller cross sectional area. Depending on your combination, most engines will be able to rev several hundred RPM higher
26. Can I install 1970 Buick 455 heads on my 1975 block?
This is an excellent question that alot of people are confused about. In mid-year 1972 Buick 455 engines had their (center) coolant passages changed. The blocks and heads changed from single scallop passages to double scallop passages.
- 1967 thru early 1972 head castings can be installed on late 1972 thru 1976 blocks. Just be sure NOT to use the steel shim head gasket
- Late 1972 thru 1974 heads can be installed on 1970 thru early 1972 blocks, IF the center two, round coolant passages are plugged in the head.
27. Which aftermarket Buick aluminum head is better, TA Performance or Edelbrock?
Both heads are high quality cylinder heads. The right choice depends on your application, goals and budget. Both heads have their advantages. Call us to discuss your application and help you make the right decision for you.
28. Do you keep the parts on your website in stock?
Most of the parts and components that are listed are kept in stock. Hundreds of parts are keep on hand to ensure quick delivery. We are also a dealer for TA Performance and can get you almost anything they offer.
29. Do you offer replacement parts for Rochester Quadrajet carburetors?
Yes. A full line of replacement parts (such as jets, rods, floats, needle & seat, gaskets, vacuum breaks, filters) are stocked along with rebuild kits for almost any type of automotive or marine Q-Jet carb. Repair Inlet fuel fittings are also offered. Even hard to find linkages and Throttle Shaft Bushing installation kits.
We have a new website dedicated to our Rochester Quadrajet Parts, Its called:It features a secure online webstore that can accept orders 24/7.
30. I have a Buick 455. If the block in my car has been milled, would that affect the "fit " for heads/intake that I purchase from you?
Milling the block or head deck surface will lower the heads. The intake manifold will remain/sit at its original height and will still be able to use the original style rubber end seals, but the cylinder head intake ports and bolt holes will be lower by the amount milled off. Removing .030" from the deck surface should not have a large enough effect to cause bolt hole mismatch, bad enough to cause issues when installing intake manifold bolts. On a all stock engine, having the cylinder head intake ports sit lower by .030" won't be a big deal, as in stock form the intake manifold and head ports usually have a terrible relationship in regards to port alignment. If the heads are my GHP Level-3 or Level-4 heads, I purposely raise the intake ports approximately .060" to compensate for this misalignment and also to allow for future head milling without having to re-port match the intake ports. For performance application, I prefer to leave the manifold "sitting high on the head" as long as the head & intake ports line up. After .030" off the deck surface, you usually have bolt hole onterference. In a performance application I prefer to oblong the upper portion of the intake manifold bolt holes to allow proper intake bolt installation. If the intake side of the head or flange on the intake manifold are machined to maintain original port/bolt hole alignment, it will be necessary to either mill end of intake to allow original type rubber end seal or use silicone to seal the end rail.
31. Do you offer replacement parts for Rochester 2G 2 barrel carburetors?
Yes. A full line of replacement parts (such as jets, floats, needle & seat, gaskets, vacuum breaks, filters) are stocked along with rebuild kits for almost any type of automotive or marine 2G carburetor.
We have a new website dedicated to our Rochester carburetor Parts, Its called:It features a secure online webstore that can accept orders 24/7. |
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